External Wall Insulation R Value

The table below shows what levels of insulation are cost effective for different climates and locations in the home.

External wall insulation r value.

The higher the r value the better the thermal performance of the insulation. The r refers to absolute thermal resistance. R value is a measure of insulation s ability to resist heat traveling through it. Insulation level are specified by r value.

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. In construction the r value is the measurement of a material s capacity to resist heat flowfrom one side to the other. R value is a standard unit of measurement for determining among many things how effective your insulation will be. Other typical wall materials have similarly low values.

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. 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. For example a wall with 3 fiberglass batting r value of 10 8 11 9 may have an overall r value of nearly 14 because of siding sheathing and drywall. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.

Try the r value calculator available through oak ridge. 1 2 exterior plywood has an r value of 0 63 and exterior wood bevel siding has an r value of just 0 80. 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.

Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. How to achieve r 21 in a 2x4 wall. Insulation is rated in two ways r value and u 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.

Because insulation fits the width and depth of the cavity between studs when you compress insulation to fit the space you remove its. Higher r value numbers mean that the insulating material resists the cold or heat from the outside better. 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.