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Excerpts from the 1994 Uniform Building Code TM, copyright © 1994, are included in this guide with the permission of the publisher, the International Conference of Building Officials.
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Sec. 2318. Wall Framing. The framing of exterior and interior walls shall be in accordance with provisions specified in Section 2326 unless a specific design is furnished.

Wood stud walls and bearing partitions shall not support more than two floors and a roof unless an analysis satisfactory to the building official shows that shrinkage of the wood framing will not have adverse effects on the structure or any plumbing, electrical or mechanical systems, or other equipment installed therein due to excessive shrinkage or differential movements caused by shrinkage. The analysis shall also show that the roof drainage system and the foregoing systems or equipment will not be adversely affected or, as an alternate, such systems shall be designed to accommodate the differential shrinkage or movements.


Sill Plates

Sec. 2326.6. Foundation Plates or Sills. Foundation plates or sills resting on concrete or masonry foundations shall be bolted as required by Section 1806.6.

Sec. 1806.6. Foundation Plates or Sills. Foundation plates or sills shall be bolted to the foundation or foundation wall with not less than 1/2 inch (13 mm) nominal diameter steel bolts embedded at least 7 inches (178 mm) into the concrete or masonry and spaced not more than 6 feet (1829 mm) apart. There shall be a minimum of two bolts per piece with one bolt located within 12 inches (305 mm) of each end of each piece. A properly sized nut and washer shall be tightened on each bolt to the plate. Foundation plates and sills shall be the kind of wood specified in Section 2317.4.

Sec. 2317.4. Plates, Sills and Sleepers. All foundation plates or sills and sleepers on a concrete or masonry slab, which is in direct contact with the earth, and sills which rest on concrete or masonry foundations, shall be treated wood or Foundation redwood, all marked or branded by an approved agency.

Additional Local Requirements: Exterior wall sill plates bearing on concrete must be Foundation redwood or pressure treated lumber and must be nominal 2 inch thickness (2x material) with their width at least equal to the width of studs to be used. Steel bolts used for sill anchorage shall be at least 10 inches long.


Wall Studs

Sec. 2326.11.1. Size, Height and Spacing. The size, height and spacing of studs shall be in accordance with Table 23-I-R-3 except that Utility grade studs shall not be spaced more than 16 inches (406 mm) on center, or support more than a roof and a ceiling, or exceed 8 feet (2438 mm) in height for exterior walls and load-bearing walls or 10 feet (3048 mm) for interior non-bearing walls.

Sec. 2326.11.2. Framing Details. Studs shall be placed with their wide dimension perpendicular to the wall. Not less than three studs shall be installed at each corner of an exterior wall.
EXCEPTION: At corners a third stud may be omitted through the use of wood spacers or backup cleats of 3/8-inch-thick (9.5 mm) wood structural panel, 3/8-inch (9.5 mm) Type 2-M particle board, 1-inch-thick (25 mm) lumber or other approved devices which will serve as an adequate backing for the attachment of facing materials. Where fire-resistance ratings or shear values are involved, wood spacers, backup cleats or other devices shall not be used unless specifically approved for such use.

TABLE 23-I-R-3 - Size, Height and Spacing of Wood Studs
Bearing Walls Non-Bearing Walls
Stud Size
Stud Heights (1)
Roof & Ceiling
One Floor,
Roof & Ceiling
Two Floors,
Roof & Ceiling
Stud Heights (1)
(Feet) Spacing in Inches (Feet) (Inches)
1. 2 x 3 (2) 10 16
2. 2 x 4 10 24 16 14 24
3. 3 x 4 10 24 24 16 14 24
4. 2 x 5 10 24 24 16 24
5. 2 x 6 10 24 24 16 20 24

(1) Listed heights are distances between points of lateral support placed perpendicular to the plane of the wall. Increases in unsupported height are permitted where justified by an analysis.

(2) Shall not be used in exterior walls.


Top Plates

Sec. 2326.11.2. Framing Details (cont.). Bearing and exterior wall studs shall be capped with double top plates installed to provide overlapping at corners and at intersections with other partitions. End joints in double top plates must be offset at least 48 inches (2438 mm).
EXCEPTION: A single top plate may be used, provided the plate is adequately tied at joints, corners and intersecting walls by at least the equivalent of 3-inch by 6-inch (76 mm by 152 mm) by 0.036-inch-thick (0.90 mm)(20 gage) galvanized steel that is nailed to each wall or segment of wall by six 8d nails or equivalent, provided the rafters, joists or trusses are centered over the studs with tolerance of no more than 1 inch (25 mm).

When bearing studs are spaced at 24-inch (610 mm) intervals and top plates are less than two 2-inch by 6-inch (51 mm by 152 mm) or two 3-inch by 4-inch (76 mm by 102 mm) members and when the floor joists, floor trusses or roof trusses which they support are spaced at more than 16-inch (406 mm) intervals, such joists or trusses shall bear within 5 inches (127 mm) of the studs beneath or a third plate shall be installed.

Interior non-bearing walls may be capped with a single top plate installed to provide overlapping at corners and at intersections with other walls and partitions. The plate shall be continuously tied at joints by solid blocking at least 16 inches (406 mm) in length and equal in size to the plate or by 1/8-inch by 1 1/2-inch (3.2 mm by 38 mm) metal ties with spliced sections fastened with two 16d nails at each side of the joint.

Studs shall have full bearing on a plate or sill not less than 2 inches (51 mm) in thickness having a width not less than that of the wall studs.


Wall Bracing

Sec. 2326.11.3. Bracing. Braced wall lines shall consist of braced wall panels which meet the requirements for location, type and amount of bracing specified in Table 23-I-W and are in line or offset from each other by not more than 4 feet (1219 mm). Braced wall panels shall start at not more than 8 feet (2438 mm) from each end of a braced wall line. All braced wall panels shall be clearly indicated on the plans. Construction of braced wall panels shall be by one of the following methods:

  1. Nominal 1-inch by 4-inch (25 mm by 102 mm) continuous diagonal braces let into top and bottom plates and intervening studs, placed at an angle not more than 60 degrees or less than 45 degrees from horizontal, and attached to the framing in conformance with Table 23-I-Q.
  2. Wood boards of 5/8-inch (16 mm) net minimum thickness applied diagonally on studs spaced not over 24 inches (610 mm) on center.
  3. Wood structural panel sheathing with a thickness not less than 5/16-inches (7.9 mm) for 16-inch (406 mm) stud spacing and not less than 3/8-inch (9.5 mm) for 24-inch (610 mm) stud spacing in accordance with Section 2315 and Table 23-I-P.
  4. Fiberboard sheathing 4-foot by 8-foot (1219 mm by 2438 mm) panels not less than 1/2-inch (13 mm) thick applied vertically on studs spaced not over 16 inches (406 mm) on center when installed in accordance with Section 2315 and Table 23-I-P.
  5. Gypsum board [sheathing, 1/2-inch (13 mm) thick by 4 feet (1219 mm) wide, wallboard or veneer base] on studs spaced not over 24 inches (610 mm) on center and nailed at 7 inches (178 mm) on center with nails as required by Table 25-I.
  6. Particleboard wall sheathing panels where installed in accordance with Table 23-I-N-2.
  7. Portland cement plaster (stucco) on studs spaced 16 inches (406 mm) on center installed in accordance with Table 25-I.
  8. Hardboard panel siding when installed in accordance with Section 2320.6 and Table 23-I-O.

For methods 2, 3, 4, 6, 7 and 8, each braced wall panel must be at least 48 inches (1219 mm) in length, covering three stud spaces where studs are 16 inches (406 mm) apart and covering two stud spaces where studs are spaced 24 inches (610 mm) apart.

For method 5, each braced wall panel must be at least 96 inches (2438 mm) in length when applied to one face of a braced wall panel and 48 inches (1219 mm) when applied to both faces.

All vertical joints of panel sheathing shall occur over studs. Horizontal joints shall occur over blocking equal in size to the studding except where waived by the installation requirements for the specific sheathing materials.

Braced wall panel sole plates shall be nailed to the floor framing and top plates shall be connected to the framing above in accordance with Table 23-I-Q. Sills shall be bolted to the foundation or slab in accordance with Section 1806.6. Where joists are perpendicular to braced wall lines above, blocking shall be provided under and in line with the braced wall panels.

Sec. 2326.11.4. Alternate braced wall panels. Any braced wall panel required by Section 2326.11.3 may be replaced by an alternate braced wall panel constructed in accordance with the following:

1. In one-story buildings, each panel shall have a length of not less than 2 feet 8 inches (813 mm) and a height of not more than 10 feet (3048 mm). Each panel shall be sheathed on one face with 3/8-inch minimum-thickness (9.5 mm) plywood sheathing nailed with 8d common or galvanized box nails in accordance with Table 23-I-Q and blocked at all plywood edges. Two anchor bolts installed in accordance with Section 1806.6 shall be provided in each panel. Anchor bolts shall be placed at panel quarter points. Each panel end stud shall have a tie-down device fastened to the foundation, capable of providing an approved uplift capacity of not less than 1,800 pounds (816.5 kg). The tie-down device shall be installed in accordance with the manufacturer's recommendations. The panels shall be supported directly on a foundation or on floor framing supported directly on a foundation which is continuous across the entire length of the braced wall line. This foundation shall be reinforced with not less than one No. 4 deformed bar top and bottom.

2. In the first story of two-story buildings, each braced wall panel shall be in accordance with Section 2326.11.4, Item 1, except that the plywood sheathing shall be provided on both faces, three anchor bolts shall be placed at one-fifth points, and tie-down device uplift capacity shall not be less than 3,000 pounds (1360.8 kg).


Cripple Walls

Sec. 2326.11.5. Cripple Walls. Foundation cripple walls shall be framed of studs not less in size than the studding above with a minimum length of 14 inches (356 mm), or shall be framed of solid blocking. When exceeding 4 feet (1219 mm) in height, such walls shall be framed of studs having the size required for an additional story.

Such walls having a stud height exceeding 14 inches (356 mm) shall be considered to be first-story walls for the purpose of determining the bracing required by Section 2326.11.3. Solid blocking or wood structural panel sheathing may be used to brace cripple walls having a stud height of 14 inches (356 mm) or less.

Spacing of boundary nailing for required wall bracing shall not exceed 6 inches (152 mm) on center along the foundation plate and the top plate of the cripple wall. Nail size, nail spacing for field nailing and more restrictive boundary nailing requirements shall be as required elsewhere in the code for the specific bracing materials used.


Wall Headers

Sec. 2326.11.6. Headers. Headers and lintels shall conform to the requirements set forth in this paragraph and together with their supporting systems shall be designed to support the loads specified in the code. All openings 4 feet (1219 mm) wide or less in bearing walls shall be provided with headers consisting of either two pieces of 2-inch (51 mm) framing lumber placed on edge and securely fastened together or 4-inch (102 mm) lumber of equivalent cross-section. All openings more than 4 feet (1219 mm) wide shall be provided with headers or lintels. Each end of a lintel or header shall have a length of bearing of not less than 1 1/2 inches (38 mm) for the full width of the lintel.


Plywood Diaphragms

Diaphragm sheathing nails or other approved sheathing connectors shall be driven flush but shall not fracture the surface of the sheathing.

Nails shall be placed not less than 3/8" in from the panel edge, shall be spaced not more than 6" on center along panel edge bearings, and shall be firmly driven into the framing members.

Plywood diaphragms and shear walls shall be constructed with plywood sheets not less than 4' x 8' except at boundaries and changes in framing where minimum sheet dimension shall be 24" unless all edges of the undersized sheets are supported by framing members or blocking.

Framing members or blocking shall be provided at the edges of all sheets in shear walls.


Wall Framing Details

Sec. 2326.11.7. Pipes in Walls. Stud partitions containing plumbing, heating, or other pipes shall be so framed and the joists underneath so spaced as to give proper clearance for the piping. Where a partition containing such piping runs parallel to the floor joists, the joists underneath such partitions shall be doubled and spaced to permit passage of such pipes and shall be bridged. Where plumbing, heating or other pipes are placed in or partly in a partition, necessitating the cutting of the soles or plates, a metal tie not less than 0.058 inches (1.47 mm)(16 gage galvanized) and 1 1/2 inches (38 mm) wide shall be fastened to each plate across and to each side of the opening with not less than six 16d nails.

Sec. 2326.11.8. Bridging. Unless covered by interior or exterior wall coverings or sheathing meeting the minimum requirements of this code, all stud partitions or walls with studs having a height-to-least-thickness ratio exceeding 50 shall have bridging not less than 2 inches (51 mm) in thickness and of the same width as the studs fitted snugly and nailed thereto to provide adequate lateral support.

Sec. 2326.11.9. Cutting and Notching. In exterior walls and bearing partitions, any wood stud may be cut or notched to a depth not exceeding 25 percent of its width. Cutting or notching of studs to a depth not greater than 40 percent of the width of the stud is permitted in non-bearing partitions supporting no loads other than the weight of the partition.

Sec. 2326.11.10. Bored Holes. A hole not greater in diameter than 40 percent of the stud width may be bored in any wood stud. Bored holes not greater than 60 percent of the width of the stud are permitted in nonbearing partitions or in any wall where each bored stud is doubled, provided not more than two successive doubled studs are so bored.

Cutting And Notching


Fire Stops

Fire blocking is required in all stud walls at ceilings and floor levels. The vertical distance between blocking shall not exceed 10 feet. Blocking is required between studs along and in line with the run of a stair stringer in stairway sidewalls. Holes for pipes that pass from one floor level to another or into an attic space must have the opening filled with non-combustible material like fiberglass at the wall plate line.

Fire stops must be a minimum of 2X nominal thickness, two thicknesses of 1-inch nominal lumber with broken lap joints, 23/32 plywood with joints backed with 23/32 plywood, one thickness of 3/4-inch Type 2-hour particleboard with joints backed by 3/4-inch Type 2-M particleboard, gypsum board, mineral wool, or other non-combustible material securely fastened in place.