Exterior Wall And Roof Insulation R Value

The higher the r value the better the thermal performance of the insulation.

Exterior wall and roof insulation r value.

The r refers to absolute thermal resistance. Foam in place insulation can be blown into walls on attic surfaces or under floors to insulate and reduce air leakage. Foam board or insulating boards are rigid panels of insulation that have a high 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.

Best for floors foundation and basement walls interior and exterior wall sheathing and low sloped ceilings. Basics of faced fiberglass insulation from r 13 to r 19. 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. The table below shows what levels of insulation are cost effective for different climates and.

Note from this. For instance if you have a material with an r value of 12 attached to another material with an r value of 3 then both materials combined have an r value of 15. In simple terms r values measure the effectiveness of insulation and a higher number represents more effective insulation. Additional r value for a masonry wall constructed using these materials needs to add the insulating value of additional wall components typically included such as 1 solid foam polyisocyanurate r 8 extruded polystyrene r 5 expanded polystyrene r 4 or 1 of perlite r 2 7 and for an exterior air film winter no wind r 0 17 an interior.

R value of various materials. For a very good introductory overview article on r value see r values over at the website of. Some installations can yield a higher r value than traditional batt insulation for the same thickness and can fill even the smallest cavities creating an effective air barrier. You can use the small pressurized cans of foam.

These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. You should of course see the manufacturer provided technical data sheet for the r value of specific products. If your exterior walls are constructed from 2 by 4 inch studs the most insulation that can go into the wall while retaining its r value is r 13 or r 15 as these are both made to fit a cavity 3 1 2 inches deep. Because they have a high r value and can be used nearly anywhere in your home foam board insulation is one of the most common types of insulation.

R value is a measure of insulation s ability to resist heat traveling through it. Insulation level are specified by r value. Higher r value numbers mean that the insulating material resists the cold or heat from the outside better. Recommended home insulation r values.