Minimum R Values For Roof And Walls

Roofs or ceilings need to be insulated to a minimum of r 38 in zone 3 or r 49 in zone 4.

Minimum r values for roof and walls.

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 measures how well certain building insulation materials can resist heat. Note that there are many other requirements and exceptions to these figures depending on the state type of home and materials your home uses. 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. Recommended home insulation r values. 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.

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. 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. You should of course see the manufacturer provided technical data sheet for the r value of specific products.

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. 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. The higher the r value the better the thermal performance of the insulation. For a very good introductory overview article on r value see r values over at the website of.

R value is a measure of insulation s ability to resist heat traveling through it. Know exactly how much you need with our project calculators. 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. The higher the r value the greater the insulation performance.

Insulation level are specified by r value.