# What is the maximum span of a 2×8 floor joist?

The maximum span of 2×8 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 2×8 floor joists spaced 16 inches on center (16″ o.c.), the maximum span is typically around 13 to 14 feet, while the joists spaced 24 inches on center (24″ o.c.), the maximum span is usually around 10 to 12 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 2×8 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.

The maximum span for 2×8 joists depends on various factors, including the type of wood, the spacing between the joists, and the load they need to support. In general, for residential construction with typical lumber (such as Douglas fir or southern pine), 2×8 joists spaced 16 inches on center can span up to about 12 feet.

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 2×8 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 2×8 floor joist?

In general, the maximum span of a 2×8 floor joist range between 13 to 14 feet at 16″ oc, 15 to 16 feet at 12″ oc, or 11 to 12 feet at 24″ oc.

The maximum span of a 2×8 floor joist is 15 feet and 10 inches at 12-inches while at 16 inches on-center spacing, the same-size floor joist can span up to 14 feet and 5″. Moreover, at 24″ OC, a 2×8 floor joist can maximum span up to 12 feet 4 inches. That only applies to floor joists made of structural grade Douglas Fir-Larch at 10psf dead load & 30psf live load.

A typical 2×8 floor joist made of structural grade Douglas Fir-Larch can allow to span max distance of 15 feet and 10 inches at 12-inches on-center spacing, 14 feet and 5″ at 16″ OC, or 12 feet 4 inches at 24″ at OC.

A typical 2×8 Douglas-larch floor joist can allow to span maximum distance of 15 ft 10″ at 12″ oc, 14 ft 5″ at 16″ oc, or 12 ft 4″ at 24″ OC.

A 2×8 joist span:- A 2×8 floor joist made of structural grade Douglas Fir-Larch can span maximum distance of 15 feet and 10 inches at 12-inches on-center spacing. At 16 inches on-center spacing, the same-size floor joist can span up to 14 feet and 5″ while at 24″ OC, a 2×8 floor joist can maximum span up to 12 feet 4 inches at 10psf dead load & 30psf live load.

### How far can i span a 2×8 floor joist?

You can span a 2×8 floor joist as far as 13 feet and 8 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 14 feet, you can use a stronger wood like No. 2 Douglas Fir-Larch.

### How far can a 2×8 floor joist span without support.

You can span a 2×8 floor joist as far as 14 feet and 1 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 15 feet and 7″ while at 24″ OC, a 2×8 floor joist can maximum span upto 11 feet 6 inches.

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Conclusions:
The maximum span of a 2×8 floor joist is 15 feet and 10 inches at 12-inches oc, while at 16 inches on-center spacing, the same-size floor joist can only span up to 14 feet and 5″.