Encapsulate Spray Foam to block off gassing / odors
How can one encapsulate closed cell spray foam that is off gassing, giving odors — to stop the odors/gases from getting into the attic / home?
Reason for question: In the DC area it is common to encapsulate asbestos. An advisor asks me, why can’t the spray foam likewise be encapsulated?
Unable to find instances of encapsulating spray foam, after hours of internet searches and talking with more than 3 local insulation companies.
Context: Contracted to encapsulate the attic of a 1950s structural masonry home with 7″ closed cell spray foam under the roof deck and 2″ at the gable ends (~11,000 board feet over an ~1630 square foot footprint).
If the foam gasses cannot be encapsulated, then the roof will be replaced as part of removal of the spray foam. Interviews with > 10 companies (insulators and dry ice blasters) resulted in none willing to remove from underneath. Was told that the risk of water leaks from damaging the roofing nails sticking through the plywood is not worth trying to do the spray foam removal that way.
Air Test 8 weeks in:
Column A Chemical
Column B Safe Max — Residential Air Tier III Screening Level (μg/m3)
Column C Measured — Result (μg/m3)
Chemical Safe Max Measured
Chloroform .2 0.68
Dichloropropane, 1,2- .42 43.2
Dioxane, 1,4- 3.1 3.32
Three compounds were detected at concentrations greater than the screening level, chloroform, 1,2- Dichloropropane, and 1,4- Dioxane. Of these, 1,2-dichloroproane and 1,4-dioxane have been found to be associated with spay foam insulations (Dzhordzhio Naldzhiev et al 2019 IOP Conf. Ser.: Mater. Sci. Eng. 609 042053)
Based on these results, it appears that the installation of spray foam insulation has resulted in concentrations of volatile organic compounds that may pose a health risk to occupants.
Using chemicals from 2 different companies / manufacturers
Installer used chemicals from 2 different manufacturers and did not provide the required added ventilation during install. Chemical company for the polyol blend side B states that since it was not matched with our isocyanate, the installed product does not meet the requirements of our code compliance report nor the published values on our technical data sheet.
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Replies
sunpass,
I'm no expert on this but like you I have been unable to find any reports of successful foam encapsulation. I suspect that is because unlike asbestos where it is the fibers that are problematic, with spay foam it is chemical off-gassing. So rather than just sticking the surface together, you would need to provide a completely air-tight barrier.
Almost anything CAN be done.
The question is almost always should it be done.
I think the reason one is unable to find much about remediating failed spray foam is because remediation almost always happens after the law suit that is settled with a non-disclosure agreement.
Walta
Thank you for the comments and feedback. Will proceed with tearing off the roof then.
Had a good talk with an architect Friday afternoon about SIPs, specifically Thermocore, and may use that. The 8" roof panel meets Climate Zone 4 roof insulation requirements. Leary of doing 7" of closed cell spray foam again.
Since the roof needs to be rebuilt will also be looking into adding a 2 foot overhang to all sides of the home. Understand that overhangs serve a protection function to the home & walls. Just have an overhang on the south / front side at the moment.
Consider getting the HVAC out of the attic. OK that is crazy talk and total impossible but I had to say it because it really is the best idea.
Consider something like this with sheet foam on the roof.
https://www.greenbuildingadvisor.com/article/five-cathedral-ceilings-that-work
Walta
Former spray foam contractor here ...
We had a couple of times where we were asked to cover the urethane foam with a sprayed-on cementitious fireproofing - have you explored whether or not this would do an effective job encapsulating?