The provisions of Section C503 of IECC-CE are adopted by reference with the following modifications:
1. Revise Section C503.1 to read:
"C503.1 General.
Alterations to any existing building shall comply with the requirements of Section C503. Alterations shall be such that the existing building is not less conforming to the provisions of this code than the existing building was prior to the alteration. Alterations 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 portions of the existing building or building system to comply with this code. Alterations shall not create an unsafe or hazardous condition or overload existing building systems.
Exception: The following alterations need not comply with the requirements for new construction, provided that the energy use of the building is not increased:
1. Storm windows installed over existing fenestration.
2. Surface-applied window film installed on existing fenestration assemblies reducing solar heat gain, provided that the code does not require the glazing or fenestration to be replaced.
3. Existing ceiling, wall or floor cavities exposed during construction, provided that these cavities are filled with insulation with a thermal resistance of at least R-3 per inch. Insulation shall not be required to be added to existing wall cavities for masonry above-grade walls where a registered design professional indicates in the construction documents that insulation would block air circulation in the cavity and create moisture problems that would potentially lead to differential expansion and contraction.
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 scope of work does not include alterations or repairs to the remainder of the building envelope."
2. Revise the exception to Section C503.2 to read:
"Exception: Where the existing building exceeds the fenestration area limitations of Section C402.4.1 prior to alteration, the building is exempt from Section C402.4.1 provided that there is not an increase in fenestration area."
3. Revise Section C503.2.1 to read:
"Roof replacements shall comply with Section C402.1.3, C402.1.4, C402.1.5 or C407 where the existing roof assembly is part of the building thermal envelope and contains insulation entirely above the roof deck. In no case shall the thermal resistance (R-value) of the roof insulation be reduced or the thermal transmittance (U-factor) of the roof assembly be increased as part of the roof replacement. For low-sloped roofs, where the required R- value cannot be provided due to flashing height limitations presented by existing rooftop conditions that are not being altered, such as HVAC equipment, door or window sill height, parapet height, weep holes, and roof flashing heights not meeting the manufacturer’s specifications if reduced, the maximum thickness of insulation compatible with the available space and existing conditions shall be installed. New insulation shall have a minimum R-value of R-5 per inch. In no case shall a roof replacement reduce the R-value of the roof assembly."
4. Revise Section C503.2.2 to read:
"The addition of vertical fenestration that results in a total building fenestration area less than or equal to that specified in Section C402.4.1 shall comply with Section C402.1.5, C402.4.3 or C407. The addition of vertical fenestration that results in a total building fenestration area greater than Section C402.4.1 shall comply with Section C402.4.1.1 for the space adjacent to the new fenestration only. Alterations that result in a total building vertical fenestration area exceeding that specified in Section C402.4.1.1 shall comply with Section C402.1.5 or C407. Provided that the vertical fenestration area is not changed, using the same vertical fenestration area in the standard reference design as the building prior to alteration shall be an alternative to using the vertical fenestration area specified in Table C407.4.1(1)."
5. Revise the exception to Section C503.2.2.1 by replacing "permitted" with "allowed."
6. Revise Section C503.2.3 to read:
"C503.2.3 Skylight fenestration area.
New skylight fenestration area that results in a total building skylight fenestration area less than or equal to that specified in Section C402.4.1 shall comply with Section C402.1.5, C402.4 or C407. The addition of skylight fenestration area that results in a total building skylight fenestration area greater than Section C402.4.1 shall comply with Section C402.4.1.2 for the space adjacent to the new skylights. Alterations that result in a total building skylight fenestration area exceeding that specified in Section C402.4.1.2 shall comply with Section C402.1.5 or C407. Provided that the skylight fenestration area is not changed, using the same skylight fenestration area in the standard reference design as the building prior to alteration shall be an alternative to using the skylight fenestration area specified in Table C407.4.1(1)."
7. Revise Section C503.3 by replacing "duct systems" with "duct systems."