What size should beams be for a pergola?

As per thumb rule and general guidelines, it is recommended that for a 10′ span you will need at least 2″x6″ size of wood beam used for pergola, for a 12 foot span – 2×8 size timber, for a 14, 15 &16 foot span – 2×10 size timber and for 18 to 20 foot span you will need 2×12 size timber.

How far can I span a pergola beam?





There seems to be no definitive beam spans for pergolas, unfortunately. Generally speaking, though, it is recommended that for a 12′ span you will need at least 2″ x 8″ treated or hardwood timber or more. Go much above that, unsupported, and you’re looking at a reinforced beam.

How far can 2×6 pergola rafters span?

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 2×8 span on a pergola?

The IRC 2018 does not specify a maximum span for pergola beams. Because of this, it is best to go by the standard rule and multiply the depth by 1.5. This would give you 12 feet. You may be able to get away with another 1 to 2 feet depending on the species and grade of the wood but should avoid going past that.

How big can a pergola be with 4 posts?

Support Posts





For a very small pergola with only 4 to 6 feet between posts, 4×4 supports will work. For anything larger, though, the 6×6 stock will not only offer a beefier look and greater carrying capacity, but 6×6 also resists the twisting associated with the more spindly 4x4s.

What size are pergola rafters?

Typically the rafters could be 2 inches by 6 inches, 2 inches by 8 inches, or 1.5 inches by 7.25 inches. The length of the rafters be as long as you desire the pergola itself to be.

What is the maximum distance between pergola posts?

Pergolas are generally light structures so posts can be positioned up to 3m apart.

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

How Far Can a 2×10 Beam or Header Span? 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 is the maximum span for a 6×6 beam?



A 6×6 softwood beam may be able to span 20′ with limited loads. However, for structural building and compliance with Building Codes, the span ranges from 3′-5” to 8′-6” depending on a variety of factors.

What size beam do I need to span 15 feet?

Thus, for a 15 foot span, you will need atleast 3-2×12 or 6×12 size of wood beam. For a 15-foot spans, the wood beam has to be at least 12 inches in depth and 6″ in width (3-2×12) used for residential building, wood frame structure or projects.

What size rafters do I need?

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.

How far can a 2×8 beam 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.

What size beam do I need for an 18 foot span?

Wood beam size for a 18 foot span:– as per general thumb rule, for a 18 foot span, size of wood beam or lumber joist should be 2×12 which placed at 16″ apart from centre used for residential building or projects or construction in which depth of section of beam is 300mm (12″) and width of beam is 50 mm or 2″.

How big of a 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.

What size header is needed for an 8 foot span?

4×8 size header is needed for a 8 foot span or opening.

How do I calculate beam size?



Measure the distance in inches that you need the steel beam to fill. Write this figure down on a sheet of paper as your clear span for the beam. Measure the length in inches of the floor joist that the I-beam must support. Divide that number by two.

What size header do I need for a 5 foot span?

Measure the width of your door frame. Most door frames that are 4 feet wide or less require a 2-by-6 header. Between 4 and 5 feet, the header should be built 2 inches wide and 8 inches long while a larger opening needs a header that is 2-by-12. When in doubt, use 2-by-12-inch headers.

How do you calculate header beam size?

It went like this: Measure the span in feet and add 2 to that number. The sum will be the height of your double header in inches. For example, if the span is 4 feet, add 2 to 4 for a sum of 6. Therefore, the header would need to be made from doubled 2x6s.

What size header do I need for a 6 foot span?

Since the architects and engineers who designed the houses had calculated that 2×12 headers were deep enough and sturdy enough to span the longest (6-ft.)

What size beam do I need for a 10 foot span?



Thus, for a 10 foot span, you will need atleast 3-2×8 or 6×8 size of wood beam. For a 10-foot spans, the wood beam has to be at least 8 inches in depth and 6″ in width (3-2×8) used for residential building or projects.