Design Timber Floor Joists

2 grade of douglas fir are indicated below.

Design timber floor joists.

Dead load weight of structure and fixed loads 10 lbs ft 2. 1 ft 0 3048 m. A design value table shows that the joists have an fb value of 1 495 and an e value of 1 900 000. True floor joist span calculations can only be made by a structural engineer or contractor.

The floor joist spacing is the distance between the centers of any two installed joists. 1 psf lb f ft 2 47 88 n m 2. Code of practice for permissible stress design materials and workmanship and bs 5268 7 1 1990 structural use of timber section 7 1 domestic floor joists. Since the example house we are designing for is 12 feet wide we need to find in the floor joist span table a joist size and centering that can span 12 or wider.

See the image below for an example of joists spaced 16 on center 16 o c. 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. As an example consider a room with a floor area of 10 feet by 11 feet 2 inches built with no. Apa performance rated i joists pris are manufactured in accordance with pri 400 performance standard for apa ews i joists form x720 this performance standard provides an easy to use table of allowable spans for applications in residential floor construction allowing designers and builders to select and use i joists from various member manufacturers using just one set of span.

Maximum floor joist span for no. 1 grade 2 by 6 douglas fir larch joists spaced 16 inches on center.