6.2 Core Workflows and Decision Points

Studs: size, spacing, notching, and boring

After confirming stud size and spacing against Table R602.3(5), the inspector's next routine check is notching and boring under IRC R602.6 — the most-tested numeric rule in this domain because plumbers and electricians constantly cut into framing.

• Notching a stud in an exterior wall or bearing partition: maximum 25% of the stud depth.
• Notching a stud in a nonbearing (interior) partition: maximum 40% of the stud depth.
• Boring a hole in any stud: maximum 40% of stud depth. If the wall is sheathed and the hole is in a doubled stud, the bore may be up to 60%, but no more than two successive doubled studs may be so bored.
• The hole edge must be not less than 5/8 in from the edge of the stud, and a bore must not be in the same section as a cut or notch.

Worked example — notch limit on a 2x4

A nominal 2x4 stud has an actual depth of 3-1/2 in. In a bearing wall the maximum notch is 25% × 3.5 = 0.875 in (7/8 in). In a nonbearing wall the same stud allows 40% × 3.5 = 1.4 in. A plumber's 1-1/4 in notch is therefore a violation in a bearing wall but acceptable in a nonbearing partition. The exam trap is forgetting to first ask whether the wall is load-bearing.

Plates, headers, and fireblocking

Top plates (R602.3.2). Bearing and exterior walls are framed with a double top plate. End joints in the upper and lower plates must be offset at least 24 in, the plates lap at corners and intersections, and the splice is nailed per Table R602.3.2 (commonly 8-16d). A single top plate is permitted only when the tie conditions of R602.3.2 are met (rafters/joists centered over studs within 1 in, and a galvanized strap tie at splices).

Headers (R602.7). Openings in load-bearing walls need a header sized from Table R602.7(1) by species, ground snow load, building width, and what the header carries (roof/ceiling only, roof + one floor, or two floors). Headers bear on jack (trimmer) studs; king studs run full height beside the opening and are end-nailed to the header with 4-16d nails (R602.7.5). The number of jack and king studs increases with span per Table R602.7.5.

Fireblocking (R602.8). Fireblocking cuts off concealed draft paths so fire cannot travel unseen through framing. Required locations include:

• Concealed wall spaces, vertically at the ceiling and floor levels and horizontally at intervals not exceeding 10 ft.
• At interconnections between concealed vertical and horizontal spaces — such as soffits, drop/cove ceilings, and stair stringers.
• Around penetrations for vents, pipes, ducts, cables, and wires at ceiling and floor level, and at the top and bottom of chimney chases.

Approved fireblocking materials include nominal 2-in lumber, two layers of 1-in lumber, 23/32-in wood structural panel, 1/2-in gypsum, mineral wool, and fiberglass batts in the cited conditions.

Decision flow

1. Identify the member (stud, plate, header, opening, concealed space).
2. Name the IRC section (R602.3, R602.6, R602.7, R602.8).
3. Look up the threshold or table value.
4. Compare the field condition and cite the result.
5. Record the section number on your correction notice for an audit trail.

Bottom plates, cripples, and connection of the wall to the structure

The wall does not stand alone — it must transfer load down and resist uplift and sliding. The bottom (sole) plate under R602.3.4 must give studs full bearing on a nominal 2-by or larger plate at least as wide as the studs. Where the wall sits on a foundation, the plate becomes a sill plate anchored with 1/2-in anchor bolts, embedded at least 7 in, spaced no more than 6 ft on center, and within 12 in of each plate end/corner (a Chapter 4 rule the inspector applies at the wall-to-foundation joint).

Cripple studs are the short studs that run above a header to the top plate, or below a window sill to the bottom plate. Where a cripple wall (a short framed wall between foundation and first floor) exceeds 14 in in height, it is framed and braced as a story; cripple walls under 14 in are sheathed solid. These distinctions appear in scenario questions about partial-height framing.

Connection summary

Common exam trap

A stem may describe a wall with studs not aligned over the floor joists below and ask if a single top plate is acceptable. Single top plates require rafters/joists to be centered over studs within 1 in plus a strap tie; if the framing does not line up, the wall needs a double top plate. Reading the alignment cue is what tells you which rule applies.