N1102.2 (R402.2) Specific Insulation Requirements (Prescriptive)
Access doors from conditioned spaces to unconditioned spaces such as attics and crawl spaces shall be weatherstripped and insulated to a level equivalent to the insulation on the surrounding surfaces. Access that prevents damaging or compressing the insulation shall be provided to all equipment. Where loose-fill insulation is installed, a wood-framed or equivalent baffle or retainer shall be installed to prevent the loose-fill insulation from spilling into the living space when the attic access is opened. The baffle or retainer shall provide a permanent means of maintaining the installed R-value of the loose-fill insulation.
Exception: Vertical doors providing access from conditioned spaces to unconditioned spaces that comply with the fenestration requirements of Table N1102.1.2 based on the applicable climate zone specified in Section N1101.7.
Steel-frame ceilings, walls, and floors shall comply with the insulation requirements of Table N1102.2.6 or the U-factor requirements of Table N1102.1.4. The calculation of the U-factor for a steel-frame envelope assembly shall use a series-parallel path calculation method.
TABLE N1102.2.6 (R402.2.6)
STEEL-FRAME CEILING, WALL AND FLOOR INSULATION R-VALUES
|WOOD FRAME |
|Steel Truss Ceilingsb|
|R-30||R-38 or R-30 + 3 or R-26 + 5|
|R-38||R-49 or R-38 + 3|
|R-49||R-38 + 5|
|Steel Joist Ceilingsb|
|R-30||R-38 in 2 × 4 or 2 × 6 or 2 × 8 R-49|
in any framing
|R-38||R-49 in 2 × 4 or 2 × 6 or 2 × 8 or 2 × 10|
|Steel-Framed Wall, 16 inches on center|
|R-13||R-13 + 4.2 or R-21 + 2.8 or|
R-0 + 9.3 or R-15 + 3.8 or R-21 + 3.1
|R-13 + 3||R-0 + 11.2 or R-13 + 6.1 or R-15 + 5.7 or|
R-19 + 5.0 or R-21 + 4.7
|R-20||R-0 + 14.0 or R-13 + 8.9 or R-15 + 8.5 or|
R-19 + 7.8 or R-19 + 6.2 or R-21 + 7.5
|R-20 + 5||R-13 + 12.7 or R-15 + 12.3 or R-19 + 11.6 or|
R-21 + 11.3 or R-25 + 10.9
|R-21||R-0 + 14.6 or R-13 + 9.5 or R-15 + 9.1 or|
R-19 + 8.4 or R-21 + 8.1 or R-25 + 7.7
|Steel-Framed Wall, 24 inches on center|
|R-13||R-0 + 9.3 or R-13 + 3.0 or R-15 + 2.4|
|R-13 + 3||R-0 + 11.2 or R-13 + 4.9 or R-15 + 4.3 or|
R-19 + 3.5 or R-21 + 3.1
|R-20||R-0 + 14.0 or R-13 + 7.7 or R-15 + 7.1 or|
R-19 + 6.3 or R-21 + 5.9
|R-20 + 5||R-13 + 11.5 or R-15 + 10.9 or R-19 + 10.1 or|
R-21 + 9.7 or R-25 + 9.1
|R-21||R-0 + 14.6 or R-13 + 8.3 or R-15 + 7.7 or|
R-19 + 6.9 or R-21 + 6.5 or R-25 + 5.9
|Steel Joist Floor|
|R-13||R-19 in 2 × 6, or R-19 + 6 in 2 × 8 or 2 × 10|
|R-19||R-19 + 6 in 2 × 6, or R-19 + 12 in 2 × 8 or 2 × 10|
Floor framing-cavity insulation shall be installed to maintain permanent contact with the underside of the subfloor decking.
Exception: As an alternative, the floor framing-cavity insulation shall be in contact with the topside of sheathing or continuous insulation installed on the bottom side of floor framing where combined with insulation that meets or exceeds the minimum wood frame wall R-value in Table N1102.1.2 and that extends from the bottom to the top of all perimeter floor framing members.
- The minimum ceiling insulation R-values shall be R-19 in Climate Zones 1 through 4 and R-24 in Climate Zones 5 through 8.
- The minimum wall insulation R-value shall be R-13 in all climate zones. Walls separating a sunroom with a thermal isolation from conditioned space shall comply with the building thermal envelope requirements of this code.