Chapter 44 — REFERENCED STANDARDS
Section BO106 — ADDITION
2025 California Residential Code (Title 24, Part 2.5) · 2025 edition · ingested 2026-07-07 · California
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BO106.1 General. ¶
BO106.1 General. Where existing buildings with the addition are within the scope of this code, additions shall comply with this section and other applicable provisions of this code for new construction or as permitted by this appendix. Engineered design in accordance with Section R301.1.3 shall be permitted to meet the requirements of this section.
BO106.2 Structure for horizontal additions. ¶
BO106.2 Structure for horizontal additions. Where an addition involves new construction attached to an existing building, the new construction shall meet all of the structural requirements of this code for new construction. Alterations to the existing building shall comply with the requirements governing alterations within this code. In wood light-frame additions, connection of the structural components shall be permitted to be provided using wall top plates and addition studs that abut the existing building. Wall top plates shall be lapped and spliced in accordance with Section R602.3.2.…
BO106.3 Structure for vertical additions. ¶
BO106.3 Structure for vertical additions. Where an addition involves new construction that adds a story to any part of the existing building or vertically increases the height of any part of the existing building, the new construction and the existing building together shall be shown to comply with, or altered to comply with, all of the structural requirements of this code for new construction. Exception: Where the new structure and the existing structure together are evaluated in accordance with accepted engineering practice and are shown to be sufficient to support the combined loads from…