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Community and Q&A

Spray foam odor

BSlade | Posted in General Questions on
First time builder here constructing a 13’x23′ shed roof cabin with my dad in central West Virginia. Three weeks ago I had 2″ of closed cell spray foam installed in the walls/floor and 3″ in the ceiling. Walls are 2×6 and floor joists/roof rafters 2×10. I keep the place open as much as possible to allow for ventilation.
I recently started spending more time inside with an electric heater running and notice a slight paint/chemical smell. If inside for 30-60 minutes I can feel it in my throat/lungs, like when you use a strong cleaner without good ventilation. 
The installer came out, said the mix looks good and cannot detect any odor but wants to put 6 mil poly on the walls and ceiling. No core samples were taken. He thinks I’m just sensitive to the foam.
A couple questions:
– Will the odor go away with time? Even if it would take a year or so to go away I could put up with it. But I do not want it around forever.
– Will plastic sheating block the odor?
– Will adding this plastic cause any problems with moisture getting trapped in the walls? I plan on adding a mini split but will not continually condition the space.
Thanks for any help!

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  1. Expert Member
    BILL WICHERS | | #1

    The smell usually goes away in a week or two at most. If you just recently had the spray foam applied, then it’s likely been fairly cold and in an unheated building it will take longer for the smell to go away. I’d try heating AND ventilating the building, which sounds counterproductive, but the goal here is to clear the smell, not to efficiently heat the building.

    Enclosing the spray roam with poly sheeting MAY help, but also carries risk of moisture getting trapped as you mention depending on how your conditioning the building. It sounds like this isn’t a building that is conditioned and occupied year round?


    1. BSlade | | #2

      Thanks for the reassurance! I'm building this to hold a wood fired sauna and to have extra sleeping space. So it will only be conditioned when in use. I'll continue to ventilate and try heating as well.

  2. Expert Member
    Michael Maines | | #3

    Bill, the primary irritants in spray foam are isocyanates: About 50% of the isocyanates are typically released upon installation, and then the foam continues to slowly offgas forever, but the amounts are usually very low, unless the mix did not cure properly, which is possible but unlikely in such thin layers.

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