Attic Wieght Limit

Access to attic storage.

Attic wieght limit.

A typical load is 5 and 10 pounds per square foot. I m guessing you don t have the plans and don t know what live load the attic was designed for. If you want to use your attic on a regular basis or to store large items you may need to enlarge the access opening and install an access ladder or drop down stairs. If the total weight exceeds the load limit of the truss then the truss is compromised.

Scrap of plywood over the chords and set about 40 lbs. That means you could lay a 2 x 4 ft. Of stuff on it. All weight hanging from the truss has to be added to the existing dead load.

The span table for a 30 psf live load 10psf dead load floor indicates a required fb value of 1 315 and a minimum e value of 1 800 000. The dead load on the bottom chord of a truss varies with the weight of materials attached to it such as drywall on the ceiling. If the attic has the potential to become a regular living space talk with a contractor about adding a fixed stairway. So if your ceiling is unfinished you have some excess carrying capacity up there.

An uninhabitable attic not designed for storage can handle a 10 pounds per square foot live load. An uninhabitable attic designed for limited storage can handle 20 pounds per square foot live load. Make sure items are spaced so that the weight is evenly distributed over the chords. In the example the joists have a spacing of 16 inches and a span of 11 feet 2 inches.

Next consult a span table to cross reference the spacing and span to find the required fb value for that table s load limits.