WAC 51-11-1001   Section 1001 General.  


     1001.1 Scope: The following defaults shall apply to Chapters 1 through 20. This chapter includes tables of seasonal average heat-loss coefficients for specified nominal insulation. The heat-loss coefficients may also be used for heating system sizing.


     1001.2 Description: These coefficients were developed primarily from data and procedures from Standard RS-1, and taken specifically from Standard RS-2, listed in Chapter 7.


     Coefficients not contained in this chapter may be computed using the procedures listed in these references if the assumptions in the following sections and Standard RS-2, listed in Chapter 7, are used, along with data from the sources referenced above.


     1001.3 Air Films: Default R-values used for air films shall be as follows:

R-Value	Condition
0.17	All exterior surfaces
0.61	Interior horizontal surfaces, heat flow up
0.92	Interior horizontal surfaces, heat flow down
0.68	Interior vertical surfaces

     1001.4 Compression of Insulation: Insulation which is compressed shall be rated in accordance with Table 10-A or reduction in value may be calculated in accordance with the procedures in Standard RS-1, listed in Chapter 7.

TABLE 10-A

R-Value of Fiberglass Batts Compressed within Various Depth Cavities

Insulation R-Value at Standard Thickness
R-Value		38	30	22	21	19	15	13	11	8	5	3
Standard Thickness		12"	9-1/2"	6-3/4"	5-1/2"	6-1/4"	3-1/2"	3-5/8"	3-1/2"	2-1/2"	1-1/2"	3/4"
Nominal Lumber Sizes, Inches	Actual Depth of Cavity, Inches	Insulation R-Values when Installed in a Confined Cavity
2 x 12	11-1/4	37	--	--	--	--	--	--	--	--	--	--
2 x 10	9-1/4	32	30	--	--	--	--	--	--	--	--	--
2 x 8	7-1/4	27	26	--	--	--	--	--	--	--	--	--
2 x 6	5-1/2	--	21	20	21	18	--	--	--	--	--	--
2 x 4	3-1/2	--	--	14	--	13	15	13	11	--	--	--
2 x 3	2-1/2	--	--	--	--	--	--	9.8	--	--	--	--
2 x 2	1-1/2	--	--	--	--	--	--	6.3	6.0	5.7	5.0	--
2 x 1	3/4	--	--	--	--	--	--	--	--	--	3.2	3.0

[Statutory Authority: RCW 19.27A.020, 19.27A.045. 04-01-106, § 51-11-1001, filed 12/17/03, effective 7/1/04. Statutory Authority: RCW 19.27A.025, 19.27A.045. 01-03-010, § 51-11-1001, filed 1/5/01, effective 7/1/01. Statutory Authority: RCW 19.27A.020 and 1990 c 2. 91-01-112, § 51-11-1001, filed 12/19/90, effective 7/1/91.]