How to install the groundworks for an artificial grass lawn

Installing groundworks artificial grass lawn

Professionally installed artificial grass groundworks

Having chosen a high quality artificial grass I will now walk you through how we install the groundworks for an artificial grass lawn

You have chosen the ideal artificial grass for your requirements. I will now explain how we install a perfectly level artificial grass lawn that drains well and is free from weeds. Our tried and tested installation method gives our customers a long lasting, great looking artificial grass lawn.

 

We assess the area and your requirements

We take a look at the area where you want to install the artificial grass and ask these questions:

What is the current drainage like?

If there is a boggy area which is prone to puddles then the irrigation will need to be improved. One way we do this is to dig a pit 2 to 3m² and fill it with rubble. These pits are often called soakaways and are fine for lawns with minor drainage problems. If the area has a major drainage issue a drainage expert will need to be brought in and install something like a large sunken tank.

Is there a severe slope in the garden that needs flattening out?

If this is the case I will position some 4″x 2″ Timbers (set in concrete) at the top of the slope which I will later fix the artificial grass to. This is done to prevent the grass from moving. Alternatively we add a small retaining edge i.e. railway sleepers so it can be slightly raised at one end to reduce the slope. Here I have written an indepth article on how we fit artificial grass on a slope.

Does the garden have a bad weed problem?

If the garden has a weed problem we use a Weedol Weed Killer to reduce the issue. If we do not eliminate the weeds at an early stage, weeds and real grass will eventually grow through the artificial grass. We have found that doing this reduces weeds by approximately 90%.

How much Type 1 aggregate will I need for the job?

As a rule of thumb the way I calculate how much Type 1 Aggregate I need: 7sqm = 1 tonne at 2 inches. If the lawn has particularly poor drainage I will double the depth of aggregate.

How much Granite dust will I need for the job?

To calculate how much Granite Dust I need: 14sqm = 1 tonne at 1 inch.

How much timber will I require for the perimeter of the artificial grass lawn?

I simply measure the distance around the perimeter with a measuring tape.

Clear the ground

Clear the ground

To have nice clean, smooth foundations on which to lay your artificial grass I remove the turf, soil, vegetation and any large rocks or stones until I reach the natural sub base. This will generally require between 3-4 inches of excavation depending on the location. You will know when you have reached your substrate as the ground will be firm when you stand on it. We use a specialised turf lifter piece of machinery to speed this step up. We also use a mini digger / excavator if access allows. I dispose of all the old vegetation and stones etc in a skip. The skip is booked in advance and a suitable location for it is found.

Install a weed membrane

Weed barrier

I don’t want grass and weeds growing through the artificial grass. To prevent this I add a thick Pro Tec Weed Membrane once I have cleared the soil. Note we always put the membrane on the bottom for these 4 main reasons:

  1. It is out of the way so doesn’t ruck up when pulling the grass across it
  2. It acts as a worm barrier to your base materials
  3. It stops the weeds at source
  4. If the lawn owners have dogs it is an absolute must for the weed membrane to be under the aggregate to prevent the urine trapping on the top.

There are other actions I take if the owners have dogs and want to make sure there is no urine odour issues in the summer months.

We take the membrane right to the edge of the lawn and use 40mm x 2.5mm Galvanised Nails to fix it in place.

Install the perimeter fixings

Perimeter fixings

We lay 3″ x 2″ timber fixings around the perimeter of the area. To secure them I dig a trench a little wider than the timber. I then add concrete (a mix of ballast and cement) to the trench and set the timbers in it. I use plenty of concrete to make sure the timber will not move over time and I make sure it sits just below the level we wish the grass to be finished to, depending on the grass depth.

Prepare the sub-base

Add 2 to 4 inches of Mot Type1 aggregate

Type1mot

Just like in the preparation of roads professionally installed artificial grass requires a good sub-base so that the grass remains nice and flat. I start by using a 2-3 inch layer of Mot Type1 aggregate . I will only look to use chippings or Type 2 as an alternative if there is a drainage issue. These alternatives will be considered as there is less dust in the mix.

I then make sure the aggregate is evenly spread and compact it with the Belle Wacker Plate to just below the perimeter timbers.

Add 1 inch of Granite Dust

Granite dust

Next I add up to 1″ of Granite Dust which I rake across the surface of the Type 1 and then compact several times with a Wacker Plate. The more times you Wacker the Granite Dust the less chance there will be of sinkage in the lawn as the air gaps in the dust can potentially fill with water. Granite dust is a great product to use as it binds together beautifully when slightly damp. It then goes rock hard once dry but still allows water through. (We don’t use sharp sand as it doesn’t bond as well). We make sure enough granite dust is around the perimeter to make sure the edges don’t sink.

A quick self-promotion: I was the first person in the UK to use granite dust.

Screed the area

screeding

I now get down on my hands and knees and with a piece of Timber Screed (3′ x 2″ timber cut to approx 1.5m) the whole area to make it as smooth as possible. If the Granno is dry I periodically spray it with water to reduce dust. I work around the edge so the base is completely level with the timbers and drag the granite dust back making sure it is left in a nice hard but smooth shape. I generally go in semi circular motions. The reason I screed is because the artificial grass will mirror what is beneath it i.e. if you have lumpy groundworks your artificial lawn will be the same.

Here are a list of tools I use to prepare our groundworks (and links to where you can find my recommended products):

Hopefully by reading how I install the groundworks for an artificial lawn you will see our attention to detail at this very important stage of laying artificial grass. I can’t stress enough the better the groundworks the better your artificial grass lawn will look.

In my next Blog post I will show you how we professionally fit the artificial grass on to the prepared groundworks.

Have further questions on how we install artificial grass please leave your comment below. Please make sure you have read other readers questions and my answers first as your question may have already been answered. You will also find some really useful information in the comments and answers below.

For a no obligation quote please complete this:Request Free Quotation or fill out this form for your free sample

286 Comments

  1. Hi Gavin
    I have laid type 1 as a base course then put stone dust on top, I have loose laid my artificial grass to let settle and notice it seems to be wet underfoot (after slight rainfall)
    would I need to put a layer of sharp sand/drainage layer in? or have you experienced this in the past

    • The grass will be wet as it takes time to drain , also new grass has quite bad surface tension which grips on to the water . As long as the base is firm and not waterlogged it will be fine. A little trick to remove the surface tension, brush in warm soapy water. regards

  2. The link to your granite dust goes to the b&q website there granite dust in there picture doesn’t look anywhere near as fine as the stuff in your pictures is this the correct product ?

    • Hi there, the product linked is 0-6 mm which is absolutely fine. We have fitted on 10 mm chippings before. The variation in stone sizes with the really fine dust all helps the product to bind together, which is what makes it ideal for this final layer. Regards

      • Thanks for the reply Gavin. One other question I have, I read on another site that Mot type 1 offers a greater level of compaction so will give a higher strength base but the downside is that water filters through very slowly, where as 10mm limestone chippings are a better alternative for drainage than Mot type 1 but doesn’t compact so well would you agree with this? Many thanks Nic

        • Hi there, this is very true. We would only use a cleaner larger stone if there were drainage issue (the less fines there are in the aggregates the more gaps there are between stones to hold water). I have used 10 mm chippings as a top layer before however they do crunch under the grass. Regards

  3. Hi
    if i used granite dust compacted to 25mm thick would that be hard enough to stop my garden furniture
    from indenting the grass.Its a large set which will take a lot of weight also the legs taper down and are quite small
    at the bottom
    thank you

    • Hi there , this will be fine as long it has 75 mm of type one under it . My advice also would be to have coasters under the legs of the chairs and tables this will spread the weight , regards

        • Hi unfortunately I can’t comment as I have never seen this product. The reason granite dust works so well is because it binds together really well creating a firm free draining top surface. There is a link on the website where you can order directly in bulk bags. Regards

  4. Hi Gavin. Thank you so much for taking the time to write such an informative guide and also answering questions. We have dug out the installation area, however we had to take out a good 7 inches to find solid ground. I have 4×2″ timbers to fix around the perimeter. How can I do that at the correct height? You have stated that concrete is the best option for securing the timbers, but I’m confused as to how to do that when the ground is a around 3 inches below where the timber needs to sit. Your advice would be very much appreciated. Thank you

    • Hi there, that’s really not an issue. Membrane the area and then introduce 3-4 inches of type one and compact, then you can concrete in your timber fixings before adding more type one.
      Regards

      • Brilliant, thank you. So we just make a trench in the type 1 to set the timbers in? How long do we need to leave the concrete to set before we can wacker in the next level of type 1? I was planning to hire the wacker plate for a day but I suspect I’ll need it longer as the concrete will take time to set? Thank you so much

        • Hi there if you fill the area up so you have 4 inches left and wacka the type one you can simply set the 3/2 on ‘pads’ of concrete gently tapping into place using a club hammer until the are exactly how you want them. You can fill the middle up with type one and wacka but stay away from the setting timbers until the next day. regards

          • Hi Gavin I need your advice again please if you don’t mind. My granite dust arrived today. What I ordered stated dust to 6mm on the product info, and yet what was delivered was dust to 2mm. Will this be ok to use or do I need to have it collected and source it elsewhere? Eagerly awaiting your response…

      • Hi Gavin, thanks for the reply.

        We have a dog so was worried type 1 wouldn’t drain quick enough and have been told grano alone to the depth would we sufficient, is this nonsense?

        Had my suspicions but have seen a few installs on grano alone.

        • Hi there, that is nonsense. The smell actually comes from the grass itself so a simple product like we use to go in the top of the grass is an easy and quick solution. Never skimp on the base 3 inches of type one and 1 inch of granno. Regards

  5. Hi,

    So we are just starting works to do our artificial grass installation. Originally the previous owner appears to have added a layer of sand onto the soil before they put weed membrane.

    We have dug athat as best as we can but have a cleared ground that is mix of sand and soil. Is it ok to continue with Type 1 MOT, on top of this before sharp sand and then weed membrane.

    Thanks

    • Hi there as long as the ground is firm. We always put the membrane on the top for several reasons then use type one 2-3 inches before adding granite dust , which gives a far superior end product . I would also recommend putting in fixings. regards

  6. Hi Gavin,

    I have compacted and screed the Grano to a depth of 25mm 2 days before the grass arrives. We have had 12 hours of torrential rain and puddles are now appearing on top of the Grano. Is this normal due to the amount of rain ? The MOT 1 is compacted underneath at a depth of 75mm

    • Hi there this is very normal and will drain through, don’t forget when the grass is on the grano it drip feeds water rather than being exposed. You can run over again with the Wacka and rescreed when it drys, or simply leave . Regards

  7. Hi

    My garden has a patio, I have taken up a large section of this to replace with an artificial lawn. It seems there is only sharp sand underneath it, no aggregate. I was hoping to put the lawn directly on top of this as I’ve had no issues with drainage or stability of the patio. Do you think this would be acceptable?

    Thanks

    Matt

    • Hi It totally depends what you are looking for i.e. this will dip and sink and have the usual issues around the edges, however it is a quick easy solution. Personally I’d put proper groundworks in and have a lawn that looks good for a long period of time. regards

    • Hi there, thank you for all the information. Really helpful.

      Do you know if whin dust can be used instead of granite dust? It is more readily available in the area we live.

  8. Hi Gavin, many thanks for publishing such an in depth guide. Having come across it while researching artificial grass and seeing how many corners a local installer had cut whilst doing a friends garden, I decided that the only way to get a half decent job done was to attempt it myself. I would be so grateful if you could answer a couple of questions I have.
    We have 2 dogs and pretty poor drainage in the garden so I have removed a good 5-6inches and was planning on going the limestone chippings route as suggested. However there doesn’t seem to be anywhere local to me that does anything other than what seems to be purely decorative chippings. Am I right in thinking that as long as the chippings are angular, then they will compact down well enough with a plate compactor?
    Also going to lay the geotextile underneath the subbase due to the dogs, does this need to be woven or non woven type?

    Many thanks once again

    • Hi there we use woven, however as long as it is permeable i.e. not plastic sheeting its fine to use. Stonewise it will cost an absolute fortune to do it with decorative stone, yes it is angular and will grip but have a good look round. Builders merchants etc to find Type 1 regards

      • Thanks for the reply, Our local builders merchants do the type 1 but I was concerned about it not being permeable, B&Q seem to do the limestone chippings at a good price, going to have a look at them when the lockdowns over.
        Many thanks once again and I hope you and your team have a speedy return to normal.

    • Hi Gavin,

      I was hoping for some help. I am taking up patio stones and laying my base I have the height as I’m raising it all up to match some decking. The problem I have is I’ve just taken a shed down and it’s actually a full concrete base underneath. Am I ok to pack my mot 1 on top of the concrete just for that section of garden?

      Thanks

      • Hi there, yes definitely anything solid is good and if you have the height build it up with type one if you have more than 50 mm to play with above concrete. If you don’t simply use granite dust as the method to raise. I always make sure that the surrounding areas to the base are deeper with type one as the base will hold up more against any movement and you don’t want a defined line appearing as the area around it drops. regards

  9. Really enjoyed reading through your comments Gavin.

    We have a dog, so have gone 20mm limestone chippings, laid to 70mm depth and whackered. I am about to order in grano dust to lay 25mm on top.

    Concerned about crunching…which you make reference to a lot…any way to avoid this?

    Also, I dont know where to get my grano from. I was gonna use B&Q but seen a post above suggesting its not a good product…
    Do you have any known good suppliers?

    • Hi there , the granno will hold the 20 mm chippings in place and reduce/stop the chances of crunching. However this is simply the latex back of the grass against the loose stone , which can be stopped by kiln sanding the grass so it holds it in place. Im sorry I don’t know anywhere nationally for the granite dust we buy ours in 20 t loads . regards

    • Hi, great read about laying artificial grass I’m just at last stage of laying the grano, when whacker for first time to compact it some where near level , then after screening for last time do you whacker it again or just go with that cheers

      • Hi there , once it has been whackered a few times until its pretty solid (lightly spray with water to avoid dust) you can simply screed it off , this is the finished surface . We always go around edges before we screed and stamp in granno so there is no chance of sinking around perimeter. regards

  10. Hi Gavin – amazing site. The effort you put in to answer people’s queries is incredible.

    My girls’ love of football and trampolining has finally destroyed the lawn and I’ve taken the plunge to replace it with artificial grass!

    Can I just run through my plan with you and see if I’ve missed anything?

    My garden is 12m long by 7m wide in a No.8 shape (basically 2 circles ~6m x 7m) with a small block bricked perimeter. No drainage issues.

    1. Remove turf and around 3-4 inches of soil (assuming I find firm base) and level off roughly.

    2. Install weed membrane onto soil using large U pins?

    3. Make a channel and install Edjmate perimeter using clips provided (and fix in place (not fully so can be adjusted later) using 6 inch galvanised nails. I decided to use this rather than 3×2 timber because of the shape of the lawn. Is this a mistake?

    4. Prepare sub-base – Compact MOT Type 1 aggregate using Wacka plate. Do I build this up in layers – and do I spray lightly with a hose from time to time to help compact (without over-wetting)? Leave overnight.

    5. Prepare Granite Dust top – again use compactor and lay in layers using a bit of water spray to reduce dust.

    6. Screed the area using long timber.

    7. Fully fix Edjmate perimeter into groundworks at the right level. I was thinking about adding a dab or two of concrete underneath to secure it in place?

    8. Lay grass out overnight to acclimatise. I’ve got 32mm grass and I was assuming I’d get the backing level with the perimeter paving so the grass slightly protrudes (well 32mm) or would it be better to have it slightly lower so it is completely flush with the surrounding paving?

    9. Install grass. Grass is in one 4m x 25 m roll (my God it was heavy – didn’t think about access! Schoolboy error). Was planning to make one cut on the back and cut it into two 4m x 12.5 metre lengths and then run it with the pile facing the house up the middle of the lawn. It’s just one 12 metre join and trimming around the edges. I saw you said you tried to keep joins smaller than this – but thought it might be simpler than laying the grass the other way round with the pile sideways on? Is this OK? Finally glue underside of the grass to the perimeter.

    10. Brush in kiln-dried sand.

    Grass 1.25 inch (32mm)
    Granite Dust 1 inch
    MOT Type1 2 inch
    Membrane
    Depth of Turf/Soil to remove ~ 4 inches

    What have I missed? Any advice on my questions would be most appreciated.

    Thanks
    Laurie

    • Hi there. Right here we go I don’t know what edjimate is and it seems fiddly and expensive.
      Because the area already has a brick edging why don’t you simply either put a 2 inch x 3 inch concrete fillet around leaving it 20 mm below lip, you can cut to edge and stick to this or alternatively use the 3/2 timbers and cut into smaller bits and concrete in again leaing it 20 mm below lip (this is a great finish).
      Grass wise you should have treated them as seperate areas if they are bricked off. You should have bought 4×7 and 2×7 twice, easier to move and get in place!
      I would only sprinkle type 1 and granno if it is dusty and dry otherwise no need, build up in layers and compact several times. No need to leave overnight if done properly.
      I use a 1 1/2 m bit of timber to screed, work around edges first running off your fixing then screed middle in circular motions.
      Lay your grass out, cut in joins, dont forget to go in 2-3 seam lines, do not stick until happy!
      regards

  11. Hi Gavin, can you use more than 1 inch of granite dust. We’ve put around 4 inches of mot type 1 but the last bags we had, had large stones in and we’ve ended up having to take up the last load because it wasn’t whakering in properly. We’ve got the granite dust and probably got too much of the stuff but wondered can we take the level up by doing another inch or so if the granite dust? We don’t have a drainage problem we just needed to bring the level of the garden up quite a bit. Any advice would be much appreciated. Thanks

  12. Hi,

    Great website very informative.

    Can I just ask, I’m in the middle of excavating my garden, from our garden is enclosed by a brick wall, am I right in thinking I need to put my timber frame an easy niche or so inside the existing brick work and concrete into place? I read on be of the comments you advised someone to have the artificial grass overlap the timber slightly then “bolster” down to form a knuckle like finish; I’m a little confused what you mean apologies is probably something simple!

    My artificial lawn will be laid on top of type 1 within timber frame (one end will butt up to a new patio) am I better off using pins or nails for fixing and would I use the same technique against the patio as I would the wall? I.e. knuckle finish?

    Apologies for the questions, hopefully they make sense and you can help me out!

    Many Thanks

    Wayne

    • Hi there, the idea is the timber fixing goes inside the brick wall, set at the level where the grass is to go.
      You then leave a gap down the back depending on grass thickness in which the grass will be bolstered and fixed at the end.
      regards

  13. Hi

    I’m a bit unsure on what to do when it comes to the grano dust? Do you screed it first. Compact it and then wet it allittle so it goes hard?

    • Hi there it needs compacting several times as you put it down in layers. Once it is nice and firm you may wish to little rake it and then screed it with a board. regards

  14. What would you use to secure the lawn? My grass is laid inside a sleeper frame, galvanized nails or decking screws driven at 45 degree angles?

    Thanks for all your advice as without it I would surely make mistake.

  15. Brillant website and i am just about to install my own 8x4m site. my existing lawn is on a slight slope (front to back) and was wondering if i should level it out completely as it will create a small step one end? Or can i just carry on with installation? Left to right is level.

    Also instead of timber pegs for securing the 3×2 i will be using galvanised timer fixing pegs, these ok to use?
    Would you recommend using sleepers as the edging course or is this a bit overkill? My original idea was to use 3 x 2 as the fixing perimeter and then creating a photo frame around the lawn with either sleepers or wooden fence posts (i know its more cost but seen some pics and it looks nice)

    thanks again

    • Hi the slope is purely down to choice , either run with it or maybe use a retainer like sleepers or simply go with a 4×2 depending on slope and how much you are trying to re-level. We never use pegs of any form as they tend to move, we always concrete the timbers in place.
      Sleepers around the edge can be used ,but you still need to put your fixings inside.
      regards

      • Hi Gavin.
        I’ve prepared my area of approx. 7m x 4m. I’m edging the entire area with sleepers. Can I fix timber battens onto the entire inside edge for securing my grass, or is it enough just to set posts into concrete?
        (How far apart do the posts need to be please? )

        Regards
        Steve

        • Hi , when we put in a row of sleepers we simply concrete our timber inside at the correct height once the sleepers have gone off. This allows for a very nice clean finish. Regards

  16. Hi
    I’ve been reading all the information you have provided which has been very informative indeed. I will be putting artificial grass down in my back garden the next few days.
    I’ve a couple of questions I hope you don’t mind answering. With the 3×2 or 4×2 timbers for the perimeter frame do you concrete these in as well as using wooden pegs or just one or the other. Part of my perimeter will be around a raised decking area so was just wondering if in this area wooden pegs would be best, so I can get nice and close or would use still use concrete?
    Also, I have a wooden perimeter fence with wooden 4×4 post on my side of the garden and then the fence panels fix on the opposite side. If I wanted the artificial grass to go all the way to the fence panel how would you normally deal with this? Would you lay the 3×2 in-between the fence post or still lay the 3×2 up to the fence post and simply fill the small 4inch area between the fence post with aggregate and grano dust?
    Many Thanks

    • Hi there, we always concrete in our timbers and don’t get involved with pegs at all. This enables you to get really exact with the position of the timber. We generally set the timber inside the posts and then run a concrete fillet around the post linking up the timbers, however this depends how much the post protrude. regards

  17. Hi

    I’ve read and re-read your very helpful blogs and all comments over quite a while and have taken the plunge and are fitting our lawn (quite small only 5mx2m). I ordered MOT type 1 and grano dust for the top. The membrane is down and the mot (not yet compacted) and I’m worried that it looks like it has a lot of fine particles and having read and reread that mot isn’t very permeable because of the fine dust wonder whether I should take this up and put 20mm clippings under first? Wonder if you could let me know if I’m panicing for no reason! I don’t want puddles on the lawn!! Thanks!

  18. HI, I have read over the comments and the help you have given people and I wondered if you could give me some advice. We have purchased a 5.6m x 3.5m above ground swimming pool which will contain about 13.5 tones of water.. I wanted to create a base and cover it with artificial grass so during the months the pool is not up we are not left with a big compacted dip in the garden. I was going to dig down and fit some 200 x 100mm timbers around the edge and compact in some type 1 about 40mm and then grano dust on the top again about 40mm. Do you think this will be solid enough to take the weight of the pool or should I look at concrete instead of the compacted grano.
    Thank you for any advice given

    • Hi there, personally I would go deeper. I would look to go down 150 mm, membrane the bottom, timber the edges. I would fill with Type 2 (larger stone) 50-75mm , 50- 75mm Type 1 and no more then 25mm of granno. Regards

      • Thank you so much for the help and advice, I have been looking around at the cost of grano and it seems to be quite location dependent. I am SW london and my builder merchants are saying to use Limstone Scalpings. I can’t seem to find much online to compare the two. Are they a comparable thing. Thank you once again.

  19. Morning Gavin,

    Further to my comment/questions a week ago I am ready to order my sub base now and I am trying to figure out how much 20mm limestone to order which will go below the MOT Type 1 (140mm depth in total to fill). But more to my point I am in two minds as to whether to just use 20mm limestone for the whole base? I don’t want the Type 1 to wash away and degrade over time or have the dust fall through the gaps in the limestone. Limestone is more expensive but if it provides a more stable base and helps drainage I will go that route.

    Then I’d apply a 10-20mm layer of grano dust for the final layer before grass. Do you think i’d get a lot of crunching with 140mm of limestone? compacted in stages of course followed by 40mm grass.

    Thanks bud hopefully you can advise what route I should take!

  20. Hi Gavin,

    Thanks for the tutorials and information. I am on the last section of my garden redesign. This section of the design will have decking around the perimeter. Could you advise how I would install the artificial grass? For example, would I need to install a second perimeter specifically for the artificial grass, or is there some way I could combine the decking frame to be used with the artificial grass?

  21. Hi Gavin,

    Firstly, thanks for all the info!

    Just need a bit of help on a few points, if you wouldn’t mind:
    1/ do I dig the trench deeper than the rest of the base and fill (compact) the bottom of it with Type1 before I lay the wood frame down? also, do I cover the bottom with cement and squish the wood into that? what about the gap on the outside of the frame (between the frame and fence at base level)? do I put some Type1 or granite in there too (leaving enough room to tuck the grass at the end of course)?
    2/ the 3×2 timber – do I lay that down as 2 wide and 3 high?
    3/ is it fine to use self-adhesive joining tape for joins?
    4/ I have a tree that has a couple roots that stretch out a meter or so at ground level. how would you deal with this?

    appreciate you taking the time to read this, and look forward to your advice.

    thanks

    • Hi there , no worries.
      1/ Yes dig a small gully around the edge which you will fill with your concrete mix. The 3×2 timbers will then be knocked into it using a club hammer 3 inches upward if you can (not always achievable) . Ideally you want the timbers no further than 20-40 mm from fence , there is no need to fill this gap as the grass will get bolstered down here (also there will be concrete pushing up into this gap when you set the timbers).

      2/I have never used self adhesive joining tape so can not comment.

      3/ You may need to either knock out the roots , or cut the root so a timber can be laid . Alternatively lay timbers to the root and then start again the other side of the root and then fill the gap with concrete mix.
      cheers

  22. Hi Gavin, great resource thanks.

    I am taking up the soil in my back garden (55sqm) and I am going down a good 150mm due to poor drainage in certain areas. The whole area isn’t bad, just 1 or 2 spots at the bottom of the garden. I am wondering if I separate these 2 areas off into effectively 2 large slightly deeper squares and add 20mm limestone into them, would that be OK? rather than fill all of the 55sqm with 20mm. i would then cover the whole 55sqm in type 1 and compact before the grano. It means the type 1 would be sitting next to the 20mm in some areas as well as on top. Hopefully you see what I mean. Cheers

    • Hi there , what you are doing is textbook ! Dig the bad areas down lower and add larger stones , maybe even some smashed up hardcore (this creates larger gaps to hold the water as is works its way through into the sub soil). Great work

      • Wow thanks so much! I have spent months researching. I almost threw in the towel with how much hard work it is but with determination and comments like yours it gives me the push I need to get it finished. As you know, the sweat and back ache now will reflect in the finished product. Cheers for the reply!

        • Gavin what are your thoughts on self adhesive joining tape appose to the adhesive in a tube? I have not decided how I am going to join my grass yet. I have seen pro’s and con’s for both methods.

          • Hi there, I will be very honest and say I have never come across the self sticking tape.
            I have always used the same methods and products, as I find they have served me so well over the years getting the finish I require every time.
            If I ever do add another variant of the same product ie from a new manufacturer, I always give it rigorous testing before using.
            regards

        • Hi Gavin. Great site for a DIY’er. I am just digging up my lawn and will soon be ordering type 1 and granite dust as you recommend. How do I secure the grass to the ground? I have 2 boys that will play a lot of football on the grass. YouTube etc suggest nailing it but to what? Could you nail it to the timber surround? Thanks
          Mike

          • Hi there, we concrete in timber fixings inside the perimeter line, they are usually 3 x 2. Simply wrap the grass over these and bolster down the rear before nailing into the timber. You can also add weight and improve durability by adding kiln sand and brushing into the grass. Regards

  23. We had a retaining wall built and backfilled. We plan to install grass on top of this. We have found that there is some rubbish, roots and timber in amongst the backfill. Is this likely to cause sinkage in the grass? We plan to compact it first. Thanks

    • Hi there, if it is extremely well compacted and you then put a good 3-4 inches of type 1 on it top of it, it should be ok.
      I would try and take out the timber as this will rot quicker. regards

  24. Hi Gavin, excellent site, inevitably more questions though…..
    Area I’m doing is only 20 sq metres or so & although I’ve improved drainage with trenches, shingle & perforated slotted solid pipe, the soil over the top is still slow to drain so I’m planning to put 75mm sub base of chippings over the weed barrier followed by 25mm of 2-6mm granite dust.
    A few questions for you:
    Can’t seem to find granite chippings at sensible price but can get limestone ones. Are they ok instead of granite chippings? Got choice of 10 or 20mm, guess 20mm better for drainage?
    The granite dust I’m planning to use is B&Q’s and looks alright to me (almost all <6mm, most 2-3) although an earlier questioner had bad experience I believe.
    Thanks in advance & regards Steve

    • Hi there , your make up sounds ok …as long as the base stone is angular a 20 mm or bigger would be fine. The idea being if the dust element is
      removed it allows water to pass through it quicker and there is more holding space for the water. You may wish to enquire about type2 or 3 (less dust larger stones ) however you may struggle due to the small amount you will need.
      Granite dust 0-6mm is fine , don’t let it get wet so keep under wraps until you need it .
      best regards

    • Hello Steve, Wondering if you went with B&q grano dust in the end? I am also looking to buy that bag and would like to know your experience with it. Thanks

  25. Hi after a bit of advice around the substrate as have an area of about 55m2 that is currently a very poor lawn that the dogs have destroyed over the last couple of years.

    I want to put down a base but trying to decide exactly what I need to put down. I was going with removing all the old turf and grading the site as it is slightly sloped then putting the 3″ timbers around the outside and back filling with Type 1 at 50mm and 25mm of scalping dust.

    After reading your blog about installing the base you mention either using the Type 1 or Granite Chippings at 10mm which would also be a benefit as I have dogs. I was a bit unclear after reading this if you meant to use the two together or one in place of the other.

    My question is what am I better to go with, the 50mm of type 1 or a base of granite chippings compacted down with the dust put over the top? If the granite chippings, what size should they be and how thick of a layer since it is being installed over an old lawn.

    My other concern is just how much of this stuff I need to move as it seems I will need about 8 tonnes of the Type 1 to back fill that area and then another 2.5-3 tonnes of the dust….. That’s a lot of wheel barrow fulls to get it from the front of the house to the back which is about 25-30m down the drive, through a 1m passage and then down some steps that I will need a ramp built down them.

    Would appreciate your advice on which method would provide the most stable base and best drainage for the dogs using the area and would prefer that it doesn’t stat smelling as all the urine has soaked in and gets trapped in the Type 1.

    The land does seem to drain very well and it never floods or stays very wet.

    Thanks

    • Hi there, I would simply use type 1 50-75 mm and then top of with granite dust 0-5 mm. The chippings are ok but they tend to crunch under foot but are much more freely draining, since you don’t have an issue with that stick to type 1.
      regards

  26. Hi Gavin just reading about timbers round perimeter of garden, I’ve got concrete gravel boards around perimeter so what would be right way for me to do it?
    Many thanks.

  27. hello Gavin

    we are about to undertake the laying of our artificial grass which we allready have, and we are very pleased with the quality. so here is where we need the help, we allready have the sides in place two sides are raised flower beds, one side is a decking step which leads on to a decking area,and the fourth side is the patio edge. we have a concrete path running down the middle which we want to cover with the grass we don’t want a path. on iether side of the path are the two large areas that are covered in gravel these too we want to cover with the grass. we don’t want to break the path up ,my dad put it in back in the early 80s and we know for a fact it is at least 6inches deep, this for us is going to be too much hard work we are both in our early 60s. also we don’t want to remove the gravel its been down now for 20 years and the ground underneath is very firm. so we was wondering could we just wacker the gravel to same height as path, or should we pull some of the gravel over the path, but could this lead to movement uder that particular area and then lead to problems. also because we have gravel can we just use grano dust to top the whole lot of and then wacker down. and can the grano dust go if need be straight on top of the concrete path. i hope this all makes sense my husband can’t use a computor so i have tried to exsplaine as best i can.

    many thanks

    • Hi there , no sorry you can not use the gravel as it is round and will not bind together. You will need to remove as much of the gravel as possible and replace with Type 1. Ideally if you can raise the area above path as you find this will sink off the edges and the path will become noticeable through the grass over time.
      So as much Type 1 as possible and then top it off with granite dust to create the perfect top layer to fit on.
      regards

  28. If my sub-frame is too low (requires more than 2 inches of type 1 and 1 inch of granite dust) to bring it level – can I use decorative stones that I have got at the bottom and then compact the type 1 on top of that to save on having to order loads of type 1?

    • Hi there decorative stone is fine to use underneath the type 1 as long as its angular and not round like gravel , as this moves about as the stones do not lock into each other.
      regards

  29. Hi
    We are about to lay artificial grass. We have cleared and excavated the area, fixed a timber perimeter and laid the weed membrane. In order to keep costs down we were considering putting down the paving slabs within the type 1 – leaving spaces between the slabs for drainage and then filling the gaps with mot type 1 and a layer of type 1 on top, before compacting and adding granite dust on top. Would there be any issues with doing this? It is a family garden with swing and trampoline. Many thanks

    • Hi there is nothing wrong with smashing up some old slabs underneath (make sure they are properly broken up) and then add the type 1 on top, however bare in mind if you are having a large trampoline etc on top you may wish to add more type 1 than usual as this is what gives the solidity to the base.
      regards

  30. Hi Gavin

    I have really bad clay garden the rain water never drains away so i know this needs to be taken away to storm drain etc.
    I have been reading about different drainage materials and wanted your thoughts on swapping out typical mot type 1 base for graded washed gravel for better drainage
    So i was thinking of laying almost a herringbone style pattern of fabric covered perforated pipes in washed 4/20 graded driveway gravel wacked down inside my timber frame at a depth of 6ish inches almost creating a type of massive french drain on top of weed barrier, then finish 1 inch of grano dust or sand whatever is more permeable in your opinion and screed to height of frame ready for the artificial grass

    the perforated pipe underneath the artificial grass area will then go to a silt trap and then to solid pipe to storm drain

    What i don’t wan to happen is that i put down mot type 1 base and water can’t get through it to the perforated pipe and my artificial grass is sitting in a bog of water as the rain water wont drain away – i know above may seem overkill but with the clay soil and being at a bottom of a hill catching everyones water I’m a bit lost as to the correct route to take

    Any advice would be great….many thanks elliot

    • Hi there I would consider looking at a bigger stone and dropping it down more ie 12-18 inches and filling it up with type 2 or 3 . Then when you get higher up , either go type 1 and granno or even consider using just 10 mm granite chips . The gaps lower down will allow storage areas for the water before it can escape and the 10 mm chippings will allow it to be always free-draining. On fitting the grass if you go down the chippings route , always heavily top dress the grass with kiln sand as this will stop any crunching under feet.
      Good luck.

  31. Hi,

    We have followed your guides, thank you very much. We are at the stage of compacting down the granite dust. However we are struggling to get it firm up, we bought the granite dust from B&Q and are worried its not the correct material. While it impacted down ok initially, we run through another time today (in the rain) and it doesnt seem to create a firm base as in the stones are loose. Maybe the rain has washed any dust away from it leaving just loads of stones. But i cant see how it will adhere to one another if there just stones…

    If we walk on it, our foot prints distrub the stones slightly or if we kneel down etc..
    When your guide said the good thing about granite dust is that it firms up alot, thats whats got us wondering if its the correct stuff. This is what we have https://www.diy.com/departments/tarmac-grano-6mm-dust-790kg/165422_BQ.prd

    I presume granite dust is mainly dusty stones (6mm). Any tips to getting the layer to be firmer, maybe adding some kiln sand with it? We have a dog so urine odour is a concern.

    Thanks
    Adrian

    • Hi there that’s not dust you have bought , we use 0-5 mm and it binds together a treat . The 6mm will work and will be extremely free draining but you may need to work on it slightly differently to get the desired effect . Try using an upturned rake on it to get it smooth and be careful walking on it till the grass is laid. Once you have fitted the grass, sand it with kiln sand quite heavily, as this will stop any crunching under foot ,as the weight of the sanded grass holds the stone together. regards

      • Hi Gavin, thanks for taking the time to reply.

        Gutted this is the wrong product when they sell it as grano dust, didn’t think there were different types. We poured in some stone dust for patios (permeable) in the end and its binded it together okay so far as no binding was going on at all after a big rainy day. I may fix the issue next year if the stones don’t hold firm and put some proper granite dust down.

        We do definitely have some crunching at the moment which is very annoying, I have a dog so worried using klin sand heavily will hold onto urine, is there an alternative sand we can use that you know off? or do you know if klin sand is ok with dog urine as one reason we went with granite dust was to prevent urine odours.

        Maybe we can use the sand on top of the granite dust if it’s ok for dog wee.
        Thanks so much

        • Hi there, the kiln sand is fine on top but you may wish to add a dog urine sand to hold on to the ammonia in the urine. The kiln on top weighs the grass down and stops the crunching, so there is no point in putting it underneath.
          cheers

  32. Hi Gavin?

    Just wondering if you can help. My husband and myself are laying astroturf in our back garden. My husband has measured a border within the area of 30mm (the height of astroturf). We have Indian slabs around the outer area. He has put down weed underlay to prevent weeds coming through.He has then made a mix of 6 buckets of granite dust, 1 x cement, 1 x sand and laid it on the area and tapered the section for the sub base. We have a drain in the garden in that section where we are putting the astro turf down and my husband has dropped it so that it is level with the rest of the garden. We have also ordered a 10mm astrocushion underlay to go under the astro turf but i am worried about the drainage with adding cement to the sub base and also we have folds in the astro as its not lying flat. What would you suggest.
    Thank you.

    • Hi there , ok firstly never add cement to your aggregates as you are effectively creating concrete and a non permeable base, which will hold the water. Secondly you do not require any form of cushion if you put in a correct base. I would send them back to the supplier and get your money back and then get the base prepared to our spec on our install page as you will have nothing but issues going forward.
      regards

  33. Hi Gavin,

    We’re looking to install some artificial grass in a 12m2 garden, it has a perimeter of brick around 3 of the 4 sides, it is slabbed on the 4th side. I know you recommend doing a timber perimeter, would this still be the case if the 3 perimeters have got concrete at a depth of 7cm below the surface and there is brick around 3/4 of it (there is a manhole that meets the slabbed side of the perimeter and grass). Is the timber used just to nail into and create a ‘box’ for the materials? Would we still need to timber all of the sides and just find a thinner piece, so 3x3in so it’ll fit on top of the concrete edging? I know companies just hammer in galvanized nails into the grass through the weed membrane and into the granite dust, so not sure which option to choose. I hope that all makes sense. Thanks!

    • Hi there the timber fixings serve a few purposes
      1/ they stop the grass pulling away from the edge over time (nails don’t do this)
      2/ they will prevent worm casts pushing up the edges and causing issues.
      3/ it stops pressure on fence panels caused by compacted aggregates.
      4/If you leave a small gap down the rear it enables a tuck which leave a fantastic knuckle finish.
      regards

  34. Great site.. such a useful resource!
    I have a question regarding underlay.
    I would like to give my artificial turf a bit more bounce, to make it feel nicer underfoot.
    Can I install standard cheap, laminate, underlay to achieve this? or do I need specialist artificial grass underlay?

    Fyi, I will be installing on top of granite dust.
    Thanks Rob

    • Hi no definitely not you need a specific free draining under lay . I use a product called x matting which is available online , alternatively you can use shockpadding , however Im not a fan as this for under climbing frames but is commonly misused to make money out of people. regards

      • Hi Gavin,

        I’d like to install artificial grass for under a climbing frame. Would you recommend using the x matting on top of the granite layer or is it possible to use a combination… I’m thinking that there are 2 likely fall points from my frame around the ladders… but i’m not sure how I would use the matting in some areas surrounded by the granite.

        I also need to anchor the frame, at what point would you drive the anchors in?

        Thanks for your help

        • Hi there, on this occasion x matting is not sufficient, you should use 25mm shock padding. This is exactly what it has been designed for, critical falls.

          I usually dig out a little deeper 4-5 inches, membrane, Type 1 within our timber fixings, concrete in any anchors needed before fitting the shock padding.

          I would suggest doing the whole area under the climbing frame, we usually keep these in place using concrete around the perimeter before adding the granno as usual up to the edge of the padding.
          regards

    • Hi Gavin

      My existing ground conditions were pretty good and also dry when I dug down so i laid my weed membrane and sharp sand on top and whacker plated down. I am just waiting for the grass to come so I can install that over the sand however I am now worried that the grass might move with the sand. Would it be worth putting some cement on top of the sharp sand to bind it together to give it some extra strength? I was advised by the grass company that it is fine to just lay on top of sharp sand but I am just looking for a second opinion

      • Hi , sorry this is a very lazy method of install and how we were fitting 15 years ago . The companies are only interested in selling their product as quickly as possible. What you have to remember it has been very dry and warm and all gardens are rock hard , however you need to imagine what that garden will be like after 4 weeks rain .
        We would never recommend this method as the grass appearance will deteriorate very quickly as the base moves. My honest opinion , dig it up and start again , a type 1 sub base on top of your membrane , topped off with granite dust . If you really want to do it correctly concrete in timber fixings.
        regards

  35. Hi Gavin,

    Thanks for the indepth guides. We are following them and have installed a weed membrane but we have found that water seems to pool on the membrane. Lifting it up, the ground is barely wet but then by lifting it slightly it seems to drain.

    Not sure if it was our installation that done this, it was slack on the floor. its like the floor was plugging it, if its over a bucket, it drains quite quickly.

    After some research it seems we need a geotextile non woven type, is this correct?

    Cheers, Samantha

    • Hi Gavin, Thank heavens for your website! If the counties you cover included our address we would definitely have used your services. I am so concerned with the ‘finished’ sub-base my local installer has completed. I relayed my wishes and passed all of your instructions for preparation and laying grass to our installer who at every stage sees fit to ignore them (we have two lively dogs and asked for mot and granite dust as a sub-base and had to stop them from using the sharp sand that appeared on our drive!) That sorted, and granite dust ordered, they used Mot and whacked it and then applied the granite dust. (There are other concerns and issues I have with edgings they have done as they have gone their own way with it but for the sake of this being urgent I won’t cover them here right now.) Today they laid the grass out in their widths and the first width they installed glued and pinned to edge. The other two widths are laid freely waiting to be fitted. Here is my concern. When I walked on the fitted grass I could feel that the ground was uneven in parts and has gravelly lumps. I then pulled back the other widths waiting to be laid and discovered that the granite dust was, in the great majority of the base still loose and uneven to the extent you can dig your hands in. The binding process has not been done in my opinion. I called the installer who came over tonight and said that it ‘had been done to the book’ and there was nothing wrong with it all being loose. He went on to say that the grass would bed in with the granite and be flat. He wants to come back and install the remaining two pieces without any further process. Could you tell me if I should let him continue or what I should do next. I will be so grateful for your input. I shall send a video of what I describe to your email.

      • Hi there I have watched your video a few times , the base looks pretty good. I don’t understand the hard areas but as long as they are at the same levels of the rest and the granite is wackered down and wont move I don’t see this as a major issue. The granno does bind together but remember it needs to be free draining so if it was solid all over like concrete the water wouldn’t be able to get through . If its uneven it needs to be pulled back recompacted and then re screeded -better to do it now than leave it till grass is fitted then nothing can be done. regards

  36. Hello!
    I have just bought some artificial grass and weed membrane.
    My garden is currently stones. (about 2-4cm size stones) and has been like this for 10 yrs.
    Under the stones is a weed membrane which has done a pretty good job. I’ve ripped some of the membrane to see under it and it looks like just soil – no sub base.
    It’s all pretty flat overall. I have a dog btw.
    So I was thinking of raking the stones to one side (for some sort of side border), laying new membrane, then granite sand then the grass? Or granite sand then membrane?
    OR leaving the stones there, put down granite sand to fill in the gaps, then membrane, then the grass? In amongst the stones are 10 years worth of leaf dust and sow sticks which I’ll try to pull out.
    I can’t afford to get all the stones removed. And I can’t be bothered to dig and start from scratch.
    What do you think I can get away with ?
    Thank you!

  37. Fantastic, helpful site. Thanks Gavin.
    Laying lawn in my Mum’s backyard, 4.6m x 4m. Old patio concrete slabs are there at present.
    Also need to work round the drain from the kitchen.
    So… timber round the edges (and the drain?) then 2 jumbo bags of MOT type 1 and 2 jumbo bags of granite dust. That gonna do it?
    Many thanks
    Jon

    • Hi I would have a good look under the slabs prior to ordering any aggregates as it may be a rock solid mortar base and this simply would be used as the sub-base.
      Always put a timber fixing around and around the drain , then you can use granite dust to level off.
      regards

    • Hi Gavin. I am just in the process of laying the membrane and have put the mot aggregate on top .l am going to whack it in at the weekend. When I have done that does the granite dust have to be done as well . Will I need to put sand on top of the granite. If so what type .thanks

      • Hi no the granite dust is better replacement for the sand and it can played around with when compacted to create a free draining rock hard smooth top layer to fit the grass on.
        regards

  38. Hi I am struggling to level out my type 1 sub base – any tips?
    does it need to be 100% flat – will the sand/granite dust help level it out (but this will be different depths after screening and compacting)

  39. Hi,

    Fantastic blog, much more concise than I have found many others.
    I have a funny site, it is brownfield (former factory) with decorative stone/pebbles over a weed membrane. We have removed the majority of the stones but ground beneath seem similar but mixed with soil but quite uneven due to old tree roots etc, however it is very firm.

    Would you advise excavating everything in the hope there is a natural substrate? Or use the existing firm ground as your base and add the aggregate to level it out?

    Also we have excavated significantly so it is already 6 inches below the level we would ideally like the grass. As you advise using 2×3 batons within a concrete base how do you advise getting them up to the required level. Do you build upto the level using aggregate then dig a trench into that when you are 3 inches off the desired level?

    Thanks In Advance

    • Hi if you are already 6 inches below level and the ground is solid it will be fine to start filling up with type 1 on top of the membrane.
      When halfway up simply compact and then concrete in your 3 x 2 timbers , then continue to fill.
      regards

  40. Hello there Looking for a bit of advice if possible? I am laying some artificial grass in a small back garden 20m2.

    I have ordered Hardcore Crusher Run aggregate. Is this correct? The place I’ve ordered it from don’t do Aggregate type 1.

    When do I put the membrane down? Does it go between the granite dust and grass?

    Finally, can I bring the grass right up to the garage wall or will I have to put timber edging down along the wall first?

    Many thanks!

    • Hi there this will be recycled concrete , its ok but sometimes is a bit dusty where as the type 1 is a mixture of stones to dust and binds better , its freely available .
      The membrane always on the bottom below type 1 .
      regards

    • That’s great thanks Gavin. Unfortunately 4tons of the crusher run already arrived yesterday so I’ll have to go with that.

      Can I ask what the reasoning is as to why you put membrane underneath the aggregate rather than directly under the grass, as other websites suggest.

      Also, should I put a timber perimeter against garage wall or can I bring grass directly up to the wall itself?

      Thanks for your advice, it’s greatly appreciated

      • Hi put the timbers all the way round as it will stop the grass from pulling away from the side as the ground moves under the base and also prevent worms pushing the sides up.
        The membrane always goes underneath for many reasons , firstly it stops worms dragging the fines in the aggregates down into the soil causing dipping, secondly it doesn’t trap the urine of dogs thirdly it doesn’t ruck up when dragging the grass across when lining up joins and getting it into position.
        regards

        • Thanks so much for your very informative response, your advice is invaluable and very much appreciated! How much Kiln sand will I need for the top of the grass? It’s 20sqm.

          Thanks again!

          • Hi you could simply use one bag if there is no real issues with puffing or its not needed for weighing down , however the grass will swallow up a lot more than that if needed .
            regards

  41. Hi, thanks for posting such an informative blog. I’ve just started my own DIY artificial lawn project and am at a bit of a cross roads.

    Our lawn was previously covered in a mix of decking and a few inches of concrete. We had this all taken up a year ago leaving just some very firm and fairly rocky soil. Unfortunately I allowed weeds to take hold over the year and it became a jungle! Anyway, I’ve now removed all of the weeds and am again left with the solid/rocky soil.

    I have begun the back breaking task of excavating with a shovel. I’ve done about 4 sqm to a depth of approximately 70mm but the total area is 24 sqm and I’ve been shocked by the amount of space the excavated soil has taken so far. I am now looking in to hiring a skip but have also had the alternative the idea of putting the soil back and building upwards instead of excavating down. Considering the solid nature of the existing ground, would there be any problems with just installing the edging and building upwards to a finished height of about 50mm? Or should this always be built downwards?

    • Hi, ask yourself why dig down and pay for a lot of soil to be removed if it is possible to raise up. The answer will be in the garden and the surrounding areas of the area you want grassed.
      I.e. are there any defining levels, patio, steps etc? Or are there air bricks along the house line?….If none of these are present and defining your finished level then fill it up with type 1 and raise away.
      regards

  42. Great site and some fantastic advice, thanks for taking the time to share your knowledge. If granite dust has been whacked and then screeded level, is it then a good idea to soak it all to bind it together or should it be wetted down and whacked again ?

    • Hi many thanks, we keep our granno under tarps as we don’t want it getting too dry or wet as it turns to slop. I suggest once its raked out, to give it a light dampening with the hose just to keep the dust from annoying the neighbours and it will help it bind if its very dry. Do not over water it as it becomes difficult to screed.
      regards

  43. Hi, I am laying grass onto tarmac which is sound. it has a slope so water naturally runs to the bottom. I have also broken up the tarmac in areas to allow water to drain. I am about to lay grano dust and membrane first to about 1 inch. Is this best or deep enough before I lay the grass?

    • Hi I personally wouldn’t use a membrane as I find this will stop the granno binding with the tarmac and will slide on it. Also you need to consider the perimeter as the granno will get washed through over time causing dipping .Regards

      • Hi,

        There are sleepers around the perimeter housing flower beds plus one wall of the house along one edge.
        Are you saying that the grano dust will wash through the tarmac eventually thus reducing the height or becoming lumpy? Is it worth mixing it with sand for example?

        • Hi hopefully the surrounding wall/sleepers will prevent this happening , adding sand will make no difference . If you can access under it , you can always top up if you do have any issues.
          regards

  44. Hi Gavin,
    I have been reading your blog as I am in the process of laying some artificial grass at home. It being layed over old uneven slabs so I knew I needed to install a wooden perimeter and thought I would level the garden off while I was at it as it is quite small. When discussing the job with a friend who is a brickie he said not to lay sharp sand on my ground for the grass but to use builders sand (wet sand) as it will be better. Being a bit of a diy novice I took his advice and have laid and compacted 4 tonnes of builders sand (which hasn’t brought me to the height I need) and am now wondering have I made a big mistake and my my drainage not work through this.
    I could still do with laying another layer of around 10-15mm to bring the level of the base to where it needs to be so could that maybe save me if I lay granite of limestone dust now?

    • Hi building sand is not a good idea !! If you build the rest up by using granite dust it will bind together and create a solid free-draining surface to fit your product on. regards

  45. Hi Gavin, Thanks for this very helpful website. I’m a little unsure about the quantity of hardcore needed. I have an area of 90m2, and if I used your theory of 1 ton per 7m2 I would need 13 bags. However using the paving expert calculator for hardcore it comes out to be 9tonnes needed. Can you advise?

    • Hi there 1 bulk bag is approximately 0.7 of a tonne, if you go by 1 loose tonne per 10 sqm for your type 1 that’s should work for approx. 3 inches. I always advise under ordering by a tonne and then you can top up as there is nothing worse than to end a job with spare that needs to be moved somewhere!

  46. Hi Gavin. I have one question about using two weed membranes because some recommend to use two membrane. I already wacker plate the sub base of MOT and I am thinking if is ok to put one weed membrane on top of sub base then the granite stone and then one more layer of weed membrane?

    Thanks

    RemuI

    • Hi there this is not a good idea. The membrane goes on the bottom always, unless it’s on a steep slope. This will stop worms dragging the aggregates into the soil. The other reason it goes on the bottom as it allows the aggregates to bind into each other i.e. if you put it inbetween the type 1 and the granno they will not bind together and it will move and slide when you try and screed the to layer. I never put on the top as its a real problem when dragging the grass in to position.
      Regards

    • You state the membrane goes on top of the aggregate and granite at the opening introduction, however your replies all state that you put the membrane down before the aggregate and granite?

  47. hi Gavin i am absolutely flummoxed now i thought a bit of flattening the soil sand then grass on top it seems a lot more complicated now and very expensive i calculated 3 bulk bags of sub base 2 bags of granite dust (which i cant seem to find in East london) 6×4 metre patch of grass and i have to baton around with wood . do you always have to baton around the perimeters ???? but thanks for the knowledge from your self not sure ill be able to do it now but very good information given

  48. Hello again, I have followed your excellent web site and it is all going well so far. I am up up to the stage where I am installing the top layer of granite dust. Can I ask please do you whacker this later down as well? Is the grano ok to use the whacker plate on, would you advise this ? In your directions it says you compact it down and I presume this is as well as screeding the area also.

    And lastly can I just ask when I got the grass – how far in do you advise I should tuck the grass over the 4×2 timbers ? It will sit flush up to my decking on on one side and the patio on the other. I left a 20mm gap like you said for a 32mm pile grass. And how far apart should your nails/screws be when securing the grass to the timbers?

    Kind regards

    • Hi yes please wacka the granite dust so it is extremely compacted before screeding it off to create a smooth surface . Use a bolster chisel to get the grass down the rear of the timbers and then simply use small nails to hold into place and to remove any puffing every 12 inches or so. regards

  49. Hi, fantastic article thank you.
    Looking to put down artificial grass on our slightly sloped garden for the kids to play on. The soil is clay and at the moment doesn’t drain well at all, it’s gets very waterlogged and boggy. Would you consider a land drain along the bottom of the slope? Thanks

    • Hi I would advise digging maybe a 12 inch deep trench along the bottom and filling it up with broken rubble . Make sure you use timber fixings around perimeter that are heavily concreted in at the top to hold the grass in place and then infill with type 1 before preparing the top layer for the grass to be fitted.
      regards

  50. Hi Gavin, great post which I’ve arrived at late in the day. I’ve already prepared my base using several centimetres of type one and a decent layer of sharp sand, which I’ve compacted and screeded. It remains a little bumpy though. Is it worth putting a thin layer of granite dust on top of the sharp sand? If so, how much will I need for 40 square metres? Thanks.

    • Hi there granite dust does mix quite well with sharp sand and helps to bind it . The amount totally depends on the depth you have to play with ie. where it meets a patio etc .If you are not limited by levels why not stick couple of tonnes on top and really get it flat.
      regards

      • Great. Thank you. I wish I’d got here earlier as I was also planning to put the membrane directly under the grass. How about I put the membrane on top of the sharp sand then put a layer of granite dust on top of that prior to laying the grass. Thanks again and good luck to West Ham next season!!

  51. Hi, quick question: I have a small area (16sqm) that i am going to lay artificial grass on. Doesnt have any drainage problems, so would i be ok just removing the turf, packing it down, covering with weed membrane then going straight onto that with sharp sand? If so, how deep a layer of sharp sand (i cant get granite dust local to me)? Thanks

    • Hi , if you are doing this yourselves and are not to concerned about the long term this is absolutely fine. I don’t have an issue with this kind of quick install if you are doing it cheaply on your own for a small area . However it does make me angry when installers install this way charging £1000 s for their services as it isn’t a long term solution.
      regards

      • Hi gavin,
        Thanks for the reply. So if im going sharp sand only, how deep a layer?
        Also, if this method is more of a short term solution, am i going to get 5 or 10 years out of it?
        What is the drawback of me doing it this way?
        Sam

        • Hi the draw back is the grass will not always look its best and if you are spending a lot of money on the grass I would want it looking as good as possible. The grass will last indefinitely but it will simply mirror whats underneath .

  52. Hello, can you please advise me on the concreting in of the perimeter timbers stage. How deep and wide do you dig your trenches ? I am going down 4 inch for the area first (using 3 inch MOT type 1 and 1 inch granite dust on top layer) so when I dig the trenches il be using 4×1 treated timbers. I would like to know what you advise for how much concrete depth the timber should be set on to be sufficient. And how wide the trenches need to be either side of the timbers. Also … to save work/time is it ok to patch the concrete… say do a metre trench then leave a metre and do another metre etc? Or in feet.
    Great web site too.
    Kind regards

    • Hi there , I wouldn’t use 4 x 1 , we use 3 x2 as there is less chance of bending and warping . Simply have a small channel around perimeter and drop the timber in 3 inches up on to 3 or 4 dobs of mix then simply tap into place using a club hammer . If there is a drop away the other side fill the trench with mix so no base can escape.
      cheers

  53. Hi, would sharp sand be better than granite dust if you don’t want the surface to be too hard? The area will mainly be used as a kids play area. Also there are sections of the garden by the fence where the concrete foundations extend outward at ground level, would you recommend covering this with an inch of sand or maybe some shock pads just for the concrete areas to provide a little extra cushioning for those areas?

    • Hi the reason we use granite dust is because we want a solid base , don’t forget the grass gives the cushioning , sharp sand doesn’t bind together and has too much give in so is not suitable as far as we are concerned as over time it will move and dip. Shock pads have to be built into the base and I don’t believe are necessary , simply raise the area and use the fines on the surface layer to cover the concrete.

      • Thanks Gavin. Haven’t been able to source any granite dust from the local quarries. They did have limestone dust though, which to you think would be the better option between limestone dust and sharp sand? Or is there any other alternative to granite dust that is better than these two?
        Regards

        • Hi there I haven’t used limestone dust so cant comment . If you cant get granite dust I would take the type 1 as high as poss (not above level though) and use sharp to screed it off , it may be worth getting some of limestone dust to help bind it.
          regards

      • Hi Gavin, firstly to say you have here an excellent blog, first rate. Glad I found it.
        Similar question of course to some but slightly different.
        I’m wanting to lay good quality artificial grass on a concrete drive in sections to make it blend in with a raised lawn either side. The raised lawn is bounded by oak sleepers which already sit on the the edges of the drive giving the artifcal grass one sold edge.
        For the other edge I’m planning on using aluminium profiles usual used with resin bound drives screwed into the concrete. The profile rec’d for driveways is 18mm in depth. The profiles have some flex so can be bent into piano lid type shapes etc.
        So my question is I’m assuming that I can’t use type 1 aggregate as no useable depth and have a solid concrete base anyway. So I should just apply granite dust or equivalent (not shape sand) in the shaped areas between the oak sleepers and profiles for the grass to sit on? The area is not large, max 3 to 4 shapes of around total 10-15 sq m.

        I guess I could lay the grass with appropriate AG adhesives straight onto the concrete as the grass gives enough cushioning going across from one oak sleepers edge to the other, but then I could not use the aluminium profiles for the other shaped edged areas as would be exposed.
        So is it ok to use the Granite dust alone as the base, with the concrete underneath?
        The rain already drains down to a soak away.
        Many thanks.

        • Hi there effectively you wish to use the existing concrete with the natural surroundings . I would advise dropping the grass area down 4 inches and then membrane , put in your fixings and fill up with type 1 , then top with granite dust. The reason this should be done is they will move and drop off over time if you do not put in something as substantial as the concrete running along side it . You can stick the grass to the concrete but can also add granite dust on top of these and grade it into the new raised groundworks , as long as you leave a clean strip where you wish to stick.
          regards

  54. Hi, great article. Very clear instructions. I was wondering if you had any advice for me… the area we plan to lay the grass over is a mixture of concrete and previous lawn area. I’m a little nervous about how high to take the type 1 in relation to the concrete slabs to allow a layer of sand to level out the whole area. Also is this the way you would do it!? We cannot take some of the concrete up as it goes under the fence to the neighbors property. Do I need anything on the concrete against the fence? Hope this question made sense!! Thank you

    • Hi there many thanks. When working a solid area , that will never move and a soft area which will move over time I always like to dig out a little bit more , say4-5 inches this will reduce the risk of this area dropping over time.
      If the slabs are not in good condition these can be lifted and if there is a good hard mortar base underneath you can use this as your sub base , if they are pretty flat you can maybe lightly cover a layer of granite dust (or sand if you cant get this) over the whole area till level. The concrete under fence totally depends on the level of this , if you have to raise the area , so be it as long as any airbricks or drains are taken into consideration and blocked around. regards

  55. For the timber perimeter should the height be exactly level with the surrounding path?
    I was also considering putting some shock-absorbent material just under the grass, in which case should I have timber perimeter just below this so that when the shock-absorbent material is added it, it will be level with the path?

    • Hi so work on the existing aggregates as suggested in your other post , concrete in your perimeter fixing timbers leaving them slightly shy of the path depending on your grass depth , I generally like to have approx. 15 mm above the line of path so if its a 35 mm grass set the timbers 20mm below the path.
      If you are going to use shock pads , I personally see no point at all unless its a play area with swings and climbing frames as see these as complete waste of time and money . But you can use them rather than your fines top layer bringing them in completely level with your timbers , then lay the grass over them all and fix to timbers.

      • Thanks for the advice,
        Main reason I was considering the shockpads is we have a 3 year old but we probably won’t be putting a swing in so it probably isn’t necessary.

        Just on the gap for the lip, does it need to be a 25 mm gap? Would a tighter gap just wide enough to tuck the grass around be enough or is the reason you want a bigger gap is to make the concrete base of your timber perimeter more secure?

        • Hi the gap totally depends on which grass you are buying , so I would set the timber 25 mm below the lip and approx. 20 mm from side if I was using a thicker grass , this can vary depending on grass depth.
          regards

  56. I have a small back garden which is already covered in a couple inches of small stones/aggregate (it was probably put down 10-15 years ago by previous owners). Anyway there are weeds growing through it and it is a bit muddy. Could I reuse this aggregate after I remove the weeds or will I need clean aggregate? If using the existing aggegate would it be better to put the membrane above the aggregate rather than below as would there be a chance weeds could regrow in the hardcore if its not clean and the membrane is below the aggregate?

    • Hi if they are solid and not round stones like gravel etc I would simply sterilise the area of weeds using a weed killer by spraying on a warm dry day. Once the weeds have died, if required drop the stone down so you have enough to add your fines layer on the surface 25mm will suffice.
      The membrane would have to go on top of this layer, be careful it doesn’t ruck up when laying grass.
      regards

  57. Hi, I am planning on removing my turf and installing a putting green the garden drains well and is firm, the grass supplier recommended I just lay on to sharp sand after reading your comments I’ll use grano dust do you think I need to use type 1 under it ? If so what quantities of each it’s 8 m x 5 m
    Thanks Mike

    • Hi there always use Type 1 it will help it stay true and prevent dipping over the time, as the last thing you want is a putting great with loads of lumps and bumps all over it.
      I would order 4 tonnes if the area is to be dug out 3-4 inches down.
      regards

  58. Hi Gavin, firstly all your replies to comments are so helpful and answered almost all my questions, I have just one, my garden was dugout last year (3/4 inches ish), the problem is its not level, a bit wavy with approx 50mm unlevel differences (mini hills)..

    Could I be lazy and just Type 1 the lot, then level it. Or do I need to level the ground first?

    • Hi there , we use a tiler rotivator which scuffs the surface and quickly enables us to move soil from the higher areas to level.
      Its worth spending 30 mins with a pick axe and scuff the areas down and then rake the soil across.
      Levelling can be done using type 1 but its more the case of having enough underneath to prevent dipping over time.
      regards

  59. I am looking to raise the level of the existing grass lawn and replace with artificial turf. If I were to used crushed builders rubble as a first base would this be suited to an artificial turf thereafter. I recognise I will need a granite type upper layer within the sub base.

    • Hi there , if the grass is fitted correctly this shouldn’t be an issue. We always concrete in fixing timbers and then fit the grass round them making it totally dog proof.
      A lot of companies believe putting in some nails around the edge is sufficient unfortunately this really isn’t a solution and is in fact quite dangerous with dogs as they may still pull it up and expose the nails.
      All I can suggest as a short term solution is to add kiln sand around the perimeter and brush it into the pile , this should add enough weight to hold it in place.
      regards

  60. Hi Gavin, very usefull read i like the idea of leaving a gap between the edge to give a neater finish. I have 2 questions for you 1.I have been advised to put the membrane over the layer of sub base (washed pea gravel) which i was advised as i have a heavy clay soil, the idea being to stop the top layer of sand (which i have not yet purchased thankfully) or as you advise grano dust which i now intend to use from soaking into the gravel and impead the drainiage. 2 how low would you set the timbers against the patio which in my case is plastic decking set on atanalised timber frame which i have concreted in where it will be against the lawn.

    • Hi Andy , everything you have been told is wrong. Pea gravel will improve drainage on clay soils but it will move and is not a good idea for a sub base.
      Simply dig out the area slightly more maybe 4 inches or so.
      Membrane on the bottom always , it gets in the way on the top when you try getting grass in position and also traps dog wee , I like getting it down underneath where it is pinned in by the weight of the aggregates.
      Concrete in your timbers , this should be set depending on your grass depth ie 40 mm product leave say a 25 mm gap and 25 mm shy of the patio lip.
      Then simply fill the area with type 1 leaving just short of top of timbers and compact .Add granite dust to this in layers compacting each time before screeding off with a timber by hand.

      regards

    • Thanks for the quick respose Gavin, i have about 500kg of pea gravel but need more to cover the area 7.5m x 5 so would it be ok to spread the gravel out over the membrane then type 1 then the 6mm grano dust? my concern is water as it is currently puddling on the low spots on the soil/clay it does soak away after 5 or 6 hours of no rain, i just want to get it right. Thanks

      • Hi, why don’t you select a couple of areas that are holding the water and then dig out maybe 2-3 sqm soakaway only needs to be a foot deep.
        Fill it with rubble and then in fill with the pea shingle. You can top with type 1 and compact making sure there is no give. Then membrane the whole area and put down your normal 3 inches of type 1.
        regards

  61. Hi Gavin,

    My garden is approx 100m2 with about 2″ of stone dust already down, Can i lay patio slabs and fake lawn straight on top or do i need something else i am looking to slab around the outside and probably have 2 small lawns in the centre

    • Hi there when you say stone dust do you mean Type1 ?
      Is the area solid ? Does it drain?
      If so I would add a layer of granite dust on top to get it completely smooth and put in timber fixings around the edge before laying your grass.
      The slabs can easily be set on a mortar bed around the edges too.
      regards

  62. Hi
    At the moment my garden has type 1 limestone to a depth of 3 inches can i add granite dust and use wacker plate to lay artifical grass on or will i need to remove the limestone.

  63. You nail the grass at the perimeter into the timber batterns. Do you fold the grass into anything? How often would you nail the perimeter and what length and type of nails would you recommend?

    Ive also read some installers advise putting the mebrane between the MOT and granite dust, what is the reason you and most others put the granite dust on top of MOT?

    Cheers
    Aaron

    • Hi we set the timbers in concrete allowing for a small gap to tuck the grass. We use a nail gun as it makes it easier to pull up if there is ever an issue , but small nails will be ok 3/4 inch.
      We use the membrane on the bottom as it is then out of the way ie if its on top it pulls up and causes an issue when laying grass especially on larger areas.
      Never put it in the middle as the two lots of aggregates will not bind and when you compact and start screeding it will starting moving around.

  64. I’m just wondering if there is a difference (or indeed your opinion on using) limestone dust instead of granite dust as part of this process?

    • Hi there unfortunately I can not comment as I have never used Limestone dust .
      The reason why granite dust is so perfect for the top layer is because it binds so well together when just slightly moist and goes rock hard, however it still lets water pass through it.
      regards

  65. Hi Gavin
    I have been reading your instructions on carrying out the groundworks for installing a putting green. I would like to thank you as it is very informative and answered a lot of questions I had although I would like your opinion on a few issues I have.
    I am planning on placing the putting green on a area 6.5m X 2.5m which used to be a veg patch and the soil is very soft. I am planning on installing sleepers around two edges of the area. The plan is to dig out around the two edges and put in a layer of aggregate to lay the sleepers on. Once level I am going to drive re-bar through two pre-drilled holes, through the aggregate & into the earth below. I realise I will need a whacker plate to compound the soil, then the MOT Type1 and granite dust to prep it. My question is, should I whack the soil down, before I dig down to the depth for the sleepers to be bedded on the aggregate? Also, what sort of depth of aggregate would you recommend to bed the sleepers onto.
    Once the sleepers are positioned I am planning to embed some treated wood in concrete with a small gap to give a nice tuck between wood and sleeper. Again could I ask, should I embed the wood into concrete and then before I do the sub base installation or do the sub base first then whack and screed and then dig out around the edges for the wood to be concreted in. Also will any wood do, as long as it is tanalised?

    Kind regards
    Tony

    • Hi Tony, first of all before doing anything I would dig the soil out including sleeper widths until you hit harder substrate lower down. Unfortunately for you vegetable patches are generally well dug over, well fed soil and generally very deep. You may have to remove anywhere down to 1 – 2 feet before finding something solid to build your base on!
      Once this has been done membrane the area and fill up to your sleeper level with type 1 and then compact. Concrete in your sleepers (if you are only having a single sleeper rebars will not be necessary ). Once these are set, concrete in your treated timbers behind leaving your gap for a tuck (20mm). You can then fill up to just below timber level with type 1, re-compact, then add top layer. My advice for top layer is screed it many times as putting grass shows every small lump and bump.
      Happy digging!

      • Hi Gavin,
        Thanks for your speedy response. So you are saying it will not be good enough to compact the soil as it is at the moment no matter how much compacting is done? Also by substrate, I take it you mean firm compacted subsoil?
        Regards
        Tony

        • Hi the thing about veg patches they are very well dug over each year, so the soil has lots of air in it.
          Anything soft and squidgy needs to be removed as compacting doesn’t make it firm enough to start building up, if not it will simply sink.
          By substrate I mean you will find a layer underneath that hasn’t been dug over and pretty solid, you will know as you will stand on it with out any real movement.
          regards

          • Thanks for the info Gavin. When you say concrete in the sleepers, do you actually mean to set them straight into the wet concrete or let the concrete go off as in to form a plinth to lay the sleeper on?
            Regards

          • Hi once the area is dug out, membrane and Type 1 all over and compacted, mark our where you wish to put your sleepers, chuck down a bed of fairly stiff concrete mix and then proceed to set sleeper by knocking the sleeper into the mix till level etc.
            If you leave it nice and clean at the bottom you wont have any issue when setting your timbers inside it.
            cheers

          • Thanks again Gavin, it sounds like a plan.
            Sorry for asking you to elaborate about what must seem to you to be a pretty straight forward instruction. I just want to get it right and avoid any sinkage.
            Regards
            Tony

          • Hi Gavin, the excavating is going well at the moment, but I was wondering about the weed membrane. I looked at some at the builders merchant and it was called Plantex which was a weed fabric. I didn’t think this is man enough for the job. Would you advise on using a weed fabric or the polythene mesh weed membrane. Which seems much stronger and says it can be used under patios, paths etc?
            Many thanks

          • Hi Gavin, I have also managed to pinch an extra strip of garden about 1M X 4 M so my putting area will have a strip which is non vegetable patch. Should I excavate down to the same depth as the original or will I be able to dig out to a lesser depth. I am concerned that the difference in depths may cause a stress line along the edge of the two levels but you may think that the Type 1 will bond together and hold tight along this area.
            Regards

          • Hi there , it doesn’t all have to be dug out the same as long as you find the harder soli underneath , then simply build up with the type 1 which will all compact up and form solid sub base.
            I wouldn’t be too fussy with the membrane as long as it will let water pass through whilst blocking out the light , don’t forget you are going to put a healthy amount of type 1 on top too plus the latex backing of the grass.
            regards

          • Hi Gavin, I have finally managed to track down some Grano dust. Could you tell me when whacked down, does it go hard, as I have the whacker plate on hire until Monday but the artificial grass is not being delivered until Friday. My concern is that some marks, small holes may develop with walking on it from my dogs etc. If so I will have to extend the hire of whacker plate until Friday.
            Regards
            Tony

          • Gavin,
            On that point I want to give it a final going over with the whacker plate as there are a few areas along the edge that still seem to be loose and a small gouge where a lump of the dust formed on the whacker plate itself. The problem I have is that it has been raining here and the area is wet. Will this cause more lumps to stick to the bottom of the whacker plate as I don’t want to make it worse.
            Regards

          • Hi Gavin,
            forget my last post as I have bitten the bullet and gone ahead and whacked it again. I just made sure that I cleaned the base plate after every run and I am very pleased with the final result, thanks again.
            Regards

        • Hi Gavin, I am finally about ready to fit the putting cups and lay the artificial grass. What height should I set the cups below the surface of the grass. The putting surface I am installing is 14mm in height. Many thanks. Tony

          • Hi mate, concrete them in so the top of the cup is completely flush with your base surface, leaving a nice smooth rim of concrete around the top.
            Lay the grass and cut over the hole and simply cut round the inside of the cup neatly.
            Then run a bead of glue round on the top of the concrete.
            You may need to lightly sand with kiln any lumps and bumps in the grass and brush in.
            I always think a slightly damp sand spreads more evenly.
            best regards

  66. Hi,
    Thanks for the amazing blog.
    I’m installing a putting green in my garden. Does granite dust and Type 1 still drain if its been compacted?
    3m x 5m at a depth of 75mm. Would 1 tonne of each be ok?

    • Hi there on a putting green install it is even more important to get a good solid base under it , as you don’t want it to sink or become water logged.
      Install the product the same groundworks wise as a normal lawn , however spend twice the time screeding the product as the putting surface will show any imperfections.
      The tricky part is sanding the grass properly with dry kiln sand , make sure its well brushed in and evenly dispersed.
      regards

      • Thanks Gavin,
        Im not too sure what is meant by “Screeding”? This is done after the whacker plate and I’m not quite sure on the actual process.
        Is ok to have a few breaks and undulations to make the outting more interesting?

        Thanks

        Paul

          • Hi we have used 6-10 mm before and it does sit down ok , however the dust in the 0-5 mm really helps it to bind together and create a rock solid porous top layer.
            The use of larger stone (6-10mm) will not bind together as well but it is very useful in areas that have drainage issues as it lets the water pass through quicker.
            The only down side is , you don’t have the dust in it to hold it together and therefore you get a slight crunch when the product is laid on top when you walk over it.
            regards

        • Hi there screeding is the process of working over the well compacted top surface with a piece of timber (we use approx. 1 metre of 2/3).
          Simply get down on your hands and knees (knee pads help) and work over the surface scraping it back and forth, leaving a smooth surface taking out any dips or lumps.
          The end product is the screed.
          Undulations are fine but holes, lumps and dips will show up like a sore thumb especially with short tight knit products.
          This is the most important part of the process, the longer you spend the better the end product!!
          regards

          • Thanks Gavin,
            I’ll go with the dust.
            I’m going to use treated 75mm x 75mm fence posts for the border. Not sure if this is an expensive way of doing things or not.

          • So good to get some professional advice, I’m really grateful
            I keep getting told to put a geofabric membrane (white) on top sub base/under the grass. Is this necessary ? It’s more expensive than the usual black ones that are available in most diy stores.
            How do you feel about underlay on a putting green?

          • Hi there personally as long as it blocks out the light and will let the water pass through it, it will be fine.
            I always put the membrane on the bottom with the Type 1 and granite dust on top simply because the aggregates will pin it in place.
            Also the membrane will move and ruck up if it is on the top when you pull the grass into position.
            regards

  67. Hi Gavin,

    Thank you, Great site with lots of helpful information!

    Do you have much experience with laying artificial grass on a raised area? I have a raised area I have half decked and would like to put grass on the other half, I was thinking of doing it myself but having read all of your warnings about drainage and smells I am wondering if that is a good idea. I currently just have joists 50cm apart in the area I would like to grass. Are there any products you would recommend to use on top of joists to create fully draining walkable surface?

    I hope that all made sense, any help would be greatly appreciated.

    David

    • Hi we have put grass on many raised areas and there is no real issues.
      I would be careful if you do have a dog as it will consider this his lawn area and then you will have an issue as the urine will not drain away and become trapped.
      I would simply deck the area you want done with marine ply, I would even consider covering this in protective oil/varnish to prolong its life.
      You can drill lots of holes in this for drainage, then simply fit your grass by tacking around the perimeter.
      regards

  68. Hi, I have just been laying our new namgrass Elise artificial lawn but there are a lot of rucks in the sheet that don’t want to go.
    The base has been prepared well with weed membrane, then type 1 and topped off with about 35mm of grit sand that has been whackerd and screeded to be flat (it is solid and flat). Is this normal or do I need to try to use something like a carpet stretcher to get shut of them? I’ve fixed one end of the sheet to the plastic board edging temporarily but I don’t want to do something that might be wrong. Also I’ve read on some sites that kiln dried sand can be used, do you think that might weight it down to lose the rucks, what do you suggest? It;’s almost like the sheet has stretched in places but not in others.
    Thanks in anticipation of your reply
    Martin

    • Hi we sometimes get some light puffing in the grass it can be caused by the grass being squashed into a tight bordered area , too much glue on backing or the rolls being too tightly pulled at sides on manufacturing.
      We generally put a few 4 inch nails in the puffing making sure it disappears into pile. Once we have done this we add kiln dried sand to the area which will pin it to the base.
      regards

  69. Hi,

    At the moment I have Gold corn or golden gravel chippings (I think) in my garden and want to lay artificial grass. What would be the best option?

    Would I need to remove the chippings? Or can I just put something straight on top?

    Thanks

    • Hi the most important aspect is are the stones angular and are they binding together.
      I would advise if its a few inches or more deep to remove as much as you can and then build up with type and granite dust .
      Also the other issue you need to consider is the levels as you may need to drop down anyway to have a sufficient base under the area for the grass to come in at your chosen level.
      regards

      • They are decorative stones and dont seem to compact well. If i was to remove the stones id say the depth would be about 4inch from base to the patio which id like the grass to run parallel with.

        So do you think its best to remove decorative stones? (They wont go to waste i can place them in front garden)

        And is 4inch depth enough for the base for grass to be layed on?

        Thanks

          • Sorry to be a pain, the local builders merchants said they had scalpings? not MOT Type 1? And they said they had stone dust not granite dust?

            Is there any difference?

            Thanks

          • Hi scalpings are the tarmac that has been ‘scalped’ from roads. It is not good for gardens as it has tar on it and will kill the plants.
            When it gets warm it will bond together which will cause drainage issues.
            Call around Type 1 mot is readily available.
            Sorry can’t help on the other. I wouldn’t touch it as it may not bond too well.
            regards

          • last question i promise, i have sourced the material, i had an option of grano dust or grano dust 6mm?

          • Hi we use granite dust 0-5mm .
            I would ask the latter is that 0-6mm if so use that as the mixture is sizes helps the bond.
            A few do’s and dont’s ….
            Don’t let the dust get soaking wet and don’t let it get too dry (cover up with a tarp).
            Give it a light sprinkling with a hose if baking hot before you Wacka. This will help it bind.
            Put it down in layers and keep compacting.
            Screed off with a piece of timber.
            Good luck.

  70. Hi
    I’m looking to lay artificial grass onto an existing garage base of concrete construction no drainage.Surrounding this will be slabs that will be approx.70mm higher. What would you recommend to lay the grass on and will I need to drill the concrete to allow drainage.
    Thanks in advance for your advice.
    Kind Regards
    Paul

    • Hi there , due to the height of the slabs you will need to raise the area.
      Firstly drill 15mm cores in the concrete base and fill with pea shingle .
      I would then fill the area with type1 and top it with granite dust .
      Around the edge concrete in 2 x 2 timbers allowing for tucking space.
      regards

  71. Hi, we have quite a large area presently covered in granite chips which we want to replace with artificial grass. The chippings are a good depth, no drainage problems and no pets. Is it OK to put a thick membrane on top of the chippings then the grass. This is for a front garden which gets next to no use. Thank you

    • Hi there we went through a phase of laying on 10 mm granite chips .They are very free draining however we found they crunched a bit under foot.
      Ideally I recommend putting 1/2 – 1 inch of granite 0-5 mm on top and heavily compact this will create a fantastic base.
      I’m not a fan of membrane on top as it always rucks up when pulling the grass into place.
      regards

  72. Hi Gavin,

    I want to replace a gravelled area in my garden with artificial grass. I have removed the gravel and there is already a well compacted sub base and also an old concrete base for a garage that used to be there. The area is bordered by blocks that are set in concrete slightly higher than the existing sub-base.

    I was planning on installing a concrete haunch around the perimeter to give me something to glue down the edges (i cant fit a timber over the existing haunch of the blocks) and then install a weed membrane over the existing sub base and then a 25-35mm layer of sharp sand over this before laying the grass.Does this sound sensible or would you advise differently?

    Thank you in advance.

    • Hi absolutely perfect except avoid sharp sand as it doesn’t bond together that well and will sink.
      Try and source some granite dust ‘granno’ 0-5 mm, which when lightly damped off (if dusty) will compact up extremely well and provide and excellent surface to install on.
      regards

  73. Hi Gavin, I want to replace some decking with artificial grass. At the moment the decking is fixed on top of 3×2 flags. The ground under the flags is clay with very poor drainage. The flags slope slightly and at the moment and the water runs off onto a lower decked area which will remain, and down the drain.Do you think it would be best to keep the flags in place and build the area up with MOT and granite dust to the same level as what the deck was. This will require about 9 inches reducing down to about 6inches. Will the water pass through the MOT or do you think I should lay some land drains? The area is about 5m x 5m.
    Thanks
    Jake

    • Hi there I would lift the flags and then add Type 1 to the area as deeply as you can, this creates more of an area for the water to try and get into the soil, even if it is clay some water will be absorbed.
      regards

  74. Hi gavin,

    Have just laid all the subbase and got the granite dust coming in monday. Is it ok to go to depth of 35-50mm dust. I’ve been told that is ok but don’t go any deeper than the 50mm.
    Really appreciate your help

    Many thanks

    Tony

  75. Hi there just a quick question if you don’t mind I will be using timber batons round my perimeter when I have layed my base up to the level of the timber do I actually nice or screw the edge of the grass to the timbers thanks

    • Hi we use 3″ x 2″ timber and we concrete it in place. The reason we do this is so we can leave a very slight gap down the rear so the grass can be tucked.
      We then nail gun the grass to the timber, however you can use screws or small nails.

  76. Hi
    This has really put my mind d at rest in preparation for artificial grass. I’ve just got one question do you use the whacker on the granite dust or just using the 3×2 timber be sufficient???
    Thanks once again pal

    • Hi the Wacka should be used several times on the granite dust. We put it down in several layers compacting each time.
      Do not let the moisture get in (rain) as it turns to porridge you must squeeze all the air out.
      Use the timber to run over the top in circular motions to get the top surface smooth.

  77. Hi
    We fit our own grass last summer, we were told we didn’t need aggregate as it wasn’t boggy or uneven, so simply put sand down (after pulling the old grass up, digging down, putting the wood frame down etc) we then put the weed membrane on top of that.
    The grass has sunk very slightly in places, but it’s ok. The main issue is we have 2 big dogs and no matter what we do, it just smells of urine. We are going to pull it up and re-do it.. I’ve read from your post to put the membrane at the bottom.. we will get new as I imagine it will have soaked up all the urine.. but do we need to put aggregate down, and do you think we will need to replace the sand? Would it also have soaked up the urine?
    Thank you

    • Hi the answer is a bit of yes and a bit of no.
      So whoever told you that you didn’t need aggregates doesn’t know what they are talking about.
      You should have at least 2-3 inches of solid sub base under it then on top we use granite dust 0-5 mm as sharp sand tends to wash away and doesn’t bind together very well.
      The membrane should always be on the bottom as it will trap the urine flowing into the aggregate base.
      However you will always get a slight smell but this should be in warm summer months and not this time of year .
      I have 3 small dogs and there is no smell in my garden what so ever.
      I have a new product I am testing which is a top dressing sand which removes the smell of dog wee, however I am still waiting for a smell before testing.
      This says to me you need to improve the base and replace the membrane before looking at ways to remove any slight smell.
      Regards

      • Hi, thank you for the response. We will try that 🙂 would be interested to know how you got on with your new product. Unfortunately we are too far away from you to be able to buy any if it does work.
        I hope doing it the proper way will be a big improvement as currently the garden is not enjoyable 🙁

  78. Hello! I simply wish to give an enormous thumbs up for the nice data you have right here on this post. I will likely be coming back again to your blog soon.

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