WAC 51-11-1005   Section 1005: Above-grade walls.  


     Section 1005.1 General: Table 10-5, 10-5A and 10-5B list heat-loss coefficients for the opaque portion of above-grade wood stud frame walls, metal stud frame walls and concrete masonry walls (Btu/h • ft2 • °F) respectively. They are derived from procedures listed in RS-1, listed in Chapter 7. For intermediate floor slabs which penetrate the insulated wall, use the concrete wall U-factors in Table 10-5B.


     Insulation is assumed to uniformly fill the entire cavity and to be installed as per manufacturer's directions. All walls are assumed to be finished on the inside with one-half inch gypsum wallboard, and on the outside with either beveled wood siding over one-half inch plywood sheathing or with five-eighths inch T1-11 siding. Insulated sheathing (either interior or exterior) is assumed to cover the entire opaque wall surface.


     1005.2 Framing Description: For wood stud frame walls, three framing types are considered, and defined as follows:


     Standard: Studs framed on sixteen inch centers with double top plate and single bottom plate. Corners use three studs and each opening is framed using two studs. Headers consist of double 2X or single 4X material with an air space left between the header and the exterior sheathing. Interior partition wall/exterior wall intersections use two studs in the exterior wall.


Framing weighting factors: Studs and plates .19
Insulated cavity .77
Headers .04

     Intermediate: Studs framed on sixteen inch centers with double top plate and single bottom plate. Corners use two studs or other means of fully insulating corners, and each opening is framed by two studs. Headers consist of double 2X material with R-10 insulation between the header and exterior sheathing. Interior partition wall/exterior wall intersections are fully insulated in the exterior wall.


Framing weighting factors: Studs and plates .18
Insulated cavity .78
Headers .04

     Advanced: Studs framed on twenty-four inch centers with double top plate and single bottom plate. Corners use two studs or other means of fully insulating corners, and one stud is used to support each header. Headers consist of double 2X material with R-10 insulation between the header and exterior sheathing. Interior partition wall/exterior wall intersections are fully insulated in the exterior wall.


Framing weighting factors: Studs and plates .13
Insulated cavity .83
Headers .04

     1005.3 Component Description: Default coefficients for four types of walls are listed: single-stud walls, metal stud walls, strap walls, and double-stud walls.


     Single-Stud Wall: Assumes either 2x4 or 2x6 studs framed on sixteen or twenty-four inch centers. Headers are solid for 2x4 walls and double 2x for 2x6 walls, with either dead-air or rigid-board insulation in the remaining space.


     Metal Stud Wall: Assumes metal studs spaced on 16 or 24 inch centers with insulation installed to fill wall cavities. Continuous rigid board insulation is applied without creating uninsulated voids in the wall assembly.


     Strap Wall: Assumes 2x6 studs framed on sixteen or twenty-four inch centers. 2x3 or 2x4 strapping is run horizontally along the interior surface of the wall to provide additional space for insulation.


     Double-Stud Wall: Assumes an exterior structural wall and a separate interior, nonstructural wall. Insulation is placed in both wall cavities and in the space between the 2 walls. Stud spacing is assumed to be on 24 inch centers for both walls.

TABLE 10-5


DEFAULT U-FACTORS FOR ABOVE-GRADE WALLS
2 x 4 Single Wood Stud: R-11 Batt    
  Siding Material/Framing Type  
    Lapped Wood T1-11  
  R-value of

Foam Board		 STD ADV STD ADV  
NOTE:


Nominal Batt R-value:

R-11 at 3.5 inch thickness



Installed Batt R-value:

R-11 in 3.5 inch cavity		 0 0.088 0.084 0.094 0.090  
1 0.080 0.077 0.085 0.082  
2 0.074 0.071 0.078 0.075  
3 0.069 0.066 0.072 0.070  
4 0.064 0.062 0.067 0.065  
5 0.060 0.058 0.063 0.061  
6 0.056 0.055 0.059 0.057  
7 0.053 0.052 0.055 0.054  
8 0.051 0.049 0.052 0.051  
9 0.048 0.047 0.050 0.049  
10 0.046 0.045 0.047 0.046  
11 0.044 0.043 0.045 0.044  
12 0.042 0.041 0.043 0.042  
     
2 x 4 Single Wood Stud: R-13 Batt    
  Siding Material/Framing Type  
  Lapped Wood T1-11  
R-value of

Foam Board		 STD ADV STD ADV  
NOTE:


Nominal Batt R-value:

R-13 at 3.63 inch thickness



Installed Batt R-value:

R-12.7 in 3.5 inch cavity		 0 0.082 0.078 0.088 0.083  
1 0.075 0.072 0.080 0.076  
2 0.069 0.066 0.073 0.070  
3 0.065 0.062 0.068 0.065  
4 0.060 0.058 0.063 0.061  
5 0.057 0.055 0.059 0.057  
6 0.053 0.052 0.056 0.054  
7 0.051 0.049 0.052 0.051  
8 0.048 0.047 0.050 0.048  
9 0.046 0.045 0.047 0.046  
10 0.044 0.043 0.045 0.044  
11 0.042 0.041 0.043 0.042  
12 0.040 0.039 0.041 0.040  
     
2 x 4 Single Wood Stud: R-15 Batt    
  Siding Material/Framing Type  
  Lapped Wood T1-11  
R-value of

Foam Board		 STD ADV STD ADV  
NOTE:


Nominal Batt R-value:

R-15 at 3.5 inch thickness



Installed Batt R-value:

R-15 in 3.5 inch cavity		 0 0.076 0.071 0.081 0.075  
1 0.069 0.065 0.073 0.069  
2 0.064 0.061 0.068 0.069  
3 0.060 0.057 0.063 0.059  
4 0.056 0.053 0.059 0.056  
5 0.053 0.051 0.055 0.052  
6 0.050 0.048 0.052 0.050  
7 0.047 0.046 0.049 0.047  
8 0.045 0.044 0.047 0.045  
9 0.043 0.042 0.044 0.043  
10 0.041 0.040 0.042 0.041  
11 0.039 0.038 0.041 0.039  
12 0.038 0.037 0.039 0.038  
     
2 x 6 Single Wood Stud: R-19 Batt    
  Siding Material/Framing Type  
    Lapped Wood T1-11  
  R-value of

Foam Board		 STD INT ADV STD INT ADV  
NOTE:


Nominal Batt R-value:

R-19 at 6 inch thickness



Installed Batt R-value:

R-18 in 5.5 inch cavity

 0 0.062 0.058 0.055 0.065 0.061 0.058  
1 0.058 0.055 0.052 0.060 0.057 0.055  
2 0.054 0.052 0.050 0.056 0.054 0.051  
3 0.051 0.049 0.047 0.053 0.051 0.049  
4 0.048 0.046 0.045 0.050 0.048 0.046  
5 0.046 0.044 0.043 0.048 0.046 0.044  
6 0.044 0.042 0.041 0.045 0.044 0.042  
7 0.042 0.040 0.039 0.043 0.042 0.040  
8 0.040 0.039 0.038 0.041 0.040 0.039  
9 0.038 0.037 0.035 0.039 0.038 0.037  
10 0.037 0.036 0.035 0.038 0.037 0.036  
11 0.036 0.035 0.034 0.036 0.035 0.035  
12 0.034 0.033 0.033 0.035 0.034 0.033  
     
2 x 6 Single Wood Stud: R-21 Batt  
  Siding Material/Framing Type  
    Lapped Wood T1-11  
  R-value of

Foam Board		 STD INT ADV STD INT ADV  
NOTE:


Nominal Batt R-value:

R-21 at 5.5 inch thickness



Installed Batt R-value:

R-21 in 5.5 inch cavity		 0 0.057 0.054 0.051 0.060 0.056 0.053  
1 0.054 0.051 0.048 0.056 0.053 0.050  
2 0.050 0.048 0.045 0.052 0.050 0.047  
3 0.048 0.045 0.043 0.049 0.047 0.045  
4 0.045 0.043 0.041 0.047 0.045 0.043  
  5 0.043 0.041 0.040 0.044 0.042 0.041  
  6 0.041 0.039 0.038 0.042 0.041 0.039  
  7 0.039 0.038 0.036 0.040 0.039 0.037  
  8 0.038 0.036 0.035 0.039 0.037 0.036  
  9 0.036 0.035 0.034 0.037 0.036 0.035  
  10 0.035 0.034 0.033 0.036 0.035 0.033  
  11 0.033 0.033 0.032 0.034 0.033 0.032  
  12 0.032 0.031 0.031 0.033 0.032 0.031  
     
2 x 6 Single Wood Stud: R-22 Batt    
  Siding Material/Framing Type  
    Lapped Wood T1-11  
  R-value of

Foam Board		 STD INT ADV STD INT ADV  
NOTE:


Nominal Batt R-value:

R-22 at 6.75 inch thickness



Installed Batt R-value:

R-20 in 5.5 inch cavity		 0 0.059 0.055 0.052 0.062 0.058 0.054  
1 0.055 0.052 0.049 0.057 0.054 0.051  
2 0.052 0.049 0.047 0.054 0.051 0.048  
3 0.049 0.046 0.044 0.050 0.048 0.046  
4 0.046 0.044 0.042 0.048 0.046 0.044  
5 0.044 0.042 0.041 0.045 0.043 0.042  
6 0.042 0.040 0.039 0.043 0.042 0.040  
  7 0.040 0.039 0.037 0.041 0.040 0.038  
  8 0.038 0.037 0.036 0.039 0.038 0.037  
  9 0.037 0.036 0.035 0.038 0.037 0.035  
  10 0.035 0.034 0.033 0.036 0.035 0.034  
  11 0.034 0.033 0.032 0.035 0.034 0.033  
  12 0.033 0.032 0.031 0.034 0.033 0.032  
     
2 x 6 Single Wood Stud: Two R-11 Batts  
  Siding Material/Framing Type  
    Lapped Wood T1-11  
  R-value of

Foam Board		 STD INT ADV STD INT ADV  
NOTE:


Nominal Batt R-value:

R-22 at 7 inch thickness



Installed Batt R-value:

R-18.9 in 5.5 inch cavity		 0 0.060 0.057 0.054 0.063 0.059 0.056  
1 0.056 0.053 0.051 0.059 0.056 0.053  
2 0.053 0.050 0.048 0.055 0.052 0.050  
3 0.050 0.048 0.046 0.052 0.049 0.047  
4 0.047 0.045 0.044 0.049 0.047 0.045  
  5 0.045 0.043 0.042 0.046 0.045 0.043  
  6 0.043 0.041 0.040 0.044 0.043 0.041  
  7 0.041 0.040 0.038 0.042 0.041 0.039  
  8 0.039 0.038 0.037 0.040 0.039 0.038  
  9 0.038 0.037 0.036 0.039 0.038 0.036  
  10 0.036 0.035 0.034 0.037 0.036 0.035  
  11 0.035 0.034 0.033 0.036 0.035 0.034  
  12 0.034 0.033 0.032 0.034 0.034 0.033  
     
2 x 8 Single Stud: R-25 Batt  
  Siding Material/Framing Type  
    Lapped Wood T1-11  
  R-value of

Foam Board		 STD INT ADV STD INT ADV  
NOTE:


Nominal Batt R-value:

R-25 at 8 inch thickness



Installed Batt R-value:

R-23.6 in 7.25 inch cavity		 0 0.051 0.047 0.045 0.053 0.049 0.046  
1 0.048 0.045 0.043 0.049 0.046 0.044  
2 0.045 0.043 0.041 0.047 0.044 0.042  
3 0.043 0.041 0.039 0.044 0.042 0.040  
4 0.041 0.039 0.037 0.042 0.040 0.038  
  5 0.039 0.037 0.036 0.040 0.038 0.037  
  6 0.037 0.036 0.035 0.038 0.037 0.036  
  7 0.036 0.035 0.033 0.037 0.035 0.034  
  8 0.035 0.033 0.032 0.035 0.034 0.033  
  9 0.033 0.032 0.031 0.034 0.033 0.032  
  10 0.032 0.031 0.030 0.033 0.032 0.031  
  11 0.031 0.030 0.029 0.032 0.031 0.030  
  12 0.030 0.029 0.028 0.031 0.030 0.029  
     
2 x 6: Strap Wall
Siding Material/Frame Type
Lapped Wood T1-11
STD ADV STD ADV
     R-19 + R-11 Batts 0.036 0.035 0.038 0.036
     R-19 + R-8 Batts 0.041 0.039 0.042 0.040
 
2 x 6 + 2 x 4: Double Wood Stud

       Siding Material/Frame Type
Batt Configuration Lapped Wood T1-11
Exterior Middle Interior STD ADV STD ADV
R-19 ------- R-11 0.040 0.037 0.041 0.038
R-19 ------- R-19 0.034 0.031 0.035 0.032
R-19 R-8 R-11 0.029 0.028 0.031 0.029
R-19 R-11 R-11 0.027 0.026 0.028 0.027
R-19 R-11 R-19 0.024 0.023 0.025 0.023
R-19 R-19 R-19 0.021 0.020 0.021 0.020


2 x 4 + 2 x 4: Double Wood Stud
       Siding Material/Frame Type
Batt Configuration Lapped Wood T1-11
Exterior Middle Interior STD ADV STD ADV
R-11 -------- R-11 0.050 0.046 0.052 0.048
R-19 -------- R-11 0.039 0.037 0.043 0.039
R-11 R-8 R-11 0.037 0.035 0.036 0.036
R-11 R-11 R-11 0.032 0.031