Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11R - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Residential › Section 51-11R-40213 - Table R402.1.3-Insulation minimum R-values and fenestration requirements by components

Current through Register Vol. 24-14, July 15, 2024
TABLE R402.1.3
INSULATION MINIMUM
R
-VALUES AND
				FENESTRATION REQUIREMENTS BY
				COMPONENTSa
Climate Zone 5 and Marine
						  4
Fenestrationb,j
U
-Factor
0.30
Skylightb
U
-Factor
0.50
Ceilinge
R
-Value
60
Wood Frame Wallg,i
R
-Value
20+5 or 13+10
Floor
R
-Value
30
Below-Grade Wallc,h
R
-Value
10/15/21 int + 5TB
Slabd,f
R
-Value and Depth
10, 4 ft.
For SI: 1 foot = 304.8 mm, ci = continuous insulation, int =
				intermediate framing.
a
R
-values are
				minimums.
U
-factors and SHGC are maximums. When insulation is
				installed in a cavity which is less than the label or design thickness of the
				insulation, the compressed
R
-value of the insulation from
				Appendix A Table A101.4 of chapter 51-11C WAC shall not be less than the
R
-value specified in the table.
b The fenestration
U
-factor column excludes skylights.
c "10/15/21+5TB" means R-10
				continuous insulation on the exterior of the wall, or R-15 on the continuous
				insulation on the interior of the wall, or R-21 cavity insulation plus a
				thermal break between the slab and the basement wall at the interior of the
				basement wall. "10/15/21+5TB" shall be permitted to be met with R-13 cavity
				insulation on the interior of the basement wall plus R-5 continuous insulation
				on the interior or exterior of the wall. "TB" means R-5 thermal break between
				floor slab and basement wall.
d R-10 continuous insulation is
				required under heated slab on grade floors. See Section R402.2.9.1.
e For single rafter- or
				joist-vaulted ceilings, the insulation may be reduced to R-38 if the full
				insulation depth extends over the top plate of the exterior wall.
f R-7.5 continuous insulation
				installed over an existing slab is deemed to be equivalent to the required
				perimeter slab insulation when applied to existing slabs complying with Section
				R503.1.1. If foam plastic is used, it shall meet the requirements for thermal
				barriers protecting foam plastics.
g For log structures developed in
				compliance with Standard ICC 400, log walls shall meet the requirements for
climate zone
5 of ICC 400.
h Int. (intermediate framing)
				denotes framing and insulation as described in Section A103.2.2 including
				standard framing 16 inches on center, 78 percent of the wall cavity insulated
				and headers insulated with a minimum of R-10 insulation.
i The first value is cavity
				insulation, the second value is continuous insulation. Therefore, as an example
				"13+10" means R-13 cavity insulation plus R-10 continuous insulation.
j A maximum
U
-factor of 0.32 shall apply to vertical fenestration products
				installed in buildings located above 4000 feet in elevation above sea level, or
				in windborne debris regions where protection of openings is required under
				Section R301.2.1.2 of the
International Residential
				Code
.
Statutory Authority:
				  RCW
				    19.27A.020,
				  19.27A.045 and
				  chapters
				  19.27 and
				  34.05 RCW. 13-04-055, §
				  51-11R-40213, filed 2/1/13, effective
				  7/1/13.