PDFWAC 51-11C-402141
Table C402.1.4—Opaque thermal envelope requirements, U-factor method.
Table C402.1.4
Opaque Thermal Envelope Requirementsa,f
CLIMATE ZONE | 5 AND MARINE 4 | |
All Other | Group R | |
Roofs | ||
Insulation entirely above deck | U-0.027 | U-0.027 |
Metal buildings | U-0.031 | U-0.031 |
Attic and other | U-0.021 | U-0.021 |
Joist or single rafter | U-0.027 | U-0.027 |
Walls, Above Gradek | ||
Massd,g | U-0.104 | U-0.078 |
Mass transfer deck slabj | U-0.20 | U-0.20 |
Metal building | U-0.050 | U-0.050 |
Steel framed | U-0.055 | U-0.055 |
Wood framed and other | U-0.051 | U-0.051 |
Walls, Below Grade | ||
Below-grade wallb, g | Same as above grade | Same as above grade |
Floors | ||
Masse | U-0.031 | U-0.031 |
Joist/framing | U-0.029 | U-0.029 |
Slab-on-Grade Floors | ||
Unheated slabs | F-0.54 | F-0.54 |
Heated slabsc | F-0.55 | F-0.55 |
Opaque Doors | ||
Nonswinging door | U-0.31 | U-0.31 |
Swinging doorh | U-0.37 | U-0.37 |
Garage door <14% glazing | U-0.31 | U-0.31 |
Garage door ≥14% and <50% glazingi | U-0.34 | U-0.34 |
a | Use of opaque assembly U-factors, C-factors, and F-factors from Appendix A is required unless otherwise allowed by Section C402.1.4. |
b | Where heated slabs are below grade, they shall comply with the F-factor requirements for heated slabs. |
c | Heated slab F-factors shall be determined specifically for heated slabs. Unheated slab factors shall not be used. |
d | 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. | |
e | "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. |
f | Opaque assembly U-factors based on designs tested in accordance with ASTM C1363 shall be permitted. The R-value of continuous insulation shall be permitted to be added or subtracted from the original test design. |
g | Peripheral edges of intermediate concrete floors are included in the above-grade mass wall category and therefore must be insulated as above-grade mass walls unless they meet the definition of Mass Transfer Deck Slab. The area of the peripheral edges of concrete floors shall be defined as the thickness of the slab multiplied by the perimeter length of the edge condition. See Table A103.3.7.2 for typical default U-factors for above-grade slab edges and footnote c for typical conditions of above-grade slab edges. |
h | Swinging door U-factors shall be determined in accordance with NFRC-100. |
i | Garage doors having a single row of fenestration shall have an assembly U-factor less than or equal to 0.44, provided that the fenestration area is not less than 14 percent and not more than 50 percent of the total door area. |
j | Component performance in accordance with Section C402.1.5 shall be required for buildings with a mass transfer deck slab. A mass transfer deck, due to its configuration, is not insulated. The table value (U-0.20) shall be used as the baseline value for component performance or total building performance path calculations. For the proposed value, the appropriate value from Table A103.3.7.2 shall be used. |
k | Through-wall mechanical equipment subject to Section C402.1.4.3 shall be calculated at the U-factor defined in Section C402.1.4.3. The area-weighted U-factor of the wall, including through-wall mechanical equipment, shall not exceed the value in the table. |
[Statutory Authority: RCW 19.27A.045 and chapter 19.27A RCW. WSR 24-16-145, § 51-11C-402141, filed 8/7/24, effective 9/7/24. Statutory Authority: RCW 19.27A.020, 19.27A.025, 19.27A.160 and chapters 19.27A and 19.27 RCW. WSR 22-14-091, 23-12-101, and 23-20-021, § 51-11C-402141, filed 7/1/22, 6/7/23, and 9/25/23, effective 3/15/24. Statutory Authority: RCW 19.27A.020, 19.27A.025, 19.27A.160 and chapter 19.27 RCW. WSR 19-24-040, § 51-11C-402141, filed 11/26/19, effective 7/1/20. Statutory Authority: RCW 19.27A.025, 19.27A.045, 19.27A.160, and 19.27.074. WSR 16-24-070, § 51-11C-402141, filed 12/6/16, effective 5/1/17. Statutory Authority: RCW 19.27A.025, 19.27A.160, and 19.27.074. WSR 16-03-072, § 51-11C-402141, filed 1/19/16, effective 7/1/16.]