Hi,

Was wondering if you could help me out …

I reside in northern Canada where the winters can be quite cold, and my home is approximately 30 years old. My basement is partially underground and consists of a 4 foot tall concrete wall and a concrete slab for my floor. Inside my basement I have vapor barrier running down the course of the concrete wall towards the basement floor. Adjacent to the concrete wall I have a 4 foot tall framed wall attached to the floor consisting of 2X4 construction with 16 inch centers and fiberglass insulation between the studs. This is followed by drywall. Please keep in mind that there is an approximate 2 inch gap between the framed wall and the concrete wall, and as mentioned above there is a vapor barrier running down the concrete wall only, also there is no vapor barrier between the insulation and drywall. The top of the framed wall (sill area) consisted of 2x 10’s running the length; this was used as a shelf area to store things like plants and miscellaneous basement junk. Having pulled the 2x 10’s off the top of the wall this past winter and exposing what I have described to you above, I also noticed the insulation was damp with moisture as well as some moisture near the bottom sill making the drywall damp. In some cases the insulation was even frozen to the concrete wall.

I have the following questions:

1. Is this moisture a result of the framed wall not being properly sealed from the air within house? As mentioned above, 2x10’s were used to cap the framed wall and used as a shelf however there were many spaces and gaps between 2x10 and wall sill that the warm air within my house could easily infiltrate and come in contact with the cold air of the concrete wall.

2. To mitigate my moisture problem and to boost the R-value of the basement, I would like to fill the 2 inch space between the framed wall and the concrete wall with more insulation. I am either looking to double up on the fiberglass insulation or glue rigid Styrofoam against the concrete wall behind the existing fiber glass. When I do this, I will be removing the vapor barrier that is currently against the concrete and placing another one between the fiberglass insulation and fully finished drywall including a finished sill. I am hoping this will eliminate my moisture Does this sound like a practical solution to my moisture problem?

Thanks for your time.