Second Story Floor Framing Joist Size

Joist span and spacing is set by your local building code.

Second story floor framing joist size.

Builders can adjust their choice of lumber size and spacing depending on circumstances. Floor joists align with the wall studs which align with the first story floor joists. Section r502 10 of the international residential code states that header joists can be the same size as the floor joists when the header joist span isn t greater than 4 feet but if the header joist span is more than 4 feet you ll need to double the header joist and ensure that it s capable of supporting the floor joist framing. In typical deck construction with a ledger on one side of the joist and beam on the other the size of the joists is driven by the size of the deck and based on the general maximum spans mentioned above.

Maximum floor joist span for no. Normally floor joists are spaced 16 inches apart on center. 1 ft 0 3048 m. See the image below for an example of joists spaced 16 on center 16 o c.

2 grade of douglas fir are indicated below. Looking at this table you will see there is a choice in the size of floor joist 2 x 6 2 x 8 2 x 10 or 2 x 12 and there is a choice in the joist spacing 12 16 or 14. 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. 2x10 to 15 feet and 2x12 to 18 feet.

What this means is that the first story ceiling joists will also serve as the floor joists for the second story. The 2x12 lumber that i picked up a few weeks ago is perfect. The larger the deck the larger the joists. Given that 2x8s are actually 1 inches wide it works out to be 14 inches between each joist.

With some structures floor joists are required to be 12 or 24 inches apart on center. You should check with your local building department for construction requirements in your area. 1 psf lb f ft 2 47 88 n m 2. While first floor supports are needed to account for the additional weight of a second floor the walls are pretty much the same as those of a single story home.

Dead load weight of structure and fixed loads 10 lbs ft 2. The floor joist spacing is the distance between the centers of any two installed joists. Live load is weight of furniture wind snow and more. The joists are so straight that i can t hardly find the crown in the lumber.

Once the rim joist is in place which creates a frame around the perimeter of the second story floor you ll install the floor joists which are the same dimension as the rim joist.