Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11C - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Commercial › Section 51-11C-50300 - Section C503-Alterations

Current through Register Vol. 24-14, July 15, 2024
C503.1
General.
Alterations to any building or structure shall comply
			 with the requirements of Section C503 and the code for new construction.
			 Alterations to an existing building, building system or portion thereof shall
			 conform to the provisions of this code as they relate to new construction
			 without requiring the unaltered portions of the existing building or building
			 system to comply with this code. Alterations shall be such that the existing
			 building or structure is no less conforming with the provisions of this code
			 than the existing building or structure was prior to the alteration. The
			 additional energy efficiency credit requirements in Section C406.1 and the
			 renewable energy requirements in Section C411 do not apply to alterations.
EXCEPTION:
The following alterations need not comply with the
						  requirements for new construction provided the energy use of the building is
						  not increased:
1. Storm windows installed over existing
						  fenestration.
2. Surface applied window film installed on existing
						  single pane fenestration assemblies to reduce solar heat gain provided the code
						  does not require the glazing fenestration to be replaced.
3. Existing ceiling, wall or floor cavities exposed
						  during construction provided that these cavities are insulated to full depth
						  with insulation having a minimum nominal value of R-3.0 per inch installed per
						  Section C402.
4. Construction where the existing roof, wall or floor
						  cavity is not exposed.
5.
Roof recover
.
6.
Air barriers
shall not be required
						  for
Roof recover
and roof replacement where the
alterations
or renovations to the building do not include
alterations
, renovations or
repairs
to the
						  remainder of the building envelope.
7. Replacement of existing doors that separate
						  conditioned space from the exterior shall not require the installation of a
						  vestibule or revolving door, provided however that an existing vestibule that
						  separates a conditioned space from the exterior shall not be removed.
C503.2
Reserved.
C503.3
Building envelope.
New building envelope assemblies that are part
			 of the alteration shall comply with Sections C402.1 through C402.5 and Sections
			 C503.3.1 through C503.3.3.
EXCEPTION:
Air leakage testing is not required for alterations and
						  repairs, unless the project includes a change in space conditioning according
						  to Section C503.2 or a change of occupancy or use according to Section
						  C505.1.
C503.3.1
Roof replacement.
Roof replacements
shall comply
			 with Table C402.1.3 or C402.1.4 where the existing roof assembly is part of the
building thermal envelope
and contains no insulation or the
			 insulation is located entirely above the roof deck. In no case shall the
R
-value of the roof insulation be reduced or the
U
-factor of the roof assembly be increased as part of the
roof replacement
.
C503.3.2
Vertical fenestration.
Alterations that include the addition of new vertical fenestration area shall
			 comply with the following:
1. Where the
			 addition of new
vertical fenestration
area results in a total
			 building vertical fenestration area less than or equal to the maximum allowed
			 by Section C402.4.1, the alteration shall comply with Section C402.4.
2. Where the addition of new
vertical
			 fenestration
area result in a total building
vertical
			 fenestration
area greater than the maximum allowed by Section C402.4.1
			 (regardless of the ratio prior to the addition), the alteration shall comply
			 with one of the following:
2.1. Vertical
			 fenestration alternate in accordance with Section C402.1.3 for the new vertical
			 fenestration added.
2.2. Vertical
			 fenestration alternate in accordance with Section C402.4.1.1 for the area
			 adjacent to the new vertical fenestration added.
2.3. Existing building and alteration areas
			 are combined to demonstrate compliance with the component performance alternate
			 in accordance with Section C402.1.5 for the whole building.
U
-factors applied to existing envelope assemblies in the UA
			 calculation shall comply with Section C501.2.1. The Proposed Total UA is
			 allowed to be up to 110 percent of the Allowed Total UA.
2.4. Total building performance in accordance
			 with Section C407 for the whole building. The total annual carbon emissions
			 from energy consumption of the proposed design is allowed to be up to 110
			 percent of the annual carbon emissions from energy consumption allowed in
			 accordance with Section C407.3.
EXCEPTION:
Where
approved
by the
code
						  official
, additional
fenestration
is permitted where
						  sufficient envelope upgrades beyond those required by other sections of this
						  code are included in the project so that the addition of new
vertical
						  fenestration
does not cause an increase in the overall energy use of
						  the building.
C503.3.2.1
Replacement fenestration
			 products.
Where some or all of an existing
fenestration
unit is replaced with a new
fenestration
product, including
			 sash and glazing, the replacement
fenestration
unit shall meet
			 the applicable requirements for
U
-factor and
SHGC
in Table C402.4.
EXCEPTION:
An area-weighted average of the
U
-factor of replacement fenestration products being installed
						  in the building for each fenestration product category listed in Table C402.4
						  shall be permitted to satisfy the
U
-factor requirements for
						  each fenestration product category listed in Table C402.4. Individual
						  fenestration products from different product categories listed in Table C402.4
						  shall not be combined in calculating the area-weighted average
U
-factor.
C503.3.3
Skylights.
Alterations
			 that include the addition of new skylight area shall comply with the following:
1. Where the addition of new
skylight
area results in a total building skylight area less
			 than or equal to the maximum allowed by Section C402.4.1, the alteration shall
			 comply with Section C402.4.
2.
			 Where the addition of new
skylight
area results in a total
			 building skylight area greater than the maximum allowed by Section C402.4.1
			 (regardless of the ratio prior to the addition), the alteration shall comply
			 with one of the following:
2.1. Existing
			 building and alteration area are combined to demonstrate compliance with the
			 component performance alternative with target area adjustment in accordance
			 with Section C402.1.5 for the whole building.
U
-factors
			 applied to existing envelope assemblies in the UA calculation shall comply with
			 Section C501.2.1. The Proposed Total UA is allowed to be up to 110 percent of
			 the Allowed Total UA.
2.2. Total
			 building performance in accordance with Section C407 for the whole building.
			 The annual carbon emissions from energy consumption of the proposed design is
			 allowed to be up to 110 percent of the annual carbon emissions from energy
			 consumption allowed in accordance with Section C407.3.
EXCEPTION:
Additional envelope upgrades are included in the
						  project so the addition of new skylights does not cause a reduction in overall
						  building energy efficiency, as
approved
by the
code
						  official
.