Within a project area, for any project undertaken by an agency for building rehabilitation or alteration in construction, an agency may take those actions which the agency determines necessary and which is consistent with local, state, and federal law, to provide for seismic retrofits as follows:

1. (a) For unreinforced masonry buildings, to meet the requirements of Appendix Chapter A1 of the current California Existing Building Code (Part 10 of Title 24 of the California Code of Regulations).
2. (b) For any buildings that qualify as “historical property” under Section 37602, to meet the requirements of the State Historical Building Code (Part 2.7 (commencing with Section 18950) of Division 13) and the current California Historical Building Code (Part 8 of Title 24 of the California Code of Regulations).

3. (c) For buildings other than unreinforced masonry buildings and historical properties, to meet the requirements of Appendix A: Guidelines for the Seismic Retrofit of Existing Buildings of the International Existing Building Code unless superseding building standards for existing buildings are adopted in the California Building Code (Part 2 of Title 24 of the California Code of Regulations).

   If an agency undertakes seismic retrofits and proposes to add new territory to the project area, to increase either the limitation on the number of dollars to be allocated to the redevelopment agency or the time limit on the establishing of loans, advances, and indebtedness established pursuant to paragraphs (1) and (2) of Section 33333.2, to lengthen the period during which the redevelopment plan is effective, to merge project areas, or to add significant additional capital improvement projects, as determined by the agency, the agency shall amend its redevelopment plan and follow the same procedure, and the legislative body is subject to the same restrictions, as provided for in Article 4 (commencing with Section 33330) for the adoption of a plan.