Attic Joists Live Load

Standard joist spacing for the installation of attic flooring materials is 16 inches on center oc meaning the distance from the center of one joist to the center of the next joist is 16 inches.

Attic joists live load.

Sistering is the process of adding a new joist next to each existing joist. Where they connect to both the top and bottom joists each gusset pair will transfer approximately 100 pounds that s 50 psf of floor load times the 3 foot gusset spacing times the 16 inch joist spacing divided by the two joists. Attic ceiling joists with limited storage. Consult local building codes for snow load capacity and reference the span tables for joists and rafters published by the american wood council awc.

Therefore if you have an attic space according to this scenario the ceiling joists can be designed for a live load of 10 pounds per square foot psf by using table r802 4 1. In this case your joists are adequate to support a 30 psf live load and 10 psf dead load. An inaccessible attic space on the other hand might have a live load of only 20 psf. 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.

In the case of 2x6 joists you can pair them up with additional 2x6 joists by nailing them together. Strengthening attic joists for live loads by sistering. First floor live loads have higher requirements than second floor live loads 40 pounds per square foot vs. Snow and wind loads.

Use span tables for progressively heavier loads until you find the limits of your floor. There are also factors such as deflection elasticity and wood species that come in to play. Span calculator for wood joists and rafters also available for the android os. 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.

Use six 10d nails with plywood gussets or six 16d nails with 2x4s half into each 2x6 joist. If the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists. However if the attic is intended for storage the attic live load or some portion should also be considered for the design of.