Laying artificial grass on decking: A step-by-step guide

Wooden decking went through a period of intense popularity, thanks in part to television gardening programmes. But those programmes didn’t necessarily let on that decking needs a great deal of maintenance. Some gardens were also over-decked, creating a somewhat bland look.

If it’s time to bring your decked garden back to life and eliminate all that hard maintenance work, and you have your sights set on artificial grass, the good news is that you can lay fake grass straight over the top of decking. In fact, decking provides the ideal flat surface on which to fit an artificial lawn.

There’s no need to rip out the decking and do all the groundwork. Providing the wood is in good condition, you’re ready to go. Here are the instructions you need to fit artificial grass on decking.

Materials checklist:

  • Your chosen artificial grass
  • 20mm shock pad underlay
  • Artificial grass glue
  • 40mm x 2.5mm carpet tacks (optional)
  • Jointing tape (if joints are required)
  • Kiln-dried sand (for your fake grass infill – around 4-5Kg per square metre)

Tools checklist:

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

Before you start:

Start with a clean, robust surface

You’ll need to start out with a nice clear surface that is completely free from dirt, moss and debris. Thoroughly clean the decking with a scrubbing brush.

Any broken or rotten areas will need to be replaced before laying the fake grass over the top, otherwise the base will fail.

If the decking hasn’t recently been treated, then this really is a necessary step ahead of fitting the synthetic grass so that the base lasts.

Safety first

Remember, as you’re using adhesive, you’ll need sufficient ventilation.

Your step by step guide to installing fake grass on wooden decking

Important: your deck needs to be completely dry before you start. Don’t attempt to lay fake grass on a wooden deck that’s wet, or if rain is forecast.

Step 1: Fit shock pad underlay

Underlay is vital for a decked base so that the slats are covered.

Start at one end of the decked area and push the underlay up to the edge. Then roll it out towards you and cut to the required shape. Continue until the whole area is covered. 

Top tip: Underlay rolls tend to naturally back during laying. To prevent this, place a heavy object on each end.

Underlay pieces need to be joined together. This is best done using jointing tape which is applied to the reverse of the shock pad. Aim to create a single sheet before you start gluing or tacking it.

You can either tack your fake grass underlay down to the decking around the edges, or use a combination of glue and tacks. Some installers prefer tacks only as they say that if the homeowner wishes to remove the fake grass in the future, it won’t tear the decking up as glue would.

If you’re using glue, fold your underlay back from the edges. Use a spatula or filling knife to apply a generous covering of glue around 2-3mm thick around the edges of the deck. You will have about half an hour before the glue goes off, less if it’s a hot day, so work cautiously but quickly.

Once the glue is applied to the deck, you can roll back your underlay and firm down around the edges.

Step 2: Fit the fake grass

Roll your fake grass out onto the deck. Allow 5cm extra around all the edges so you have room to cut a nice clean edge.

Once it’s rolled out, leave the fake turf to settle for at least 2-3 hours before cutting it to size. This will help get rid of any creases.

Top tip: Flip the fake grass over and run your knife long the stitch lines so that you don’t cut through the stitches.

If you have a large decked area to cover, you may need to join pieces of fake turf together. Never attempt to glue individual pieces of grass directly to the underlay because they will just move independently when walked on, resulting in the joints becoming visible.

How to join fake grass

Always check that the pile of each piece of fake grass runs in the same direction.

Set the two pieces beside each other, pile upwards. Align the edges.

Fold the outer edges of both pieces back on themselves about 25cm to reveal the back of the grass and stitch lines. Now trim back two or three stitch lines down each edge. Flip the two sections over to see how they look on the pile side, before sticking the jointing tape to the underside. Apply pressure along the seam so that the adhesive sticks all the way along.

Now you have a whole sheet of fake turf, you are ready to stick it to the underlay with artificial grass glue. Fold back the turf sheet at the edges, being aware of keeping the taped joints intact. Apply a layer of glue on top of the underlay around the entire perimeter.

It’s crucial to ensure the artificial grass and underlay bond fully, so leave it to settle for at least two hours.

Step 3: Infill and brush your fake lawn

It’s good practice to infill the fake lawn with kiln dried sand. It helps to secure the turf and eliminate ripples, as well as protecting the fibres and keeping them upright.

Sprinkle the sand over the fake grass, then give it a good brush in the direction of the pile to lift the fibres.

Following fitting:

  • Brushing the lawn regularly with a stiff broom or plastic rake will keep the fibres upright. You can use the same tools to get rid of leaves and debris.
  • Any spillages can be flushed away with water.
  • When placing garden furniture or play equipment on the synthetic lawn, be sure to spread the load so as to keep indentations to a minimum.
  • Keep barbeques and other hot objects away from the fake lawn.