Above-Ground Pool Base

The situation

An above-ground pool needs a smooth, level, stone-free base. Anything sharp under the liner is a puncture risk, and any unevenness shows up as a wrinkled floor you can feel underfoot.

What to buy

Mason sand is the standard. It is washed and screened to a fine, uniform particle size with nothing sharp in it, so it beds smooth and is comfortable through a liner.

Do not use fill sand, which is unwashed and contains silt, stones and organic material. Do not use concrete sand either — it is deliberately coarse and well-graded, which is right under pavers and wrong under a liner.

Many installers also put a pool pad or foam layer over the sand. That is additional protection, not a replacement for getting the sand level right.

How much you need

Two inches of sand is the usual base. A circular pool needs radius squared times about three for the area.

• 15-foot round — about 177 sq ft — roughly 1.5 yards at 2 inches
• 18-foot round — about 254 sq ft — roughly 2 yards
• 24-foot round — about 452 sq ft — roughly 3 yards
• 15 × 30 oval — about 450 sq ft — roughly 3 yards

Order a little over. Running short halfway through levelling a pool base is a genuinely miserable way to spend a Saturday.

Not sure? Tell us the rough size of the area and how deep you want it and we will work it out with you. Nobody expects you to know this — it is our job, not yours. Or use the calculator.

How to do it

1. Clear and level the ground first. Sand is for smoothing, not for correcting a slope — a thick sand layer on one side will settle and the pool will go out of level.
2. Remove every root and stone from the footprint.
3. Spread the sand about 2 inches deep.
4. Screed it flat with a long straight board, checking with a level.
5. Dampen and tamp lightly to firm it without creating hollows.
6. Do not walk on it once it is finished.

Materials for this job

Above-Ground Pool Base — common questions

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