Expert: Bruce E. Johnson - 9/4/2008

Question
I am having my crawl space made into a basement professionally however I
am wondering about venting & moisture. is there anything you recommend
that i be sure that my contractor does, so that my new space is dry & safe?
we are doing the walls 42" off the floor & 16" deep like a shelf all around the
space. My current crawlspace is dry from what I can see & smell. It is not
being used for anything.

Answer
He merdith weiss, venting will not be a problem because the basement is now part of the house so the natural circulation in the house itself (provided you duct a/c and heat into the basement) will provide all the venting you will need.  As far as keeping moisture out, the first and foremost line of defense is the exterior walls.  They must be waterproofed properly and if possible a footing drain run around the exterior perimeter to catch and remove any water that may want to build up against the wall.  These two things alone will keep moisture from penetrating the living space.  If you haven't poured the concrete floor yet, it would behoove you to put a vapor barrier of a good 6-8 mil visqueen underneath the concrete.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com