Floor Joist Span Sizes

Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors.

Floor joist span sizes.

1 psf lb f ft 2 47 88 n m 2. See the image below for an example of joists spaced 16 on center 16 o c. 1 ft 0 3048 m. Dead load weight of structure and fixed loads 10 lbs ft 2.

This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction. Floor joist span tables for various sizes and species of wood. Live load is weight of furniture wind snow and more. The floor joist spacing is the distance between the centers of any two installed joists.

2 grade of douglas fir are indicated below. Joist span table use these tables to determine floor joist spans based on grade of lumber size of joist floor joist spacing and a live load of 30 lbs ft 2 or 40 lbs ft 2 these tables can also be used to determine deck joist span. When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started. While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length.

Joist span and spacing is set by your local building code. True floor joist span calculations can only be made by a structural engineer or contractor.