I am planning on installing framing for walls in my basement. Along the exterior walls I have a French drain. My plan was to place the bottom plate about 3 inches off the wall, away from the open channel of the drain. Do I need to put a vapor barrier on the exterior wall or on my framing, and should I be concerned about the drain itself as a source of moisture?
Re: Basement Walls
Before you start, make sure that there is absolutely no leaks in your basement walls. Your best protection has to be on the exterior. Make sure your drain is operating efficiently. I don't know where you live, but I've seen places where they get 2-3 inches of rain an hour, and their basements get flooded. That's the ultimate test - hurricane like conditions.
In a flood, a 3" distance to the exterior wall and a moisture barrier won't give you a lot of protection.
How old is the house? how good is the exterior waterproofing? Find out before you invest.