3" ridgid overtop concrete floor

carp130 said:

good evening everyone , im looking for a experts answer one this question . heres what I would like to do
I have a small area in my home under my interior stairs and landing that has no heat to it and use it as a storage area , we find this space cold a it make the tile floor on or landing cold also , the walls under the stairs are well insulated I would like to just lay ridged insulation right over top of the slab is that a good idea or am I asking for moisture ad mold that way , thanks in advance

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If you have no heat to the area, insulating the slab won't change the temperature of the floor. You might do better to insulate the underside of the tile floor.

Tape down a 3' square of plastic and leave it for a week to see if any moisture shows up underneath. If bare concrete you may only see a change in color, darker. If you try just 1" rigid insulation, it has a low permeability so it can allow some evaporation through it as opposed to the moisture accumulating under a vapor barrier.

But, any isolated space like that will eventually cool to equalize the heat flow into that area to match the outflow. Adding a louver to the door might increase the heat into the space. Any heat source, even a light, would make a difference.

Bud

+1

Get some conditioned air in there and while insulating the floor will help, you would want to look critically at the ribbon/band board areas as well for proper sealing.