2018 IECC - Residential Provisions

The residential energy code applies to new construction as well as additions, alterations, renovations, and repairs.

Residential buildings include one- and two-family homes and townhouses of any size; apartments, boarding houses, dormitories, and other buildings with two or more permanent dwelling units; and residential care and assisted living facilities with three or fewer stories, among others. 

Any unconditioned space that is altered to become conditioned space, such as heating an unfinished basement, must also fully comply with the code. 

A garage or similar spaces where heating or cooling is installed for frost protection or intermittent can be exempted.

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Residential Changes with Idaho amendments

  • Maximum fenestration U-factor is 0.32 in CZ 5 and 0.30 in CZ 6

  • Minimum R-values for attic in CZ5 is R-38

  • Minimum R-values increased to R-22 in exterior walls in Climate zone 6 due to the deletion of the exterior insulation that was required by the code

  • Duct insulation dependent on the location and diameter of the duct and building framing cavities may not be used as ducts or plenums

  • Homes must be tested and verified as having 3 air changes per her (ACH) or fewer with exceptions, or may have a Visual Inspection option in accordance with items listed in Table R402.4.1.1, as applicable to the method of construction.

  • A separate Table for Log Home Envelope requirements.

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Envelope Testing

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  • Testing must follow RESNET/ICC Standard 380, ASTM E 779, or ASTM E 1827 protocols

  • Testers must be RESNET, BPI, or DET Certified. See upcoming training options for DET Certification

  • Corrective measures are required if the home has more than 3 air changes per hour


Compliance OPtions

  • Prescriptive

  • Total UA Alternative

  • Performance

  • Energy Rating Index

Required inspections

  • Footing and foundation

  • Framing and rough-in

  • Plumbing rough-in

  • Mechanical rough-in

  • Final


Full text of the residential 2018 IECC code provisions is available on ICC’s website, here.