R30 Roof Rafters

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.

R30 roof rafters. Before you cut your boards you ll need to measure the width of your building and calculate the exact length of each rafter. 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. The roof rafters provide integral structural support to the roof.

Better than spray foam thermal break and relatively consistent r 30. Raft r mate attic rafter vents create a space between each rafter for air to. Owens corning r 30 ecotouch pink cathedral ceiling kraft faced fiberglass insulation batt 23 3 4 in. Here s how to use 3 layers of 2 inch polyiso foam board to meet code and keep your ne.

Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. If you re using fiberglass insulation you need thicker wall or ceiling cavities to fit insulation with a higher r value. 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. The rafters in cathedral ceilings are usually made of 2 in.

By installing high density 8 inch fiberglass batt insulation the rafters will then meet an r 30 roof insulation standard. The fresh air flows up between rafters to the ridge where a ridge vent roof vents or gable vents allow the air to exit. R30 needs 9 inches. 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.