Minimum R Values For Roof And Walls

For a very good introductory overview article on r value see r values over at the website of.

Minimum r values for roof and walls.

Walls need to be insulated to a minimum of r 20 if the insulation is between the studs or r 15 r 5 if the insulation is a combination of insulation between the studs and a continuous layer of exterior insulation in zones 3 or 4. If structural sheathing covers 40 or less of the exterior continuous insulation r value shall be permitted to be reduced by no more than r 3 in the locations where structural sheathing is used to maintain a consistent total sheathing thickness. Note that there are many other requirements and exceptions to these figures depending on the state type of home and materials your home uses. The higher the r value the greater the insulation performance.

The higher the r value the better the thermal performance of the insulation. Recommended home insulation r values. R value is a measure of insulation s ability to resist heat traveling through it. Basement walls require a minimum of either r 10 continuous or r 13 batted insulation.

Required r values for walls roofs and floors. With an r value of 4 0 to 5 1 per inch depending on the manufacturer pre expanded injection foam provides a higher r value than fiberglass or cellulose and it seals the building from air leakage at the same time. Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. See the department of energy s doe ranges for recommended levels of insulation below.

State applicable energy ashrae zone minimum r value state local ms mississippi ashrae 90 1 2010 2 r 20 3 r 20 state local mo missouri 2012 iecc. Below is a table outlining the basic r value requirements for walls roofs and floors. Roofs or ceilings need to be insulated to a minimum of r 38 in zone 3 or r 49 in zone 4. R value measures how well certain building insulation materials can resist heat.

R value of various materials. You should of course see the manufacturer provided technical data sheet for the r value of specific products. Know exactly how much you need with our project calculators. Insulation level are specified by r value.

When determining how much insulation you need don t guesstimate calculate.