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 Washington Administrative Code (Last Updated: November 23, 2016)
 Title 51. Enterprise Services, Department of (Building Code Council)
 Chapter 51-11C. State Building Code adoption and amendment of the 2015 edition of the International Energy Conservation Code, Commercial.

  Section 51-11C-40222. Section C402.2.2—Roof assembly.  

Latest version.
  • C402.2.2 Roof assembly. The minimum thermal resistance (R-value) of the insulating material installed either between the roof framing or continuously on the roof assembly shall be as specified in Table C402.1.3, based on construction materials used in the roof assembly. Skylight curbs shall be insulated to the level of roofs with insulation entirely above deck or R-5, whichever is less.
    EXCEPTIONS:
    1. Continuously insulated roof assemblies where the thickness of insulation varies 1 inch (25 mm) or less and where the area-weighted U-factor is equivalent to the same assembly with the R-value specified in Table C402.1.3.
     
    2. Where tapered insulation is used with insulation entirely above deck, those roof assemblies shall show compliance on a U-factor basis per Section C402.1.4. The effective U-factor shall be determined through the use of Tables A102.2.6(1), A102.2.6(2) and A102.2.6(3).
     
    3. Unit skylight curbs included as a component of a skylight listed and labeled in accordance with NFRC 100 shall not be required to be insulated.
    Insulation installed on a suspended ceiling with removable ceiling tiles shall not be considered part of the minimum thermal resistance of the roof insulation.
    [Statutory Authority: RCW 19.27A.025, 19.27A.160, and 19.27.074. WSR 16-03-072, § 51-11C-40222, filed 1/19/16, effective 7/1/16. Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-40222, filed 2/1/13, effective 7/1/13.]
RCW 19.27A.025, 19.27A.160, and 19.27.074. WSR 16-03-072, § 51-11C-40222, filed 1/19/16, effective 7/1/16. Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-40222, filed 2/1/13, effective 7/1/13.