Roof Insulation R Value Requirements

Non residential above roof deck this matrix provides the minimum insulation r values required by local and state municipalities.

Roof insulation r value requirements.

Pa302 1 ceilings with attic spaces n1102 2 1 r402 2 1. Or component performance alternative of section c402 1 5 roof solar reflectance and thermal emittance fenestration in building envelope. Existing 3 4 inches of insulation. 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.

R value measures how well certain building insulation materials can resist heat. Add insulation to attic. R value based method of section c402 1 3 u c and f factor based method of section c402 1 4. Specific insulation requirements of section c402 2 thermal requirements of either.

State applicable energy ashrae zone minimum r value state local ms mississippi ashrae 90 1 2010 2r 20 3r 20 state local mo missouri 2012 iecc 4r 25 5r 25. 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. Recommended insulation levels for retrofitting existing wood framed buildings. R 38 shall be deemed to satisfy the requirement for r 49 wherever the full height of uncompressed r 38 insulation extends over the wall top plate at the eaves.

Know exactly how much you need with our project calculators. Minimum insulation r value requirements non residential above roof deck. 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 2015 irc requires r 49 insulation for ceilings with attic spaces.

When determining how much insulation you need don t guesstimate calculate. State only ma massachusetts 780 cmr chapter 13 5 r 30 state only mi michigan ashrae 90 1 2007 5 r 20 6 r 20 7 r 20 state only mn minnesota minnesota commercial state building code 6 r 30 7 r 35 please see disclaimer on back page. Gables to be insulated as exterior walls. Mandatory minimum r 22 attic insulation unvented attics must be air sealed at roof deck eaves gables and penetrations.

However there is an exception. Minimum insulation r value requirements by state. Climate zones 1 5 and 8 16 wall assemblies must not exceed a maximum u factor of 0 051 climate zones 6 7 wall assemblies must not exceed a maximum u factor of 0 065. The higher the r value the greater the insulation performance.

Minimum insulation r value requirements non residential above roof deck.