Floor Joist Design

Dead load weight of structure and fixed loads 10 lbs ft 2.

Floor joist design.

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. Live load is weight of furniture wind snow and more. Some newer homes have manufactured i beam shaped joists. The allowable ceiling joist span tables in the 2018 version are found in section r802 5.

Open web trusses with wood webbing held together with metal plates. 2 grade of douglas fir are indicated below. A floor s framework is made up mostly of wooden joists that run parallel to one another at regular intervals. Don vandervort hometips.

See the image below for an example of joists spaced 16 on center 16 o c. I joists have major advantages in high volume construction with standard layouts. 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 joists should be spaced no more than 16 inches 41 cm apart from center to center to provide adequate stability.

In this post we will cover wood roof framing members specifically ceiling joists. Mark the position of each floor joist along the sill plate. Two types of engineered joists are most frequently used in floor systems today. Wood i joists with dimension lumber top and bottom chords and osb web.

True floor joist span calculations can only be made by a structural engineer or contractor. Also available for the android os. 1 ft 0 3048 m. Use a tape measure to measure 16 inches 41 cm in from the edge of the rim joist and draw a small notch.

Ceiling joists are usually 2 by 6s or sometimes 2 by 4s if it is an older home. Floor joists are typically 2 by 8s 2 by 10s or 2 by 12s. The floor joist spacing is the distance between the centers of any two installed joists. Span calculator for wood joists and rafters also available for the android os.

The design and construction of ceiling joists are found in section r802 4 of the irc.