Is much better

The frame for such a bath is made of a metal profile or wooden beam, the first option is much better, but it is more expensive, as for the beam, it may not withstand elevated temperatures. The frame should be as strong as possible, to fasten it, you need to use screws, insert the insulation in the crate cells. A good insulation is mineral wool or standard mineral slabs. On top of the insulation, fix the heat -refining foil, this can be done, using a stapler, in addition, you need to sheathe foil and ventilation ducts, you need to fix the foil perpendicular to the lines of the lining, which are used for the final decoration.