# Best answer: How far can roof joists span?

Contents
Maximum Span (ft – in)
Nominal Size (inches) Rafter Spacing, Center to Center, OC (inches) Lumber Grade
2 x 8 16 19′ – 7”
24 17′
2 x 10 12 27′ – 6”

## How far can a roof span without support?

A 2×6 spaced 16 inches apart can span a maximum distance of 13 feet 5 inches when used as a rafter, 10 feet 9 inches when used as a joist, and 6 feet 11 inches when used as a deck beam to support joists with a 6-foot span.

## How far can ceiling joists span?

Joist spacing of 24 inches is allowed for spans between 16 to 20 feet using 2-inch by 10-inch lumber of these three grades.

## How far can a 2×6 Rafter span without support?

How far can a 2×6 Rafter span without support? The table states that 2 X 6 rafters spaced 16 inches on center (o.c) can span a maximum distance of 13 feet 5 inches. Another option are 2 X 8 rafters spaced 24 inches o.c.

## How far can a 2×10 Rafter span without support?

In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. A 2×8 up to 12 feet; 2×10 to 15 feet and 2×12 to 18 feet.

## How far can a 2×12 span without support?

How far can a 2×12 beam span without support? 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 2×12 beam can span 12 feet; a (2) 2×10 can span 10 feet and so on.

## What size beam will span 20 feet?

In that case, you need something like a 12-16″ GLULAM or LVL to span the 20′ and can use simple 2×8-10 dimensional lumber 16″OC as floor joists.

## Can 2×4 be used for ceiling joists?

2×4 are suitable for ceiling joists where the LL is like 20 Lbs. If you got a good species with the highest Modulus of Elasticity and Best grade and use like 12″ o.c. – you might get 8” span.

## Are ceiling joists 16 on Center?

Ceiling joists are usually installed either 16 or 24 inches on center, which means roughly 16 or 24 inches apart. Once you’ve located the first one, the others are easier to find.

## Are two 2×6 stronger than a 4×6?

A 4×6 joist is theoretically stronger than a doubled 2×6 joist because it’s 1/2″ thicker, but the actual strength depends upon the knots and other inherent weaknesses of any particular piece of lumber (#2 lumber can have some nasty spike knots or large not-so-tight round knots or wane).

IT IS INTERESTING:  Best answer: Where is gable roof used?

## What is the maximum span for a 2×6 ceiling joist?

For example, the highlighted cell (below) shows that a 2″ x 6″ Southern Yellow Pine joist, with a grade of #2, and spaced 24″ apart can have a maximum span of 10 feet – 0 inches (10-0), if you are designing your structure to support a plaster ceiling.

## How far can a 2×6 span for a metal roof?

For a 2×6, the maximum span would be 9 feet, since 6 times one and a half equals 9. This rule of thumb is based on using Doug fir lumber, and is only a rule of thumb.

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

In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. A 2×8 up to 12 feet; 2×10 to 15 feet and 2×12 to 18 feet. The larger the deck, the larger the joists.

## How far can a 2×10 span for a floor?

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 3 2×10 beam span?

Dimensional Lumber Deck Beam Span Chart

Joist Spans
Southern Pine 3-2X10 8′-3″
3-2X12 9′-9″
Douglas Fir-Larch, Hem-Fir, Spruce-Pine-Fir, Redwood, Cedars, Ponderosa Pine, Red Pine 3X6 OR 2-2X6 3′-3″
3X8 OR 2-2X8 4′-3″

## Are trusses cheaper than rafters?

Because they are usually pre-constructed off-site and brought to the job, trusses are faster and cheaper to install than rafters because they use smaller, cheaper pieces of lumber and rely upon multiple components to strengthen a unit rather than relying on weight-bearing rafters alone.

IT IS INTERESTING:  What does a Class A roof mean?