Building Requirements for Partition Walls

Mark

• The IRC requires that all lumber used for framed walls, regardless of whether they are load-bearing, meet certain standards. The lumber must have a mark, called a grade stamp by the industry, that indicates the quality and species of the lumber, as well as the place where it was milled and the agency that did the grading. The grade stamp should also show the amount of moisture retained in the lumber when the stamp was applied. The mark must come from an agency the IRC recognizes as accredited.

Spacing

• The IRC provides guidelines for the amount of space allowable between the studs of a partition wall based on the width of the lumber used. Dimensional lumber that measures 2 inches thick and 4 inches wide, called 2-by-4s, remains the standard lumber used in framing house walls. You can space 2-by-4 studs a maximum of 24 inches apart. When using 2-by-3 lumber, however, you must space the studs no more than 16 inches apart.

Hole and Notch

• Builders might need to drill or notch a partition wall's studs for various reasons, such as running electrical wire. The IRC has certain requirements concerning boring a hole or making a notch in framing lumber, depending on whether it involves a structural wall or partition wall. A hole drilled into a partition wall may not measure more than 60 percent of the width of the stud. A notch cut may not measure more than 40 percent of the stud width.

Fire Block

• Fire blocking is a term for placing pieces of lumber, such as 2-by-4s, between wall cavities to slow the spread of any fire that might break out. This comes under the auspices of the IRC. The code requires fire blocking at the ceiling and the floor, as well as intervals of at least every 10 feet. Because the top and bottom plates of walls qualify as fire blocks and many framed walls do not exceed 10 feet, the typical partition wall does not need additional fire blocking.