I recently bought a non-inflatable, steel frame above ground pool (12 ft diameter, 3 ft depth). I want to set it up on a slab of concrete, but I have a couple of concerns about the wear on the bottom liner of my pool:

  • Joints in my concrete may stretch the liner to fill the joints (under water pressure)
  • Roughness of my concrete may scratch the liner

Are these valid concerns? If so, what type of underlayment should I use? I'm considering 1/2" thick foam insulation, but I'm not sure if that minds getting wet or not. Also, I'm not sure if I can put the legs of my pool on top of it without the legs tearing through over time.

Any suggestions?

  • 2
    My gut reaction is to use sand, but I'd follow recommendations of the manufacturer of the pool. You'll need to do that if you want any warranty support.
    – DA01
    May 3 '12 at 21:59
  • @DA01, I'm not that worried about warranty - it's a cheap pool, and the warranty is only 90 days and doesn't cover "water loss". Not a super compelling warranty.
    – Eric
    May 3 '12 at 22:42
  • 2
    Ha! A pool warranty that doesn't include the one thing you don't want a pool to do...leak. ;) Hmm...as for the joints, fill those in with sand. Then maybe a layer of ice and snow roofing barrier or even just roofing felt to smooth out the concrete?
    – DA01
    May 3 '12 at 23:23
  • @DA01 Thanks for the tip! I think your suggestion would make a good answer if you'd care to add it.
    – Eric
    May 3 '12 at 23:49

Per request, I'll expand my comment into an answer:

as for the joints in the concrete, I'd use polymeric sand (typically used for locking pavers).

Then the key is to create some sort of smooth pad in between the concrete and the bottom of the pool. Some options:

  • roofing felt (tar paper).
  • Ice and Shield roofing membrane
  • rubber pond liner
  • epoxy (if it's not terribly rough, a few coats of epoxy concrete sealer might smooth it out)

We installed an 18' diameter pool on top of a concrete pad using the 2' x 2' interlocking square foam pieces between the pool and the concrete. It feels great underfoot and the pool has been going strong for 4 years now.


You could use some foam underlayment like used for laminate flooring. It is about 3/16 inch thick, cheap and you can use typar or packing tape to hold the seams. The same train of thought, how about blue vinyl siding insulation. It is 1/4 " thick, 4 ft wide and folds out to about 16 feet. Also pretty cheap.


Bought 16' last year and bedded it on sand on 2x2 slabs... Worked very well but at the end of the year a ton of dry sand was a ton and a half of wet sand... Plus kids run it into the house on their wet feet... This year I was contemplating 2" polystyrene but it's working out at £96... So I'm now thinking old carpet that can be dumped or dried out to use again... The sand is good but hard work tidying up after when wet...


I have been setting up pools in the same area in my yard for about 6 years now. I have found that play sand is the best under lament for the liner. Now I went from a 18 foot to a 22 foot Coleman and need to expand the circumference extremely. I will let you folks know how it turns out.

I am an extreme leveler and compactor to be sure to protect my investment, so I do not rush to set these pools up before the ground is perfectly level, including riser pole locations, and tamped (packed) with water added between courses, add the utmost thin layer of play sand after all rocks and pebbles are removed from site. Protect your family, level and invest in play sand very thin layer upon extremely packed sand (clay) before setting up the pool.

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