How to lay artificial grass on decking

Bland decking
Large area of decking makes the garden look bland

I remember watching those garden DIY programmes many years ago and there was always some decking added to the garden design. People now find that the decking layed all those years ago is starting to look grubby and uninviting.

As well as decking becoming grubby looking some people also have the problem of having too much decking in their back garden as you can see in this recent project we undertook (photo above). This simply makes your garden look too bland. A simple way to bring life back into your garden is to lay artificial grass on it.

The benefit of laying artificial grass directly on to decking is that it will save you money as you already have a flat, firm surface that should drain well if the steps below are followed. The more expensive alternative would be to rip out the decking, prepare the groundwork’s and then install the grass. Not something we believe is necessary as long as your decking is in good condition.

Here I will give you a tried and tested step-by-step guide on how to lay artificial grass on decking:

1. Prepare the decking

  • Remove all garden furniture, plants, toys and anything else that has accumulated on it.
  • Clean the decking with a scrubbing brush and water to remove any excess dirt, moss etc.
  • If any decking is broken or rotten this will need to be replaced.
  • If the decking hasn’t been treated recently we suggest you do this at this stage to maximize its life.

2. Install the underlay

Lay underlay
Good underlay is a must to allow the grass to drain and to stop the decking showing through

If the boards of the decking have large grooves we will use an Artificial Grass Underlay. This will prevent the boards of the decking showing through the grass in the future. We have two options for an underlay.

– Foam Shock Underlay

The 20mm foam shock underlay that we currently use comes in large rolls so we simply roll it out to the edge of the decking and cut. We then allow it to settle for a few hours. Measure your decking first to make sure you order the correct length of underlay. It comes in rolls between 5 metres long and 20 metres. This Foam Shockpad Underlay has been designed to absorb weight placed upon it and is great if you have young children as it will soften any falls. The structure of it allows water to drain through it so there won’t be any puddling.

If you have dogs I wouldn’t suggest using underlay as it can potentially trap the urine and cause an odour.

We use a Paslode Nail Gun to finally secure the underlay to the decking boards.

– Marine Plywood

An alternative to Foam Shockpad underlay is Marine Ply (Plywood). When nailed directly on to the decking it will create a completely flat surface on which the artificial grass can be layed. It will be necessary to drill holes in the Marine Ply so water can drain through it.

3. Lay artificial grass on the decking

Laying artificial grass on decking
Lay the artificial grass on the underlay

To work out how much artificial grass you need take a look at this guide on measuring your garden. Once we have decided how much grass we need we roll out the artificial grass and let it rest for a few hours to flatten out.

We fit the artificial grass just like we would normally apart from one exception. To secure the grass in place we tack it around the edges with 40mm X 2.5mm Nails. We use nails instead of glue purely because if you want to remove the grass glue will tear away the decking along with the grass.

In this example we fitted the Grange grass but any of the grasses from our product range would be suitable to lay on decking but do make your final selection based on how it will be used. If you expect large footfall we recommend a grass with a short pile like the Outfield.

You may find that in the summer months when it is warmer the decking along with the artificial grass may move and a little puffing may occur. Do not worry, if this happens simply add some Kiln Sand to the grass and brush in. This will add some weight and flatten the grass back out.

 

A design tip: In our example above we wanted to give the garden some definition and to create some different areas so we left the bottom area as real grass and the top area as artificial grass.

It has taken me many years of hard work to be able to provide the type of artificial grass installation service we now offer. Because of the enduring attention to detail and the dedication of my team I am in the enviable position of receiving many requests from people all over the world looking for help with their artificial grass installations. Whilst this brings a huge smile to my face we are still only a relatively small family owned and run business with limited resources. We currently offer our services within Kent, South East London, Hertfordshire, Essex and parts of Surrey. Whilst I am happy to answer general questions in the comments section below from anyone it may take up to 1 week for me to get back to you. Please make sure you have read other readers questions and my answers first as your question may have already been asked.

Priority will be given to answering questions from people looking for Perfect Grass to fit and supply our own artificial grass products. Please fill out the quotation form or call us on 020 81664168

For others looking for a priority response to a specific question relating to their own installation a £50 consultation fee is charged. My goal is to respond within 48 hours in these circumstances. For this specific online assistance please email me at info@perfectgrassltd.co.uk with your questions. I often require photographs to accompany your question in order to provide the best answer.

91 Comments

  1. We have laid our grass on marine ply, we drilled holes in it first,we used glue to put it down, but we are finding some areas are taking forever to dry after it’s rained. Could it be the glue as blocked some drain holes, if so could we use a small sharp drill bit and go through the grass into the marine ply for more drainage.

    • Hi there , I personally would not advise drilling holes through the grass as this could lead to further tearing around the holes. However , I dont really see any other method of rectifying. I would have used small nails around the perimeter rather than glue , however the glue should only really be used around the edges allowing the water to pass under the grass and drain. regards

  2. Hi Gavin,

    Very informative Blog. Came across it by accident.
    Thank your for honestly sharing your experience. Keep up the good work.

    BR
    Stewart

  3. Hi gavin,
    I placed underlay under my artificial grass for my decking. But after the rain, although the grass dries off, the underlay holds the water for a long time. I am worried the wood might rot because of this. Is this normal?
    Many thanks in advance

    • Hi there , its sounds like you have used a foam underlay which would absorb water unfortunately and this will speed up the rotting of the timber as it will struggle to get dry .We used to use an underlay called x matting which was like grid so allowed for water to pass through. regards

  4. Hi Gavin,

    I fitted grass to my existing deck (3m x 4m). It is soaking wet after raining and takes forever to dry off. I did not fit an underlay, as the supplier said this would be counterproductive. Can you advise re drainage on grass, and how to maximise it. Its very disappointing now that after raining we take the grass up to dry it.
    Thanks in advance, and great website. Rob

    • Hi there grass should have drainage holes in it so the water passes through (obviously it will still be wet under foot but should dry off quite quickly). However , if the deck boards are tightly pushed together there will be no where for the water to go , if this is the case I would drill holes in the deck . regards

  5. Hi Gavin
    I am looking to lay some artificial grass on top of my decking. However, I need to keep the grass as short as possible (but to look good) and as such, I will also need to keep the the underlay to the thinnest possible. Can you please suggest the best of both for my situation please. Suppliers names of the aforementioned grass and underlay would be very much appreciated. Thank you in advance for your expert advice

    Kind Regards

    Terry

    • Hi there , unfortunately I am not here to promote other companies, or their products . I would simply say there are hundreds of products on the market from very short 10 mm grass upwards , the shortest we sell is a 25 mm which is a fantastic length of grass (the shorter you go below this the more unrealistic it looks). Im still on the fence with regards to underlay as it behaves the same way as the grass and will get pushed into the grooves over time anyway and by simply adding a 5-10 mm layer ,will this actually do the trick? We personally dont sell any underlay any more, your best bet would be to board the area out with marine play and use a short grass with out underlay. regards

  6. Hi, I have a raised deck area for a football pitch for the kids. I was intending to glue it bit reading the above I see nails are a better option. Have you laid artificial grass on moisture resistant flooring before? I was hoping the glue would help waterproof the flooring.

    • Hi there , when we glue we simply use a bead around the edge and not covering the whole area , so this will have no impact on the water proofing. What you will find if you use too much glue it will trap moisture as it wont let the water pass through as well , however the reason we dont use glue on decking is, we found it splits the wood over time due its strength (we also found it much easier to nail in to the deck as it gave a cleaner finish) . Dont forget also, you may one day wish to remove the grass , a nailed area will take five minutes to lift and leave no damage ! regards

  7. Hi Gavin,
    My decking is 6 inches off the floor, what would you recommend I put around the edges so the raw edge of the grass is not on show?

    • Hi you can either take the grass over the edge and neatly nail into the edge of the deck board or you may wish to fix a baton around the edge so there is a lip for the grass to be cut and fixed too. regards

  8. Hi Gavin
    What Size would you recommend for the nails that nail the grass and underlay into the decking be
    Many thanks

  9. Hi Gavin,

    Some great advice on here, but I wondered about my raised decking area (5ft high) which will be used as a seating area. I use the underneath as tool storage, so want to keep it dry. I have laid shed roofing felt to waterproof the deck and contents under it. If I lay artificial grass on top of the felt to improve appearance, would the water affect the grass over time since it cant drain straight through? I’m hoping evaporation will take care of it?
    Any advice much appreciated!

  10. Hello Gavin,
    Thanks so much for all the useful advice posted here. Can I ask about laying artificial grass on an artificial wood deck? The planks look like wood but are synthetic. The deck has open slits as usual between the planks for drainage but I was worried that moisture would not seep away into and through the planks as it would if it were a true wood deck, and collect in the underlay?
    Many thanks.
    Juliette

    • Hi there I have laid on a composite deck before with no problems at all. You can glue to a composite deck rather than nail . The water will pass through and out of the gaps in between the boards , but make sure if you are using an underlay it has adequate drainage (like x matting which is webbed). Regards

  11. We are building a deck 12footLength x16foot wide which is having to be raised around 3foot to get to the level of the bifold doors, we would like artificial grass laid on top but unsure the best way to allow drainage,
    What would you suggest?

    • Hi the grass is free draining so rain water will simply pass through. If you are building the deck especially for the grass you may wish to use marine ply on top with lots of drilled drainage holes as this will provide a smoother finish. regards

      • Hi Gav I will be laying grass on my 5meterx4me I have drilled plenty of holes for drainage do I still need underlay thanks

        • Hi there , the underlay and drainage holes are used for completely different reasons. The underlay is if you require to soften the area for maybe a young child or if the area isn’t smooth and you wish to take out some of the lumps and bumps .regards

    • Hi Gavin .if I am laying artifical grass on top of paving slabs do I need to have a membrane and underlay and artifical grass going in the same direction or do I need to alternate them

  12. Hi,
    I would like to know please what sort of treatment to put on the boards before I lay the artificial grass, is it an oil based one? Also, what size holes and how many for drainage would you recommend? My decking has been down for a number of years and has not had much treatment.
    Regards

    • Hi there, I am sorry I can’t really help you with that one. Most treatments offering protection from moisture but I would presume an oil based one would be more resilient. Another thing you can do if the boards are close together is drill cores in the deck to let water escape.
      regards

  13. With no waterproofing between the wooden deck and the turf what is to prevent moisture from draining through the turf and lingering in the wooded structures and hastening rot?
    Thanks ~ Richard

    • Hi there, the best way is to heavily treat the timber so the water cannot be absorbed. There is no other way of protecting unless you run heavy duty plastic sheeting over it and staple it into timbers allowing gaps in between for water to escape. This is obviously a labour intensive exercise and most customer are content to treat their deck prior to having it done. regards

  14. Hi Gavin
    Great Blog. I’m looking to create a small deck area using pallets as a base, laid on weed fabric membrane with hardcore. If I infill gaps with timber, obviously treat it all with preservative, lay underlay plus artificial grass would that be sufficient or do you think I’d still need deck boards then grass?

    • Hi there I’m really sorry that’s more a carpenters question, rather than artificial grass. I would advise simply using aggregates to create the correct base for grass. regards

  15. Hi Gavin

    We laid artificial grass (10 sq metres) on our decking last year, fixed down with screws around the edge, but it was stolen!!
    We’re now replacing it, but intend to use adhesive this time to prevent this happening again. Do you recommend specialist artificial grass adhesive or something else?

    • Hi there, unfortunately sticking isn’t the option as the glue you need for the grass backing is too strong and will eventually break from the wood.
      I would suggest really heavily sanding it on top with bags of kiln dried sand.
      regards

  16. Hi gavin I have a 4×4 meter decking about 2feet off the floor which I want to cover with artificial grass do I need to sand fill it .also do you have to give it a good sweep straight away

    • Hi the deck needs to be clean and debris free before laying. The grass can be attached by simply nailing into the deck using small nails (with smallish heads).
      The grass can be lightly sanded with kiln and brushed in. regards

  17. Hi Gavin.
    I have Artificial grass laid directly onto my decking, but have recently had problems with some of the decking boards rotting. the rot had actually caused rot on one of the joists as well. I have replaced the rotted decking and repaired the joist and treated the whole deck area with a lignum fungicide treatment. However the firm that supplied the fungicide
    (which is supposed to prevent both wetrot and dryrot have advised that I should relay the artificial grass with a Waterproof DPM sheet between the grass and the decking. This seems rather odd to me as I don’t see where any rainwater could go if I follow this advise. Your comments and advice would me most appreciated. Kind regards. Colin

    • Hi you a spot on there ! Look wood rots we all know that , if its treated it will last longer . The grass does protect the deck against the worst of the weather but water has to make its way to the ground , so in answer to your question do not put this under it as it will cause all sorts of issues on the top .
      regards

  18. Hi, great to find useful information here. We are building a deck around a pool, and are going to put astro turf on the top. As the new is new, we can put any material on the top of the deck, and it seems a bit excessive to run pine slats across and then cover it with the turf. The builder has suggested concrete sheeting as an idea to lay the grass on, but I’m concerned that would get too hot. Yellow tongue could work too, but then there is no holes for the water to drain through.

    What could you recommed as the best option to use as a base on a new deck to lay the turf?

    Thanks in advance!

    • Hi Im sorry your builder will probably know better on this one. Any kind of timber/ply will rot so it out of the question . Composite is ok but will bend in the heat unless really well screwed down. I cant comment on the builders suggestions as I have never used. Don’t forget you can always drill drainage holes through products. regards

  19. Hi Gavin, I’m thinking of putting a small patch of artificial grass over my decking for the dog to use. What would you recommend as being the best way to lay the grass & clean for this use?

    • Hi there I would advise against this , through experience. I have 2 circles of grass and put a third on my deck . I have three dogs and they constantly wee’d on in , the problem is it traps the urine in-between the decking and the latex of the grass and causes odour issues. Unless you have some of the dog wee infill sand I wouldn’t advise this.
      regards

  20. Hi there we have a decking 9×4 metres and have bought artificial grass for this area. The grass is quite thick and seems to have quite a thick backing. Would you advise using nails to install this grass or adhesive? My son will play football on it regularly.

    • Hi there , no simply nail into place around the edges , the glue used to stick artificial grass is so strong it will break the wood off over a few months. You may wish to use a baton along a front lip to fit too.
      You may get some puffing in the grass over time as the timber contracts and expands , simply sand out using kiln sand.
      regards

      • Hi,

        We have found you advise to others extremely useful. We’ve have many of the same issues with our own self build!

        My husband has created a raised timber area which he has covered with outdoor ply. We are going to lay a medium thickness 7mm underlay for comfort under foot. We are not sure whether to treat the ply before the underlay goes down to ensure waterproof. Also we were worried that drilling drainage holes might encourage rot…?

        Any ideas would be greatly appreciate!

        • Hi there , adding another layer of protection would certainly prolong the life of the install , so in a nutshell yes give it a good soaking and get as much as you can into/around the drilled holes, once its properly dry install your product. regards

  21. Hi Gavin

    Great blog. We have installed gabion baskets as a retaining wall. For the top of the basket (something we would need to walk on) we have looked at a number of options from coping stones to sleepers. My dad suggested an idea of 3×2 frame clad with machine ply and then wrapping with artificial grass. This would look great but I am worried about drainage and the ply rotting too quickly. Do you think this would work if we added a slight fall of 5mm over the width of the top which is 600mm?

    • Hi there I personally would simply walk on the gabions as they look amazing . The grass would be ok on a frame and marine ply , but from my experience it rots very quickly even if there is a fall.
      regards

  22. Hi, I have just had artificial grass laid on my decking, it has brown patches this was present when the chap left! How it appears to be spreading,the company tell it is because the sun has been reflecting off my double doors this was the second excuse,they will relay when it gets cooler ah but if it happens again the will not replace. Please help

    Many thanks mo brooks

    • Hi you need to be aware that the grass will burn under extreme temperatures, when the sun is at its hottest in the afternoon and is being reflected by being magnified.
      It can be something very small like a strip of metal on the windows. I believe they have been very fair by offering to relay however I would find the source of the problem before.
      regards

  23. Hi,
    In the process of artificial grass on my decking, had few quotes which are rather expensive! May fit it myself for half the price, what about the edges? Do I put beading around rather than the edge of the grass showing, large area 23ft x 11,
    Thanks,
    Bill

    • Hi there you can either put a beading around the edge or even wrap it over the end of the deck , the main importance is not just how it looks but to avert any trip hazards.
      You can fix the grass using small nails as glue that is required to hold grass will simply break the wood.
      Be aware the deck will move in the warmer months and you may get some light puffing in the grass when this happens , simply sand out with kiln.
      regards

  24. We gave a small area of fake grass laid on decking, the dogs go on it and sometimes it stinks, tried bleaching etc but it still smells. My question is we are about to lay some more elsewhere and don’t want the stink. Is there anything we should do to avoid the smell. Would under lay stop this happening? It’s going on decking again

    • Hi there unfortunately the dogs see it as there grass area to wee on . There are no solutions installation wise , do not use underlay as this will prevent the urine passing through.
      The only thing that can be done is to use a dog urine sand that will hold on to the ammonia in the urine.
      regards

  25. Hi Gavin, I have a large decking area that is starting to rot & ready to collapse in places. Would it be possible to put some sort of wood shirts down on top of the decking drill some drainage holes then put the artifical grass down?
    Thanks Claire x

    • Hi there a lot will depend on the state of the joists underneath , as Id assume they were rotting too if the top is in a bad way. If they are sound you can screw marine ply onto it and drill drainage holes.
      However I am not a fan of this as I don’t believe it lasts very long.
      regards

  26. Hi Gavin.
    I am laying artificial grass on an area of decking and an adjoining one of concrete approx 24 sq meters total. I am edging all round with decking planks and timber planters. I can obviously pin down on the decking. I will be laying underlay as well.
    Question 1 – do I need adhesive for decking as well as concrete?
    Question 2 – I have seen advice suggesting dressing the lawn with kiln dried sand. Do you recommend doing this?

    Thanks
    Alan

    • Hi there no , the glue used for artificial grass is too strong and will break the deck wood off in a short time , simply tack lightly around the edges with 1/2 inch nails.
      You can add kiln to hold into place or in case you get any puffing because the deck moves when it drys out.
      regards

  27. HI Gavin, I am considering a project for a children’s play area. The Grass is on a slope so I want to add a frame and ply-board over the top then artificial grass on top. As this will not have any groves like a decking what would you recommend as for underlay and drainage? Would the underlay and therefore Artificial grass remain wet for some time after rain (like a sponge) or is it fairly free draining? How much of an angle should I add to help drainage as the aim is to make it as flat as possible.
    Thank you
    Mick.

    • Hi there I would not recommend this method at all and have never seen anything like this. I would use our usual groundworks with the concreted in timber fixings as normal except make sure the timber at the top of the hill is maybe 4×2 and very well concreted in to act as a hanging timber to stop grass from moving.
      regards

  28. Hi Gavin just got new grass today, laying on raised decking, no underlay! Was advised to drill small holes for drainage! Is this a good idea?
    Regards M Doyle

    • Hi the water will drain through the gaps in between the deck boards , however if they are too close it is a good idea to drill holes in deck to improve drainage.
      Underlay is not essential however will slow down the grooves appearing overtime in the grass.
      regards

  29. Hey
    We just got some artificial grass and are ready to fit, but we don’t have an underlay as wasn’t told at the shop we needed this step, is it essential.
    Do we need to take the grass up and treat the decking every year like before pls
    Rose

    • Hi there I would treat the deck first . The grass will protect the deck and lifting the grass isn’t really an option. The underlay is not essential but will help hide the gaps between the boards overtime , however underlay will make it slightly spongy, a lot depends on what you are looking to achieve with usage.
      Regards

  30. Hi Gavin,
    Thanks for the blog, I stumbled upon it looking for information and it’s refreshingly honest and helpful.
    My situation is that we now have our Granddaughter living with us, she’s just about to start crawling. There is a patio area at the back of the house 4.5m wide x 2.7m deep. Its laid to 450mm slabs in good condition (just a few slight weeds in the joins between slabs) there is a good fall away from the house to the edge of the patio which then drops about 8″ to the rest of the garden.
    I want to put down artificial grass as a play area, but need some sort of fence to stop her falling off the edge. I thought perhaps picket fencing but was unsure about fixing the posts. I’ve read that artificial grass should have edging, but if I put edging at the edge of the patio then I can foresee drainage problems with the water unable to run off the edge.
    Any advice as to how to deal with the post fixing and drainage?
    ( I’m also considering using 25mm crash pad under the grass as extra protection)

    Thanks,

    Kevin

    • Hi there I can only advise of the grass as that is our profession. If the patio is in good condition and you are happy to lay on in directly simply fit the grass directly to the slabs , you will not need any fixings as the patio is your fixing. Glue around perimeters leaving gaps for water to pass through , making sure there are no trip hazards etc. I’m not a fan of shockpadding , it is designed to go under swings , my advice would be to go for a denser grass.
      regards

  31. Hi Gavin, I have a fibreglass covered wood deck over a 3 Bay garage. Can I install this artificial grass overtop of the fibreglass?

    Thanks, Mike

    • Hi yes is the answer it can be laid on almost anything . However the questions you should be asking is how strong is the fibreglass and what size joists is it fitted on as its all about the weight and the load baring of the area when fitting or for future use.

  32. Hello,
    I see you recommend underlay on the deck for AstroTurf. Would you be kind enough to tell me exactly what kind of underlay? IE is there a specific brand of underlay that you use and should it be at least 10mm or ideally thicker?
    Thanks in advance
    John

    • Hi there , we use a 10 mm matting with drainage crosses in it. It is not a must it depends what you are looking for and the state of the deck. Remember the grass will mirror the deck.
      regards

  33. Hi Gavin cay someone lay artificial grass on the patio without removing the slabs? Please advise. Awaiting your reply thank you.

    • Hi in a word yes. Remember the grass will mirror the patio , so if its uneven and loose it may need lifting .If it is in pretty good condition and is free draining simply fit the grass on top and lightly glue allowing gaps in the glue for the water to escape.
      regards

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