Above ground swimming pools are less expensive propositions than in-ground pools when choosing a back garden pool. Of course, an above ground swimming pool needs to be properly sited on whatever surface it's put on. For example, you may have a concrete slab on which you plan to place your above ground pool. An above ground pool on a concrete slab, though, will need to have padding beneath the pool floor if sand isn't an option.
Sand padding beneath the floor of an above ground pool sitting on a concrete pad isn't a good idea because the sand could let the pool move slightly. If you want to put an above ground swimming pool on a concrete pad or slab, find a material that's soft yet won't easily shift. A good solution to the problem of padding under the floor of an above ground pool on concrete is solid or rigid foam insulation.
Solid foam insulation
Solid foam insulation can be an ideal padding, or underlayment, that sits between the bottom of a pool floor and a concrete surface. One of the benefits of solid foam insulation is that it's made of polystyrene or polyurethane and is easily cut and shaped. Plus, solid foam insulation can be purchased in a variety of thicknesses. Also, solid foam insulation won't slide around on concrete when an above ground pool's water weight is placed on it.
Certain types of carpet padding can also be used as padding for an above ground pool sitting on concrete. Like solid foam insulation, carpet padding comes in different thicknesses and is easily cut and shaped. If you're considering carpet padding for use under an above ground swimming pool's floor, go with one that's rated for high-traffic areas. Depending on how soft you want your pool floor to be, you may need two layers of carpet padding beneath it to be effective, though.
If you want to spend more money for padding to go beneath an above ground pool's floor when it's sitting on concrete there are commercial alternatives. One company in particular makes a pad specifically for pool floors that are cut to fit most standard-shape above ground swimming pools. At the time of publication, preformed pool floor padding costs about £91 for an 5.4 m (18 foot) round above ground pool. Commercial pool floor padding isn't very thick so you'll probably need two or more layers.
At minimum, select above ground pool floor underlayment padding that's smooth surfaced. Smooth surfacing is needed as underlayment padding to avoid pool floor wrinkling or bumps. Also, the concrete that you put an above ground pool on needs to be very level to avoid possible issues such as pool wall collapses. Concrete slabs run from 10 to 20 cm (4 to 8 inches), which is more than enough to accommodate an above ground pool's weight.