What is the maximum span for a 2×8 floor joist

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 2x8 floor joist?

Maximum Span (ft – in)Nominal Size (inches)Joist Spacing Center to Center (inches)Lumber Grade2 x 81215′ – 10″1614′ – 5″2412′ – 4″

Can I use 2x8 for floor joists?

The rule of thumb is 1″ of depth for each foot of run. EX an 8′ span should have a 2×8 joist. The same rule of thumb applies to door and window headers but you should use 4x wood. Ex an 8 foot window header should have an 8′4×8.

How far can 2x8 span without support?

In general, a 2×8 will span 1.5 x 8, so 12-feet. Based on all factors though, a 2×8 joist span is 7′-1” to 16′-6”, and a rafter 6′-7” and 23′-9”. In this guide, we’ll explain what span means in terms of construction, factors that impact the span, and how much weight a 2×8 can support.

How far can a 2x10 floor 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 you cantilever a 2x8 joist?

The American Wood Council states that cantilevers are limited to 1/4 the span of the joists. Joist Spacing (o.c.) Maximum allowable overhang cannot exceed 1/4 of the actual main span.

How much load can a 2x8 support?

Span (feet)Weight Supported (lb)2 x 2″ x 6″2 x 2″ x 8″42250469061680313082660

How far can a double 2x8 deck beam span?

A 2×6 joist can span up to 9 feet, a 2×8 can span up to 12 feet, and a 2×10 can span up to 15 feet.

How big of a beam do I need to span 16 feet?

Wood beam size for a 16 foot span:- as per general thumb rule, for a 16 foot span, size of wood beam or lumber joist should be 2×10 which placed at 16″ apart from centre used for residential building or projects or construction in which depth of section of beam is 250mm (10″) and width of beam is 50 mm or 2″.

How do you strengthen a 2x8 floor joist?

The best way to strengthen floor joists from underneath is to make a supporting mid-span beam or wall beneath the wobbling joists. Using jack posts or 6×6 posts and 2×10 or 2×8 beams perpendicular to the joists will solve any wobble and ensure your joists never move again.

Article first time published on

Should deck joists be 2x6 or 2x8?

That’s a model deck code which includes joist span tables. If there is to be a railing, you need the joists to be at least 2x8s. 2x6s don’t have the depth needed to resist the leverage that can be placed on a railing post bolted to them.

Can a 2x10 span 14 feet?

An SYP (Southern Yellow Pine) 2×10 lumber span can reach up to 14′ when used as a joist with 16” spacing. If using SPF or Redwood lumber, then the span maximum for the same distances will be half to a full foot less.

Can a 2x10 span 15 feet?

As the table shows, no 2×8’s meet the span and spacing requirements, but a 2×10 with an E of 1,300,000 psi and Fb of 1093 psi can span 15 feet 3 inches – more than enough.

What is the longest span for floor joists?

A floor joist can span nearly 26′ in the most extreme cases. A select douglas fir 2×12 supporting a 30 psf live load and 10 psf dead load, spaced at 12” will have the greatest span length.

Will a 2x8 span 10 ft?

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.

Can I drill a 2 hole in a 2x8 floor joist?

The hole cannot be larger than one-third the depth of the joist, so the maximum hole size for a 2×12 joist (actual size 1-1/2 x 11-1/4 in.) is 3-3/4 in. diameter—plenty big enough for running cable! You can drill the holes anywhere along the length of the joist (first photo).

How much does a 2x8 weight per foot?

Weight of Dimensional Lumber2 x 61.5 x 5.52.342 x 81.5 inch x 7.25 inch3.09 lbs2 x 101.5 x 9.253.952 x 121.5 x 11.254.80

How far can I cantilever a 2x8 deck?

A Wood Council document (here) gives some very high-end detail about decks, but the take-away as far as cantilevers go is almost exactly the same: 400mm/16” for 2×6 or 2×8 lumber, and 600mm/24” for 2×10 or 2×12 lumber.

How far can you cantilever a 2x8 deck joist in Ontario?

3. Maximum cantilever (overhang) for 2″ x 8″ joists is 16″ and for 2″x 10″ joists is 24″.

How far can a 4X8 beam span?

Joist SpansDouglas Fir-Larch, Hem-Fir, Spruce-Pine-Fir, Redwood, Cedars, Ponderosa Pine, Red Pine4X66′-2″4X88′-2″4X109′-8″4X1211′-2″

How big of a beam do I need to span 20 feet?

Wood beam size for a 20 foot span:- as per general thumb rule, for a 20 foot span, size of wood beam or lumber joist should be 2×14 which placed at 16″ apart from centre used for residential building or projects or construction in which depth of section of beam is 350mm (14″) and width of beam is 50 mm or 2″.

What size lumber can span 13 feet?

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.

What is the standard floor joist spacing?

Most often, floor joist spacing is 16 inches apart on center, but this can vary depending on building codes and the requirements of the structure in the blueprint. Floor joists help distribute the load of a structure.

How big of a header do I need for a 8 foot span?

Header SizeMaximum SpanNumber of TrimmersDouble 2×64 ft., 0 in.OneDouble 2×85 ft., 0 in.TwoDouble 2×106 ft., 2 in.TwoDouble 2×127 ft., 1 in.Two

What is a sister joist?

Joist sistering is adding an extra identical floor joist, to a damaged or inadueqate floor joist, and tieing the two together with screws or nails. It is a very effective way of adding the additional strength needed to hold up a sagging floor.

Why does my floor bounce when I walk on it?

Trusses that are undersized for the weight that they are carrying will often sag, be bouncy or spongy when walked upon. … The closer that floor joists or trusses are together, all other things being equal, the more weight that they can carry and there is less bounciness or deflection.

Can I use 2x8 for deck boards?

Q: Can I use 2×8 treated lumber as deck boards? A: No, that’s a not a good idea. Lumber wider than 6 inches should not be used as a flat surface. Wide, flat boards have a tendency to pool rain water, which can lead to cupping problems.

How many joists do I need for a 12x12 deck?

For example, a 12-foot x 12-foot deck of 5/4 x 6 pressure treated wood decking on 16 inches on center spacing of joists will require: A 12-foot long deck with joists 16 inches on center will require 10 joists.

How many joists do I need for a 16 foot deck?

For example, when you space joists 16″ apart — which is standard for residential decks — a deck spanning 9 1/2′ would require 2-by-6 joists, a 13′ deck would need 2-by-8 joists and a 16′ deck calls for 2-by-10 joists.

How big of a hole can you drill through a 2x10 floor joist?

The maximum allowable diameter of a hole in any solid-lumber joist is one-third of the joist’s depth. Notches can’t be deeper than one-sixth of the joist depth. In the case of your 2×10 joists, the maximum diameter is 35⁄64 in. (91⁄4 in.