Roof Joist Deflection Criteria

Approximate joist deflection of 1 360 of the span.

Roof joist deflection criteria.

Top running crane trc beams. D ll l 360. Deflection criteria for rafters roof beams joists and floor beams. Structural design criteria 9 by 360.

Steel roof panel systems west conshohocken pa. 3 mezzanine beams and joists. Primary floor beam supporting secondary beam. Check your code and follow the awc tables accordingly.

Monorail crane mr beams. Deflection criteria default deflection criteria for the following members. Relative deflection of adjacent frames at point of support of uhc or mr beam. Identify the live and dead load condition.

Underhung crane uhc beams. 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. A uniform load which will produce a joist deflection of 1 240 of the span may be obtained by multiplying the red figure by 360 240. These limit states are mathematic expressed as.

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. 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. D tl l 240.

This load can be linearly prorated to obtain the uniform load for supplementary deflection criteria i e. Table r301 7 allowable deflection of structural members. 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. Scan down the column until you meet or exceed the span of your application.

Determine the appropriate live load deflection criteria. Floor beam double span. When using the tables to size rafters there are two points to keep in mind. Trus joist tji joist specifier s guide tj 4000 may 2013 4 floor span tables and material weights how to use these tables 1.

L 16 ft. 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. The following example is for a floor joist with a 16 ft. Floor beam single span.

Joists double span. Allowable deflection 192 in 360 0 53 in.