R502.1 General. Additions to an existing building, building system or portion thereof shall conform to the provisions of this code as those provisions relate to new construction without requiring the unaltered portion of the existing building or building system to comply with this code, except as specified in this chapter. Additions shall not create an unsafe or hazardous condition or overload existing building systems. An addition shall be deemed to comply with this code where the addition alone complies, where the existing building and addition comply with this code as a single building, or where the building with the addition uses no more energy than the existing building. Additions shall be in accordance with Section R502.3 or R502.4.
R502.1.1 Small additions.Additions not greater than 150 square feet (13.9 m2) shall not be required to comply with Section R406.
R502.2 Change in space conditioning. Any nonconditioned or low-energy space that is altered to become conditioned space shall be required to be brought into full compliance with this code.
EXCEPTION: | Where the total building performance option in Section R405 is used to comply with this section, the annual energy use of the proposed design is permitted to be 110 percent of the annual energy use otherwise allowed by Section R405.3. |
R502.3 Prescriptive compliance. Additions shall comply with Sections R502.3.1 through R502.3.4.
R502.3.1 Building envelope. New building envelope assemblies that are part of the addition shall comply with Sections R402.1, R402.2, R402.3.1 through R402.3.5, and R402.4.
EXCEPTION: | Where nonconditioned space is changed to conditioned space, the building envelope of the addition shall comply where the UA, as determined in Section R402.1.5, of the existing building and the addition, and any alterations that are part of the project, is less than or equal to UA generated for the existing building. |
R502.3.1.1 Existing ceilings with attic spaces. Where an addition greater than 150 square feet (13.9 m2) adjoins existing ceilings with attic spaces, the existing attic spaces shall comply with Section R402.
R502.3.2 Heating and cooling systems. HVAC ducts newly installed as part of an addition shall comply with Section R403.
EXCEPTION: | The following need not comply with the testing requirements of Section R403.3.3: |
| 1. Additions of less than 150 square feet. |
| 2. Duct systems that are documented to have been previously sealed as confirmed through field verification and diagnostic testing in accordance with procedures in WSU RS-33. |
| 3. Existing duct systems constructed, insulated or sealed with asbestos. |
R502.3.3 Service hot water systems. New service hot water systems that are part of the addition shall comply with Section R403.5.
R502.3.4 Lighting. New lighting systems that are part of the addition shall comply with Section 404.1.
R502.4 Existing plus addition compliance (Total Building Performance). Where nonconditioned space is changed to conditioned space the addition shall comply where the annual energy use of the addition and the existing building, and any alterations that are part of the project, is less than or equal to the annual energy use of the existing building when modeled in accordance with Section R405. The addition and any alterations that are part of the project shall comply with Section R405 in its entirety.
[Statutory Authority: RCW
19.27A.020,
19.27A.045,
19.27A.160, and chapter
19.27A RCW. WSR 24-03-084, § 51-11R-50200, filed 1/16/24, effective 3/15/24; WSR 23-02-060, 23-12-102, and 23-20-022, § 51-11R-50200, filed 1/3/23, 6/7/23, and 9/25/23, effective 3/15/24. Statutory Authority: RCW
19.27A.020,
19.27A.045,
19.27A.160 and chapter
19.27 RCW. WSR 20-01-047, § 51-11R-50200, filed 12/9/19, effective 7/1/20. Statutory Authority: RCW
19.27A.025,
19.27A.045,
19.27A.160, and
19.27.074. WSR 17-10-063, § 51-11R-50200, filed 5/2/17, effective 6/2/17. Statutory Authority: RCW
19.27A.020,
19.27A.045,
19.27A.160, and
19.27.074. WSR 16-02-127, § 51-11R-50200, filed 1/6/16, effective 7/1/16.]