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  1. #1

    Default Unrelenting crawlspace ODOR -- am at a complete loss

    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 try to 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.

  2. #2
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Quote Originally Posted by mwagter View Post
    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.
    Any idea what used to be stored there?
    Francois


    Truth is just one man's explanation for what he thinks he understands. (Walter Mosley)

  3. #3
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Could it have been a dumping site for chemicals?
    Randy

  4. #4
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    I was thinking more along the lines of wine, if it smells like corked wine.

    ... apparently TCA comes out of "interaction between fungi and chlorophenols,compounds which can be generated through the use of chlorine for bleaching and sanitation."

    http://www.winesandvines.com/templat...&content=48435

    Maybe it used to have a big mold issue, and someone used bleach?
    Francois


    Truth is just one man's explanation for what he thinks he understands. (Walter Mosley)

  5. #5
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    I would have my sewer lines inspected for breakage, to make sure no sewer gas is getting into the crawlspace, or worse yet sewage seeping out of the pipes into the ground.
    Mark


    If I had a dollar for every time I heard someone say, "If I had a dollar for every time....", I'd be a rich man.

  6. #6
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    have a tracer gas test done on your sewer vents. I'd be willing to bet that it has something to do with that. I've done a lot of these weird smell forensics type of things, and it almost always comes down to a leaking sewer vent, whether or not the odor smells like "sewer gas". Call some indoor air quality people and ask if they can do tracer gas testing on your sewer vent. It would probably cost around $1500 or so.

  7. #7
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    mwagter

    First name please

    By all you have done it seems that you are willing to go the better route and not cheap out.
    I would try yo find the history of the place in depth and see if there could have been any dumping of anything.
    Does it smell like any sort of sewer gas? What about a broken sewer line as Mark suggests?

    Your crawl space depressurization would have a tendency to pull the odor up into the space even though it would then remove it.
    Have you ever thought of doing a soil gas vent to depressurize the soils underneath the crawlspace? This would pull the gasses down and out instead of up into the crawlspace.
    This type of vent would end up being classified as a radon vent.
    Mark Parlee
    BESI(building envelope science institute) Envelope Inspector
    EDI Certified EIFS Inspector/Moisture Analyst/Quality Control/Building Envelope II
    Level one thermagrapher (Snell Training)
    www.thebuildingconsultant.com
    www.parleebuilders.com
    You build to code, code is the minimum to pass this test. Congratulations your grade is a D-

  8. #8
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Friend of mine rented a house that had cat urine problem. It was the worst smell. Maybe it was soaked into the subfloor?

    If you are concerned about the dirt, I'd take a few buckets and close them up in something, see if you can isolate it as the dirt, if not look at the existing floor.

    Don't forget, air movement in a structure can suck oder from the strangest remote places. It could be in the attic and traveling down through the wall cavities.

    You might not be able to determine the cause, but you should be able to determine the source.

  9. #9
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Ted's suggestion seems like an obvious first choice. Go in the crawl, fill a bucket with dirt, set the bucket on the passenger seat of your truck, leave the windows up for a couple of hours, then get in the truck. If the smell is there then it's in the dirt, and knowing that would inform your next move.

    Rob's is also good, but I would stop short of the $1500. Last year a client of mine had a smell problem in the house. It was obviously sewer gas. The plumber put a plug in the drain leaving the house, capped all the roof vents and traps, and injected smoke into the piping using a July 4th smoke bomb and a jury-rigged bath fan with a hose connected to it. Found out right away where the leak was (an unfinished, uncapped riser in the kitchen wall... yummy).

    Given the type of building and use you describe I am betting something was poured or spilled into the floor framing and/or soil. Imagine a forklift with a pallet of barrels on it accidentally dropping a barrel, the barrel breaks open, the liquid spills on the floor and leaks thru the floor into the crawl. The guys get a hose and rinse off the floor. I don't know if your poly will stop smells, probably not.

    Anyway, interesting puzzle. Got any pics of the building?

  10. #10
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Having been a railroad building, is there any framing that might have been treated with creosote or other preservatives? I did some work on several such buildings in our area and I remember that the floor joists and of course all exterior docks were creosoted. That smell just never seems to go away, especially if you have cut into it recently. The smell could be aggravated by the hot weather you were describing.
    "ALS IK KAN" - Stickley

  11. #11
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Dave's description of the cheaper way to test for leaking sewer vents is right on. There isn't really a need to spend the $ for a tracer gas test in most cases. A lot of people use smoke, or peppermint oils to find leaks. The difference is that a real tracer test, using SF6, is the most sensitive way to do things, and can find even the smallest leak. The cheaper methods also make it difficult to find leaks if they are under the soil. The resaon these tests are so expensive is the SF6 detectors are around $15k to purchase.

    You might also consider positvely pressurizing the living space relative to the crawl space, to keep the air flowing in a favorable direction.

  12. #12
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Rob, is that a test using a radioactive isotope? I had heard of such a thing for leak tracing and looked into it out of curiousity, couldn't find anyone nearby who did it. Smoke worked well, mostly because the house is question was panelled with 1x6 pine boards, so the smoke leaked right out of the wall. Given drywall I don't know if it would have worked.

  13. #13
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Dave,
    SF6 is sulphur hexaflouride, which is a non-radioactive compound that doesn't exist in nature, and is detectable at the ppb range with the right equipment. I beleive the sensors used for leak detection may have a small amount of radioactive something or other in them, but there isn't enough to require special handling or anything. You can find the smallest of leaks this way. I once detected a crack in a sewer pipe 4 feet away from a toilet, under a slab, because the SF6 leaked out near the toilet. You'd be amazed at how such a small crack in a very hard to get to place can wreck the air quality if the conditions are right.

    Smoke tests, being much cheaper, are great when you don't have to look too hard for the leak, but when dealing with pipes in the ground smoke doesn't cut it too well.

  14. #14
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Where are you located in the Bay Area? Are you near Pt Richmond or Berkeley Marina?

  15. #15
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    Default Re: Unrelenting crawlspace ODOR -- am at a complete loss

    Rob, I did a little bit of reading on SF6. Sounds like it's not a great thing to leak into the environment.

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