Floor Stiffness 360 Or 480

L 360 ll 80 psf.

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. For l 480 deflection the maximum span drops to 15 feet 6 inches. The l stands for length. L 360 60 psf ll 80 psf.

And since it is small i will leave the source for where it is found here 1. I prefer to go with a span chart that uses l 480 for the live load. So if you have a beam 20ft long the allowable deflection limit is 20ftx12in ft 240 1. Strength of a material is obviously important.

L 300 girders spans to 36 ft b ll 60 psf. The deflection for exposed ceiling beams at the roof is often allowed to be 50 to 100 greater l 240 or l 180. Bedrooms and habitable attic floors l 360 30 psf. Chapter 3 of the international residential code irc provides the maximum allowable deflection for a given structural member floor roof wall etc.

Looking for a wood floor which will give exemplary performance with a minimum of bounce. Joists and rafters must be strong enough not to break when loaded. Please read everything on the attached photo below. Increased floor stiffness is desired used with permission.

Applied load dead load a. 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. 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.

The solution is to specify an upgrade to a lesser deflection than the code required l 360. Unlike stiffness live loads and dead loads are added together to determine minimum design values for strength. Ask your building designer about the investment difference to increase stiffness to l 480 or even l 720. That means l 360 is implied for the total load deflection and it will result in much better floor performance.