Foam underlay between decking and artificial grass

4 Jun 2022
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United Kingdom
Hi. I installed artificial grass onto my decking last year and it looks pretty good.

However, I also installed the underlay supplied by the grass company and at the time I thought it an odd product to offer as it is similar to foam carpet underlay, ie spongy and holds water.

Research on the Internet hasn't discounted using such underlay (as similar products are offered by other auppliers). However I'm worried that the underlay will hold excess moisture and quicken the deck rotting process.

Pulling up the grass at the edges reveals that the underlay is almost constantly damp. So I'm wondering if I rip up the grass and remove the underlay before any major damage is done?

Anyone else had experience using the foam style underlay on decking?
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I imagine the underlay will give a softer feel to the grass and to remove it may make it feel like walking on boards underneath, especially if you go bare foot.
If you can carefully lift both the grass and underlay, without damaging them, I would be tempted to install a damp proof membrane on top of the decking and then re-lay the underlay and grass. Hopefully this would protect the decking from being constantly wet and any moisture in the underlay may run out the sides and off the decking or eventually evaporate through the grass. Either way, the decking would be better protected than it is now.
Thanks Conny, I'll look into this. The grass and underlay were only stapled in place, so should be easily removed.

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