Roof Insulation R Value Requirements

Mandatory minimum r 22 attic insulation unvented attics must be air sealed at roof deck eaves gables and penetrations.

Roof insulation r value requirements.

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. 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. 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.

See the department of energy s doe ranges for recommended levels of insulation below. However there is an exception. The higher the r value the greater the insulation performance. When determining how much insulation you need don t guesstimate calculate.

Minimum insulation r value requirements non residential above roof deck. Or component performance alternative of section c402 1 5 roof solar reflectance and thermal emittance fenestration in building envelope. These energy code r value requirements change from state to state and even city to city. 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.

R value measures how well certain building insulation materials can resist heat. Non residential above roof deck this matrix provides the minimum insulation r values required by local and state municipalities. Existing 3 4 inches of insulation. Know exactly how much you need with our project calculators.

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. 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. Specific insulation requirements of section c402 2 thermal requirements of either. Minimum r value non residential above roof deck title.

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 2015 irc requires r 49 insulation for ceilings with attic spaces. 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. Recommended insulation levels for retrofitting existing wood framed buildings.

Gables to be insulated as exterior walls.