Floor Load Width Explained

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.

Floor load width explained. Bearer floor joist design example simple rectangular shaped light weight home floor joists bearers 3600 section gable roof 25o pitch steel sheet. Drywall attached to the underside of this system is not expected to crack when the floor joist system deflects 1 3. Floor load width flw 78. First floor live loads have higher requirements than second floor live loads 40 pounds per square foot vs.

This is referred to as the floor load width flw. Example flw floor if x 2000mm load width y 4000mm a 900mm flw a x 2 a flw a 1900mm flw b x y 2 flw b 3000mm flw c y 2 flw c 2000mm 79. Critical reinforcement beam stress and deflection conditions occur based upon maximum wheels loads for the floor beams joists spaced less than 8 0. Floor loads whether the bearers are supporting load bearing walls or only floor loads the area of the floor supported by an individual bearer must be determined.

A room used solely for sleeping might need to carry only 30 psf whereas a garage floor over a basement would need 50 psf or higher. The dead load on a floor is determined by the materials used in the floor s construction. For an office building the live load is normally a uniform load of 50 pounds per square foot psf over the entire floor area for a framing member or a 2 000 pound load placed upon any 2 1 2 x 2 1 2 square foot space. In both instances the floor load width is equal to the sum of half of the total span on either side of the bearer total span 4m floor load width 2m for a visual representation of the floor load width see the sketch below.

If there s wall board covered ceiling suspended from the underside of that floor the dead load increases to about 10 pounds per square foot. The load is an average value. An inaccessible attic space on the other hand might have a live load of only 20 psf. Where the bearer supports load bearing walls the type of roof covering also needs to be determined.