Chapter 25 of the Building Code is amended as follows:
(A) Section 2513.4 is amended to read as follows:
2513.4 Height-to-Length Ratio. The maximum allowable height-to-length ratio for the construction in this section shall be 2 to 1. Wall sections having height-to-length ratios in excess of 1-1/2 to 1 shall be blocked. All shear walls designed to resist seismic loads in Seismic Zone 4 shall have a maximum allowable height-to-length ratio of 1 to 1.
(B) Table 25-I of the Building Code is amended to read:
TABLE 25-I ALLOWABLE SHEAR FOR WIND OR SEISMIC FORCES IN POUNDS PER FOOT FOR VERTICAL DIAPHRAGMS OF LATH AND PLASTER OR GYPSUM BOARD FRAME WALL ASSEMBLIES1 | ||||||
Type of Material | Thickness of Material | Wall Construction | Nail Spacing2 Maximum | Shear Value | Minimum Nail Size | |
X 14.6 for N/m | ||||||
x 25.4 for mm x 304.8 for mm | x 25.4 for mm | Seismic4 | Wind | x 25.4 for mm | ||
1. Expanded metal or woven wire lath and portland cement plaster | 7/8 in. | Unblocked | 6 | 90 | 180 | No. 11 gauge, 1-1/2 in. long, 7/16-in. head, with 1/4-in. thick furring |
2. Gypsum lath | 3/8 in. lath and 1/2 in. plaster | Unblocked | 5 | 30 | 100 | No. 13 gauge, 1-1/8-in. long, 19/64-in. head, plasterboard blued nail |
TABLE 25-I ALLOWABLE SHEAR FOR WIND OR SEISMIC FORCES IN POUNDS PER FOOT FOR VERTICAL DIAPHRAGMS OF LATH AND PLASTER OR GYPSUM BOARD FRAME WALL ASSEMBLIES1 | ||||||
Type of Material | Thickness of Material | Wall Construction | Nail Spacing2 Maximum | Shear Value | Minimum Nail Size | |
X 14.6 for N/m | ||||||
x 25.4 for mm x 304.8 for mm | x 25.4 for mm | Seismic4 | Wind | x 25.4 for mm | ||
4. Gypsum wallboard or veneer base | 1/2 in. | Unblocked | 7 | 30 | 115 | 5d cooler (0.086" dia., 1-5/8-in. long, 15/64-in. head) or wallboard (0.086-in. dia., 1-5/8-in. long, 9/32-in. head) |
4 | 30 | 145 | ||||
Blocked | 7 | 30 | 145 | |||
4 | 30 | 145 | ||||
4. Gypsum wallboard or veneer base (Cont’d) | 5/8 in. | Unblocked | 7 | 30 | 115 | 6d cooler (0.092-in. dia., 1-7/8-in. long, 1/4-in. head) or wallboard (0.0915-in. dia., 1-7/8-in. long, 19/64-in head) |
4 | 30 | 145 | ||||
Blocked | 7 | 30 | 145 | |||
4 | 30 | 175 | ||||
Blocked two-ply | Base ply: 9 Face Ply: 7 | 30 | 250 | Base ply - 6d cooler (0.092-in. dia., 1-7/8-in. long, 1/4-in. head) or wallboard (0.0915-in. dia., 1-7/8-in. long, 19/64-in. head) Face ply - 8d cooler (0.113-in. dia., 2-3/8-in. long, 9/32-in. head) or wallboard (0.113-in. dia., 2-3/8-in. long, 3/8-in. head) | ||
1 These vertical diaphragms shall not be used to resist loads imposed by masonry or concrete construction. See Section 2513.2. Values shown are for short-term loading due to wind or due to seismic loading. Values shown must be reduced 25% for normal loading. 2 Applies to nailing at all studs, top and bottom plates, and blocking. 3 Alternate nails may be used if their dimensions are not less than the specified dimensions. 4 This construction shall not be used below the top level of wood construction in a multi-level building. | ||||||
(C) Section 2514 of the Building Code is hereby amended to read as follows:
Section 2514 - Suspended Ceilings
2514.1(a) Scope. This section shall apply to the support of lighting fixtures and mechanical services installed in metal ceiling suspension systems.
(b) Classification. The terms “Intermediate” and “heavy-duty” shall be as defined in the Standard Specifications for Metal Suspension Systems for Acoustical Tile and Lay-in Panel Ceilings, ASTM C635-86.
(c) Lighting Fixtures. “Intermediate or “heavy-duty” ceiling systems as defined in Subsection (b) of this section shall be used for the support of lighting fixtures.
All lighting fixtures shall be positively attached to the suspended ceiling system. The attachment device shall have a capacity of 100% of the lighting fixture weight acting in any direction.
When “intermediate” systems are used, No. 12 gauge hangers shall be attached to the grid members within 3 inches of each corner of each fixture. Tandem fixtures weight act in any direction.
Where “heavy-duty” systems are used, supplemental hangers are not required if a 48-inch modular hanger pattern is followed. When cross runners are used without supplemental hangers to support lighting fixtures, these cross runners must provide the same carrying capacity as the main runner.
Lighting fixtures weighing less than 56 pounds shall have, in addition to the requirements outlined above, two No. 12 gauge hangers connected from the fixture housing to the structure above. These wires may be slack.
Lighting fixtures weighing 56 pounds or more shall be supported directly from the structure above by approved hangers.
Pendant-hung lighting fixtures shall be supported directly from the structure above using No.9 gauge wire or approved alternate support without using the ceiling suspension system for direct support.
(d) Mechanical Services. Ceiling-mounted air terminals or services weighing less than 20 pounds shall be positively attached to the suspension main runners or to cross runners with the same carrying capacity as the main runners.
Terminals or services weighing 20 pounds but not more than 56 pounds, in addition to the above, shall have two No. 12 gauge hangers connected from the terminal or service to the ceiling system hangers or to the structure above. These wires may be slack.
Terminals or services weighing more than 56 pounds shall be supported directly from the structure above by approved hangers.
(`83 Code, § 15.04.330) (Ord. 2003-01, § 1, 2003; Ord. 2007-21, § 1 (part), 2007)