Stud Wall Calculator

Stud height tables

The tallest exterior bearing wall, floor to the top of the top plate, for Douglas Fir-Larch studs in a 28′ wide building with 15 psf roof dead load, 30 psf of snow and 20 psf of wind on the wall (25 psf near the corners), with siding. Floors bear on a wall down the middle. Worked out by the calculator, not copied from the code tables.

Stud grade, roof and ceiling

Stud grade, roof, ceiling and one floor

Stud grade, roof, ceiling and two floors

No.2, roof, ceiling and one floor

Stud grade, roof, ceiling and one floor, 30 psf of wind (36 psf near the corners)

For other species, grades, loads and finishes, use the calculator above.

How the calculator checks the studs

Each stud is checked as a column to the 2018 National Design Specification (NDS) for wood, with allowable stress design (ASD), as dry lumber. The sheathing on both faces stops it buckling sideways in the wall, so it can only bow across the wall, over its full length between the plates. Its share of the load comes from the building's width, like the International Residential Code (IRC) header and stud tables:

• Roof: the dead load and snow or roof live load over half the building's width plus the overhang, with rafters or trusses that span from wall to wall.
• Each floor above: 15 psf dead and 40 psf live load over a quarter of the width when the joists bear on a wall in the middle, or half when they span the building, plus 90 lb/ft for that story's wall.
• Wind: the components and cladding pressure on the wall, at strength level, as the wind load calculator gives it: zone 4 away from the corners, and the stronger zone 5 suction within 3 ft or more of each corner (10% of the building's smaller plan dimension or 40% of its height, whichever is less). The studs have to work in both places.
• King studs: the full-height studs each side of a door or window. The header and the short studs over and under the opening hand them the wind on half its width, plus their own half stud space. The jack studs carry the header, so the kings hold up only their half stud space of wall. Kings nailed together share the load; the calculator finds how many each side need, up to 4.

The studs pass when they meet every check under each load combination of ASCE 7-16 (the same in 7-22):

• Compression, with the column stability factor for the stud's height over its depth, and the load duration factor for the shortest load: 0.9 for dead load alone, 1.0 with floor live load, 1.15 with snow, 1.25 with roof live load and 1.6 with wind.
• Bending and compression together under 0.6 times the wind, with the 1.15 factor studs get for sharing load through the sheathing.
• Shear from wind, and bearing on the bottom plate, where the stud crushes the plate across its grain.
• Deflection under 0.42 times the wind, as the International Building Code (IBC) allows, to the height over 120 with siding, 240 with brick or another brittle finish, and 360 with stucco or plaster.
• Slenderness: the stud's length is at most 50 times its depth.

The calculator doesn't check the plates and their connections, or the wall as a shear wall bracing the building against wind and earthquakes; the shear wall calculator does that. Walls from 4 to 20 ft.

Stud wall questions

How tall can a 2x4 wall be?

In a 28 ft wide house with 30 psf of snow and 20 psf of wind, 2x4 Stud grade studs 16 in apart reach 10′ 2″ holding up the roof, and 8′ 9″ with a floor above. At 24 in apart they reach 8′ 4″ under the roof alone. The IRC's stud table stops 2x4 bearing walls at 10 ft; taller walls need to be designed.

How tall can a 2x6 wall be?

In the same house, 2x6 Stud grade studs 16 in apart reach 17′ 1″ under the roof and 15′ 1″ with a floor above; 24 in apart, 13′ 11″ and 12′ 4″.

Can studs be 24 in apart?

Often, in a one-story wall: 24 in apart takes two-thirds the studs of 16 in apart and leaves more room for insulation, but each stud carries 50% more load and wind. The tables above show where it works. Siding, drywall and sheathing need to span 24 in too.

What grade are wall studs?

Most studs sold for walls are Stud grade, a grade made for vertical wall framing. No.2 is a little stronger. Southern Pine's Stud grade shares its design values with No.3.

Which wind pressure do I enter?

The wall pressure from the wind load calculator, zone 4, at strength level (the pressure the ultimate wind speed gives). About 20 psf at 115 mph in Exposure B (suburbs), 30 psf in Exposure C (open country), and over 50 psf near the coast in hurricane regions. Enter 0 for an interior bearing wall.

How many king studs does an opening need?

In a 2x4 wall 8 ft tall with studs 16 in apart and 20 psf of wind, one king stud each side carries a 6′ opening. Wider openings need two or three; enter the widest opening in the wall to see. The header span calculator sizes the header and the jack studs under it.

Why check the studs near the corners?

Wind wrapping around a corner pulls harder on the wall for the first few feet, about 20% more than further along. Studs that work in the middle of a wall can fail there, especially tall walls in windy places. The fix is usually closer stud spacing near the corners.