Floor Joists For 2nd Floor

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.

Floor joists for 2nd floor.

In buildings with basements the first level of floor joists serves the same purpose. Floor joists are relatively large and are designed to support the floor of living spaces and large storage areas. Ceiling joists are usually 2 by 6s or sometimes 2 by 4s if it is an older home. An inaccessible attic space on the other hand might have a live load of only 20 psf.

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. 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. Dead load weight of structure and fixed loads 10 lbs ft 2. Framing for floor openings a staircase is essential for commuting between floors but it creates an opening in the second floor so you can t run the joists from one side of the house to the other without interruption.

Floor joists installed on second or third or higher levels double as ceiling joists for the level below. A floor s framework is made up mostly of wooden joists that run parallel to one another at regular intervals. 1 ft 0 3048 m. Live load is weight of furniture wind snow and more.

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. Floor joists align with the wall studs which align with the first story floor joists. The floor joist spacing is the distance between the centers of any two installed joists. Joist span and spacing is set by your local building code.

First floor live loads have higher requirements than second floor live loads 40 pounds per square foot vs. The joists are so straight that i can t hardly find the crown in the lumber. This size is no longer acceptable when framing a structure. In the main floors of a home the floor joists also form the ceiling structure for living spaces.

The 2x12 lumber that i picked up a few weeks ago is perfect. Maximum floor joist span for no. 2 grade of douglas fir are indicated below. Some newer homes have manufactured i beam shaped joists.

Floor joists are typically 2 by 8s 2 by 10s or 2 by 12s. If you re concerned about the structural integrity of sagging cracked or twisted joists in your house first call in a structural engineer to inspect the floor and recommend strengthening measures that ll take out the sags and bring the framing up to code search online or for engineers structural in the yellow pages. In the past 2x4s or 2x6s were sometimes used as floor joists. See the image below for an example of joists spaced 16 on center 16 o c.