Although building codes differ by region builders typically use r5 and r10 insulation under the concrete slab but floors insulated with r20 contain the heat in your basement far better than those insulated with lower r values.
Concrete floor insulation options.
Another option for insulating your concrete floor are some more flexible materials such as knauf rock wool insulation slabs or rockwool insulation slabs which also offer a level of sound insulation apart from known as being great and versatile insulators.
Concrete slab floors are typically insulated with polystyrene board.
Overlap the seams about 6 to 8 inches and seal the seams with waterproof construction tape.
Insulating concrete garage floors begins with covering the entire floor with 6 mil polyethylene which will serve as a vapor barrier.
The good news is that all the mentioned products can be found right here at insulation shop.
Insulating concrete slab floors timber frame floors are typically insulated with polystyrene boards or sheet insulation made from glasswool fibreglass wool polyester wool polyester mix and mineral wool.
Spray foam insulation is likely the best option for below floor insulation.
Foam in place insulation is sprayed into spaces between the joists and goes around venting pipes and electrical work.
The most expensive option.
Run the polyethylene up the sides of the walls 3 to 4 inches and secure to the walls with construction tape.