R30 Roof Rafters

The rafters in cathedral ceilings are usually made of 2 in.

R30 roof rafters.

Here s how to use 3 layers of 2 inch polyiso foam board to meet code and keep your ne. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. R30c and r38c are available in both kraft faced and unfaced. The roof rafters provide integral structural support to the roof.

If you re framing a gable roof on a new house or building a shed or even a doghouse with a gable roof you ll need to cut a number of roof rafters. Owens corning r 30 ecotouch pink cathedral ceiling kraft faced fiberglass insulation batt 23 3 4 in. R30 needs 9 inches. The fresh air flows up between rafters to the ridge where a ridge vent roof vents or gable vents allow the air to exit.

39 installing r30 bat insulation 2x8 rafters compress insulation fit. Better than spray foam thermal break and relatively consistent r 30. And owens corning ecotouch high density insulation products are designed specifically for these rafters. For instance if the roof has 2 by 6 rafters and you want r 30 insulation which is standard in many communities you can add a 2 by 4 which will give you an 9 inch rafter space.

If insulation is allowed to bunch against the inside slope of the roof between the rafters air will be blocked before it can traverse the attic. I 39 m stapling the bats between two 2x8 rafters and the attic roof. By installing high density 8 inch fiberglass batt insulation the rafters will then meet an r 30 roof insulation standard. Raft r mate attic rafter vents create a space between each rafter for air to.