Technical Booklet D Structure·Page 25·4B.6
Notches and holes in timber members
Notches and holes in simply supported floor and roof joists must be within limits shown in Diagram 4B.1; roof rafters may only be birdsmouthed at supports to a depth not exceeding 0.33 times the rafter depth.
Notches and holes in simply supported floor and roof joists should be within the limits shown in Diagram 4B.1. No notches or holes should be cut in roof rafters, other than at supports where the rafter may be birdsmouthed to a depth not exceeding 0.33 times the rafter depth.
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