Standard wall stud spacing in the US is 16 inches on center, with 24 inches on center as the common alternative. The 2021 IRC sets the maximum spacing in Table R602.3(5) by stud size, wall height and load: for example, 2x4 bearing studs carrying one floor plus a roof must be no more than 16" o.c., while 2x6 studs in the same wall may go to 24" o.c.
The table below is copied from the 2021 IRC. If you are new to the parts of a wall, read wall framing basics first.
How stud spacing is measured
Stud spacing is measured on center (o.c.): from the centerline of one stud to the centerline of the next, not the clear gap between them. Layout usually starts at one end of the wall so that the 4-foot edges of sheathing and drywall sheets land on the center of a stud. Both 16 and 24 divide evenly into 48 and 96 inches, which is why these spacings dominate.
How far apart are studs in practice? In an existing house, studs are most likely 16" o.c. Newer energy-focused construction, and many 2x6 exterior walls, use 24" o.c. Extra studs at corners, openings and wall intersections break the pattern, so measure from more than one point before cutting into a wall.
Table R602.3(5): size, height and spacing of wood studs
2021 IRC Table R602.3(5), Size, Height and Spacing of Wood Studs. Spacing in inches on center; heights in feet are distances between points of lateral support perpendicular to the plane of the wall. Studs must meet the minimum grade in R602.2 (No. 3, standard or stud grade). No deflection limit or species is stated in this table.
| Stud size | Bearing: max unsupported height (ft) | Bearing: roof-ceiling or habitable attic only | Bearing: one floor + roof-ceiling or habitable attic | Bearing: two floors + roof-ceiling or habitable attic | Bearing: one floor only | Nonbearing: max unsupported height (ft) | Nonbearing: max spacing |
|---|---|---|---|---|---|---|---|
| 2x3 (note b) | not permitted | not permitted | not permitted | not permitted | not permitted | 10 | 16 |
| 2x4 | 10 | 24 (note c) | 16 (note c) | not permitted | 24 | 14 | 24 |
| 3x4 | 10 | 24 | 24 | 16 | 24 | 14 | 24 |
| 2x5 | 10 | 24 | 24 | not permitted | 24 | 16 | 24 |
| 2x6 | 10 | 24 | 24 | 16 | 24 | 20 | 24 |
Table footnotes, paraphrased closely:
- Note a: Bearing walls must be sheathed on at least one side, or bridging installed not more than 4 feet apart measured vertically from either end of the stud. Taller unsupported heights are allowed under Exception 2 of R602.3.1 or with engineering.
- Note b: 2x3 studs shall not be used in exterior walls.
- Note c: A habitable attic assembly supported by 2x4 studs is limited to a roof span of 32 feet. Above that, the studs must be increased to 2x6 or designed by accepted engineering practice.
"Not permitted" is our wording for the dashes in the code table: the prescriptive table gives no value for that combination.
2x4 vs 2x6 stud spacing
Reading across the table for the two common sizes:
- 2x4 bearing walls can be 24" o.c. when they carry only a roof-ceiling assembly (one-story house, or the top story), or only one floor. When a 2x4 wall carries one floor plus a roof-ceiling assembly, the limit drops to 16" o.c. The table lists no 2x4 option for two floors plus a roof.
- 2x6 bearing walls can be 24" o.c. for a roof only or for one floor plus a roof, and 16" o.c. when carrying two floors plus a roof.
- Nonbearing walls in either size can be 24" o.c. The difference is height: 14 feet unsupported for 2x4 and 20 feet for 2x6.
- Bearing wall height is 10 feet unsupported for every size in the table. Taller bearing walls need Exception 2 below, Table R602.3(6), or engineering.
So for a typical two-story house framed with 2x4, the first-floor bearing walls (carrying the second floor plus the roof) are limited to 16" o.c., while the second-floor walls (roof only) could go to 24" o.c. Switching the first floor to 2x6 opens up 24" o.c. there too.
Exceptions in R602.3.1
Section R602.3.1 adds three exceptions to the table:
- Utility grade studs shall not be spaced more than 16" o.c., shall not support more than a roof and ceiling, and shall not exceed 8 feet in height for exterior and load-bearing walls or 10 feet for interior nonbearing walls.
- Taller 2x6 walls. Where the ground snow load is 25 psf or less and the ultimate design wind speed is 130 mph or less, 2x6 studs supporting a roof load with not more than 6 feet of tributary length may be up to 18 feet tall at 16" o.c., or 20 feet tall at 12" o.c. Studs must be No. 2 grade or better.
- Table R602.3(6) gives an alternate method for exterior bearing studs up to 12 feet tall, in Exposure B, with roof live load not over 20 psf and ground snow load not over 30 psf, using No. 2 grade or better studs and plates. In that table, every 24" o.c. condition calls for 2x6 studs, except one combination (12-foot studs carrying roof and one floor at 24" o.c., 140 mph, 24-foot span) that is marked "design required".
16 vs 24 inch stud spacing: the trade-offs
The code tells you what is allowed. It does not tell you which to choose. The practical differences:
16" o.c.
- Stiffer wall face, which helps with tile, heavy cabinets and long runs of drywall.
- More nailing for trim, siding and fixtures.
- The default for most drawings and lumber takeoffs, so fewer coordination surprises.
24" o.c.
- Fewer studs, which means less lumber and fewer thermal bridges through the insulation. This is a core part of advanced framing (optimum value engineering).
- Sheathing, siding and drywall must be rated or installed for 24-inch support. Check the panel's span rating and the finish manufacturer's instructions.
- Loads from above should line up with studs. R602.3.3 says that where joists, trusses or rafters are spaced more than 16" o.c. and the bearing studs below are 24" o.c., those members must bear within 5 inches of the studs beneath, unless the top plates are two 2x6 or two 3x4 members, a third top plate is added, or solid blocking equal in size to the studs reinforces the double top plate.
If you go to 24" o.c. walls, the corners usually change too. See California corner framing for the two-stud corner that pairs with advanced framing.
Spacing on interior partitions
Interior nonbearing walls have their own allowance in R602.5: 2x3 studs at 24" o.c., or, where not part of a braced wall line, 2x4 flat studs at 16" o.c., with at least a single top plate. Note that the R602.5 allowance for 2x3 at 24" o.c. is separate from the 16" o.c. 2x3 row in Table R602.3(5). Before treating any wall as nonbearing, check what it supports; the load-bearing walls guide covers how to tell.
Where the numbers stop
Table R602.3(5) is a prescriptive limit for the stated conditions only. It does not cover wall bracing, header sizing (see the header size chart), point loads from beams or girders, or engineered studs such as LSL or LVL, which use the manufacturer's tables. Your jurisdiction's adopted code edition and local amendments govern. The International Code Council publishes the 2021 IRC online for reference.
Lay out the framing above the walls
Wall stud spacing and floor joist spacing are easiest to coordinate when you can see both. Framing Plan is a preliminary drawing aid for framing plans: it draws joist layouts, beams and openings and exports PNG, PDF and DXF. Its sample span profile uses demo figures and the editor works in millimetres, so treat it as a sketching tool, not a code check. Open the framing studio to lay out joists over your wall lines.