Section SPS 322.32 - Specific insulation requirements(1) CEILINGS WITH ATTIC SPACES. (a) R-38 will satisfy the ceiling R-value requirement for a dwelling where the full height of uncompressed R-38 insulation extends over the wall top plate at the eaves.(b) An attic-access cover shall be weatherstripped and insulated to a level equivalent to the insulation on the surrounding surfaces when the attic is an unconditioned space. A wood framed or equivalent baffle or retainer is required to be provided when loose fill insulation is installed, the purpose of which is to prevent loose fill insulation from spilling into the living space when the attic access is opened, and to provide a permanent means of maintaining the installed R-value of the loose fill insulation.(2) CEILINGS WITHOUT ATTIC SPACES. Where the design of the roof or ceiling assembly does not allow sufficient space for the required R-49 insulation, the minimum required insulation for the roof or ceiling assembly shall be R-30. This reduction of insulation shall be limited to 500 square feet of ceiling area.(3) MASS WALLS. The requirements of Table 322.31-1 are applicable to mass walls.(4) STEEL-FRAME CEILINGS, WALLS AND FLOORS. (a) Steel-frame ceilings, walls and floors shall meet the insulation requirements of Table 322.32 or shall meet the U-factor requirements in Table 322.31-2.(b) The calculation of the U-factor for a steel-frame envelope assembly shall use a series-parallel path calculation method.(5) FLOORS. Floor insulation shall be installed to maintain permanent contact with the underside of the subfloor decking.(6) BASEMENT WALLS. (a) Walls associated with conditioned basements shall be insulated from the top of the basement wall down to the basement floor.(b) Walls associated with unconditioned basements shall meet the requirement in par. (a) unless the floor overhead is insulated in accordance with Table 322.31-1.(c) Where the total basement wall area is less than 50 percent below grade, the entire wall area, including the below-grade portion, is included as part of the area of exterior walls.(7) BOX SILL AND RIM JOIST SPACES. Box sills and joist spaces at outside walls shall be insulated to the required wall R-value with air-impermeable insulation that is sealed on all sides to all framing members and the foundation, or with air-permeable insulation held in place as required under s. SPS 322.21(1).(8) OVERHANG JOIST SPACES. (a) Joist spaces that extend beyond exterior walls shall be insulated with an R-value of 30 or higher with insulation that completely fills the cavity including over the top of the exterior wall supporting the joists.(b) The joist space insulation shall be air sealed either by using an air-impermeable insulation that is sealed to all framing members or by covering the insulation with a rigid material that is caulked or sealed to all framing members.(c) If piping that is subject to freezing is located in the joist space, additional insulation shall be provided on the unconditioned side of the space.(9) WALL INSULATION. (a) Except for closed-cell sprayed foam, wall insulation shall completely fill the wall cavity.(b) The vertical and flared walls in a skylight shall meet the insulation requirements for walls. Tube skylights shall be insulated per the manufacturer's recommendations. TABLE 322.32
STEEL-FRAME CEILING, WALL AND FLOOR INSULATION R-VALUES
Wood Frame R-Value Requirement | Cold-Formed Steel Equivalent R-Valuea |
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 2X4 or 2X6 or 2X8 R-49 in any framing |
R-38 | R-49 in 2X4 or 2X6 or 2X8 or 2X10 |
Steel Framed Wall |
R-13 | R-13 + 5 or R-15 + 4 or R-21 + 3 |
R-19 | R-13 + 9 or R-19 + 8 or R-25 + 7 |
R-21 | R-13 + 10 or R-19 + 9 or R-25 + 8 |
Steel Joist Floor |
R-13 | R-19 in 2X6 R-19 + 6 in 2X8 or 2X10 |
R-19 | R-19 + 6 in 2X6 R-19 + 12 in 2X8 or 2X10 |
a Cavity insulation R-value is listed first, followed by continuous insulation R-value.
b Insulation exceeding the height of the framing shall cover the framing.
Wis. Admin. Code Department of Safety and Professional Services SPS 322.32
CR 08-043: cr. Register March 2009 No. 639, eff. 4-1-09; correction in (3) (a), (b), (4) (a), (6) (b), (7) made under s. 13.92(4) (b) 7, Stats., Register December 2011 No. 672.Amended by, CR 15-041: renum. (1) to (1) (a), cr. (1) (b), renum. (3) (a) to (3) and am., r. (3) (b), renum. (9) to (9) (a), cr. (9) (b) Register December 2015 No. 720, eff.1/1/2016