Good Building Score: 13

Recommendation: Avoid

Spray foam has been marketed incredibly well. To the point where it is the conventional approach in high performance building. To the point where energy codes practically force you to use foam in unvented roof systems.

However, in the real world, spray foam tends to fail and fail hard. Its extremely high carbon impact, high toxicity, and terrible for people throughout its entire product lifecycle. In addition, due to being low density and low specific heat capacity, it typically doesn’t provide the comfort or efficiency it promises. Lastly, due to building movement from wetting/drying and heating/cooling cycles, spray foam tends to crack and then allow a large amount of moisture to get trapped in your walls and roof, which leads to rot and mold.