Heads up: There are no amended sections in this chapter.

Climate zones from Table C301.1 shall be used in determining the applicable requirements from Chapter 4.

TABLE C301.1

CLIMATE ZONES, MOISTURE REGIMES, AND WARM-HUMID DESIGNATIONS BY STATE AND COUNTY

Key: A — Moist, B - Dry, C - Marine

Absence of moisture designation indicates moisture regime is irrelevant

WASHINGTON
5B Adams
5B Asotin
5B Benton
5B Chelan
4C Clallam
4C Clark
5B Columbia
4C Cowlitz
5B Douglas
5B Ferry
5B Franklin
5B Garfield
5B Grant
4C Grays Harbor
4C Island
4C Jefferson
4C King
4C Kitsap
5B Kittitas
5B Klickitat
4C Lewis
5B Lincoln
4C Mason
5B Okanogan
4C Pacific
5B Pend Oreille
4C Pierce
4C San Juan
4C Skagit
5B Skamania
4C Snohomish
5B Spokane
5B Stevens
4C Thurston
4C Wahkiakum
5B Walla Walla
4C Whatcom
5B Whitman
5B Yakima
The interior design temperatures used for heating and cooling load calculations shall be a maximum of 72°F (22°C) for heating and minimum of 75°F (24°C) for cooling.
The heating or cooling outdoor design temperatures shall be selected from Appendix CC.
Materials, systems and equipment shall be identified in a manner that will allow a determination of compliance with the applicable provisions of this code.

An R-value identification mark shall be applied by the manufacturer to each piece of building thermal envelope insulation 12 inches (305 mm) or greater in width. Alternatively, the insulation installers shall provide a certification listing the type, manufacturer and R-value of insulation installed in each element of the building thermal envelope. For blown or sprayed insulation (fiberglass and cellulose), the initial installed thickness, settled thickness, settled R-value, installed density, coverage area and number of bags installed shall be listed on the certification. For sprayed polyurethane foam (SPF) insulation, the installed thickness of the areas covered and R-value of installed thickness shall be listed on the certification. For insulated siding, the R-value shall be labeled on the product's package and shall be listed on the certification. The insulation installer shall sign, date and post the certification in a conspicuous location on the job site.

Exception: For roof insulation installed above the deck, the R-value shall be labeled as required by the material standards specified in Table 1508.2 of the International Building Code.

The thickness of blown-in or sprayed fiberglass and cellulose roof/ceiling insulation shall be written in inches (mm) on markers for every 300 square feet (28 m2) of attic area throughout the attic space. The markers shall be affixed to the trusses or joists and marked with the minimum initial installed thickness with numbers of not less than 1 inch (25 mm) in height. Each marker shall face the attic access opening. Spray polyurethane foam thickness and installed R-value shall be listed on certification provided by the insulation installer.
Insulating materials shall be installed such that the manufacturer's R-value mark is readily observable upon inspection.

U-factors of fenestration shall be determined as follows:

  1. For windows, doors and skylights, U-factor ratings shall be determined in accordance with NFRC 100.
  2. Where required for garage doors and rolling doors, U-factor ratings shall be determined in accordance with either NFRC 100 or ANSI/DASMA 105.

U-factors shall be determined by an accredited, independent laboratory, and labeled and certified by the manufacturer.

Products lacking such a labeled U-factor shall be assigned a default U-factor from Table C303.1.3(1), C303.1.3(2) or C303.1.3(4). The solar heat gain coefficient (SHGC) and visible transmittance (VT) of glazed fenestration products (windows, glazed doors and skylights) shall be determined in accordance with NFRC 200 by an accredited, independent laboratory, and labeled and certified by the manufacturer. Products lacking such a labeled SHGC or VT shall be assigned a default SHGC or VT from Table C303.1.3(3).

Exception: Units without NFRC ratings produced by a small business may be assigned default U-factors from Table C303.1.3(5) for vertical fenestration.


TABLE C303.1.3(1)

DEFAULT GLAZED WINDOW, GLASS DOOR AND SKYLIGHT U-FACTORS

FRAME TYPE WINDOW AND
GLASS DOOR
SKYLIGHT
SINGLE
PANE
DOUBLE
PANE
Metal 1.20 0.80 See Table C303.1.3(4)
Metal with Thermal Breaka 1.10 0.65
Nonmetal or Metal Clad 0.95 0.55
Glazed Block 0.60

For SI: 1 inch = 25.4 mm.

  1. Metal Thermal Break = A metal thermal break framed window shall incorporate the following minimum design characteristics:

    1. The thermal conductivity of the thermal break material shall be not more than 3.6 Btu-in/h/ft2/°F;
    2. The thermal break material must produce a gap in the frame material of not less than 0.210 inches; and
    3. All metal framing members of the products exposed to interior and exterior air shall incorporate a thermal break meeting the criteria in Items 1 and 2 above.

TABLE C303.1.3(2)

DEFAULT OPAQUE DOOR U-FACTORS
See Appendix CA, Section CA107


TABLE C303.1.3(3)

DEFAULT GLAZED FENESTRATION SHGC AND VT

  SINGLE GLAZED DOUBLE GLAZED GLAZED
Clear Tinted Clear Tinted
SHGC 0.40 0.40 0.40 0.40 0.40
VT 0.6 0.3 0.6 0.3 0.6


TABLE C303.1.3(4)

DEFAULT U-FACTORS FOR SKYLIGHTSa, b, c, d

FENESTRATION TYPE FRAME TYPE
Aluminum Without
Thermal Break
Aluminum With
Thermal Break
Reinforced Vinyl/
Aluminum-Clad Wood
or Vinyl
Wood or Vinyl-Clad
Wood/Vinyl without
Reinforcing
Single Glazing        
Glass U-1.58 U-1.51 U-1.40 U-1.18
Acrylic/Polycarb U-1.52 U-1.45 U-1.34 U-1.11
         
Double Glazing        
Air U-1.05 U-0.89 U-0.84 U-0.67
Argon U-1.02 U-0.86 U-0.80 U-0.64
Double Glazing, e=0.20        
Air U-0.96 U-0.80 U-0.75 U-0.59
Argon U-0.91 U-0.75 U-0.70 U-0.54
Double Glazing, e=0.10        
Air U-0.94 U-0.79 U-0.74 U-0.58
Argon U-0.89 U-0.73 U-0.68 U-0.52
Double Glazing, e=0.05        
Air U-0.93 U-0.78 U-0.73 U-0.56
Argon U-0.87 U-0.71 U-0.66 U-0.50
         
Triple Glazing        
Air U-0.90 U-0.70 U-0.67 U-0.51
Argon U-0.87 U-0.69 U-0.64 U-0.48
Triple Glazing, e=0.20        
Air U-0.86 U-0.68 U-0.63 U-0.47
Argon U-0.82 U-0.63 U-0.59 U-0.43
Triple Glazing, e=0.20 on 2 surfaces        
Air U-0.82 U-0.64 U-0.60 U-0.44
Argon U-0.79 U-0.60 U-0.56 U-0.40
Triple Glazing, e=0.10 on 2 surfaces        
Air U-0.81 U-0.62 U-0.58 U-0.42
Argon U-0.77 U-0.58 U-0.54 U-0.38
         
Quadruple Glazing, e=0.10 on 2 surfaces        
Air U-0.78 U-0.59 U-0.55 U-0.39
Argon U-0.74 U-0.56 U-0.52 U-0.36
Krypton U-0.70 U-0.52 U-0.48 U-0.32

Notes for Table C303.1.3(4)

  1. U-factors are applicable to both glass and plastic, flat and domed units, all spacers and gaps.
  2. Emissivities shall be less than or equal to the value specified.
  3. Gap fill shall be assumed to be air unless there is a minimum of 90% Argon Or Krypton.
  4. Aluminum frame with thermal break is as defined in Note a to Table C303.1.3(1).

TABLE C303.1.3(5)

SMALL BUSINESS COMPLIANCE TABLE DEFAULT U-FACTORS FOR VERTICAL FENESTRATION

VERTICAL FENESTRATION DESCRIPTION FRAME TYPE
Any Frame Aluminum
Thermal Breakb
Wood/Vinyl/
Fiberglass
Panes Low-ea Spacer Fill
Doublec A Any Argon 0.48 0.41 0.32
B Any Argon 0.46 0.39 0.30
C Any Argon 0.44 0.37 0.28
C High Performance Argon 0.42 0.35 Deemed to complye
Tripled A Any Air 0.50 0.44 0.26
B Any Air 0.45 0.39 0.22
C Any Air 0.41 0.34 0.20
Any double low-e Any Air 0.35 0.32 0.18
  1. Low-eA (emissivity) shall be 0.24 to 0.16.
    Low-eB (emissivity) shall be 0.15 to 0.08.
    Low-eC (emissivity) shall be 0.07 or less.
  2. Aluminum Thermal Break = An aluminum thermal break framed window shall incorporate the following minimum design characteristics:

    1. The thermal conductivity of the thermal break material shall be not more than 3.6 Btu-in/h/ft2/°F;
    2. The thermal break material must produce a gap in the frame material of not less than 0.210 inches; and
    3. All metal framing members of the products exposed to interior and exterior air shall incorporate a thermal break meeting the criteria in Items 1 and 2 above.
  3. A minimum air space of 0.375 inches between panes of glass is required for double glazing.
  4. A minimum air space of 0.25 inches between panes of glass is required for triple glazing.
  5. Deemed to comply glazing shall not be used for performance compliance.
The thermal resistance (R-value) of insulation shall be determined in accordance with the U.S. Federal Trade Commission R-value rule (C.F.R. Title 16, Part 460) in units of h × ft2 × °F/Btu at a mean temperature of 75°F (24°C).
The thermal resistance (R-value) shall be determined in accordance with ASTM C1363. Installation for testing shall be in accordance with the manufacturer's installation instructions.

Table C303.1.5 provides default U-factors for the spandrel section of glass and other curtain wall systems. Design factors that affect performance are the type of framing, the type of spandrel panel and the R-value of insulation. Four framing conditions are considered in the table. The first is the common case where standard aluminum mullions are used. Standard mullions provide a thermal bridge through the insulation, reducing its effectiveness. The second case is for metal framing members that have a thermal break. A thermal break frame uses a urethane or other nonmetallic element to separate the metal exposed to outside conditions from the metal that is exposed to interior conditions. The third case is for structural glazing or systems where there are no exposed mullions on the exterior. The fourth case is for the condition where there is no framing or the insulation is continuous and uninterrupted by framing. The columns in the table can be used for any specified level of insulation between framing members installed in framed curtain walls or spandrel panels.

TABLE C303.1.5

U-FACTORS FOR SPANDREL PANELS AND GLASS CURTAIN WALLS

RATED R-VALUE OF INSULATION BETWEEN FRAMING MEMBERS
None R-4 R-7 R-10 R-15 R-20 R-25 R-30
FRAME TYPE SPANDREL PANEL A B C D E F G H
Aluminum without
Thermal Break
Single glass pane, stone or metal panel 1 0.360 0.242 0.222 0.212 0.203 0.198 0.195 0.193
Double glass with no low-e coatings 2 0.297 0.233 0.218 0.209 0.202 0.197 0.194 0.192
Triple or low-e glass 3 0.267 0.226 0.214 0.207 0.200 0.196 0.194 0.192
Aluminum with
Thermal Break
Single glass pane, stone or metal panel 4 0.350 0.211 0.186 0.173 0.162 0.155 0.151 0.149
Double glass with no low-e coatings 5 0.278 0.200 0.180 0.170 0.160 0.154 0.151 0.148
Triple or low-e glass 6 0.241 0.191 0.176 0.167 0.159 0.153 0.150 0.148
Structural
Glazing
Single glass pane, stone or metal panel 7 0.354 0.195 0.163 0.147 0.132 0.123 0.118 0.114
Double glass with no low-e coatings 8 0.274 0.180 0.156 0.142 0.129 0.122 0.117 0.114
Triple or low-e glass 9 0.231 0.169 0.150 0.138 0.127 0.121 0.116 0.113
No Framing,
or Insulation
is Continuous
Single glass pane, stone or metal panel 10 0.360 0.148 0.102 0.078 0.056 0.044 0.036 0.031
Double glass with no low-e coatings 11 0.297 0.136 0.097 0.075 0.054 0.043 0.035 0.030
Triple or low-e glass 12 0.267 0.129 0.093 0.073 0.053 0.042 0.035 0.030
Where "window wall" or similar assembly that is discontinuous at intermediate slab edges is used, the slab edge U-value shall be as listed in Appendix Table CA103.3.7.2 or as determined using an approved calculation.

In addition to the spandrel panel assembly, the construction assembly U-factors assume an air gap between the spandrel panel (with an R-value of 1.39) and one layer of 5/8-inch (15.9 mm) gypsum board (with an R-value of 0.56) that provides the interior finish. The gypsum board is assumed to span between the window sill and a channel at the floor. For assemblies that differ from these assumptions, custom U-factors can be calculated to account for any amount of continuous insulation or for unusual construction assemblies using Equations 3-1, 3-2 or 3-3 where appropriate. Spandrel panel U-factors for assemblies other than those covered by Table C303.1.5 or Equations 3-1 through 3-3 may be determined using an alternate approved methodology. Equations 3-1 through 3-3 do not calculate the value of any insulation inboard of the curtain wall assembly.

Aluminum without Thermal Break

(Equation 3-1)

Aluminum with Thermal Break

(Equation 3-2)

Structural Glazing

(Equation 3-3)
Materials, systems and equipment shall be installed in accordance with the manufacturer's instructions and the International Building Code or International Residential Code, as applicable.
Insulation applied to the exterior of basement walls, crawl-space walls and the perimeter of slab-on-grade floors shall have a rigid, opaque and weather-resistant protective covering to prevent the degradation of the insulation's thermal performance. The protective covering shall cover the exposed exterior insulation and extend not less than 6 inches (153 mm) below grade.
Where two or more layers of continuous insulation board are used in a construction assembly, the continuous insulation boards shall be installed in accordance with Section C303.2. Where the continuous insulation board manufacturer's instructions do not address installation of two or more layers, the edge joints between each layer of continuous insulation boards shall be staggered.
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