Code Library › Volume 1 › Section 9.23 — Wood Frame Construction
PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code

9.23.9.6.Trimmer Joists

(1) Trimmer joists around floor openings shall be doubled when the length of the header joist exceeds 800 mm. (2) When the header joist exceeds 2 m in length the size of the trimmer joists shall be determined by calculations.
← Previous9.23.9.5. Header JoistsNext →9.23.9.7. Support of Tail and Header Joists

Common questions about this part of the code

What stud size and spacing does the Ontario Building Code require for walls?What are the notching and drilling limits for floor joists in Ontario?What are the wall bracing and sheathing requirements for houses in Ontario?

Understand this provision in seconds

BUILDAiD Assist explains any article of the building code in plain English — with exact citations, exceptions and related requirements.

Try BUILDAiD Beta

Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.