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 far can you span a 2×8 roof rafter?

Maximum allowable span for a 2×8 rafter:- the maximum allowable span for 2×8 rafter is 21 feet 7 inches when spaced 12 inches apart from centre, 19 feet 6 inches at 16″ OC & 18 feet 6 inches at 24″ OC with best quality No.

## How far can pergola rafters span?

Spacing of the rafters will vary according to your visual preference and the size of the pergola. Spacing the rafters 16 to 20 inches apart is common. The most important rule in spacing is to keep the distance consistent between all the rafters.

## How far can a 2×8 span without sagging?

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 should pergola rafters be?

Pergola rafter size:- typically the rafters size used for pergola could be 2×6 (2 inches by 6 inches), 2×8 (2 inches by 8 inches), or 1.5×7.25 (1.5 inches by 7.25 inches). The length of the rafters be as long as you desire the pergola itself to be. The longer the rafters, the more you need.

## How far can 2×8 span 12?

Max. Live Load 30 lbs/ft2 (1436 N/m2)

Maximum Span (ft – in)
Nominal Size (inches) Joist Spacing Center to Center (inches) Lumber Grade
2 x 10 24 15′ – 0″
2 x 12 12 24′ – 8″
16 21′ – 4″

## 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.

## How far apart should pergola slats be?

You want about 5 in. of space between each slat. One slat at 1-3/4 in.

## Should pergola rafters be notched?

Mark on the board where the four support beams are located on your cross beam. You will need to notch out this area so that the board fits over the support beams.

## How much overhang can a pergola have?

The standard overhang of a pergola roof is one foot. If the pergola is an attached pergola, the overhang will only be on the sides not attached to the Ledger Board. If the pergola is unattached and freestanding next to the primary building then there are several roof options.

## What size timber should I use 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

## How do you calculate rafter span?

Rafter span = rafter run divided by cos °. Overhang = eaves width divided by cos ° (add dimensions for brick veneer).

## What size rafters do I need for a 20 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 roof rafters be?

Max. Live Load 20 lbs/ft2 (956 N/m2)

Maximum Span (ft – in)
Nominal Size (inches) Rafter Spacing, Center to Center, OC (inches) Lumber Grade
2 x 6 16 14′ – 11”
24 13′
2 x 8 12 21′ – 7”

## Can a 2×6 span 16 feet?

If you’re finding this confusing, we’re here to help. The maximum distance a 2×6 can span, according to the 2018 IRC, for a floor joist, is 12′-6”, ceiling joist 20′-8”, rafter 18′-0”, deck board 24”, deck joist 9′-11”, deck beam 8′-3”, and 6′-1” as for header.

## Can you use 2×6 for roof 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.

## What is the best wood to use for rafters?

Kiln-dried Douglas fir wood presents the number one choice for building a rafter-styled roof in a wood frame house. This tree grows prodigiously in the Pacific Northwest. Since it is readily harvested in substantial quantities, the price is reasonable.

## Can you use pressure treated wood for rafters?

The 2012 International Building Code® (IBC 2012) and 2012 International Residential Code® (IRC 2012) do not include provisions for the use of preservative-treated wood for roof assembly components such as blocking, nailers and roof deck sheathing or structural members supporting roof assemblies such as joists, rafters …

## Can you use pine for rafters?

pine and they are still standing. You could always install some additional gusseting or metal to hold the rafters to the plates if you want to be safe. Just make sure you wait 6-8 weeks before any sheet rocking.