Hot Roof Closed Cell Spray Foam

I plan to use the closed cell spray foam insulation on 3 4 inch sheathing.

Hot roof closed cell spray foam.

Both low density open cell and medium density closed cell spray foam can be used in an unvented attic to provide the needed thermal resistance and airtightness. With enough closed cell spray foam under the deck or enough rigid above the deck interior moist air can t condense if the there is no condensation you don t need drying thus no need to vent. It rots roofs people have told me. Instead i like to build a fully vented roof assembly that is insulated with closed cell spray foam.

Closed cell spray foam. Unless you live in climate zones 2b or 3b desert area s in texas new mexico arizona california the codes and common sense will point you to closed cell foam. The foam must be thick enough to meet minimum code requirements. There are fewer reports of problems with closed cell spray foam than with open cell spray foam.

Closed cell spray foam uses blowing agents with a high global warming potential and open cell spray foam needs a. With two strategies employed the airtight vapor impermeable foam plus the ventilation as a safety valve you might call this a belt and suspenders approach to building. If you want to use spray foam here s my advice. Closed cell foam has a higher r value per inch and installers generally spray 2 in walls and 3 in roof lines to meet the energy code requirements of r 13 and r 19 respectively.

Todd miller isaiah industries inc. And again to reiterate hot roof or hot attic assemblies where the foam is beneath the roof deck are okay. The main drawback is high cost. The evaluation service report esr for spray foam insulation products provides a valuable resource based on a third party review of testing information useful for utilizing these products successfully and according to code.

Murmurs and hearsay about open cell spray foam insulation have been gaining traction for a while. Since it s air impermeable spray polyurethane foam can be installed alone on the underside of roof sheathing. Closed cell spray foam is made of cells that are encapsulated and pressed tightly together to prevent air and moisture penetration inside the foam. Not long ago someone even told me that in florida roofing companies won t let their workers go up on roofs with open cell spray foam because the roofs are so spongy the guys fall right through.

Will i be looking at any problem with going to a metal roof. This roof assembly is often referred to as a cold roof and is the antithesis of a hot roof. It doesn t fill the cavity though so spot checks may be required to check you don t get shorted. More common of the two types of spray foam closed cell is mostly used for commercial roofing.

Closed cell or open cell foam.