But first, generally, how far can a 2×8 span without support? 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”.

What is the maximum span for a 2×8 ceiling joist?

A rule of thumb is 1.5 times a joist’s depth but in feet when spaced at 16” centers. In general, a 2×8 will span 1.5 x 8, so 12-feet.

How many rafters do I need for a 16 foot span?





As per general rules and guideline, for 10 -12 foot span, generally you need 2″×6″ size of rafter, for 15 -16 foot span, you need 2″×8″ rafter, for 18 – 20 foot span, you need 2″×10″ rafter & for 24 foot span, you need 2″×6″ size of rafter placed at 16″ apart from centre.

What is the span of a 2×10 ceiling joist?

A #2-2×10 joist can span between 11′-5” and 18′-0”, as a rafter between 13′-9” and 21′-7”, and as a beam 3′-6” and 13′-0” or more. The span depends on spacing, lumber species, and grade, and for a beam, the lamination thickness, as well as numerous other factors.

How much weight can a 2×8 beam hold?

Weight supported by a double or triple wood headers.

Span (feet) Weight Supported (lb)
2 x 2″ x 6″ 3 x 2″ x 8″
4 2250 5850
6 1680 4690
8 3990

What size ceiling joist do I need to span 16 feet?

What size ceiling joist for a 16′:- as per general thumb rules and guideline, for a 16 foot span you will need 2″×8″ size of ceiling joist made of #2 spruce – pine- fir when spaced 24 inches apart.

Can you use 2×8 for rafters?





But first, generally, how far can a 2×8 span without support? 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”.

What size should ceiling joists be?

Standard Size of Joists
Though there is no standard joist size for the ceilings in all buildings, most average homes use ceiling joists in a board size of 2-by-6 inches. The range of joist sizes used in homes varies though, between 2-by-4 inches and 2-by-12 inches.

How far can a rafter 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 a 2×10 rafter span without support?

A 2×10 beam – made up of two 2x10s nailed together – can span up to 11′ without support beneath a deck that is 4′ wide. For a more normal-sized deck, the same beam can span 8′, supporting a deck that is 8′ wide. You can also triple a 2×10 beam.

What size beam do I need to span 16 feet?



For a 16 foot span, you will need atleast 3-2×14 or 6×14 size of wood beam. Thus, a 3 nailed 2×14 or 3-2×14 or 6×14 wood beam can allow to span 16 feet. For a 16-foot spans, the wood beam has to be at least 14 inches in depth and 6″ in width (3-2×14) used for residential building, wood frame structure or projects.

Can a 2X12 span 16 feet?

A 2×12 (2-by-12) floor joists can span up to 23 feet 3 inches, 2×10 (2-by-10) up to 19 feet 1 inches, 2×8 (2-by-8) up to 15 feet & 2×6 (2-by-6) up to 11 feet 4 inches at 16″ spaced by using southern yellow pine graded as #1 when live load of 30 lbs/ft^2 & dead load of 10 lbs/ ft^2.

How far can a 3 ply 2X8 beam span?

Dimensional Lumber Deck Beam Span Chart

Joist Spans
Southern Pine 3-2X8 10′-7″
3-2X10 12′-9″
3-2X12 15′-0″
Douglas Fir-Larch, Hem-Fir, Spruce-Pine-Fir, Redwood, Cedars, Ponderosa Pine, Red Pine 3X6 OR 2-2X6 5′-2″

What lumber will span 16 feet?



Max. Live Load 60 lbs/ft2 (2873 N/m2)

Maximum Span (ft – in)
Nominal Size (inches) Joist Spacing Center to Center (inches) Lumber Grade
2 x 8 24 10′ – 5″
2 x 10 12 16′ – 8″
16 15′ – 2″

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

Example: The highlighted cell (below) shows that a 2″ x 6″ Douglas Fir joist, with a grade of #2, spaced 24″ apart, can have a maximum span of 10 feet – 8 inches (10-8).

How long can a 2×6 rafter span?

Depending on the factors, a 2×6 rafter can span between 4′-11” and 18′-0”, which is a rather large difference. The span decreases as the spacing and load increase and is dependent on the type and grade of timber. The stronger the species and higher the grade, the farther it can span.

Can 2×6 be used for rafters?

You can use either 2×6 or 2×4 rafters for roofs with a 3/12 pitch or greater, but it depends on the overall size of your shed. For roofs that won’t experience heavy snow loads, a gable roof can span up to 22′ with 2×4 rafters.

How do you reinforce 2×6 ceiling joists?



Strengthening Attic Joists for Live Loads by Sistering
In the case of 2 x 6 joists, you can pair them up with additional 2 x 6 joists by nailing them together, side by side. The best-case scenario is to run the sisters the entire length of the existing joists so that you have two additional resting points.

What size should roof rafters be?

The industry standard for roof joist or rafter spacing is 12”, 16”, 19.2”, and 24” on-center, typically though, rafters are spaced 16” or 24” on-center. The gap between members can be different provided it meets code requirements.

What size timber is used for rafters?

Roof pitch between 30 and 45 degrees with rafter spacing strength class C16

Size of rafters in mm 400mm 600mm
100 x 47 1.91 1.78
125 x 47 2.52 2.33
150 x 47 3.14 2.88