北美地板托梁，大梁开槽,开洞,切割要求

Cutting, Notching, and Bored Holes in Floor Joist

Notching in floor joists and beams and girders. Notches located at the ends of solid lumber floor joists are permitted, provided they do not exceed one-fourth (D/4) of the joist’s depth. Notches are not permitted in the middle third of the span of the joist. Notches in the outer third of the joist span are allowed, but they should not exceed one-sixth (D/6) of the joist’s depth. The diameter of any bored holes in floor joists should not exceed one-third of the joist’s depth (D/3).