---
kind: "section"
citation: "10 C.F.R. § 460.102"
title: "10"
number: "460.102"
heading: "Building thermal envelope requirements."
url: "https://uscodex.org/cfr/10/460.102"
---

# §460.102. Building thermal envelope requirements.

- (a) **Compliance options.** The building thermal envelope must meet either the prescriptive requirements of [paragraph (b)](#b) of this section or the performance requirements of [paragraph (c)](#c) of this section.
- (b) **Prescriptive requirements.**
  - (1) The building thermal envelope must meet the applicable minimum R-value (nominal value of insulation), and the glazing maximum U-factor and SHGC, requirements set forth in table 1 to [§ 460.102(b)(1)](#b-1) and table 2 to [§ 460.102(b)(2)](#b-2) or component U-values set forth in table 3 to [§ 460.102(b)(5)](#b-5) and table 4 to [§ 460.102(b)(5)](#b-5).
  - (2) For the purpose of compliance with the exterior ceiling insulation R-value requirement of [paragraph (b)(1)](#b-1) of this section, the truss heel height must be a minimum of 5.5 inches at the outside face of each exterior wall.
  - (3) A combination of R-21 batt insulation and R-14 blanket insulation may be used for the purpose of compliance with the floor insulation R-value requirement of table 2 to [§ 460.102(b)(1)](#b-1), Climate Zone 3.
  - (4) An individual skylight that has an SHGC that is less than or equal to 0.30 is not subject to the glazed fenestration SHGC requirements established in [paragraph (b)(1)](#b-1) of this section. Adapted from section R402 of the 2021 IECC.
  - (5) **U—** factor alternatives to R-value requirements. Compliance with the applicable requirements in [paragraph (b)(1)](#b-1) of this section may be determined using the applicable maximum U-factor values set forth in table 3 to [§ 460.102(b)(5)](#b-5) and table 4 to [§ 460.102(b)(5)](#b-5), which reflect the thermal transmittance of the component, excluding fenestration, and not just the insulation of that component, as an alternative to the minimum nominal R-value requirements set forth in table 1 to [§ 460.102(b)(1)](#b-1) and table 2 to [§ 460.102(b)(1)](#b-1), respectively.
- (c) **Performance requirements.**
  - (1) The building thermal envelope must have a Uo that is less than or equal to the applicable value specified in table 5 to [§ 460.102(c)(1)](#c-1) and table 6 to [§ 460.102(c)(1)](#c-1).
  - (2) Area-weighted average vertical fenestration U-factor must not exceed 0.48 in Climate Zone 2 or 0.40 in Climate Zone 3. Adapted from section R402 of the 2021 IECC.
  - (3) Area-weighted average skylight U-factor must not exceed 0.75 in Climate Zone 2 and Climate Zone 3. Adapted from section R402 of the 2021 IECC.
  - (4) Windows, skylights and doors containing more than 50 percent glazing by area must satisfy the SHGC requirements established in [paragraph (b)(1)](#b-1) of this section on the basis of an area-weighted average. Adapted from section R402 of the 2021 IECC.
- (d) [Reserved].
- (e) **Determination of compliance with paragraph (c) of this section.**
  - (1) **U—** o must be determined in accordance with Overall U-Values and Heating/Cooling Loads—Manufactured Homes (incorporated by reference; see [§ 460.3](/cfr/10/460.3.md))
  - (2) [Reserved]

## Notes

### Authority

Authority: 42 U.S.C. 17071; 42 U.S.C. 7101 et seq.

### Source

Source: 87 FR 32818, May 31, 2022, unless otherwise noted.