R Value For Roof Rafters

The higher the r value the greater the insulation performance.

R value for roof rafters.

The greater the r value the more protection you ve got until ice dams form. R value of various materials. It always melts at the joists first. Know exactly how much you need with our project calculators.

The weak link in your r value chain will be your wall studs and ceiling rafters. The r value of a 2x4 stud is only about 4 5. Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. When determining how much insulation you need don t guesstimate calculate.

Figure the rafter depth needed to provide the desired r value. R value measures how well certain building insulation materials can resist heat. Recommends an r 60 roof. Ever seen as snow melts of a vaulted ceiling.

You should of course see the manufacturer provided technical data sheet for the r value of specific products. They are very thin and require insulation to be installed over them. There is no r value with this item. If the garage is open to the rafters the boards that support the roof use r 38 insulation between the rafters at the roof if they are 10 inches deep.

Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value. Raft r mate attic rafter vents create a space between each rafter for air to flow freely up the rafters and into the attic. 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. These are designed to be installed on the underside of the roof sheeting so the insulation doesn rsquo t make contact with plywood.

For a very good introductory overview article on r value see r values over at the website of. Owens corning raft r mate attic rafter vents. Creates an air space to keep the roof shingles cool and the plywood dry. Assist in the constant flow of fresh air from soffit vent to the ridge by preventing blockage of the airway at the soffit.