Floor Joists What Size Do I Need

For conventional guardrail post installation bolted to the side of the framing larger framing will provide more strength in the rails.

Floor joists what size do i need. First floor live loads have higher requirements than second floor live loads 40 pounds per square foot vs. In the past 2x4s or 2x6s were sometimes used as floor joists. Live load is weight of furniture wind snow and more. See the image below for an example of joists spaced 16 on center 16 o c.

1 ft 0 3048 m. A structure with a 10 foot 3 05 m length and joists set 12 inches 304 8 mm apart would require using a floor joist size of 2 x 8 50 8 x 203 mm. My house is 100 years old. For upper level decks 2x10 is recommended as the minimum size to use for strong guard post connections.

Maximum floor joist span for no. Chris october 23 2015 at 7 11 am. The floor joist spacing is the distance between the centers of any two installed joists. The most common option for your floor joist is your standard 2 6.

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. 2x6 joists should only be used on ground level decks that do not require and will not provide for any guards. 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. Joist span and spacing is set by your local building code.

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. How far apart do i need to have the floor joists and what size joists do i need for the floor. These tables can help calculate whether floor joists are strong enough to support themselves and the load they carry without the help of any walls underneath. An inaccessible attic space on the other hand might have a live load of only 20 psf.

In general practice 2x8s 2x10s or 2x12s are used when framing a raised floor instead. This size is no longer acceptable when framing a structure. The joists are real 2 x 12 spaced at around 20 inches centered. 1 psf lb f ft 2 47 88 n m 2.

Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors. If the joist spacing will be 16 inches 406 4 mm a joist size of 2 x 8 should be used even if the length is only 8 feet 2 44 m. What size floor joist do i need. 2 grade of douglas fir are indicated below.

Dead load weight of structure and fixed loads 10 lbs ft 2. The problem is the noise when walking on the floor. The exact size necessary may be stipulated by the building code required for a particular structure.