# What is the maximum span of a 2×12 floor joist?

The maximum span of 2×12 floor joists depends on various factors, including the species and grade of the wood, the spacing of the joists, the type of floor load (live load and dead load), and local building codes.

Here’s a rough estimate based on common conditions: common Species and Grade of Lumber (e.g., Douglas Fir-Larch, Southern Pine):

In general, for 2×12 floor joists spaced 16 inches on center (16″ o.c.), the maximum span is typically around 18 to 20 feet, while the joists spaced 24 inches on center (24″ o.c.), the maximum span is usually around 16 to 18 feet. If you use a stronger species or a higher-grade lumber, you might achieve a slightly longer span.

There are different depth of floor joists are used in deck floor construction such as 2×6, 2×8, 2×10, 2×12 and 2×14. Joists are made of different species of wood (southern yellow pine & Douglas fir) and different grade such as grade- 1, grade- 2, grade- 3. Southern yellow pine is strongest species of wood that can span more distance compared to other species of wood as Douglas fir. Grade 1 lumber have higher strength than other grade Lumber due to fewer knots.

A 2×12 floor joists are typically a horizontal structural member that runs across an open space of building on supporting wall or studs, or deck. Their function is similar as beams, except floor joists are supported by wall, foundations, or beams framing.

Floor joists usually run between walls or rafters to support a floor. They transfer the dead load of the subfloor and floor finishes and live load of people, furniture and furnishings to beams, walls,or foundation walls. It is like the skeleton/ framing of a building that supports the load which the floor is built to bear. Joists are technically beams that typically spans relatively short distances compared to beams and are made of wood, steel, or engineered wood or lumber

How far can i span a 2×12 floor joist?, it is depending on different size of Lumber, species of wood, grade of wood, spacing between the joist, expected dead and live load of structure that coming to joist. The loading includes dead load of the weight of the frame structure & fixed weight and live load of People, furniture, appliances and a snow on the roof.

Spacing between floor joist for different sizes are kept at 12 inches, 16 inches and 24 inches apart. The joist which are kept at lower spacing can allow longer distance to span as compared to joist spaced further apart. Standard spacing between floors joist is 16 inches.

## What is the maximum span of a 2×12 floor joist?

In general, the maximum span of a 2×12 floor joist range between 18 to 20 feet at 16″ oc, 20 to 24 feet at 12″ oc, or 16 to 18 feet at 24″ oc.

The maximum span of a 2×12 floor joist is 24 feet and 8 inches at 12-inches on-center spacing. At 16 inches on-center spacing, the same-size floor joist can only span up to 21 feet and 4″ while at 24″ OC, a 2×12 floor joist can maximum span upto 17 feet 5 inches. That only applies to floor joists made of structural grade Douglas Fir-Larch at 10psf dead load & 30psf live load.

### How far can i span a 2×12 floor joist?

You can span a 2×12 floor joist as far as 16 feet and 6 inches using No. 2 Southern yellow pine lumber spaced at 16 inches on-center. For the same size floor joist and spacing, if you need to reach about 20 feet, you can use a stronger wood like No. 2 Douglas Fir-Larch.

### How far can a 2×12 floor joist span without support.

You can span a 2×10 floor joist as far as 19 feet and 11 inches without support by using No. 2 Douglas fir lumber spaced at 16 inches on-center and total load of 40psf. At 12 inches on-center spacing, the same-size floor joist can span up to 23 feet and 0″ while at 24″ OC, a 2×12 floor joist can maximum span upto 16 feet 3 inches.

What is the maximum span of a 2×10 floor joist?

How far can a 2×10 ceiling joist span without support

How far can you span a 2×6, 2×8, 2×10 and 2×12 floor joist

How far can a 2×6 ceiling joist span without support

How far can a 2×8 ceiling joist span without support

Conclusions:
The maximum span of a 2×12 floor joist is 24 feet and 8 inches at 12″ oc, while at 16 inches on-center spacing, the same-size floor joist can only span up to 21 feet and 4″.