1604.3 Serviceability.
BC § 1604.3
Structural systems and members thereof shall be designed to have adequate stiffness to limit deflections as indicated in Table 1604.3 of this code. Drift limits applicable to earthquake loading shall be in accordance with ASCE 7 Chapter 12, 13, 15 or 16, as applicable. Table 1604.3Deflection Limits a, b, c, h, i ConstructionL or LrS or W fD + L d, gConstructionL or LrS or W fD + L d, gRoof members: e Supporting plaster or stucco ceilingl/360l/360l/240 Supporting nonplaster ceilingl/240l/240l/180 Not supporting ceilingl/180l/180l/120Floor membersl/360—l/240Exterior walls: With plaster or stucco finishes—l/360— With other brittle finishes—l/240— With flexible finishes—l/120—Interior partitions: b With plaster or stucco finishesl/360—— With other brittle finishesl/240—— With flexible finishesl/120——Farm buildings——l/180Greenhouses——l/120 For SI: 1 foot = 304.8 mm. a. For structural roofing and siding made of formed metal sheets, the total load deflection shall not exceed l/60. For secondary roof structural members supporting formed metal roofing, the live load deflection shall not exceed l/150. For secondary wall members supporting formed metal siding, the design wind load deflection shall not exceed l/90. For roofs, this exception only applies when the metal sheets have no roof covering. b. Flexible, folding and portable partitions are not governed by the provisions of this section. The deflection criterion for interior partitions is based on the horizontal load defined in Section 1607.15. c. See Section 2403 for glass supports. d. The deflection limit for the D + (L + Lr ) load combination only applies to the deflection due to the creep component of long-term dead load deflection plus the short-term live load deflection. For lumber, structural glued laminated timber, prefabricated wood I-joists and structural composite lumber members that are dry at time of installation and used under dry conditions in accordance with the ANSI/AWC NDS, the creep component of the long-term deflection shall be permitted to be estimated as the immediate dead load deflection resulting from 0.5D. For lumber and glued laminated timber members installed or used at all other moisture conditions or cross laminated timber and wood structural panels that are dry at time of installation and used under dry conditions in accordance with ANSI/AWC NDS, the creep component of the long-term deflection is permitted to be estimated as the immediate dead load deflection resulting from D. The value of 0.5D shall not be used in combination with ANSI/AWC NDS provisions for long-term loading. e. The preceding deflections do not ensure against ponding. Roofs that do not have sufficient slope or camber to ensure adequate drainage shall be investigated for ponding. See Chapter 8 of ASCE 7. f. The wind load shall be permitted to be taken as 0.42 times the "component and cladding" loads or directly calculated using the 10-year mean return interval wind speed for the purpose of determining deflection limits in Table 1604.3. Where framing members support glass, the deflection limit therein shall not exceed that specified in Section 1604.3.7. g. For steel structural members, the deflection due to creep component of long-term dead load shall be permitted to be taken as zero. h. For aluminum structural members or aluminum panels used in skylights and sloped glazing framing, roofs or walls of sunroom additions or patio covers not supporting edge of glass or aluminum sandwich panels, the total load deflection shall not exceed l/60. For continuous aluminum structural members supporting edge of glass, the total load deflection shall not exceed l/175 for each glass lite or l/60 for the entire length of the member, whichever is more stringent. For aluminum sandwich panels used in roofs or walls of sunroom additions or patio covers, the total load deflection shall not exceed l/120. i. I = Length of the member between supports. For cantilever members, l shall be taken as twice the length of the cantilever. (Am. L.L. 2023/077, 6/11/2023, eff. 6/11/2023) Editor's note: For related unconsolidated provisions, see Appendix A at L.L. 2023/077.
