Section 51-11C-402121. Table C402.1.3—Opaque thermal envelope assembly R-value requirements.

Table C402.1.3

Opaque Thermal Envelope Insulation Component

Minimum Requirements, R-value Methoda,g

For SI:	1 inch = 25.4 mm. ci = Continuous insulation. NR = No requirement.
LS =	Liner system—A continuous membrane installed below the purlins and uninterrupted by framing members. Uncompressed, unfaced insulation rests on top of the membrane between the purlins.
a	Assembly descriptions can be found in Chapter 2 and Appendix A.
b	Where using R-value compliance method, a thermal spacer block shall be provided, otherwise use the U-factor compliance method in Table C402.1.4.
c	Exception: Integral insulated concrete block walls complying with ASTM C90 with all cores filled and meeting both of the following:
	1. At least 50 percent of cores must be filled with vermiculite or equivalent fill insulation; and
	2. The building thermal envelope encloses one or more of the following uses: Warehouse (storage and retail), gymnasium, auditorium, church chapel, arena, kennel, manufacturing plant, indoor swimming pool, pump station, water and waste water treatment facility, storage facility, storage area, motor vehicle service facility. Where additional uses not listed (such as office, retail, etc.) are contained within the building, the exterior walls that enclose these areas may not utilize this exception and must comply with the appropriate mass wall R-value from Table C402.1.3/U-factor from Table C402.1.4.
d	Where heated slabs are below grade, below-grade walls shall comply with the exterior insulation requirements for heated slabs.
e	Steel floor joist systems shall be insulated to R-38 + R-10ci.
f	"Mass floors" shall include floors weighing not less than: 1. 35 pounds per square foot of floor surface area; or 2. 25 pounds per square foot of floor surface area where the material weight is not more than 120 pounds per cubic foot.
g	For roof, wall or floor assemblies where the proposed assembly would not be continuous insulation, an alternate nominal R-value compliance option for assemblies with isolated metal penetrations of otherwise continuous insulation is:

This alternate nominal R-value compliance option is allowed for projects complying with all of the following:

1.	The ratio of the cross-sectional area, as measured in the plane of the surface, of metal penetrations of otherwise continuous insulation to the opaque surface area of the assembly is greater than 0.0004 (0.04%), but less than 0.0012 (0.12%).
2.	The metal penetrations of otherwise continuous insulation are isolated or discontinuous (e.g., brick ties or other discontinuous metal attachments, offset brackets supporting shelf angles that allow insulation to go between the shelf angle and the primary portions of the wall structure). No continuous metal elements (e.g., metal studs, z-girts, z-channels, shelf angles) penetrate the otherwise continuous portion of the insulation.
3.	Building permit drawings shall contain details showing the locations and dimensions of all the metal penetrations (e.g., brick ties or other discontinuous metal attachments, offset brackets, etc.) of otherwise continuous insulation. In addition, calculations shall be provided showing the ratio of the cross-sectional area of metal penetrations of otherwise continuous insulation to the overall opaque wall area.

For other cases where the proposed assembly is not continuous insulation, see Section C402.1.4 for determination of U-factors for assemblies that include metal other than screws and nails.

[Statutory Authority: RCW 19.27A.025, 19.27A.160, and 19.27.074. WSR 16-03-072, § 51-11C-402121, filed 1/19/16, effective 7/1/16. Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-402121, filed 2/1/13, effective 7/1/13.]

RCW 19.27A.025, 19.27A.160, and 19.27.074. WSR 16-03-072, § 51-11C-402121, filed 1/19/16, effective 7/1/16. Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-402121, filed 2/1/13, effective 7/1/13.