Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11C - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Commercial › Section 51-11C-402141 - Table C402.1.4-Opaque thermal envelope requirements, U-factor method

Current through Register Vol. 24-14, July 15, 2024
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
Massg
U-0.104
U-0.078
Mass transfer deck
						  slabi
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 [GREATER THAN IS EQUAL TO]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 25 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 A104.3.7.2 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.