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Title: Section 2326 • Size: 44850
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Only the following occupancies may be constructed in accordance with Section 2326 :
1. One-, two- or three-story buildings housing Group R Occupancies.
2. One-story Occupancy Category IV buildings, as defined in Table 16-K, when constructed on a slab-on-grade floor.
3. Group U Occupancies.
4. Top-story walls and roofs of Occupancy Category IV buildings not exceeding two stories of wood framing.
5. Interior nonload-bearing partitions, ceilings and curtain walls in all occupancies.
When total loads exceed those specified in Tables 23-I-V-J-1, 23-I-V-J-3, and 23-I-V-R-1, 23-I-V-R-2, 23-I-V-R-3, 23-I-V-R-4, 23-I-V-R-7, 23-I-V-R-8, 23-I-V-R-9 and 23-I-V-R-10; 23-V-R-1, 23-V-R-3, 23-V-R-7, 23-V-R-9, 23-VI-A, 23-VI-B, 23-VI-C, 23-VI-D, an engineering design shall be provided for the gravity load system.
Other approved repetitive wood members may be used in lieu of solid-sawn lumber in conventional construction provided these members comply with the provisions of this code.
2326.2 Design of Portions. When a building of otherwise conventional construction contains nonconventional structural elements, those elements shall be designed in accordance with Section 1603.3.
2326.4 Additional Requirements for Conventional Construction in Seismic Zones 0, 1, 2and 3.
EXCEPTION: In one-
and two-story Group R, Division 3 buildings, interior braced wall
line spacing may be increased to not more than 34 feet (10 363
mm) on center in order to accommodate one single room per dwelling
unit not exceeding 900 square feet (83.61 ).
The building official may require additional walls to contain
braced panels when this exception is used.
2326.4.4 Unusually shaped buildings. When of unusual shape as defined in Section 2326.5, Item 4, buildings of light-frame construction located in Seismic Zone 3 shall have a lateral-force-resisting system designed to resist the forces specified in Chapter 16.
2326.5 Additional Requirements for Conventional Construction in Seismic Zone 4.
EXCEPTION: In one-
and two-story Group R, Division 3 buildings, interior braced wall
line spacing may be increased to not more than 34 feet (10 363
mm) on center in order to accommodate one single room per dwelling
unit not exceeding 900 square feet (83.61 ).
The building official may require additional walls to contain
braced panels when this exception is used.
2326.5.4.1 When exterior braced wall panels, as required by Section 2326.11.3, are not in one plane vertically from the foundation to the uppermost story in which they are required.
EXCEPTION: Floors with cantilevers or setbacks not exceeding four times the nominal depth of the floor joists may support braced wall panels provided:
1. Floor joists are 2 inches by 10 inches (51 mm by 254 mm) or larger and spaced at not more than 16 inches (406 mm) on center.
2. The ratio of the back span to the cantilever is at least 2 to 1.
3. Floor joists at ends of braced wall panels are doubled.
4. A continuous rim joist is connected to ends of all cantilevered joists. The rim joist may be spliced using a metal tie not less than 0.058 inch (1.47 mm) (16 galvanized gage) and 1 1/2 inches (38 mm) wide fastened with six 16d nails.
5. Gravity loads carried at the end of cantilevered joists are limited to uniform wall and roof load and the reactions from headers having a span of 8 feet (2438 mm) or less.
EXCEPTION: Portions of roofs or floors which do not support braced wall panels above may extend up to 6 feet (1829 mm) beyond a braced wall line.
2326.5.4.3 When the end of a required braced wall panel extends more than 1 foot (305 mm) over an opening in the wall below. This provision is applicable to braced wall panels offset in plane and to braced wall panels offset out of plane as permitted by Section 2326.5.4.1, exception.
EXCEPTION: Braced wall panels may extend over an opening not more than 8 feet (2438 mm) in width when the header is a 4-inch by 12-inch (102 mm by 305 mm) or larger member.
2326.5.4.5 Construction where portions of a floor level are vertically offset such that the framing members on either side of the offset cannot be lapped or tied together in an approved manner as required by Section 2326.8.3.
EXCEPTION: Framing supported directly by foundations.
2326.5.4.6 When braced wall lines do not occur in two perpendicular directions.
2326.5.4.7 Other configurations which, in the opinion of the building official, create irregularities or discontinuities which are not addressed by Section 2326.
2326.5.5 Lumber roof decks. Lumber roof decks shall have solid sheathing.
EXCEPTION: Two-story buildings may have interior braced wall lines supported on continuous foundations at intervals not exceeding 50 feet (15 240 mm) provided:
1. Cripple wall height does not exceed 4 feet (1219 mm).
2. First-floor braced wall panels are supported on doubled floor joists, continuous blocking or floor beams.
3. Distance between bracing lines does not exceed twice the building width parallel to the braced wall line.
2326.6 Foundation Plates or Sills. Foundations and footings shall be as specified in Chapter 18. Foundation plates or sills resting on concrete or masonry foundations shall be bolted as required by Section 1806.6.
2326.8.1 General. Spans for joists shall be in accordance with Tables 23-I-V-J-1 and 23-I-V-J-3.
Notches on the ends of joists shall not exceed one fourth the joist depth. Holes bored in joists shall not be within 2 inches (51 mm) of the top or bottom of the joist, and the diameter of any such hole shall not exceed one third the depth of the joist. Notches in the top or bottom of joists shall not exceed one sixth the depth and shall not be located in the middle third of the span.
Joist framing from opposite sides of a beam, girder or partition shall be lapped at least 3 inches or the opposing joists shall be tied together in an approved manner.
Joists framing into the side of a wood girder shall be supported by framing anchors or on ledger strips not less than 2 inches by 2 inches (51 mm by 51 mm).
Joists under and parallel to bearing partitions shall be doubled.
2326.8.6 Blocking. Floor joists shall be blocked when required by the provisions of Sections 2306.7 and 2326.8.3.
2326.9.1 Lumber subfloor. Sheathing used as a structural subfloor shall conform to the limitations set forth in Tables 23-I-R-1 and 23-I-R-2.
Joints in subflooring shall occur over supports unless end-matched lumber is used, in which case each piece shall bear on at least two joists.
Subflooring may be omitted when joist spacing does not exceed 16 inches (406 mm) and 1-inch (25 mm) nominal tongue-and-groove wood strip flooring is applied perpendicular to the joists.
2326.9.2 Wood structural panels. Where used as structural subflooring, wood structural panels shall be as set forth in Tables 23-I-S-1 and 23-I-S-2. Wood structural panel combination subfloor underlayment shall have maximum spans as set forth in Table 23-I-T-1.
When wood structural panel floors are glued to joists with an adhesive in accordance with the adhesive manufacturer's directions, fasteners may be spaced a maximum of 12 inches (305 mm) on center at all supports.
In lieu of such design, 2-inch (51 mm) tongue-and-groove planking may be used in accordance with Table 23-I-U. Joints in such planking may be randomly spaced, provided the system is applied to not less than three continuous spans, planks are center-matched and end-matched or splined, each plank bears on at least one support and joints are separated by at least 24 inches (610 mm) in adjacent pieces. One-inch nominal strip square-edged flooring, 1/2-inch (13 mm) tongue-and-groove flooring, 3/8-inch (9.5 mm) wood structural panel or 3/8-inch (9.5 mm) Type 2-M particleboard shall be applied over random-length decking used as a floor. The strip and tongue-and-groove flooring shall be applied at right angles to the span of the planks. The 3/8-inch (9.5 mm) plywood shall be applied with the face grain at right angles to the span of the planks.
2326.9.4 Particleboard. Where used as structural subflooring or as combined subfloor underlayment, particleboard shall be as set forth in Table 23-I-T-2.
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 ceiling, or exceed 8 feet (2438 mm) in height for exterior walls and load-bearing walls or 10 feet (3048 mm) for interior nonload-bearing walls.
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 particleboard, 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.
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 shall 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 (0.9 mm) 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 a 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 nonbearing partitions 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 on 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.
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 the 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 inch (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 Tables 23-I-M-1 and 23-I-N-1.
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 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.
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 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).
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 material used.
In no case shall the edge of the bored hole be nearer than 5/8 inch (16 mm) to the edge of the stud. Bored holes shall not be located at the same section of stud as a cut or notch.
2326.12 Roof and Ceiling Framing.
Holes bored in rafters or ceiling joists shall not be within 2 inches (51 mm) of the top and bottom and their diameter shall not exceed one third the depth of the member.
2326.12.8 Blocking. Roof rafters and ceiling joists shall be supported laterally to prevent rotation and lateral displacement when required by Section 2306.7. Roof trusses shall be supported laterally at points of bearing by solid blocking to prevent rotation and lateral displacement.
2326.12.9 Roof sheathing. Roof sheathing shall be in accordance with Tables 23-I-S-1 and 23-I-S-2 for wood structural panels, Tables 23-I-R-1 and 23-I-R-2 for lumber or Table 23-I-S-3 for particleboard.
Joints in lumber sheathing shall occur over supports unless approved end-matched lumber is used, in which case each piece shall bear on at least two supports.
Wood structural panels used for roof sheathing shall be bonded by intermediate or exterior glue. Wood structural panel roof sheathing exposed on the underside shall be bonded with exterior glue.
In lieu of such design, 2-inch (51 mm) tongue-and-groove planking may be used in accordance with Table 23-I-U. Joints in such planking may be randomly spaced, provided the system is applied to not less than three continuous spans, planks are center-matched and end-matched or splined, each plank bears on at least one support, and joints are separated by at least 24 inches (610 mm) in adjacent pieces.
2326.13 Exit Facilities. In
Seismic Zones 3 and 4, exterior exit balconies, stairs and similar
exit facilities shall be positively anchored to the primary structure
at not over 8 feet (2438 mm) on center or shall be designed for
lateral forces. Such attachment shall not be accomplished by use
of toenails or nails subject to withdrawal.
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