Even small gaps can allow the passage of warm air through the foam rendering the foam all but useless as an insulator.
Spray foam insulation under metal roof without air space good.
To get the best performance out of spray foam insulation you must cover the roof rafters and surrounding areas as thoroughly as possible.
You take a shower but forget to turn the bath fan on.
For best protection professional contractors recommend at least 6 inches of foam insulation board.
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.
In the knee wall area the insulation is in the floor and on the.
You just need to make sure that you put in enough insulation to keep the sheathing above dew point temperature in the cold months.
Since spray foam is both insulation and air barrier proper alignment of insulation and air barrier is guaranteed.
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.
The building envelope should completely surround the conditioned space and the insulation needs to be in contact with the air barrier.
Moisture from the house picture this.
They are not susceptible to moisture infiltration and will keep the roof dry even without a good ventilation system.
What s not guaranteed however is that all spray foam homes will be efficient and comfortable.
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.