In cold climates, can unvented roof assemblies rely on thick open-cell spray foam without exterior rigid insulation and…

[reno_questions]

In cold climates, can unvented roof assemblies rely on thick open-cell spray foam without exterior rigid insulation and still avoid wetting of the roof deck long-term?

[Tim_Michael1 (Ayomikun Peter)]

Relying only on thick open-cell spray foam without exterior insulation is risky in cold climates. It can work if done perfectly, but it’s not the safest or most code-friendly method.

[Lexi_Carter1 (Ogun Mekpon)]

No,in cold climates, thick open-cell spray foam alone can let moisture reach cold roof sheathing and condense. To stay safe and code-compliant long-term, pair it with exterior rigid insulation, closed-cell foam, or a tested hybrid assembly.