under liner styrofoam placement

[FNC1962]

Hello to all. This is my first post.
I am having an 18' oval AG pool installed in a couple of weeks by a local dealer. It will have a sand base and foam cove . I have told by a couple of previous PO's to put styrofoam under the liner and would like your input. The dealer never mentioned if he thought this was a good idea or not. What do you all think?
Thanks!

p.s. I have looked at several past posts about the subject.

[Sean OBrien]

From a strictly mechanical perspective - having a base like styrofoam should help protect the liner over time. It will will be firmer than a simple sand base which means foot traffic will be less likely to stress the liner, it would also provide a barrier between the frictional wear of the sand on the liner due to shifts. It also won't errode or wash out should drainage be an issue in your area (a few friends had problems with that on their pools).

I had helped a friend two years ago do a foam underlayment because the layout of the property meant that rain and snow melt was washing away the sand under one corner of his pool. We removed the old sand and left about an inch or two for leveling purposes (easier to level sand than level dirt). After the sand was level and compacted, we laid out 1" foam over the pool area. The foam we used was kind of nice since it had tongue and groove edges, so it didn't shift around as we worked. I would also say it would probably be a good idea to spend a little bit more for the extruded foam (pink or blue) as opposed to the expanded foam (white crumbly stuff). The extruded is easier to cut for your curves and from other applications I have used it for insulation - the white stuff tends to fall apart much faster due to moisture and light (light shouldn't be a problem here - but moisture will be). Once the foam was installed we taped all the joints using a wide 3" underlayment tape (think it was designed for similar use in basement floating floors). He used the preformed foam cove and we put that on the foam and also taped that down to the foam underlayment. After that - the liner went in like it would have over a sand base.

Took care of the problem he was having with wash out - and the pool felt more comfortable under foot too. It went through two swimming seasons and winters in freeze/thaw territory (South Dakota) and when I talked to him last week he said it was still holding up great. The only thing you really want to do is make sure that you clean off the foam before you put the liner over the top of it. A little piece of gravel or a twig between the liner and the foam could create a wear point that could poke a hole in the liner or cause it to wear through prematurely.

That said - up until this point, I have always used OPP (other peoples' pools)...so my long term experience with the foam is somewhat limited.

[sunlove]

My folks' AG pool has a gorilla pad under the liner, and it makes the floor of the pool soft to walk on and they have no wrinkles or bumps on the pool floor. My pool just has a sand subfloor with no pad, and over the past several years it has some wrinkles and lots of bumps/dips. Whenever we replace the liner I definitely will put one in. I guess all this to say you might as well do it right the first time and get padding or foam. I don't know that there are any negatives to having one.

[FNC1962]

Thanks! I went to the pool store and asked the owner about the styrofoam and he said that he would install "Happy Feet" under the liner at no charge to me. I do not know what that is, exactly. I was happy that he agreed to do that.