Minimum R Values For Roof And Walls

Insulation level are specified by r value.

Minimum r values for roof and walls. You should of course see the manufacturer provided technical data sheet for the r value of specific products. 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. See the department of energy s doe ranges for recommended levels of insulation below. 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.

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. Note that there are many other requirements and exceptions to these figures depending on the state type of home and materials your home uses. Roofs or ceilings need to be insulated to a minimum of r 38 in zone 3 or r 49 in zone 4. The higher the r value the greater the insulation performance.

Basement walls require a minimum of either r 10 continuous or r 13 batted insulation. Below is a table outlining the basic r value requirements for walls roofs and floors. R value measures how well certain building insulation materials can resist heat. 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.

R value is a measure of insulation s ability to resist heat traveling through it. 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. R value of various materials. Required r values for walls roofs and floors.

Minimum r value state local al alabama 2015 alabama commercial energy code 2 r 25 3 r 25 state local ak alaska 2012 alaska building energy efficiency standard 7 r 35 8 r 35. For a very good introductory overview article on r value see r values over at the website of. 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. Know exactly how much you need with our project calculators.

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