Ceiling Joist and Rafter Boring and Notching

 Ceiling Joist and Rafter Notching

1. Notch structural dimension lumber ceiling joists, rafters, blocking, and beams not deeper than () one-sixth of the actual depth of the member. Notch the member not longer than () one-third of the actual depth of the member. Do not place any notches in the middle one-third of the member. Example: notch a 2×8 ceiling joist not more than () 1 ¼ inches deep and not more than () 2 ½ inches long.

2. You may notch (taper) the end of ceiling joists not deeper than () one-quarter of the actual depth of the joist where the joist bears on a wall. Measure the depth at the inside face of the support wall.

3. You may notch (bird’s mouth cut) the cantilever portion of rafters (rafter tails) if the remaining rafter above the notch is at least () 3 ½ inches deep and the cantilever length is not more than () 24 inches. Measure the cantilever length along the rafter.

4. Notch the tension side (bottom) of a ceiling joist, rafter, or beam that is more than (>) 4 inches thick only at the ends.

Ceiling Joist and Rafter Boring

1. Bore holes in structural dimension lumber ceiling joists, rafters, and beams not more than () one-third of the depth of the member. Place holes at least () 2 inches from the edge of the member and at least () 2 inches from the edge of any other hole or notch. Example: bore a hole in a 2×6 rafter not more than ()1 inches in diameter. 

I-Beam Ceiling Joist and Rafter Notching and Boring

1. Notch and bore wood I-Beam (TJI-type) ceiling joists and rafters only according to manufacturer’s instructions.

2. Do not notch the top and bottom flange unless allowed by the manufacturer.

3. Bore holes in the middle third of the span and not near the ends unless allowed by the manufacturer.

4. Refer to the wood floor joist section for additional information.

Roof Truss Notching and Boring

1. Do not notch or bore wood roof trusses unless specifically permitted in writing by the manufacturer or by an engineer.

Engineered Wood Notching and Boring

1. Do not notch or bore laminated veneer lumber and glue-laminated lumber unless specifically permitted in writing by the manufacturer or by an engineer.