How Tall Are Floor Joists

You can always use bigger lumber closer spacing or a smaller span.

How tall are floor joists.

This is the most common as the typical span is 15 feet. The floor joist spacing is the distance between the centers of any two installed joists. Floor truss span tables alpine engineered products 17 these allowable spans are based on nds 91. Bci joists are specially constructed floor i joists with flanges made from strong versa lam lvl.

Joists must exhibit the strength to support the anticipated load over a long period of time. 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. 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. Considering the cross section of a typical joist the overall depth of the joist is critical in establishing a safe and stable floor or ceiling system.

Live load is weight of furniture wind snow and more. 18 1 6 first hole 18 from leading edge. 1 psf lbf ft2 47 88 n m2. Basic lumber design values are f 2000 psi f 1100 psi f 2000 psi e 1 800 000 psi duration of load 1 00.

18 to center of first hole. 2 grade of douglas fir are indicated below. Maximum floor joist span for no. Builders can adjust their choice of lumber size and spacing depending on circumstances.

In many countries the fabrication and installation of all framing members including joists must meet building code standards. 48 to center of each additional hole but not closer than 48 o c to the last trailing edge hole. The heaviest joist along with the above factors will span a maximum of 23 feet 8 inches. Last hole is centered 18 from end of the joist trailing edge for example.

12 0 long joist will have holes at. Bci joist span and size charts available for download. With these factors the lightest joist will have a maximum span of 17 feet 8 inches. Just don t go smaller further apart or a longer span.

Below is a table giving the minimum size floor joists needed for 16 and 24 on center o c spacing when using 2 lumber with 10 pounds per square foot of dead load and 40 pounds of live load. Dead load weight of structure and fixed loads 10 lbs ft2.