Allowable Deflection In Floor Trusses


Is there a chart available on the allowable amount of deflection on floor trusses?


As a general rule, the allowable amount of deflection is l/360, where l is span length in inches. For a stiffer floor, it is common to use l/480. You can also use a length to depth ratio, which is typically 18 for good performance. The lower the number, the stiffer the floor.

Standard code requirements are outlined in IRC 2012/2015 table R301.7, IBC 2012/2015 table 1604.3 and section 7.6.2 of the Truss Plate Institute's ANSI/TPI 1. Most building codes have a similar standard, but it's best to check local codes to be sure you’re in compliance.

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