Musty Odor From A Crawl Space / Leaking Chimney Clean-out / Wet Crawl Space / Wet Chimney Insulation

In Crawl Space, Odors, Q&A on May 8, 2012 at 2:33 pm

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I have a musty odor emitting from the crawl space. How can I stop the odor from rising through the floor?


Check to make sure that a plumbing fixture or pipe is not leaking into the crawl. The leak could be rotting some of the sub-floor and possibly the insulation.

You’ll need to crawl under the house with a flashlight and look directly under the kitchen and bathroom areas. Check for plumbing leaks or leaking through the foundation walls.

Check the insulation around the perimeter or is it attached to the underside of the floor joists? In either case, it could be trapping moisture or critters and the smell could be originating from either. In both cases, it’s not uncommon.

If you’re sure that neither one of these issues is the cause of the problem, than you’ll have to remove the insulation away from the band joists. That is the insulation stuffed between the joists along the top of the exterior walls. Oftentimes when inspecting houses, I find evidence of leaking, rotting and wood destroying insect activity in that area and it is usually caused by improperly installed door walls, entries or brick flashing on the exterior.

Remember, where there’s smoke there’s fire and in your case, you need to find the leak and eliminate the odor.


I am confused. My real estate agent said I have to hire a home inspector, but the seller says it must be a licensed home inspector.


There is no licensing for inspectors in Michigan. That’s not entirely bad. I’ve talked to inspectors where there is licensing and it seems to “dumb down” the industry.

The best inspectors are qualified and must undergo ongoing continuing education training. They also must be members of the American Society of Home Inspectors (www.ashi.org) or the National Society of Home Inspectors (www.nahi.org).

Both organizations set standards of practice, require continuing education and establish guidelines regarding ethics for inspectors.

Make sure any inspector is a member of one of these organizations and has errors and omissions insurance.


I have water in my crawl space. It has a dirt floor that is covered with plastic and I put extensions on the downspouts. There are no problems with rot or mold but there is a slight musty odor.


With time you will have mold and rot so correcting the leak is imperative.

I am assuming the ground around the exterior is sloped away from the house and not toward it.

Your next step would be to either waterproof the foundation walls and install a drain tile system on the exterior or put in a drain tile system to a sump pump in the crawl.

Whatever you do is expensive, but necessary. Check in the yellow pages under basement waterproofing companies.


My water heater and furnace are in the basement and exhaust into a mutual chimney quite apart from the fireplace. There is an ash clean-out door at the base of the chimney. In rainy weather or at a thaw, through this door comes a pretty good flow of water.


First, install a metal chimney cap and screening on top of the flue. Also make sure the wash at the top of the chimney is not cracked, broken, rusted through and/or leaking.

While those are the common sources of leaking, your problem may be because the chimney below grade is cracked and water is getting into it and leaking through the clean-out door.

If that’s the case, basement waterproofers should be able to repair the problem.


When it rains, water drips into our basement under the fireplace. The contractor who installed the fireplace for us has told us, that the water coming through the chimney has also ruined the insulation inside the chimney. He says the cold drafts we get in our living room each winter coming from the firebox are the result of the insulation having been soaked and no longer doing its job. I’m trying to decide what to do.


I agree that the insulation is most likely ruined. The leak probably originated from the chimney wash. If it is masonry, (which I doubt) it can be patched with vinyl concrete. If it’s a metal pan, it is a poor design and prone to leaking.


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