Roof Insulation R Value Code

The higher the r value the better the thermal performance of the insulation.

Roof insulation r value code.

The higher the r value the greater the insulation performance. See the department of energy s doe ranges for recommended levels of insulation below. 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.

State applicable code ashrae zone minimum r value state local al alabama 2015 alabama commercial energy code 2 r 25 3 r 25 state. Recommended home insulation r values. Know exactly how much you need with our project calculators. Minimum insulation r value requirements non residential above roof deck.

Building and energy codes almost always specify a required minimum r value for exterior walls and roof assemblies with above deck insulation so the minimum required r value in your local jurisdiction is something that you need to take into account when planning a building project. 2015 code requires walls to be insulated with a minimum of r 20 or r 13 5 13 5 means r 13 cavity insulation plus r 5 insulated sheathing. When determining how much insulation you need don t guesstimate calculate. Energy codes and roofs.

R value measures how well certain building insulation materials can resist heat. 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. These energy code r value requirements change from state to state and even city to city. State applicable energy ashrae zone.

Tapered insulation is the most common method for creating a slope on a low slope roof but frustratingly neither code addresses compliance for tapered systems. The table below shows what levels of insulation are cost effective for different climates and. Types of roof insulation. Insulation level are specified by r value.

In addition the common belief that an average r value is just as good as the code requirements is just that a common belief not a fact.