Installing Foam Board as a Pool Bottom

by Elaine

I've seen your pages about using foam board as a pool bottom and love the idea. I ordered an armor shield liner which claimed to be thicker that other pool pads and would be a cushion for the feet. When it came it was paper thin. I was very disappointed and sent it back.

I feel a foam bottom will be easier to keep clean when vacuuming since you don't have the foot print impressions to deal with. Do you have any advice for installation in a 24 foot round above ground pool? I'm replacing my liner and now is the time to do this. I'm concerned that any gaps in the foam will be detrimental to the liner. Thank you in advance for your input. Elaine

Hi Elaine.

Styrofoam does make a nice base for an above ground pool, and I agree about the pool pads, they are all very thin.

I start by laying out as many full sheets as possible and taping them all together with duct tape. Next comes the hard part of cutting all the pieces for the curved areas. You can use a razor knife to score the foam, then snap it to make your cuts. Making the correct size templates out of cardboard is a good way to get the foam cut correctly the first time so you are not wasting any. As each piece is cut and fitted, tape it in place.

The outer edge does not have to be perfect because it will be covered up with preformed pool cove. Pool cove comes in two varieties, the type with plastic on the back for snapping into the bottom rail and the type with tape on the back. You will not have a bottom rail to work with so get the less expensive cove with the sticky back.

Use as much tape as needed on the pool cove. All the joints need taped as well as any place it is not fitting firmly against the side wall.

Using 4 x 8 sheets of Styrofoam for a pool base is not hard to do but it is time consuming. It requires a lot of patience to get all the pieces placed just right and securely taped.

Below are a few of the pages related to using foam for a pool base.

Pool Cove and Foam Pads

Gorilla Pad, Happy Bottom and Foam

Styrofoam For Above Ground Pool

The Best Above Ground Pool Base

Base For Above Ground Pool

Foam Pool Base

Pool Floor Pads

Pool Underlay

Comments for Installing Foam Board as a Pool Bottom

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Aug 01, 2009
Foam or sand on on concrete blocks?
by: Mike D

I have a new 15'round pool and I want to install it on a new patio made with 8"x16" concrete
blocks. The patio is flat, level, solid and perfect for the pool. My question is what type of base? I'm starting out with a nice surface so I'm thinking foam would be ideal. But if things start to settle there might be to many seems in the foam. Sand is good but the foam might save some weight over time.

Thanks, Mike D

Yonkers, NY

Hi Mike. The foam sounds like a good idea to me. If you go with a thicker foam, like 1 1/2" you would have less of a chance of any settling showing through to the liner.

Mar 31, 2012
Pool btm
by: Chris

I am trying to figure out my Pool bottom.
Which foam to use. The white 3/4" is like $11 a sheet which the 1-1/2 is like 25 a sheet. Which would be way to expensive to use.

Also there is two types, hard and soft foam at Lowes.

I have a piece of both in my basement, the white is soft and you can see where you walked on it. The green harder stuff is hard but still dents with my heal if I walk to hard on it.

Sand and the soft white would be about the same price. But thinking though the sand is a lot of work myself and foam would be a lot easier.

When I ask people about the foam they just look at me weird and have all these concerns.

I feel like I want to do the foam, I just want to make sure it will be fine and buy the right stuff. It's all really called polystyrene foam right?

Which foam should I buy hard or soft?

Hi Chris. The 3/4" hard foam should work just fine. Once the weight of the water gets on the foam your footprints will be very minimal. The foam base I had worked out great, I loved it.

Aug 21, 2012
Those ground squirrels
by: Bruce

I have an above ground pool. Ground squirrels sometimes tunnel underneath the pool and when their tunnel collapses, the liner in pulled downwards. So far there have not been any leaks and the squirrel activity has apparently stopped, at least for now. My question is if I chose to replace the liner is there anything that can be put underneath to prevent the liner from collapsing into a new tunnel? I have heard of people using rigid foam, 1" to 2" thick, but was wondering what you recommend? The 1"foam seems to be the way to go.

Hi Bruce. The 1" foam should work just fine for you.

Mar 15, 2013

973-696-0780 They carry all thickness of the perfect type used!! No more lumpy pool bottoms.
They also carry thin material for the walls to protect sharp edges from going through the liner while insulating the walls.

Dec 28, 2014
pool pad foam
by: Anonymous

I have rolls of closed cell foam for pool pad and precut foam for the cove around the wall. 1/2" if you already have a sand base or 1" if this is a new installation. The kit is $200(up to 18' round) $250(24' round), $350 (up to 33' round), $250(oval up to 15x30), $350 (up to 18x45), $450 for bigger ovals, plus shipping depending on where you are located.

I will precut for your pool size for additional $50

Ships from Charlotte NC

I am a professional installer and use it instead of sand, as sand will accelerate the wall rusting out at the base of the pool(it holds water/moisture).

It is the absolute best, smooth pool bottom you can possibly have for basically the same cost as sand. Waterproof, mold/mildew inhibiting- no footprints, easy cleaning! Plus you dont have to shovel 6,000lbs of sand!!

***wholesale pricing for you builders out there for purchase of 5 or more kits****

Nov 21, 2017
Concrete Pad Size
by: Jonthan C

You have mentioned here and other places that a concrete pad is an ideal base for an above ground pool.

You have also stated that any sort of built up "platform" type area with compacted crushed rock, dirt, etc. should be at least 3 feet wider than the diameter of the pool, if I have been reading the comments correctly.

What I am wondering is, does the same hold true for a concrete pad? If I were to lay down a concrete pad for a 24 foot diameter pool could I get away with say a 25x 25 pad or would it have to include the 3 feet wider rule referenced above?

Thanks... :) Jon

Hi Jon Concrete needs to be just big enough to hold the pool out past the ends of the footplates. Not all footplates are the same and not all pool pool measurements are the same. 25' should be enough but be sure before you pour the slab.

Nov 28, 2017
concrete pad
by: Anonymous

Wall to wall, the pool will be 24ft but the uprights on the outside of the pool wall/the feet to those uprights can be 6" each. So side to side the true footprint of the pool could be 25ft or a bit more depending on the model.

If you are trying to save a little concrete, just pour a round pad with a 26/27ft diameter or 26x26 square.

Apr 16, 2018
Pool foam
by: Zach

Puting up a new pool In Illinois clay soil I hear a lot about pink Polystyrene foam for pool bottom. I have an above ground 24' round pool, what’s best sand or dirt bottom with 1" thick foam?

Hi I would use sand and then the foam.

Apr 19, 2018
poly board
by: Anonymous

Sand would be easier to work with. Just get it flat and level and firm before you lay the foam board down. Save a buck just use loose dirt, maybe sifted to remove any stones.

May 18, 2018
Intex Pool Inquiry
by: John

We just purchased an Intex Pool 105" x 105", (8' 9") we have a brick patio that we will be laying it on. What type of underpadding would you recommend?

Hi You could use a little sand with the foam board over it.

May 25, 2019
We have foam board as our pool bottom
by: Angi

Our pool was installed 16 years ago and has blue insulation foam board 1" thick. We are just now replacing our liner ONLY because we have hard water and the liner is caked with lime, it's faded - it's not too pretty. The only issues we have had with our foam bottom is it is separating some and the liner has slipped inside of the small openings between the boards. It's as if weather has caused it to shrink a bit and the weight of the water caused the liner to fall into the small crack. You can see the exact outline of the boards. Or maybe the duct tape didn't withstand the weight of the water or the extreme temperatures of hot to cold (summer to winter)? Not sure -- never looked under there. We live on a rocky bluff so this was very ideal because our ground is horrible. They did put base chat on the ground when installing the pool, so it's a fine rock/sand mix, and then the foam went down on top of that. We just ordered a new liner and are hoping to just re-tape the boards with Gorilla tape (which wasn't invented 16 years ago). And possibly taping on underneath and on top to help keep boards pulled tightly together. I am convinced that our pool liner has lasted so long because it sits on this foam bottom. The pool store owner where we bought our pool and buy chemicals every summer cannot believe we have never replaced that liner.

May 19, 2020
2" vs 1" Foam
by: Eric

I'm setting up a 24'x12' Intex above ground pool on top of level ground in Virginia. The landscapers did not do a great job of removing all the small rocks before tamping the soil and I want to put down foam instead of sand under the pool liner.

Is 1" foam good enough, or should I use the 2" foam sheets? We are sold out of the 1.5" foam up here, otherwise I would go that route.

I'm looking to install this week, so any advice appreciated!

May 29, 2021
Foam board
by: Tom from Pa

I’m doing the same thing. I called an installer and he told me to use 2" foam board. I have shale and rock under my pool and the original installer dug into my hillside and made a base using that and then put sand in the bottom. After a couple years, i had to pull back my liner and get the rocks out and relevel the sand. It lasted another couple years. I can’t Even sweep my pool or use an automatic sweeper. Liner is in bad shape. That’s why i was told to use 2" foam board. I hope it works out.

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