Hi there, I live in Toronto (cold winters, hot summers). I am about to finish my basement. Today, I was told by a hvac sales guy that I should put foam boards where my headers are and seal the cracks with spray foam insulation (great stuff). However, I also read a post that said, insulating that space in that way would create and trap condensation and rot (and or mildew) the wooden joists which are unfortunately in direct contact with the concrete. Please help.