What Type of Foamboard for a Pool Foundation 

**BEWARE** I used the pink colored, one inch, XPS foam board made by Owens Corning under my portable above ground pool which remained set up for four years. A storm caused a tree branch to fall on the pool wall which caused me to remove the pool. I discovered the foam board had been largely/70% destroyed by some kind of burrowing insect that made tunnels throughout the foam. They ate/removed so much of the foam board that the structural integrity of the foam failed. The remaining foam had collapsed and was rotting. The pad site was elevated crushed gravel covered by sand. It was well drained/dry. It was at the highest point of the property. There was no standing water underneath. I think the foam is a good solution IF YOU ARE REMOVING THE POOL ANNUALLY. Otherwise, if your intent is to leave the pool set up, in place for years, I would not choose foam.

Hey I’m actually currently setting up my pool. I’ve laid my foam down. One thing I noticed is if I walk on it the foam starts to crack. If it’s already cracking with my weight…. Wouldn’t it crack with all of the water in the pool from the weight? Does your foam crack?

Not a big deal, but "Styrofoam (R)" is a brand name - like "Coke" or "Kleenex" made by Dupont Dow also nicknamed "Blue Board". ALL Styrofoam is extruded polystyrene (EPS) but not all EPS is Styrofoam. The Pink Stuff by Owens Corning (Pink Panther ad) is also extruded polystyrene. The foam you are calling styrofoam, is actually bead board, which - as you stated, is NOT extruded, and would be horrible as a pool foundation. Dupont Dow Styrofoam can also be purchased with shiplap edges, which make an ideal seam for pool foundations. Unfortunately, the EPS is more costly than the bead board, but vastly superior in quality for this application.

Do you have to replace foam every year? My pool stays up year round

What size and brand pump do you use?

Greetings from Poland! What about Expanded polyethylene foam (EPE)? Is this type of foam suitable for a swimming pool foundation?

I'm using styrofoam (EPS - Expanded Polystyren) under my 13 feet above ground pool. I went with 3 inch/7 cm thick boards, much because I'm located in the northern hemisphere at 60° Latitude in Sweden. The thickness helps me prevent my pool water to cool down from the ground temperature and it's really, really soft and nice to walk on. I've had the foam for 3 years and yes, the surface on the foam is starting to look like the moon with some recesses from walking and jumping feets. It isn't visible when the pool is up and running, but you feel it when you go in the pool. The surface on the foam is still smooth, so there's nothing falling of yet. The visible foam outside the pool is covered and protected with a green, fake grass balcony mat and melts in pretty good with the real grass. The foam I used has the measurement of 47,2x23,6x3 inch / 120x60x7 cm. I used 24 of them for an octagonal shape and in Sweden it had the price of 5,63 USD a piece, 135 USD in total. Worth every penny!