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A question about straw insulation…

vx2c6AXiQr | Posted in Energy Efficiency and Durability on

My name is Michael Garrison, a 30 year carpenter with 17 years building experience in Alaska. I had a friend who used straw insulation. The condensation inside the structure caused a mold to develop that put off a gas that caused a serious lung infection and almost killed him. Have you heard of any other instances of this effect? Thank you for your time.

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  1. user-788447 | | #1

    I've heard of many structural failures in bale construction in cold climates due to moisture getting into the bales and not being able to dry out before decomposition. Doesn't surprise me that a dangerous mold could be involved. There are many varieties of molds. A mold expert I've met has a Ph.D and charges high hourly rates so I'm assuming the science is involved.

  2. vx2c6AXiQr | | #2

    I'm not sure of the total structural design of the dwelling. They probably didn't have a vapor barrier. But that would seem essential which in the book I'm reading, it doesn't even mention a vapor barrier applied to any straw insulating techniqes, which should be highly essential. My friend almost died.

  3. GBA Editor
    Martin Holladay | | #3

    Most straw-bale builders assume that the plaster that is installed on the interior side of the straw bales will isolate any possible mold from the occupants of the home.

    Here's an article that may interest you:
    The article discusses mold, including "Stacybotrys atra, which causes Farmers' Lung disease."

  4. Boro | | #4

    This question has my attention! I live in a straw bale house in upstate NY.
    Question: Did your friend insulate with bales, or did he use loose straw in the stud cavities?
    A vapor barrier would be a death sentence for a straw bale home. The bales need to breath and since they are so thick, (18" typically) preventing moisture to escape from one or both sides of would promote mold.
    It is also extremely important to fill in any and all voids created where the bales meet. Otherwise warm interior air will escape and condensate on the back side of the exterior plaster. It's not unlike any conventionally built wall for that matter.
    Very interesting and I hope your friend is OK.

  5. jklingel | | #5

    Mike: Are you in Frb? I'm curious about whose house this is. One was built many years ago by a guy I used to work w/, and I always wondered how it worked out. jolinak at gci dot net

  6. user-788447 | | #6

    GBA has a case study of a successful stray bale in an almost comparable climate:

    The owner/builder of the home ran into high moisture levels in some parts of the wall which they later alleviated by drilling holes in the plaster high near the exterior soffit condition to increase the outward drying potential. Don't know for sure if that measure alone fixed the problem.

  7. vx2c6AXiQr | | #7

    To Dave: Knowing the individual, though highly intelligent, he's pot smoking drunken ways, no doubt in a race against the weather of Fairbanks, Alaska and not able to afford a better product in a pinch he grabbed whatever was available. And no doubt, compromised the intregrity of the installation. It was loose straw and probably did not research the best way to apply it as insulation inside of a framed exterior walls.

  8. vx2c6AXiQr | | #8

    To John: The guys name was John T----. He worked for Nail It Construction or Steve Marley, one and the same. He ended up in the hospital on his death bed, from a mold that developed in the straw. The last I knew in 2005 he was still alive but maybe not so well. Not as a byproduct of the mold, but more due to his lifesyle. LOL.

  9. jklingel | | #9

    Michael: OK, this is not the individual I mentioned. I'll have to look him up. Thanks.

  10. kevin_in_denver | | #10

    With all due respect to the successful, diligent straw bale builders, one of my personal mottos is, "Dont. Put. Moist. Food. sealed up in your. Walls."

  11. Boro | | #11

    No offense taken but let it be known; straw is the dead woody stalk leftover and "hay is for horses."

  12. vx2c6AXiQr | | #12

    To John: I'd hate to think that he used leftover straw out of his doghouses..he had 4 dogs some retired sled dogs. He lives off of farmers loop back towards the university as you cross over the hill over musher's just before you hit the curve Capricorn street on the left. Down around that curve over a couple hundred yards up over the right you'll see a shack back there and probably some junk cars.

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