I have high levels of radon in my home. I was thinking of installing an attic fan in my crawl space to reduce them. What are the drawbacks? If it sounds reasonable, should it draw fresh air in our push contaminated air out?

First, I would like to issue a disclaimer stating that I am not an expert in Radon remediation. I do have some observations and intuition that I would like to share and perhaps later when a real expert drops by, we'll see how far off target I am.

I would think that a fan would not be a good idea for two reasons; (1) If you were to positively pressurize your crawl space, then you should expect a certain amount of leakage to the upper floors, radon and moisture included. I'm not sure where you live but you wouldn't want to pump in cold air in the winter. (2) If you were to discharge the air (apply negative pressure) then the makeup air has to come from somewhere, either conditioned air from the house or air from the outside. Either air source is not a good one for self explained reasons. The air would come from point(s) of least resistance leaving stagnant areas in the crawl space thus not accomplishing your objective.

I would think that the best course would to apply a sufficient vapor barrier over the crawl space floor (dirt) and to insulate and seal the exterior walls. Better yet if you could install a perforated pipe beneath the crawl space grade, around the perimeter and exhaust stack it above the roof prior to installing the vapor barrier that would be even more desirable.

Ok, let's see where that takes us

Mike C.

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