IRC R602.3 · R602.7 · 2021 / 2024 IRC

How to read IRC wall framing, header & fastening tables

The fastening schedule, stud size/height/spacing, and header and girder spans — which inputs pick the cell and what the footnotes change. Free link to the official code.

Need the actual tables? Read Tables R602.3(1), R602.3(5), and R602.7 free at codes.iccsafe.org →

Table R602.3(1) fastening schedule — how to read it

Step	What you do	Watch out for
1	Find the connection by building element (roof, wall, floor, sheathing) and description	The same two members can appear more than once — toe-nailed and end-nailed are different lines
2	Read the number and type of fastener	Several equivalent options are often listed — any one of them satisfies the line
3	Check the nail dimensions (length × shank diameter) listed next to the pennyweight	A "16d" box nail and a "16d" common nail have different shank diameters — the table specifies which
4	Read the spacing column (edges vs. field for sheathing, o.c. for face nailing)	A dash means a count per connection, not a spacing
5	Read the footnotes	High-wind areas and braced wall panels can require tighter nailing than the base schedule

Our own summary, not the code text. Look up the tables free at codes.iccsafe.org and verify against the IRC edition adopted by your AHJ. Not engineering advice.

Table R602.3(5) stud size, height, and spacing — how to read it

Step	What you do	Watch out for
1	Decide bearing or nonbearing	Nonbearing partitions get much more latitude on height and spacing
2	For a bearing wall, count what is above it: roof and ceiling only, one floor plus roof, or two floors plus roof	Each added floor tightens the allowed spacing — some sizes drop out entirely
3	Go to the stud size row	Stud grade must meet the section’s grade rules
4	Read the laterally unsupported height limit	Tall walls beyond the table go to the tall-wall provisions or a design
5	Read the maximum spacing for your loading	Spacing also has to work with the sheathing, siding, and drywall spans

Our own summary, not the code text. Look up the tables free at codes.iccsafe.org and verify against the IRC edition adopted by your AHJ. Not engineering advice.

Tables R602.7(1) / R602.7(2) header and girder spans — how to read them

Step	What you do	Watch out for
1	Pick the table: exterior bearing walls or interior bearing walls	Interior bearing walls carry floor load from both sides
2	Pick the ground snow load band (exterior walls) from the jurisdiction’s R301.2	A higher snow band shortens every header
3	Pick what the header supports: roof and ceiling, plus one center-bearing floor, plus one clear-span floor, and so on	Count everything bearing on the wall above the opening
4	Pick the building width column	Building width is measured perpendicular to the ridge
5	Find the header size and ply count row (for example, a doubled 2x10)	The tables assume the listed species groups and grades
6	Read the maximum span and the NJ value	NJ is the number of jack studs required at each end — longer spans usually need more

Our own summary, not the code text. Look up the tables free at codes.iccsafe.org and verify against the IRC edition adopted by your AHJ. Not engineering advice.

Worked example — first-floor exterior wall of a two-story house

Input / step	Value	Source
Wall	Exterior bearing wall, 2x4 studs, 9 ft tall	Plans
What the wall supports	One floor plus the roof and ceiling	Plans
Maximum stud spacing for 2x4 with that load	16 in o.c.	Table R602.3(5)
Laterally unsupported height limit for a 2x4 bearing stud	10 ft — the 9 ft wall is within it	Table R602.3(5)
Plate-to-stud nailing (end nail)	2 nails, 16d, through the plate into each stud	Table R602.3(1) — use the nail diameter your edition lists
Header over a window in this wall	Enter R602.7(1) with the local snow band, "one floor plus roof and ceiling," and the building width; pick the smallest header whose span covers the opening and install its NJ jack studs	Tables R602.7(1) — look up the span

Worked example values only. Look up the full tables free at codes.iccsafe.org.

Common field mistakes

Mistake	What to do instead
Framing a first-floor bearing wall at 24 in o.c. because the top floor is	The lower wall carries a floor too — check the spacing for that loading
Using box nails where the schedule calls for common-nail diameter	Match the shank diameter the table lists, or use a listed alternate
Picking header size from "what we always use"	Read the snow band, what’s supported, and building width — they all move the span
One jack stud under a header that needs two	Check the NJ value for the span you used
Measuring building width along the ridge	Building width is measured perpendicular to the ridge

Our own summary, not the code text. Look up the tables free at codes.iccsafe.org and verify against the IRC edition adopted by your AHJ. Not engineering advice.

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Framing walls straight from the tables

Read the tables free at codes.iccsafe.org. ICC offers free read-only access to the IRC. This page explains how to use the wall framing tables; it does not reproduce them. It covers the 2021 and 2024 IRC — verify against the edition your AHJ adopted.

Fastening schedule (Table R602.3(1)). Every framing connection — plates to studs, top-plate laps, headers, rim joists, rafters to plates, sheathing — has a line with the number and type of fasteners and, where it applies, the spacing. The table lists nail length and diameter because pennyweight alone doesn’t tell you if it’s a common, box, or gun nail. Footnotes tighten nailing in high-wind areas and at braced wall panels.

Studs (Table R602.3(5)). Allowed stud spacing depends on stud size and on what the wall carries: roof and ceiling only, one floor plus roof, or two floors plus roof. There’s also a limit on how tall the stud can run between lateral supports. Headers and girders (Tables R602.7(1) and (2)). Exterior and interior bearing walls have separate tables, entered by snow load, what the header supports, and building width. Each cell gives the maximum span and NJ, the number of jack studs required at each end.

Worked example. A 9 ft first-floor exterior wall of a two-story house is framed in 2x4. Because it supports one floor plus the roof, Table R602.3(5) limits it to 16 in o.c., and a 2x4 bearing stud may run up to 10 ft between supports, so the 9 ft wall works. The bottom plate is end-nailed with two 16d nails into each stud per Table R602.3(1). For the window header, enter R602.7(1) with the snow band, “one floor plus roof and ceiling,” and the building width, then pick the smallest header that spans the opening and set its NJ jack studs.

Related: how to read IRC joist and rafter span tables, snow load and design criteria (R301.2), and deck framing (R507). Build your stud and header list with the quantity takeoff template and track the framing inspection in the inspection request log.

FAQ

How do I read the IRC fastening schedule?+

Table R602.3(1) lists each framing connection by element and description, then the number and type of fastener and, where it applies, the spacing. Where several fasteners are listed for a line, any one option satisfies it. Check the nail length and shank diameter the table gives, not just the pennyweight. Read it free at codes.iccsafe.org.

Can I frame 2x4 bearing walls at 24 inches on center?+

Only where Table R602.3(5) allows it for the load the wall carries. A 2x4 bearing wall supporting only a roof and ceiling can generally go to 24 in o.c.; a 2x4 wall supporting one floor plus the roof is limited to 16 in o.c. Check your edition and the sheathing and finish spans too.

How do I pick a header size from the IRC tables?+

Use R602.7(1) for exterior bearing walls or R602.7(2) for interior ones. Choose the ground snow load band, what the header supports, and the building width, then find the smallest header size whose listed span covers your opening. Install the number of jack studs (NJ) the table lists.

What does NJ mean in the header tables?+

NJ is the number of jack (trimmer) studs required under each end of the header or girder for that span. Longer spans or heavier loads need more jack studs to carry the bearing.

Do the IRC header tables cover LVL headers?+

No. The IRC header tables are for sawn lumber. Engineered headers (LVL, PSL, LSL, glulam) are sized from the manufacturer’s tables or by design.

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