Walls, Headers, and Openings
Wall framing under Wisconsin's code: stud size and spacing from the UDC table (2×4s at 16 inches carry a floor, roof, and ceiling; 24 inches a roof alone), double top plates with offset joints, headers of two 2-inch members sized from the code tables, king and jack studs (one shoulder stud each end past 3 feet, two past 6), and the 1/3 rule for cutting studs. A worked header pick for a 28-foot house.
- 4 min
- 6 steps
- 3 questions
- Lesson 10 of 111
In this lesson
- Studs
- Plates
- Headers
- Cutting studs and plates
- Corners and partitions
- What to take from this
Picking up where you left off.
Studs
The UDC’s stud table sets size and spacing by what the wall carries 1:
| Stud | Max unsupported height | Roof and ceiling only | One floor + roof | Two floors + roof |
|---|---|---|---|---|
| 2×4 | 10 ft | 24 in. o.c. | 16 in. o.c. | not allowed |
| 2×6 | 12 ft* | 24 in. o.c. | 24 in. o.c. | 16 in. o.c. |
*Over 10 feet needs structural analysis. Studs are stud grade or better; utility grade only at 16 inches for short, lightly loaded walls. Exterior wall studs go with their wide faces perpendicular to the wall 1. Many Wisconsin houses now use 2×6 walls at 16 or 24 inches to hold R-20 or R-21 cavity insulation (the energy code lesson).
Plates
- Bearing walls get a double top plate. End joints in the two layers are offset at least two stud spaces, and the plates overlap at corners and intersections 1.
- A single top plate is allowed only with a rafter directly over each stud and the plate tied at joints, corners, and intersections 1.
- The bottom plate on an open-top block wall is as wide as the wall, at least 5 1/2 inches per piece if bolted 1.
Headers
Every door and window in a bearing wall needs a header to carry the load across the opening, traditionally two 2-inch members on edge 2 1. Header sizes come from the code’s tables by house width, what the wall carries, and snow zone 1. For a 28-foot-wide house:
| Header | Roof/ceiling, zone 2 (30 psf) | Roof/ceiling, zone 1 (40 psf) | One floor only | Floor + roof, either zone |
|---|---|---|---|---|
| Two 2×6 | 4 ft | 3 ft | 3 ft | 2.5 ft |
| Two 2×8 | 5 ft | 4 ft | 5 ft | 3 ft |
| Two 2×10 | 6 ft | 6 ft | 6 ft | 4 ft |
| Two 2×12 | 8 ft | 7 ft | 7 ft | 5 ft |
The tables assume lumber with 1,000 psi bending strength; stronger species can span farther by the square root of the ratio 1. Longer openings need engineered headers (LVL is common).
Support at each end of a header in a bearing wall 1:
- Up to 3 feet: the full-height king stud plus one jack (shoulder) stud, or a framing anchor.
- 3 to 6 feet: king stud plus one jack stud.
- Over 6 feet: king stud plus two jack studs.
Above the header, short cripple studs carry the plate; below a window, cripples hold the rough sill.
Quick check
In the southern zone (30 psf), two 2×8s would reach 5 feet.
Quick check
Up to 3 feet: one shoulder stud or a framing anchor; 3 to 6 feet: one shoulder stud.
Cutting studs and plates
- Studs may be cut or bored no more than 1/3 of their depth unless reinforced 1: about 1 1/8 inches in a 2×4.
- Posts and columns: no notching or boring without engineering 1.
- If a pipe or duct removes more than half of a top plate in an exterior or bearing wall, bridge it with a steel angle at least 2 by 2 inches, 20 gauge, reaching to the middle of the stud bays on each side 1.
Quick check
If more than half a top plate is cut for a pipe or duct, a steel angle bridges it.
Corners and partitions
Corners need enough wood to nail sheathing and drywall on both faces, built from three studs or two studs and blocking. Where a partition meets an exterior wall, extra studs or blocking give the drywall something to land on 2. Insulation-friendly versions (two-stud corners, ladder blocking at partitions) leave room for insulation in the outside corners.
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What to take from this
Pick studs from the UDC table: 2×4s at 16 inches carry one floor plus roof, 2×6s at 24 inches do the same, and only 2×6s at 16 carry two floors. Cap bearing walls with a double top plate, joints offset two bays and lapped at corners. Size headers from the code tables by house width, load, and snow zone (two 2×10s span 6 feet under roof only on a 28-foot house), support them with one jack stud past 3 feet and two past 6, and keep cuts in studs to 1/3 of their depth.
Lesson complete
Nice work.
Sources for this lesson
- 1Wis. Admin. Code ch. SPS 321, Uniform Dwelling Code: Construction Standards. Wisconsin Department of Safety and Professional Services. verifiedDesign loads (SPS 321.02): complete load path to the foundation; live loads 40 psf floors, 50 garage floors, 40 decks and porches, 20 ceilings with storage, 5 without; roof snow loads from the zone map, Zone 1 (north) 40 psf and Zone 2 (south) 30 psf; wind 20 psf horizontal and uplift or ASCE 7-05; span tables in SPS 325 Appendix A. Frost (321.16): footings and foundations, including stoops and landings, below frost penetration or at least 48 inches below grade, whichever is deeper, never on frozen material; exceptions for ASCE 32 frost-protected shallow foundations, areaways, and clean bedrock. Exits (321.03): two first-floor exit doors separated by the greater of 20 feet or a third of the floor's longest diagonal; egress windows at least 20 by 24 inches net clear opening, sill no more than 60 inches above the floor (a platform if over 46); basement sleeping rooms need a second exit. Ceilings at least 7 feet (321.06). Smoke alarms (321.09) in each sleeping room, outside sleeping areas within 21 feet, and on every level, hardwired and interconnected with battery backup.
- 2L. O. Anderson, O. C. Heyer. Wood-Frame House Construction (Agriculture Handbook No. 73). USDA Forest Service, Forest Products Laboratory. 1955. verifiedPublic domain handbook. Platform construction: the subfloor extends to the outside edges and walls are framed flat on it, raised, plumbed, braced, then capped with a second top plate lapping at corners; balloon framing runs studs from sill to rafter plate. Studs commonly 2x4 at 16 inches on center; framing lumber at no more than 19 percent moisture. Wood basement posts at least 6x6 on a pedestal; girders carry the inner ends of joists; joists usually 2-inch nominal, 6 to 12 inches deep, 16 inches on center, crown up, doubled under bearing partitions, lapped at girders; openings framed with doubled headers and trimmers; cross-bridging at midspan, no more than 8 feet apart; subfloor of boards or plywood; headers of two 2-inch members on edge over openings; diagonal or K bracing at corners; rafters erected in pairs after ceiling joists are fastened.