A steel wall vinyl liner pool is basically the above ground pool of the 1970 modified to go in the ground. The steel walls are very thin galvanized steel with bracing to give it rigidity. The floor of this type of pool is basically the dirt under the pool, it is typically covered with a thin layer of a cement mixture called vermiculite. Then the liner is protected from puncture by a thin layer of foam sheets. The Steel Wall Liner Pool is a popular choice mainly due to its affordability, as well as an easier installation process, thus more companies do it, but mostly do it with subcontractors that do all the work. But if you will upgrade this pool with options such as brick coping and paver patio around, then the price difference pound for pound or size of pool to size of pool will be closer to the gunite or cement pool cost.
A Steel Wall Vinyl Liner Pool uses mostly thin 14- gauge steel panels as a support structure. The floor of the pool is made of a thin layer of vermiculite with a smooth finish, to hold the vinyl liner. This material is called vermiculite, it is typically very thin layer.