You can use two options.
The first. In the place of the future steam room, it is necessary to remove the soil. It will be enough to go deep by 30 cm. Cover the bottom with sand and tamp. As a result, a sand cushion should be at least 10 cm thick. Next, a expanded clay layer, about 20 cm, is poured and spilled with a solution of cement and sand. No less than a day later, foam is placed on top of the dried screed. Its thickness, as a rule, is 10 cm. Next comes a reinforcing mesh, over which a cement or concrete screed is poured. It is done with the necessary biases, to a pre-prepared drain for water. On top of the screed, you can put a wooden ladder of slats or bars. And you can make a full-fledged floor with lags and boards. Only between them it is necessary to leave at least 5 mm clearance for the passage of water.
Second. On the lower edge on one or the other side of the lag a block is packed. They spread the rough floor. In this case, the board is used with a thickness of 25 mm. Top cover with waterproofing material. Between the lags I fill in expanded clay, or lay mineral wool, to their upper level. Then a layer of waterproofing is laid again. And the last is the grooved floor board. This option is applicable in steam rooms, where a large amount of water will not spill onto the floor.
You need to start insulating the walls with the battens. 50 * 50 mm bars are attached to the walls.
The distance between the bars must be made a couple of centimeters less than the size of the insulation that will be laid there.
Further, on top of the insulation, directly to the bars, a foil is attached.
She will give the steamy effect of a thermos.
On top of the foil, a crate of a bar is also mounted, without it the effect of a thermos is impossible. On the bars the walls are lined with clapboard.
Most often, lime or aspen is used.
When insulating the ceiling, one must remember that its insulation should be twice as thick as the wall insulation. For this, both expanded clay, which is poured from the attic, and mineral wool are suitable.
Do not neglect fire protection. All adjoining to the heater and the pipe passage must be insulated with non-combustible materials based on asbestos or basalt.
Following these rules, the steam room will give you a lot of pleasure.
