N1108.1 (R502.1) General. Additions to an existing building,
building system or portion thereof shall conform to the
provisions of this chapter as they relate to new construction
without requiring the unaltered portion of the existing building
or building system to comply with 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 chapter where the addition alone complies,
where the existing building and addition comply with this
chapter as a single building, or where the building with the
addition does not use more energy than the existing building.
Additions shall be in accordance with Section N1108.1.1 or
N1108.1.2.