Spray Foam Insulation Under Metal Roof Without Air Space Good

An unvented attic air sealed with spray foam insulation limits outdoor air entry and as a result indoor combustion air should not be considered available for fuel fired combustion appliances located within the attic space.

Spray foam insulation under metal roof without air space good.

They are not susceptible to moisture infiltration and will keep the roof dry even without a good ventilation system. The biggest benefit of spray foam insulation is its air sealing quality so if air is infiltrating into a spray foam attic then the installers missed some spots and need to go back and make it right. You take a shower but forget to turn the bath fan on. Even small gaps can allow the passage of warm air through the foam rendering the foam all but useless as an insulator.

What s not guaranteed however is that all spray foam homes will be efficient and comfortable. Nail 1 furring along every rafter side against the roof deck. Since spray foam is both insulation and air barrier proper alignment of insulation and air barrier is guaranteed. You just need to make sure that you put in enough insulation to keep the sheathing above dew point temperature in the cold months.

Moisture from the house picture this. A roof breathes without spray on foam insulation to some extent and it also allows you to see where any dampness is coming in and repair it in this area. The building envelope should completely surround the conditioned space and the insulation needs to be in contact with the air barrier. Other products that say they repair roofs we have seen a product called stormflex that s says it does a better job at repairing tiles etc than spray on foam.

Cut and insert 1 or thicker high r foam insulation sheets r 8 per inch against the furring giving a 1 or greater air path between the insulation and the roof deck under the cathedral ceiling.