How far can floor joists span?
In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. A 2x8 up to 12 feet; 2x10 to 15 feet and 2x12 to 18 feet. The larger the deck, the larger the joists.
Max. Live Load 30 lbs/ft2 (1436 N/m2)
|Maximum Span (ft - in)|
|Nominal Size (inches)||Joist Spacing Center to Center (inches)||Lumber Grade|
|2 x 8||12||15' - 10"|
|16||14' - 5"|
|24||12' - 4"|
- The rim joist, for those who are not familiar with building terms, is the edge of the wood floor framing system. It sits on top of the foundation walls, secured to the sill plate. In a typical home, the rim joist area is a huge source of energy loss.
- For interior framing, that means using only the thicker 10d, 12d or 16d common nails (rather than skinnier sinker nails) to fasten a joist hanger's face flange to wall ledgers, headers and beams. Outdoors use 16d double-dipped galvanized nails (or stainless steel when called for) for installing hangers.
- Replacing your soffit generally costs about $20 to $30 a linear foot installed, while replacing your fascia costs about $15 to $25 a linear foot installed. Prices for the project depend on a number of factors, including the materials used and the size of your house.
Normally, floor joists are spaced 16 inches apart on center. This means from the center of one upright joist to the center of the next. Given that 2x8s are actually 1-¾ inches wide, it works out to be 14-¼ inches between each joist. With some structures, floor joists are required to be 12 or 24 inches apart on center.
- Start by aligning your top and bottom plate ends flush together and measure 15 1/4 inches to side of first stud placement. Each corresponding measurement should be 3/4 of an inch shy of stud marks on your tape measure. This will give you studs that are on 16 inch center layouts.
- If you don't have a stud finder, there are several methods that can be effective in finding studs. When a home is framed, the wall studs are usually spaced 16 or 24 inches apart. If you start in a corner and measure out 16 inches and you don't find a stud, you should find one at 24 inches.
- Standard Spacing. Most trusses are spaced 24 inches on center, which means the centers of the truss members are 2 feet apart laterally. Building codes in some severe weather areas or governing roofs in special situations may require 16- or even 12-inch spacing, but 24 inches is the universal basic dimension.
When supporting joists that span 12 feet with no overhang beyond the beam, a double ply beam can span in feet a value equal to its depth in inches. A double 2x12 beam can span 12 feet; a (2) 2x10 can span 10 feet and so on.
- There's not quite enough information here to give a definitive answer, but for decks, a rule of thumb is when supporting joists that span 12 feet, a double ply beam can span in feet a value equal to its depth in inches. Thus, a double 2x12 beam could span 12 feet - with 20' beams, posts at 10' might look the best.
- Figure B: Example of Calculating Header Size
Header Size Maximum Span Number of Trimmers Double 2×6 4 ft., 0 in. One Double 2×8 5 ft., 0 in. Two Double 2×10 6 ft., 2 in. Two Double 2×12 7 ft., 1 in. Two
- The rough framing should be 2-1/2 inches wider than the door itself. That leaves room for the 3/4 inch finish frame on each side of the door, and then 1/2 inch on each side for the shims between the finish frame and the rough frame.
Updated: 6th October 2019