IRC Wall Framing Inspection: Studs, Headers, Bracing and the B1 Exam

Wall Types, Grade and the Load Path

Chapter 6 of the IRC is wall construction and R602 is the prescriptive path for wood walls. R602.3 requires studs to run from sole plate to top plate, except jack, trimmer and cripple studs at openings sized from Tables R602.7(1) and R602.7(2). R602.2 sets grade at a minimum No. 3, standard or stud grade, with utility grade limited to nonbearing studs.

2x4 and 2x6 at 16 and 24 Inches on Center

Table R602.3(5) lists stud size, maximum laterally unsupported height and spacing by bearing condition.

• 2x4: 24 inches on center with a roof and ceiling only, 16 with one floor above, none for two floors, 10 feet maximum height.
• 2x6: 24 inches on center with a roof and ceiling or one floor plus roof, 16 with two floors, at 10 feet.
• 2x3: barred from exterior walls (footnote b), nonbearing at 16 inches on center only.

Height means the distance between points of lateral support, not plate to plate.

Bearing and Nonbearing Walls

R602.4 requires interior load-bearing walls to be framed and fireblocked as exterior walls. R602.5 lets nonbearing partitions use 2x3 studs at 24 inches on center, or flat 2x4 studs at 16 inches on center off a braced wall line, with a single top plate.

Notching, Boring and Top Plates

• Notching (R602.6): 25 percent of the stud in an exterior or bearing wall, 40 percent in a nonbearing partition.
• Boring: 60 percent of the stud maximum, hole edge at least 5/8 inch from the stud edge, never in the same section as a notch.
• Doubling: a stud in an exterior or bearing wall drilled over 40 percent must be doubled, with at most two successive doubled studs bored.
• Top plate (R602.6.1): a cut over 50 percent of the plate width needs a galvanized tie 0.054 inch thick and 1-1/2 inches wide, eight nails each side, unless that face is fully sheathed.

Headers, King Studs and Jack Studs

R602.7 sends header spans to Tables R602.7(1) and R602.7(2). Table R602.7(1) is entered by ground snow load, building width and the load above, and its NJ column gives the jack studs at each end. A 2-2x8 header is two 2x8s nailed together and set on edge, the double header.

R602.7.5 requires each end to bear on one or more jack studs or approved framing anchors, and the king stud to be end nailed to the header with four 16d nails. R602.7.4 allows a single flat 2x4 header in a nonbearing wall for openings up to 8 feet, so cripples above it are not required.

Cripple Studs and Cripple Walls

Cripple studs are the short studs above a header and below a sill, excepted from the continuity rule only where the opening matches the header tables. A cripple wall between foundation and floor is braced under R602.10.10, with bracing length multiplied by 1.15.

Wall Bracing: Panels, Let-In and Continuous Sheathing

R602.10 designates braced wall lines, allows 4 foot exterior offsets (R602.10.1.2), and sets the bracing length per line from Tables R602.10.3(1) through (4). Methods are in Table R602.10.4, panel lengths in Table R602.10.5.

• Let-in bracing: 1x4 or metal strap let into the studs at 45 to 60 degrees, studs not over 16 inches on center.
• Structural sheathing: wood structural panel, diagonal boards, fiberboard or gypsum board, 48 inches minimum at 8 to 10 foot heights.
• Let-in length: 55 inches at an 8 foot wall, 69 at 10 feet, not permitted at 11 feet and above.
• Continuous sheathing (CS-WSP, CS-SFB) replaces intermittent panels along a fully sheathed line.

Fireblocking at Wall Junctions

Fireblocking cuts off concealed vertical and horizontal draft openings. The 2018 IRC puts the wall rule in R602.8, which points to R302.11; later editions hold it in R302.11.

• Vertically at ceiling and floor levels in stud spaces, and horizontally at intervals not exceeding 10 feet.
• Where vertical and horizontal spaces meet at soffits, drop ceilings and cove ceilings, and between stair stringers at the run ends.

R302.11.1 accepts 2 inch lumber, 23/32 inch sheathing with backed joints, 1/2 inch gypsum board or mineral wool batts. Draftstopping under R302.12 is separate.

Anchor Bolts and the Wall to Foundation Connection

R602.11 anchors braced wall line sills through R403.1.6: 1/2 inch bolts, 7 inches of embedment, 6 feet on center maximum, within 12 inches of each plate end. R602.11.1 adds 0.229 by 3 inch plate washers in Seismic Categories D0, D1 and D2.

Interior Wall Intersections

An intersecting partition must be tied to the wall it meets, since the through wall is usually the bearing or braced element. It is nailed through the face of the through wall stud, plates follow Table R602.3(1), and the junction is fireblocked where a vertical space meets a horizontal one.

What the Inspector Writes Up

• A stud notched or bored past the R602.6 limits.
• A top plate cut over half its width with no tie.
• A header on one jack stud where the NJ column calls for two.
• Braced panels missing from a line the plan shows braced, or no fireblocking under the top plate.

How the B1 Exam Asks

Three shapes repeat: a dimension and a request for the minimum, a site finding and a request for the section, or a table lookup. Tab R602.3(5), R602.6, R602.7(1) and R602.10.5 before exam day.

The load path continues below the wall: sill plate rules are in the IRC foundations guide. The top plate to rafter connection is in the IRC roof guide, the study sequence is in the IRC study guide, and the blueprint is in the B1 certification guide. Try a free ICC practice question, then the full bank on the pricing page.