External Wall Insulation R Value

The r refers to absolute thermal resistance.

External wall insulation r value.

Higher r value numbers mean that the insulating material resists the cold or heat from the outside better. The r value is a calculation which measures the flow of heat through an insulation product or its. In simple terms r values measure the effectiveness of insulation and a higher number represents more effective insulation. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.

In construction the r value is the measurement of a material s capacity to resist heat flowfrom one side to the other. The table below shows what levels of insulation are cost effective for different climates and locations in the home. R value is a measure of insulation s ability to resist heat traveling through it. Find your zone on the map and then use the above insulation r value chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces.

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. Let me explain when the general public hears an r 13 wall insulation they believe that in. Thickness density and type of materials are some factors that contribute to. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system.

Other typical wall materials have similarly low values. Try the r value calculator available through oak ridge. But when you add 3 1 2 of fiberglass insulation with an r value of 11 0 the entire wall structure can have a thermal resistance of nearly 14 not bad but not ideal especially in. Insulation level are specified by r value.

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. Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. Because insulation fits the width and depth of the cavity between studs when you compress insulation to fit the space you remove its. R value is a standard unit of measurement for determining among many things how effective your insulation will be.

1 2 exterior plywood has an r value of 0 63 and exterior wood bevel siding has an r value of just 0 80. How to achieve r 21 in a 2x4 wall. 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.