Re: interior basement insulation
Marg --- welcome to the forum
Originally Posted by eagleton
Having the rigid foam installed on the exterior side of the foundation wall below grade is a good thing. Not only for providing a continious thermal break for insulation but also helps with preventing moisture infiltration.
If there was at least a continious damp proof coating applied first along with proper footing drains and if the rigid foam was extruded foam, there shouldn't be any concern for moisture issues.
The exterior rigid foam should be only as far as the grade level with the rest of the exterior exposed. This is to allow any moisture in the concrete that may be present an avenue to exit.
Perhaps some of the information you received was pertaining to vapour since you shouldn't have moisture ( from the exterior ) issues.
Before finishing the walls I recommend cutting a number of clear plastic squares ( from sheet plastic such as used for a vapour barrier ) about a foot square.
Tape these ( continiously around all the four edges ensuring a tight seal ) to the bare concrete walls in a variety of spots on all the walls.
I like to place some near the corners and have them placed with one low near the floor --- midway --- and up at around grade level.
After about one week inspect them to see if moisture has accumulated --- notate if any moisture is under the plastic or on top. If under then there is moisture migrating from the exterior inward and needs to be addressed before finsihing the walls. If any moisture is on top of the plastic this indicates an interior relative humidity ( RH ) condensation issue. This will likely be a non issue when insulation is applied and by keeping the humidity level under control.
Personally I would apply a continious layer of one inch rigid foam panels to cover the inside walls --- from the floor to ceiling. Use a house wrap tape to seal all butt joint seams of the foam panels. In the corner butt joints and along the bottom ( where the panels meet the floor ) use foam in a can like a caulk to provide an air tight seal.
Then frame the wall studs so they are in front of the foam but touching the foam. --- run the wires ---- apply the drywall and you will have dry warm walls.
Hopefully this helps and makes sense.
"" an ounce of perception -- a pound of obscure "