External Wall Insulation R Value

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.

External wall insulation r value.

R value is a standard unit of measurement for determining among many things how effective your insulation will be. 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. How to achieve r 21 in a 2x4 wall. The r value is a calculation which measures the flow of heat through an insulation product or its.

In construction the r value is the measurement of a material s capacity to resist heat flowfrom one side to the other. Because insulation fits the width and depth of the cavity between studs when you compress insulation to fit the space you remove its. 1 2 exterior plywood has an r value of 0 63 and exterior wood bevel siding has an r value of just 0 80. Other typical wall materials have similarly low values.

Thickness density and type of materials are some factors that contribute to. 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. Try the r value calculator available through oak ridge. Let me explain when the general public hears an r 13 wall insulation they believe that in.

R value is a measure of insulation s ability to resist heat traveling through it. The table below shows what levels of insulation are cost effective for different climates and locations in the home. 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. 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.

These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. 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. Higher r value numbers mean that the insulating material resists the cold or heat from the outside better. Insulation is rated in two ways r value and u value.

Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. 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. In simple terms r values measure the effectiveness of insulation and a higher number represents more effective insulation.