Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11R - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Residential › Section 51-11R-50300 - Section R503-Alterations

Current through Register Vol. 24-14, July 15, 2024
R503.1
General.
Alterations
to any building or structure
			 shall comply with the requirements of the code for 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 to the provisions of this
			 code than the existing building or structure was prior to the
alteration
.
Alterations
shall not create an unsafe or
				hazardous condition or overload existing building systems.
Alterations
shall be such that the existing
				building or structure uses no more energy than the existing building or
				structure prior to the
alteration
.
Alterations
to existing buildings shall comply with Sections
				R503.1.1 through R503.2.
The
code official
may approve designs of
alterations
which do not fully conform to all of the
				requirements of this code where in the opinion of the
code
				official
full compliance is physically impossible and/or economically
				impractical and:
The
alteration
improves the energy efficiency
				of the building; or
The
alteration
is energy efficient and is
				necessary for the health, safety, and welfare of the general public.
R503.1.1
Building envelope.
Building envelope assemblies that are part of the
alteration
shall comply with Section R402.1.3 or R402.1.5, Sections R402.2.1 through
			 R402.2.10, R402.3.1, R402.3.2, R402.3.5, and R402.4.2.
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. Existing ceiling, wall or floor cavities exposed
						  during construction provided that these cavities are filled with insulation. 2
						  x 4 framed walls shall be insulated to a minimum of R-15 and 2 x 6 framed walls
						  shall be insulated to a minimum of R-21.
3. Construction where the existing roof, wall or floor
						  cavity is not exposed.
4.
Roof recover
.
5. Roofs without insulation in the cavity and where the
						  sheathing or insulation is exposed during reroofing shall be insulated either
						  above or below the sheathing.
6. 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.
R503.1.1.1
Replacement fenestration.
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 R402.1.3. Where
			 more than one replacement
fenestration
unit is being
			 installed, an area-weighted average of the
U
-factor and SHGC
			 of all replacement
fenestration
shall be permitted to be used
			 to demonstrate compliance.