Laying fake grass on slabs:
A step-by-step guide

Replacing tired, ageing slabs with premium quality fake grass can transform the look of a garden in quite a spectacular way. The great news is that you don’t have to take up those old slabs before you start, because it is possible to lay artificial grass over slabs, as well as concrete and tarmac.

Looking to lay fake grass on a slabbed area such as a patio, balcony or roof terrace? Then these are the instructions you’re going to need. Be sure to read the guide thoroughly and gather the materials and tools you need before you get started.

Materials checklist:

  • Your chosen artificial grass
  • 20mm shock pad underlay
  • Artificial grass glue
  • Jointing tape (if joints are required)
  • Kiln-dried sand (for your fake grass infill – around 4-5Kg per square metre)

You may also need:

  • Sand (to fill any uneven areas)
  • 10mm shingle (to fill any drainage holes)
  • Quick-drying cement (to fill any large gaps between slabs)

Tools checklist:

  • Stiff broom
  • Spirit level
  • Tape measure or straight edge
  • Sharp knife and spare blades
  • Spatula or filling knife (to spread the glue)
  • Garden hose (to check drainage)
  • Drill with 16mm bit (to create drainage holes should drainage be an issue)

Before you start:

Start with a clear, even surface

Before you start to lay fake grass on slabs, make certain you have a surface that’s smooth, clear and free from the likes of stones, grit and leaves.

Treat any moss or weeds that are growing up between the slabs with strong weedkiller and remove them.

Use a spirit level to check that your surface is perfectly flat. If there are any uneven areas, spreading a thin layer of sand or other self-levelling compound will help to fill them in. Always do this on a dry day.

If there are gaps larger than 25mm between each slab, this may lead to sagging once the fake grass is laid. The solution is to fill them with quick drying cement. Be absolutely certain that the cement is dry before you start the installation process.

Check drainage

Be sure that the area to be laid benefits from adequate drainage. You can test this by hosing it down and observing whether puddles form. If they do, then you’ll need to drill some drainage holes wherever the puddles form.

Use a 16mm bit to drill the holes and then fill them with shingle. This will prevent puddles forming on your newly laid artificial lawn.

Always wait for the surface to dry before starting the installation stage.

Safety first

Because you’ll be using adhesive, ensure you have sufficient ventilation.

Your step by step guide to installing fake grass on slabs

Step 1: Install shock pad underlay

Only start this step once your slabbed paving is thoroughly dry.

Begin at one end of the slabbed area and make sure that the underlay butts right up to the edge. Then roll out the underlay and cut to the required shape. Continue until the entire area is covered. 

Top tip: Because the shock pad underlay comes on a roll, it will naturally try to roll itself back. To prevent this, place a heavy object on each end to hold it in position.

Use your jointing tape to secure all the pieces of underlay together. Once that’s all done, you can start the gluing process.

Fold your underlay back from the edges of the slabbed area. Then, using a spatula or filling knife, apply a generous covering of glue around 2-3mm thick around the edges of the slab base. You will on average get around 30 minutes to work with the glue, so be sure to work swiftly.

Now you can roll back your underlay and firm down around the edges so that they are glued in place.

Step 2: Install artificial grass

Roll out your fake grass onto the area to be covered, allowing 5cm extra around all the edges. This will allow enough material to ensure a perfect edge.

Leaving the grass to settle for 2-3 hours will help remove any creases.

Once you are satisfied that the fake grass is crease-free, you can now start to trim carefully using your sharp knife.

Top tip: Turn the fake grass over and run your knife long the stitch lines. This will avoid cutting through the stitches.

Now you can join the pieces together using your jointing tape so that you have one entire piece of artificial grass. Never attempt to glue each piece of grass directly to the underlay as they will move independently when walked on which will make the joints visible.

How to join artificial grass

The crucial thing when joining pieces of artificial grass is to ensure the pile of each piece is running in the same direction.

Set the two pieces beside each other, pile upwards, then line the edges up.

Fold the edges of both pieces back on themselves about 25cm so you can see the back of the grass and the stitch lines. Now trim back two or three stitch lines down each edge. Now turn the two sections over to see how they look on the right side before you go ahead and join them with the jointing tape. Be sure to get the two pieces butting up nicely, then apply pressure along the seam to ensure the adhesive sticks all the way along.

The last step is to secure the fake turf to the perimeter with artificial grass glue. Fold back the grass at the edges, taking care to keep the joints intact. Now apply a layer of glue on top of the underlay around the entire perimeter. You can copy the method you used for gluing the underlay.

You will need to ensure the artificial grass and underlay bond fully, so do not walk on the installation or place anything on it for at least two hours.

Step 3: Sand and brush your fake grass

The benefit of adding kiln-dried sand to your fake lawn is that it will help to secure the installation, preventing any wrinkles or creases appearing. It will also help protect the fibres and keep them in an upright position so that the lawn stays looking its best.

If you can find weed-free kiln dried sand this will be of advantage as it will naturally inhibit the growth of weeds.

Once the sand has been applied you can then brush the fake grass. Do this in the direction of the pile, and it will lift the fibres nicely.

Following fitting:

  • Regular brushing of your artificial lawn with a stiff broom or plastic rake will keep the fibres nice and even.
  • Remove leaves and debris with a broom, leaf rake or leaf blower.
  • Wash any spillages away with water.
  • When placing garden furniture or children’s play equipment on the lawn, be sure to spread the load to keep indentations to a minimum.
  • Barbeques and other hot objects should be kept away from any artificial lawn.