Pergola Rafter Spacing

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 apart should rafters be?

Standard industry roof rafter spacing is 12”, 16”, 19.2”, and 24” on-center, however other spacing may be used by a Structural Engineer. Depending on all contributing factors though, 16” and 24” are commonly used for most buildings. The wider the space between rafters often results in rafters of greater depth too.

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.

Should I notch pergola rafters?

You will need to notch out this area so that the board fits over the support beams. Take your board down and using your marks as guides draw a rectangle where the notch is to be.

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 size should pergola rafters be?

Geoff, a builder friend, once said that for a smaller sized pergola, with 4″ x 2″ rafters, the pergola beam span should be no bigger than the width of a standard fence panel, or 6ft. Good advice! Try to keep as near to that as possible.

How far can 2×4 rafters span?

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. Due to the small spans of 2x4s, they often are not used in horizontal load-bearing capacities.

Should I use 2×8 or 2×10 for pergola?

Most builders use a minimum of 2×8 for the upper framing members, and that’s for a small pergola. On this pergola, the builder Ricky Chavez used 2×12 for the girders, 2×10 for the rafters, and 2×4 for a layer of decorative purlins fastened atop the rafters.

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

Based on different manufacturers’ specifications, the maximum span a 2×8 LVL is from 12′ to 15′. Spans are also affected by the species of wood used in the manufacture of the laminated joists, with western woods edging out eastern woods in unsupported span distance.

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.

How far apart should purlins be spaced on a pergola?

Purlins are usually spaced 8” OC.

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″.