R Value For Floor Joists

Recommended home insulation r values.

R value for floor joists. A double layer is recommended. R value is a measure of insulation s ability to resist heat traveling through it. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. For example us r10 si r 1 76.

Add blown in cellulose to attic. Whether the floor of your crawl space is bare earth gravel or concrete it is going to exude moisture. Most common r value upgrades. A 6 mil polyethylene plastic vapor barrier covering the ground keeps the wet at bay.

To convert to si r values multiply by 0 176. If you are starting with an un insulated space it is very important to read the section below titled estimating r values for un insulated spaces note. The r value per inch for different types of insulation varies depending on the. The idea that heat rises has prevented many builders in the past from insulating floors but adding insulation for floor joists can actually improve a home s energy efficiency as well as its insulating capabilities.

Insulation level are specified by r value. While there are additional considerations such as venting and moisture problems to take into account when you insulate under floors the united states department of energy recommends an r 25 rating in cold climates and an r 11 in warmer parts of the country. These are all us r values. The higher the r value the better the thermal performance of the insulation.

The thicker the insulation the higher the r value. But most floor joists are typically 8 to 10 inches deep or more when used to support a floor in most homes so installing r 19 shouldn t be a problem. This type of crawl space also allows insulation with an r value of 19 installed in the floor joist if the crawl space and has a permanently installed dehumidifier. Add r3 1 for each inch of new cellulose you blow in 1.

Add a vapor barrier. You need to have open access beneath the. If this crawl space has a concrete floor it may or may not have a vapor barrier under the concrete. A 4 by 8 foot sheet of 2 inch thick expanded polystyrene insulation r value 7 7 is 26.