Perfect for cooling off during summer, above-ground pools come in several categories — self-supporting pools and frame pools. Whether octagonal, round, rectangular, or oval, every above-ground pool needs a perfectly flat, stable surface underneath. The good news: you have plenty of options — sand, lawn, concrete slab, and more.
Here's a complete guide to what to put under your above-ground pool.
The Different Types of Above-Ground Pools
Faster and easier to install than an in-ground pool, above-ground pools come in a wide range of styles. Check out our guide to choosing your above-ground pool for more detail.
First, there are demountable above-ground pools:
- Inflatable above-ground pool: available in round, oval, and rectangular shapes. Affordable, easy to set up, and easy to handle — but fairly fragile. Avoid leaning on the edges or hitting the structure.
- Self-supporting pool: also called a freestanding pool, similar to an inflatable pool. Must be installed on a flat surface.
Before you dive in, grab some inflatable pool loungers for the whole family:
Then there are kit pools with rigid structures. The two main types are:
- Frame pool: features a PVC liner basin supported by a steel tube frame. Usually round or rectangular.
- Rigid above-ground pool: built from modular panels (steel, resin, aluminum, wood, composite wood, etc.). More design options in terms of shapes and dimensions — and can even be partially buried.
The Best Base Options for an Above-Ground Pool
Whatever type of above-ground pool you're installing, the right base makes all the difference. Also check out our guides on "what to put under a frame pool" and above-ground pool decks.
Geotextile Membrane
Ideal for small pools, inflatable pools, Intex frame pools, and self-supporting pools, geotextile is laid directly on the lawn. It prevents plant regrowth that could tear the liner over time. Think of it like a protective carpet under the pool — comfortable underfoot and easy to lay, as long as it's properly flat.
Sand Bed
A sand bed adds stability and evens out any surface imperfections. It's easy to install and affordable, though it does require some ground preparation. Dig a hole about 4 inches deep, remove all soil, stones, roots, and debris, then spread the sand evenly inside. You can mix sand with cement for added firmness. Finish with a geotextile layer on top to suppress weed regrowth.
Lawn
Placing your pool directly on the lawn is the simplest and cheapest option — but it comes with a trade-off. The grass will be deprived of light for months and will likely die off, requiring replanting later. If you go this route, mow the lawn short, clear the area of anything sharp or damaging, and always place a durable ground mat between the grass and the pool base.
Concrete Slab
The most stable and flat option — and the most expensive and complex to install. Also called a pool raft foundation, a concrete slab is compatible with all types of above-ground pools.
To install: mark out the area, excavate the ground, lay about 4 inches of gravel and 2 inches of sand, and check that the surface is perfectly level. Build formwork from wooden planks, mix and pour the concrete, and let it set fully. Before placing your pool, lay a ground mat or protective tarp on top of the slab.
As you can see, there are plenty of great base options for an above-ground pool — choose the one that best suits your budget, pool type, and backyard setup!
FAQ: What to Put Under an Above-Ground Pool
What should I put under an above-ground pool to protect the liner?
The best protection under an above-ground pool includes: geotextile matting (thick non-woven fabric, impermeable to roots), EVA foam ground mat (comfort and stone protection), concrete slab with geotextile (most durable solution), or PVC protective panels. Avoid plastic sheeting alone, which traps moisture and encourages mould.
Can I put sand under an above-ground pool?
Fine sand (washed river sand) is used by some to create a soft, comfortable base. However, it tends to shift and create uneven spots under the liner. If you use sand, compact it well and spread no more than 5 cm deep. Building sand (masonry sand) is too abrasive and not recommended.
Is it mandatory to put something under an above-ground pool?
No, it is not mandatory, but strongly recommended. Without protection, the liner rests directly on soil or grass. Stones, roots and sharp edges create pressure points that can puncture the liner within weeks. A ground mat costing under €20 can extend the liner's life by several years.
How do I correctly lay a ground mat under an above-ground pool?
Choose a mat slightly larger than your pool's diameter or format (50 cm overlap on each side). Lay it on a levelled surface, cleared of all sharp objects. Centre the pool on the mat. The overlap protects the liner edges during filling. Avoid folds that could create uneven spots under the pool.
Can I set up an above-ground pool directly on grass?
Yes, short grass is the most suitable natural surface: it is soft, level and free of protruding stones. Mow very short before installation and pull up weeds. Still place a ground mat to protect the liner. Note that grass under the pool will die during summer and leave a yellow patch after dismantling.
