spray foam insulation, is it safe?


Well-known member
There's been so many issues with spray foam around here they tried to ban it but in the end settled with requiring a Building Envelope Engineer to OK the use. The biggest issues are in the roof where is not if but when the foam will come in contact with water. Once it does there is no way of knowing it until a small issue has turned in to a massive (rotting the trusses) issue.

Companies will tell you it's closed cell but it's not. Under ideal (something that never happens) conditions the best foam has 5% open cell. That's 5% or more that can absorb water.

Another issue is remodeling. There is no way to remove it other than by hacking it out (I've done it) by hand.

You'll also want to look into thermal drift. This what happens as the foam looses gas (and R value) over several years. An application under the floor if it can't be seal from the living space may not be the best.



Well-known member
Ah, but Matt Risinger did use Spray Foam in that house in some places.
It wouldn't surpise me if Rocwool sponsored the video and he's gets his labor at cost which he doesn't mention. Someone else may use more SF due savings on installation.

The important part is knowing that with ever material there are places it should be, can be and shouldn't be used.

The best application I've see of SF in a roof was it being sprayed over 1" EPS. The EPS was spaced down to allow venting/drying and drainage if the roof leaked.

The ideal solution is to have a continous layer of insulation on the outside of the structure.

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