You suggested that there is a lot of condensation with new construction. We are keeping air circulation moving, but are still wondering if this is the problem. We have a poured concrete basement with a part jutting out for a gas fireplace on the main floor. We have taken the vapour barrier off and insulation to find that the concrete underneath is very wet. We have had 2-3 inches of rain in the last few days. It is a half chimney (slanted on the top) with brick covering the plywood chimney. We can't figure out where the water is coming from. Everything above seems dry. Is it possible that the bricks are letting in water?
Answer:
Although it is possible, it is highly unlikely. If anything, there might be some leaking of the chimney cap immediately next to the flue liner. If the chimney is to blame, that is the most likely place for it to do so. My hope is that the mortar between the bricks has not already deteriorated to that point.
