How far apart are studs? Wall stud spacing (2021 IRC)
Wall studs are spaced no more than 16 or 24 inches on center, and 2021 IRC Table R602.3(5) decides which by the stud size and what the wall holds up. A 2×4 bearing wall carrying only a roof and ceiling may run at 24 inches; put a floor on it as well and it tightens to 16. A nonbearing partition runs at 24 inches in every size the table lists except 2×3, which is held to 16.
Maximum spacings, per 2021 IRC Table R602.3(5). Any wall may be framed closer than its maximum; none wider.
Start from what the wall carries
The spacing is not a property of the stud alone. The same 2×4 is allowed 24 inches in one wall and 16 in the next, because the table asks what sits on top of the wall before it gives a number. Read it that way round — find the load, then your stud size — and the table collapses to this:
| The wall carries | 24” o.c. allowed | 16” o.c. maximum | No spacing listed |
|---|---|---|---|
| Roof-ceiling or habitable attic only | 2×4, 3×4, 2×5 and 2×6 | — | 2×3 |
| One floor, plus roof-ceiling or habitable attic | 3×4, 2×5 and 2×6 | 2×4 | 2×3 |
| Two floors, plus roof-ceiling or habitable attic | — | 3×4 and 2×6 | 2×3, 2×4 and 2×5 |
| Supporting one floor height | 2×4, 3×4, 2×5 and 2×6 | — | 2×3 |
| Nonbearing wall | 2×4, 3×4, 2×5 and 2×6 | 2×3 | — |
Three things fall out of that. 2×4 is the only size the table tightens to 16 inches for one floor plus a roof-ceiling assembly; 3×4 and 2×6 are the only sizes listed under two floors at all. 2×3 never appears in a bearing wall. And the widest spacing anywhere in the table is 24 inches.
Wood stud size, height and spacing — 2021 IRC Table R602.3(5)
Here is 2021 IRC Table R602.3(5) in full: every size the code lists, bearing and nonbearing walls, heights in feet and spacings on center in inches. The bearing-wall columns stack — a roof and ceiling, then a floor on top of that, then a second floor — and a blank is a limit, not a gap in the record: the code lists no value there. The fifth bearing-wall column is titled the way the code titles it.
| Stud size | Bearing walls | Nonbearing walls | |||||
|---|---|---|---|---|---|---|---|
| Laterally unsupported height | Roof-ceiling or habitable attic only | One floor, plus roof-ceiling or habitable attic | Two floors, plus roof-ceiling or habitable attic | Supporting one floor height | Laterally unsupported height | Maximum spacing | |
| 2×3 | — | — | — | — | — | 10 ft | 16” o.c. |
| 2×4 | 10 ft | 24” o.c. | 16” o.c. | — | 24” o.c. | 14 ft | 24” o.c. |
| 3×4 | 10 ft | 24” o.c. | 24” o.c. | 16” o.c. | 24” o.c. | 14 ft | 24” o.c. |
| 2×5 | 10 ft | 24” o.c. | 24” o.c. | — | 24” o.c. | 16 ft | 24” o.c. |
| 2×6 | 10 ft | 24” o.c. | 24” o.c. | 16” o.c. | 24” o.c. | 20 ft | 24” o.c. |
2021 IRC Table R602.3(5) — size, height and spacing of wood studs. Heights in feet, spacings on center in inches. table source
What the table's footnotes add
- A listed height is the distance between points of lateral support placed perpendicular to the plane of the wall. A bearing wall is sheathed on at least one side, or bridged at no more than 4 feet vertically from either end of the stud.
- A 2×3 stud is not permitted in an exterior wall.
- A habitable attic assembly on 2×4 studs stops at a 32-foot roof span; past that the studs go to 2×6 or an engineer sizes them.
The three exceptions in R602.3.1
Stud size, height and spacing come out of Table R602.3(5). Under that sentence sit three exceptions, and each moves a limit in the table:
- R602.3.1 exception 1. Utility grade studs are held to 16-inch centres, may carry no more than a roof and ceiling, and stop at 8 feet in exterior and load-bearing walls or 10 feet in interior nonload-bearing walls.
- R602.3.1 exception 2. Where the ground snow load is 25 psf or less and the ultimate design wind speed is 130 mph or less, a 2×6 stud carrying a roof load over no more than 6 feet of tributary length may run to 18 feet at 16-inch centres, or 20 feet at 12-inch centres, in No. 2 grade or better.
- R602.3.1 exception 3. Exterior load-bearing studs up to 12 feet may instead be taken from Table R602.3(6), in Exposure B, with roof live load no more than 20 psf and ground snow load no more than 30 psf, in No. 2 grade or better.
Exception 1 is the one that overrides the table's 24-inch cells outright: a utility grade stud stays at 16 inches whatever the table allows its size. Exception 3 points to Table R602.3(6) and to the full-height stud count at openings in R602.7.5 — neither is on this site, so both are named here and left in the code. Point loads, cantilevers beyond the table footnotes, unusual snow loads, or anything else outside the table's stated conditions — that's an engineer's question.
What the spacing does to wall sheathing — 2021 IRC Table R602.3(3)
Wood structural panel sheathing on the outside of an exterior wall has to hold against wind pressure, and R602.3 sends it to 2021 IRC Table R602.3(3) to do it. That table is keyed to the stud spacing. At 16-inch centers it lists 2 panels; at 24-inch centers only the 24/16 panel is left, and the same panel is listed for less wind than it takes on studs 16 inches apart. Wind speeds are ultimate design wind speeds by exposure category — the figures for your address are your building department's to give.
| Panel span rating | Minimum thickness | Minimum nail | Penetration | Nail spacing | Up to this wind speed | |||
|---|---|---|---|---|---|---|---|---|
| Panel edges | Field | Exposure B | Exposure C | Exposure D | ||||
| Studs at 16 inches on center | ||||||||
| 24/0 | ⅜” | 6d common (2.0 × 0.113 in) | 1.5 in | 6 in | 12 in | 140 mph | 115 mph | 110 mph |
| 24/16 | 7/16” | 8d common (2.5 × 0.131 in) | 1.75 in | 6 in | 12 in | 170 mph | 140 mph | 135 mph |
| Studs at 24 inches on center | ||||||||
| 24/16 | 7/16” | 8d common (2.5 × 0.131 in) | 1.75 in | 6 in | 12 in | 140 mph | 115 mph | 110 mph |
2021 IRC Table R602.3(3) — requirements for wood structural panel wall sheathing used to resist wind pressures, reordered by stud spacing. Nail sizes are length × diameter. table source
- A panel may run with its strength axis along the studs or across them — except three-ply plywood on studs more than 16 inches apart, which goes on with the strength axis across the studs.
- It is a wind-pressure table: it sets what the sheathing must hold against wind pushing on and pulling off the wall (R301.2). How the wall is braced is a separate section, R602.10, which this site does not carry.
- A panel rated Wall-16 or Wall-24 may stand in for the 24/0 panel, and plywood siding rated 16 o.c. or 24 o.c. for the 24/16 panel — but Wall-16 panels and 16 o.c. siding only on studs no more than 16 inches apart.
What the spacing does to drywall thickness — 2021 IRC Table R702.3.5
Gypsum board is held to its framing by 2021 IRC Table R702.3.5, and on a wall the first thing that table reads is how far apart the studs are. At 16-inch centers it lists ⅜”, ½” and ⅝” board; at 24-inch centers it drops the ⅜” and starts at ½”, with the screws pulled in closer. Every wall line lets the board run either direction.
| Board thickness | Nail spacing | Screw spacing |
|---|---|---|
| Studs at 16 inches on center | ||
| ⅜” | 8 in apart | 16 in apart |
| ½” | 8 in apart | 16 in apart |
| ⅝” | 8 in apart | 16 in apart |
| Studs at 24 inches on center | ||
| ½” | 8 in apart | 12 in apart |
| ⅝” | 8 in apart | 12 in apart |
2021 IRC Table R702.3.5 — minimum thickness and application of gypsum board and gypsum panel products: the wall lines, board fastened without adhesive, reordered by stud spacing. The ceiling lines and the adhesive lines are in the same table. table source
Common questions
How far apart are studs in a house?
There is no one spacing for a house: the 2021 IRC sets a maximum for each wall, and Table R602.3(5) sets it by the stud size and what that wall carries. Of the 19 spacings the table lists, 15 are 24 inches on center and 4 are 16. The 16-inch ones are the limits to know: a 2×4 bearing wall carrying a floor plus the roof and ceiling, 3×4 and 2×6 carrying two floors, and a 2×3 nonbearing wall — and utility grade studs are held to 16 inches in any wall (R602.3.1 exception 1). A wall may always be framed closer than its maximum, never wider.
Should studs be 16 or 24 inches on center?
Whichever the table allows for your stud and your wall — and then whichever the rest of the wall can live with. On spacing alone, Table R602.3(5) allows 24 inches for 2×4, 3×4, 2×5 and 2×6 bearing walls under a roof and ceiling only, and for 2×4, 3×4, 2×5 and 2×6 in a nonbearing wall; it holds a 2×4 bearing wall to 16 inches once it carries a floor as well, and 3×4 and 2×6 to 16 under two floors. Wider spacing then narrows what goes on the wall: Table R602.3(3) lists no ⅜” wall sheathing panel at 24-inch centers (the thinnest listed there is 7/16”), and Table R702.3.5 lists no ⅜” wall board at 24-inch framing (the thinnest is ½”).
How far apart are studs in a wall that is not load-bearing?
A nonbearing wall is read from its own two columns of Table R602.3(5): 2×4, 3×4, 2×5 and 2×6 at 24 inches on center, and 2×3 at 16. The same columns cap the laterally unsupported height — 2×3 10 feet, 2×4 14 feet, 3×4 14 feet, 2×5 16 feet, 2×6 20 feet. A 2×3 is kept out of exterior walls altogether.
What does 16 inches on center mean?
On center is measured from the center of one stud to the center of the next — the same distance as from one stud's left edge to the next stud's left edge — and every spacing on this page is measured that way. It is not the gap between studs: a dry-dressed 2×4 is 1½” thick (NDS Supplement Table 1B), so 16 inches on center leaves 14½” of clear space between two 2× studs, and 24 inches leaves 22½”.
What size stud do I need for a wall?
Size comes with height and load. Table R602.3(5) lets every bearing size it lists run to 10 feet of laterally unsupported height; in a nonbearing wall a 2×4 runs to 14 feet and a 2×6 to 20. The table lists no 2×4 or 2×5 under two floors plus a roof-ceiling assembly, which is where 3×4 and 2×6 take over. A habitable attic assembly on 2×4 studs stops at a 32-foot roof span; past that the studs go to 2×6 or an engineer sizes them. Exception 2 of R602.3.1 lets a 2×6 carrying a roof run taller under stated snow and wind limits. Point loads, cantilevers beyond the table footnotes, unusual snow loads, or anything else outside the table's stated conditions — that's an engineer's question.
Can drywall go on studs 24 inches on center?
Yes, at ½” or thicker. Table R702.3.5 lists ½” and ⅝” board on walls framed at 24 inches on center, nailed at 8 inches or screwed at 12; ⅜” board is listed on walls only at 16-inch framing. On a wall the board may run either direction. Those are the lines for board fastened without adhesive; the adhesive lines and the ceiling lines are in the same table.
Around the wall
The jack studs under each end of a header are studs out of this table; how far the header itself may span is on the header and girder span tables page. What a stud weighs, size by size, is on the lumber weight page, and the floor a bearing wall carries is read from the floor joist span tables.