Insulating sub- terrain living areas
Foundation Insulating Question
I just started working with our local Habitat for Humanity (HFH) chapter in NE Ohio. None of the “guys†come from the construction field and we are currently building a split level house. A decision was made to use 2″ blue board (with capillary features) on the exterior below grade. Although we have begun finishing the lower (“sub terrain†living area) we’re already “debating†whether to:
1) put foam insulation behind the dry wall in this lower area of the house and,
2) provide a vapor barrier in this area, if we don’t insulate with the rigid foam board
What is the appropriate practice in our area?
Also, when we damp proofed (or water proofed) the masonry block. we use a roofing asphalt based tar substance & roofing membrane behind the blue board. I’m not too “nuts†about this but it was done. I would have preferred a more flexible damp proofing product that we could have applied behind the blue board and skipped the roofing membrane. Any recommendations on this task for the future?
Replies
Roofing material is not recommended for use underground. There are all sorts of microsopic bugs that live in the earth and consider the UV-resistant materials to be a veritable feast.
Do you have a building code authority there who needs to inspect the house? IF so, you may need to contact that office before you get too far along, although you are probably too far now, anyway.
Insulating sub- terrain living areas.
I've also read where blue board is UV sensitive and that termites like it, so we kept the board below grade & approx 8"-10" below the treated sill board.
Any thoughts on using an interior vapor barrier in this area?
Per your request: I would have used Tuff n dri on the basement exterior wall, but that's water over the dam. I guess you are using the roofing to protectthe foam board from the asphalt.
I don't know if termites like foam board, but they do not mind tunneling
through it to get to wood.If the wall is now truly waterproofed, you can proceed with an interior wall.
I would put plastic on the wall. You could consider this to be a seepage barrier, not a vapor barrier. Without any experience with the wall, I would avoid any penetrations into the wall.
You could also have the wall foam sprayed prior to a stud wall. You must cover any foam board or foamed fixtures with a fire proof material such as sheetrock in most areas.
I agree with an early poster, check with the local BI for his input.
Keep us posted. Paul
Energy Consultant and author of Practical Energy Cost Reduction for the Home