Applicability to Non-Residential Structures The L/Δ LL=240 deflection limit basis is consistent with deflection limits for members supporting roofs and ceilings as shown in IRC Table R802.5.1 and IBC Table 2308.7.2 for rafters with ceilings attached to rafters and IRC Table R802.4 and IBC Table 2308.7.2 for ceiling joists, respectively. Roof header span tables have been revised to be based on L/Δ LL=240 instead of L/Δ LL=360. Excerpt from 2015 WFCM Table 3.25B2 for common lumber ceiling joist spans. Flexible finishes are denoted as “(including gypsum board)” and brittle finishes are denoted as “(including plaster and stucco).”įigure 3. Tables for ceiling joist spans/capacities, rafter spans/capacities, and hip and valley beam capacity requirements have been revised to clarify the live load deflection basis of these deflection criteria, and to associate live load deflection limits to cases with “no ceiling attached” and ceilings with “flexible finishes” and “brittle finishes.” Tables are added to address deflection criteria of L/Δ LL=360 for brittle finishes (Figure 3). Rafters and Ceiling Joists with Brittle Finishes The American Lumber Standard Committee (ALSC) Board of Review approved changes to these design values for all grades and all sizes of visually-graded Southern Pine and Mixed Southern Pine lumber, with a recommended effective date of June 1, 2013. Notably, the 2015 NDS Supplement incorporates new design values for visually-graded Southern Pine. Tabulated spans for lumber framing members now reflect changes to design values referenced in the 2015 National Design Specification ® for Wood Construction Supplement: Design Values for Wood Construction.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |