Roof Joist Deflection Criteria

Table r301 7 allowable deflection of structural members.

Roof joist deflection criteria.

The following example is for a floor joist with a 16 ft. Deflection criteria default deflection criteria for the following members. Monorail crane mr beams. Primary floor beam supporting secondary beam.

This simplistic criteria puts a limit of the span divided by 360 on the incremental deflection due to live or transient load only and a limit of the span divided by 240 on deflection under total load. Relative deflection of adjacent frames at point of support of uhc or mr beam. Underhung crane uhc beams. Determine the appropriate live load deflection criteria.

This load can be linearly prorated to obtain the uniform load for supplementary deflection criteria i e. Steel roof panel systems west conshohocken pa. When using the tables to size rafters there are two points to keep in mind. Deflection criteria for rafters roof beams joists and floor beams.

Joists double span. Structural design criteria 9 by 360. Astm e1592 05 2017 standard test method for structural performance of sheet metal roof and siding systems by uniform static air pressure difference west conshohocken pa. Trus joist tji joist specifier s guide tj 4000 may 2013 4 floor span tables and material weights how to use these tables 1.

Floor beam single span. Floor beam double span. Allowable deflection 192 in 360 0 53 in. If that same joist had gypsum ceiling l 240 the allowable deflection is 0 6.

For example the allowable deflection of a 12ft span floor joist with plaster l 360 is 0 4 12ft divided by 360. These limit states are mathematic expressed as. D tl l 240. Approximate joist deflection of 1 360 of the span.

L 16 ft. D ll l 360. Top running crane trc beams. Scan down the column until you meet or exceed the span of your application.

Astm e1646 95 2011 standard test method for water penetration of. Check your code and follow the awc tables accordingly. Ceiling joists are sized like floor joists except that deflection limits vary depending on whether the joists will be used for attic storage or will have a plaster or drywall finish. Span rafter with a 4 12 slope and no ceiling attached has an allowable deflection of l 180.

3 mezzanine beams and joists. Floor joist span is 14 allowable deflection from table r301 7 is l 360 l 14 x 12 168 168 360 0 47 allowable deflection is 0 47 2018 irc essentials workbook page 43.