# How far can wood I joists span?

## How far can wood I joists span?

With these factors, the lightest joist will have a maximum span of 17 feet, 8 inches. This is the most common as the typical span is 15 feet. The heaviest joist, along with the above factors, will span a maximum of 23 feet, 8 inches.

## How do you calculate joist span?

As a rule, the larger the deck, the larger the joists. For example, joists spaced 16 inches from the center of the joist next to it can span 1.5 times in feet the depth of their inches. To learn more about deck joist sizing, spacing, and allowable span, reference this chart.

**How far can a 2×10 I joist span?**

Douglas fir 2-by-10 joists graded as “Structural Select” allows joist spans up to 21 feet for a live load of 30 pounds per square foot when spaced 12 inches apart, 19 feet 1 inch for 16 inch spacing and 16 feet 8 inches for 24 inch spacing.

### How far can an I joist span without support?

The maximum distance a 2×6 can span, according to the 2018 IRC, for a floor joist, is 12′-6”, ceiling joist 20′-8”, rafter 18′-0”, deck board 24”, deck joist 9′-11”, deck beam 8′-3”, and 6′-1” as for header. Always check the codes for determining factors or consult a Structural Engineer.

### How far can a 2×8 joist span?

Depending on various factors, the maximum span for a 2×8 floor joist is 16′ 6”. The maximum span for roof rafters is 23′ 9”. For headers, the maximum span is 11′ 2”. Finally, a single deck beam has a maximum span of 5′ 11” and double maxes out at 8′ 9”.

**How far can you span a 2×4 floor joist?**

A 2×4 can span a maximum of 6′ 7” when spaced 16” apart and used as a floor or deck joist. When used as a ceiling joist or a roof rafter, a 2×4 can span up to 7′ 3” spaced at 16”, and 6′ 4” when spaced 24” apart.

## Will a 2×8 span 12?

The Depth of Structural Element The depth of the joist, beam, or other structural element is crucial for the allowable span. Using this rule, a 2×6 will span 9 feet, a 2×8 will span 12 feet, and a 2×10 will span 15 feet. As you can see, the larger the depth, the longer the span.

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

With 16” spacing, a floor joist can span up to 14’ as long as it is not cantilevered and terminates with support on either end. If the joists are 24” apart, then one 2×10 joist can span up to 11’ 5”. These lengths are for SYP lumber. If you have Spruce-pine-fir lumber, then your span changes to 13’ 7” for 16” joist spacing.

**How far can you span a 2×6 floor joist?**

The maximum span for a No. 1 quality 2×6 floor joist made from southern pine with a maximum load of 40 psf at standard 16-inch spacing is 10 feet 9 inches, according to the International Residential Code. When we break this down, the variables determining floor joist span are joist spacing, load, wood species, and lumber quality.

### What size joist per span?

While most residential construction uses 2×8 joists with 16 inch spacing, there are many other factors you need to consider when determining the proper joist span length. Joist span and spacing is set by your local building code. You should check with your local building department for construction requirements in your area.

### How many ceiling joist calculator?

Joist Span Calculator. Select a load. There are six choices. The lowest is a plain ceiling joist with no storage (10 pounds per square foot). The highest is a fully loaded floor (70 pounds per square foot). Select the on center spacing for the joists. This is how far apart they will be. Most lay outs are on 16″ so the field is pre-selected.