Exterior Rigid Foam Insulation R Value

For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3.

Exterior rigid foam insulation r value.

C or thermal conductance of these materials is the reciprocal of the r value. The 1 inch foam on the outside of the 2 8 is ok but you ll need more r value planning on more insulation in the wall cavity. For example a house with 2 6 walls in climate zone 6 would need rigid foam with a minimum r value of r 11 25. Owens corning foamular 150 1 1 2 in.

This foam board insulation is available with straight or tongue and groove edges to help limit air movement. Falls in the middle of the three types of rigid foam insulation in both cost and r value used most in walls or below grade applications recyclable and at about r 5 per inch costs around 42 per sq. The article explains that the r value of the rigid foam layer needs to be high enough to keep the osb or plywood sheathing above the dew point during the winter. 3 benefits of rigid foam sheathing.

Rigid foam insulation one option is to use polyurethane rigid foam insulation. For a 1 in thick 4 8 panel comes unfaced or with a number of different plastic facings. Closed cell foams are more dense and rigid typically about 2 lb cu. This foam board insulation is the rigid pink or blue panels that can be found at home centers in many different thicknesses.

Polyurethane rigid foam is a. More effective insulation with r values ranging from 3 6 to 8 0 rigid foam sheathing has much better insulation per inch than other materials i e. R 7 5 scored squared edge rigid foam board insulation sheathing model 88wd view the owens corning exterior insulation. House wrap is a good idea even with foam on the outside of the house.

Plywood has an r value of 1 25 and fiberglass batts have an r value of 3 14. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. It is denser than eps and provides more r value with a rating of 5 per inch of thickness. Open cell foams are typically about 1 2 lb cubic foot.