WAC 51-11-1332   Component U-factors.  The U-factors for typical construction assemblies are included in Chapter 10. These values shall be used for all calculations. Where proposed construction assemblies are not represented in Chapter 10, values shall be calculated in accordance with Chapters 23 through 30 in Standard RS-1 listed in Chapter 7, using the framing factors listed in Chapter 10. For envelope assemblies containing metal framing, the U-factor shall be determined by one of the following methods:

1.	Results of laboratory measurements according to acceptable methods of test.
2.	Standard RS-1, listed in Chapter 7, where the metal framing is bonded on one or both sides to a metal skin or covering.
3.	The zone method as provided in Chapter 25 of Standard RS-1, listed in Chapter 7.
4.	Effective framing/cavity R-values as provided in Table 10-5A.

     When return air ceiling plenums are employed, the roof/ceiling assembly shall:

a.	For thermal transmittance purposes, not include the ceiling proper nor the plenum space as part of the assembly; and
b.	For gross area purposes, be based upon the interior face of the upper plenum surface.

[Statutory Authority: RCW 19.27A.020, 19.27A.045. 04-01-106, § 51-11-1332, filed 12/17/03, effective 7/1/04. Statutory Authority: RCW 19.27A.025. 93-21-052, § 51-11-1332, filed 10/18/93, effective 4/1/94.]