Styrofoam sheeting is often used as the bottom base below the liner of an aboveground pool. The foam provides a smooth surface for the liner and protects it from sharp rocks that may puncture it.
Concrete is probably the best option since it is usually 100% level and smooth. Also, grass can't grow through concrete and animals and bugs can't damage or burrow through it either. Grass or dirt is also another great option, as long as it has been properly leveled and you've killed off the grass first.
Economy foam flooring, designed for home basement floors, workout rooms and kid spaces also works well as an under pool mat.
Gorilla Pads are pre-cut floor pads designed to protect and cushion the bottom of above ground pools. Unlike old pool foam padding, which can be easily be cut or pierced by grass, roots, or rocks under your above ground pool liner, Gorilla Bottom pool floor padding is impervious to almost any sharp object.
Plastic sheeting is the absolute worst material to place under an above ground pool during installation. It does not prevent weed growth and does not control bugs and critters. But the biggest reason to avoid plastic sheeting is the fact it causes a swimming pool to rust out very quickly.
The use of sand is one of the cheapest ways in which to level the ground without digging, and it is far easier to level the sand than it is to level the ground itself. Sand can be poured on the installation area, spread evenly around the region, and compacted down to create level ground.
Aside from the pool liner, you should have something like Armor Shield or Gorilla Pad and a pool cove, as well, to avoid punctures. Using sand or soil over concrete is not advisable as it can be washed off. When the floor protective layer and pool cove is all set, follow the regular pool installation steps.
Traditional felt carpet padding is usually frowned upon as a pool padding material, according to the Pool Homeschool blog, but modern closed-cell foam carpet pads can work well. Those marketed as "memory foam" pads work for an above-ground pool sitting on concrete.
If cutting costs without cutting corners is on your agenda, do yourself and the planet a favor by padding your pool with newspapers and cardboard. Both materials are readily available -- and free for the asking -- from recycling centers, store refuse containers or your own recycling bins.
Pre-Cut Pool Pad
A pool pad is a material designed specifically to place under your above ground pool. They are generally used on a concrete slab. The pool pads can be cut to perfectly fit your pool's base. Pre-cut pool pads are made of a super durable material and will not trap moisture.
Underneath the liner is a sand or cementitious floor, troweled into place. The floor sidewalls come up to meet the walls, which are commonly 42” x 8 ft panels made of galvanized steel or thermoplastic. These walls are supported from behind so that they won't bow out against the weight of the water.
The water will press with more force on one section of the pool than the others. This uneven weight distribution can buckle, twist or even collapse the pool wall, resulting in property damage and injury to anyone in or around the pool when it fails.
Less than an inch of unevenness is acceptable, but anything beyond that can lead to the leveling problem. Such a pool won't last for long, and you would need to bring it down and get it reinstalled by a professional. Leveling the surface first before assembling the pool is important.
While you could place your pool directly on top of your grass, that isn't the best idea. The grass isn't a firm base since it is alive and growing. Your pool can shift over time and settle into an unfavorable and potentially dangerous position.
Yes you DO want pavers under your legs. That will keep them from sinking. The pavers need to be level with the ground so they do not poke your liner. The ground prep is a lot of work BUT it will pay off in the end!
Pavers must sit on solid earth, level and covered up with a solid layer of 3-4 inches of compacted stone dust inside the pool. This will make for a solid base and a professional pool bottom that will last the lifetime of the pool. Pools are heavy when water is in them. Make sure the pavers are on solid earth!
A common cause of pool collapse is a build up of snow, rainwater, and ice on the pool's cover. The weight of the elements can be too heavy for the pool walls to contain, causing them to fracture and collapse.
You'll need to keep draining water off the cover with a pump or siphon to protect it from damage. Important: Never drain an above ground pool completely when winterizing. Your vinyl liner can dry out, shortening its life considerably.