Existing buildings. From Ohio which is IRC based.
Additions or
alterations to
residential buildings shall conform with the requirements of the code for new construction and shall be
approved by the
residential building official. Additions or
alterations shall not be made to an existing
residential building or structure which will cause the existing
residential building or structure to be in violation of any provisions of this code. Portions of the structure not altered and not affected by the
alteration are not required to comply with the code requirements for a new structure.
Exception: For
residential buildings and structures in
flood hazard areas, any additions,
alterations or
repairs that constitute substantial improvement of the existing structure, shall comply with the flood design requirements for new construction and all aspects of the existing structure shall be brought into compliance with the requirements for new construction for flood design.
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Replacements of an existing system (egress, fire protection, mechanical,
plumbing, etc.) and materials or building components not otherwise provided for in this section, shall conform to that required for new construction to the extent of the
alteration. The existing systems, materials, or components shall not be required to comply with all of the requirements of this code for new construction except to the extent that they are affected by the
alteration. Replacement of existing systems, materials, or components shall not cause them to become unsafe, hazardous, overloaded, or become less effective than when originally installed, constructed, and/or
approved.
