The provisions of Section R503 of IECC-RE are adopted by reference with the following modifications:
1. Revise the first paragraph of Section R503.1 to read:
"Alterations to an existing building or building system 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 building system is not less conforming to the provisions of this code than the existing building or building system was prior to the alteration."
2. Revise the exception to Section R503.1.1 to read:
"Exception: The following alterations shall not be required to 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 to reduce solar heat gain provided that the code does not require the glazing or fenestration assembly 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. 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.
7. For roof replacement of low-sloped roofs, where the required thermal resistance 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 thermal resistance of R-5 per inch. In no case shall a roof replacement reduce the thermal resistance (R-value) or increase the thermal transmittance (U-factor) of the roof assembly.
8. The R-value for roof assemblies with tapered above-deck insulation shall average R-42.
9. Air barriers shall not be required for roof recover and roof replacement where the scope of work does not include alterations to any other portion of the building thermal envelope."
3. Revise the exception to Section R503.1.4 by replacing "alterations" with "alterations."