You can use either one or two layers of plywood or osb and the subflooring can either be fastened to the concrete with long tapcon screws or it can simply float above the foam.
Tile over foam insulation.
If anything i would use 3 4 exterior plywood over the styrofoam and then an isolation membrane and tile over that.
It comes in standard size 4 8 sheets and smaller sizes in many different thicknesses from 1 4 inch to 2 inches.
Foam board insulation is easy to use and is a great diy way to add some insulation.
There are several ways to install subflooring above the rigid foam.
It s important that there is no movement under the tile.
The other way you could approach it is by using a heating pad over the concrete floor with tile i d also use a isolation membrane here over it.
Both require an isolation board or slip sheet.
If your basement slab lacks sub slab foam you ll have to install the insulation above the slab.
For tile i d contact the tile council of america or now it s called tile council of north america.
2x2 foot foam tiles are easy to install over concrete tile or any hard flat surface for basement floors kids room and home exercise areas.
12 pk blue charcoal acoustic foam tiles soundproofing foam panels sound insulation soundproof foam padding sound dampening studio sound proof padding 1 x 12 x 12 4 2 out of 5 stars 501 19 99 19.