The Ontario Building Code | Trimmer Joists

9.23.9.6. Trimmer joists

(1) Trimmer joists around floor openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">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.