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06:47PM | 12/08/08
Member Since: 12/07/08
1 lifetime posts
My crawlspace smell problem is not ordinary or easily resolved but I am hoping someone might have some thoughts on what might be the cause.

First let me give you some back ground information on the building and steps taken to remediate the smell so far.

The original building was built in the 30's, was a warehouse next to a railroad spur so the floor is set at dock height about 4 feet off the ground. The crawl space ranges from 30 - 40" of clear space from dirt to bottom of floor joist. The framing, by the way, is old growth cedar nominal size lumber (a 2x12 is really 2" by 12") with super tight grain. The smell was present when reconstruction began. I disassembled the entire skin of the structure and reassembled to current building codes. Several exterior wall sections had areas of wrought and mold due to bad stucco or roof leaks but all of that framing and materials were removed. Basically, I have built a new building on top of an existing foundation and floor.

From the beginning I had planned to seal the crawlspace using the latest techniques and procedures outlined in many of the trade journals but not adopted by local building codes yet.

Crawlspace conditions:

the dirt has been dry on the surface and even dry at 12" deep in some locations where I installed a emergency drainage system. During most of the construction The side walls were open and the space had complete ventilation during the hot dry summer here in California . At that time there was a crawlspace smell. There are no signs of mold or fungus on the exposed cripple walls and sub flooring system. The dirt floor has been cleared of all cellulose materials and large rocks, exterior cripple wall framing and band joists have been insulated with R19 and exterior concrete footing walls insulated with rigid insulation boards R11 (with termite inspection gap of 2"). The dirt areas have been covered with not one but 2 layers of 6mil poly sheets sealed to the concrete cripples 12" up with polyurethane caulk. Still I have smell.

I then brought in two crawlspace experts who do this sort of thing for a living, both said they didn't see any signs of mold, said I have done better work than their own crews at drying in the space, and they had no idea as what or where the smell was from.

So, as a precaution I installed a commercial grade dehumidifier set the automatic controls to 48% relative and off near 43%, it turns on maybe once a day for 30 minutes. In addition I rented a fogging machine and fogged the entire space and all surfaces of the crawlspace with Concrobium Mold Control. Still I have smell.

I have bought a commercial grade Ozone generator to combat the smell and anything producing the smell. I have performed many 8 -10 hour treatments to the crawlspace when no person is in the building. The results are a combination of heavy ozone smell and the crawlspace smell, still not gone. I run the ozone machine once a week now, still no help.

My last effort has been to at least remove the smell from the building living space by creating a negative pressure in the crawlspace, which of course slightly defeats the efficiency of sealing the crawlspace. I now have a continuous duty inline fan pushing crawlspace air outside which draws outside air from the living areas. The result is very little smell inside (my wife, with her bionic nose, can still smell it) but now we have the strong odor outside. I have just diverted the smell problem but have not stopped or removed it.

To help monitor the air conditions I installed remote humidistats in the crawlspace, one near the NE corner and the other near the SW corner of the space, another is based in our living room and finally one outside. I am in the Bay Area in California so outside humidity levels range from 20% on very dry summer days to 85% on foggy mornings and higher when we have rain, which has not happened very much( we are on 3rd year of drought). The crawlspace NW reader ranges from 48% - 52% consistently and the SW ranges 41%-46%(closest to the dehumidifier). The living space has been 45% lately.

I am pulling my hair out on this problem.

Do you know of any case like mine? What could be producing this unrelenting smell?

Could it be a gas of some sort?

If you have any thoughts about my crawlspace smell I would really appreciate them. It has taken the last two years to complete our home but my wife refuses to move in (understandably) until the smell has been removed. It seems to smell like trichloroanisole known as TCA (cork taint in wine).

Any thoughts would be greatly appreciated.


11:08AM | 12/12/08
Member Since: 12/10/08
2 lifetime posts
If it is trichloroanisole Wikipedia says it is non-polar molecule so I don't think the ozone generator will work. Have you treated it with Borax?

If it is some sort of contamination try replacing as much of the soil down there as you can.


10:28PM | 09/24/19
How would you describe the smell


09:26AM | 03/26/20
1 house from 30s but property may be old example out house livestock or if premise added on to
2 check history of neighborhood for non res. use i.e. gas station nearby, ex owner worked at smelter etc used waste tailings for fill
3 fill dirt was from a factory or processing facility
? need a clue as to what it does smell like; rotten eggs(sulfur)etc

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