Timber Floor Deflection Limits

A floor joist appropriately selected to span 10 feet with an l 360 limit will deflect no more than 120 360 1 3 inches under maximum design loads.

Timber floor deflection limits. Horizontal deflection limits are given in table na2 examples of limiting values of horizontal deflections. They are expressed as a fraction. A the aitc includes a modifier on dl depending on whether or not the timber is seasoned. Span calculator for wood joists and rafters also available for the android os.

B for cantilever members l shall be taken as twice the length of the cantilever. B for girder spans greater than 36 ft and joist spans greater than 26 ft special design considerations may be required such as more restrictive deflection limits and vibration considerations that include the total mass of the floor. For example a timber floor joist spanning 4m between supports and provided with solid strutting can if designed to bs 5268 have a maximum permissible deflection of 12mm. Now consider the same floor joist supporting stone tile flooring such that floor dead load is now 20 psf.

They are expressed as a fraction. Note it gives the allowable deflection based on a fractional span quantity so a larger denominator will yield less deflection. For aluminum structural members or panels used in roofs or walls of sunroom additions or patio covers not supporting edge of glass or sandwich panels the total load deflection shall not exceed l 60. For example the allowable deflection of a 12ft span floor joist with plaster l 360 is 0 4 12ft divided by 360.

For a bay in which mode b could not be assumed the span at which the limit of l 300 affects the design would be even less. Spacing in exterior exposure. So at mid span 2m there could be 12mm out of level and potentially at 1m intervals there could be a 6mm drop in level per metre. Live load psf dead load psf span calculator for wood joists and rafters available for the iphone.

Maximum deflection limits are set by building codes. For the purpose of the determining deflection limits herein. See the table below. A floor joist appropriately selected to span 10 feet with an l 360 limit will deflect no more than 120 360 1 3 inches under maximum design loads.

Clear span in inches l over a given number. However the limit on total deflection is span 720 resulting in the need for total deflection to be only 0 50 half of the 1 00 value for span 360. Clear span in inches l over a given number. Maximum deflection limits are set by building codes.