Floor Stiffness 360 Or 480

A general rule for limiting deflection of simple spans is that the deflection should not exceed the span in inches divided by 360 max d l 360.

Floor stiffness 360 or 480.

And since it is small i will leave the source for where it is found here 1. Attic floors with limited storage l 240 10 psf. Looking for a wood floor which will give exemplary performance with a minimum of bounce. Applied load dead load a.

The deflection for exposed ceiling beams at the roof is often allowed to be 50 to 100 greater l 240 or l 180. Ask your building designer about the investment difference to increase stiffness to l 480 or even l 720. Bedrooms and habitable attic floors l 360 30 psf. Please read everything on the attached photo below.

Joists and rafters must be strong enough not to break when loaded. L 300 girders spans to 36 ft b ll 60 psf. Increased floor stiffness is desired used with permission. The amount of flex depends on the magnitude of the load applied span of the member and stiffness of the member.

L 360 60 psf ll 80 psf. Floor beams commercial office institutional floor joists spans to 26 ft b ll 60 psf. The solution is to specify an upgrade to a lesser deflection than the code required l 360. The l stands for length.

I prefer to go with a span chart that uses l 480 for the live load. For this reason i don t recommend using a span chart for any kind of floor member that uses l 360 as the deflection criteria. That means l 360 is implied for the total load deflection and it will result in much better floor performance. For l 480 deflection the maximum span drops to 15 feet 6 inches.

Strength of a material is obviously important. Typically for better performing floors minimal defection is desired. To take weyerhaeuser s trus joist span tables as an example 17 feet 2 inches is the maximum span with an l 360 deflection ratio allowed by code for a floor that s framed with the company s 9 inch deep nominal 2x10 series 110 tji joists spaced 16 inches on center. So if you have a beam 20ft long the allowable deflection limit is 20ftx12in ft 240 1.