AboutDavid Deal Expertise Indoor air quality, mold, compliance questions as well. Also, expert on lead, asbestos, radon, and most any other environmental/industrial hygiene issues.
Expert: David Deal Date: 1/12/2008 Subject: Musty smell after rain
Question I have a musty smell in the house. I lived in this 60 year
old house in San Diego for 15 years. We had some dry years
recently and finally got a good ground saturating rain 5
days ago and that's when the odor started. I went under
the house and it is damp in places. We've been wrestling
with moisture problems in the crawl space, (and I suspect
the previous owners did, too) but I've never had it smell
like this. How do I dry it out down there and stop the
odor. I'm concerned about the mold. (Furnace, ductwork,
and plumbing is all down there, too.)
Answer Standard crawlspace protocol:
1) Pull any existing moisture barrier in area (plasic sheets)
2) Correct any leaks or grade issues. This means making certain all gutter downspouts run water away from home and also make certain all ground water flows away by adjusting the grade near the home. Usually this can be done by simply adding soil to the area near the foundation. Topsoil purchased at garden store works well and normally is more cost effective and easier than ordering a truck. Most home need 10-20 bags, some less even.
3) Add lime to crawlspace soil. Any garden type lime will work. Spread 50 lb bag over area.
4) cover area with 6-mil plastic sheets. I use black for aethetics but color is not relevant. Cut to go around columns etc. Not exact science, just get area covered.
5) Good idea to check air ducts since they are in area. Seal any leaks and insulate any exposed metal supply (cold air going into home). Seal with duct sealant from hardware store. Leaks out of the system will appear dark and into system will appear color of soil. Either is bad and costs energy.
