insulating concrete wall & ceiling in cold cellar

[hubops]

I'm considering using some sort of rigid insulation on the inside walls and ceiling of my cold cellar, which is under the front porch - presently bare poured concrete. I don't wish to frame & finish but just insulate ~ 2 inch thick rigid 4 x 8 sheets - but what product would be easiest to work with and resist moisture, mold & mildew during the summer humidity ? A quick look at the building store web sites has served to convince me how out-of-touch I am .. Polyisocyanurate ; graphite-enhanced expandable polystyrene ; extruded polystryene ; etc Attachment ideas also - rust resistant tapcon screws ? Any suggestions are welcome. John T.

[danny burstein]

If you're installing this on the _inside_ of the walls, you have to be _super duper careful_ about flammability concerns. This refers to both the material itself and any fireproofing and cladding.

[hubops]

Thanks for the warning - inside it is. I was hoping to find a product that didn't need to be cladded-over ... perhaps I'm beat before I start ? I recently used a couple small pieces of ROCKWOOL COMFORTBOARD 80 for 2 attic access spots

- it seems benign for fires but 2 inch thick is quite heavy ! and would involve framing .. 1 inch is just R4 .. John T.

[Ed Pawlowski]

The foam materials will be made from a modified material but the code still requires they be covered. They will not burn on their own but will if there is another source of combustion.

I'd use the 4 x 8 sheets putting it up with construction adhesive and then put 3/8 drywall over it.

This is going to be more expensive but will give you some ideas on how to work with the materials

[gfretwell]

Make sure you put up a good vapor barrier on the outside wall before you put the mold growth media in there. ;) You still might want to dehumidify the cellar. I seem to remember the humidity runs high in there. I haven't had one since 1964. The walls were weeping at times tho.