Dear Inspector,

This month I will discuss notching & boring in beams and joists. This discussion will only include standard sawn dimensional lumber.

Engineered lumber, such as wood I-joists are altered (if allowed at all) by completely different rules, usually available at the manufacturer's website. Do not use these rules below for engineered lumber.

In most houses we find it necessary to notch and bore at least some of the joists and beams during construction. Improper alteration is usually blamed on the plumber or HVAC technician. However, it is actually lack of planning between the trades and/or building designer that causes the need to remove framing that is in the way of house system components. Most residential drawings I have seen have no details at all for plumbing and HVAC except where to place the furnace, tub or toilet. The routing of the systems is left up to the technicians to figure out where to place them with minimal damage.

Inspecting framing requires using judgment. Just because the hole or notch is a bit larger than recommended does not mean the home will not perform. Look for redundant defects or severe cutting that can severely weaken the building. The consumer deserves a home that will perform as intended for the expected time. Determine what the member does before "calling it." Some members are merely fill framing or nailers and don't really take much of a load. Understand the system and you will be able to make reasonable, informed inspections.

The rules below are "from the books" and will assist you in determining the magnitude of notches and bores in the field. The International Residential Code and the Uniform Building Code have the same requirements for notching and boring of beams except that the IRC does not allow notching at the bottom, except for the ends, of beams four inches or thicker. For more detailed explanation see Code Check Building, available from Kaplan by clicking here.

Mike Casey
Kaplan Professional Schools
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