How far can roof joists span?
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 8 | 16 | 19′ – 7” |
| 24 | 17′ | |
| 2 x 10 | 12 | 27′ – 6” |
How do you calculate beam span on a roof?
How to Size a Beam to Hold a Porch Roof
- Determine the load per square foot that the roof must support.
- Multiply the load per square foot by the total area of the roof.
- Divide the total load according to how many supporting beams the roof will have.
- Write down the beam strength formula: Total load in pounds = FBd^2 / 9L.
How far can a roof beam span without support?
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”.
How far can a 2×10 ceiling joist span without support?
2×10 floor joists can span up to 20′. However, this is for 12” o.c. spacing for live loads that are 30 psf. This is unrealistic because any living space or deck requires a joist that can support a 40 psf live load.
What size should roof joists be?
Wherever possible, joists should span the shortest distance. Common joists sizes are 200 x 50mm, 175 x 50mm, and 150 x 50mm. The joists will normally be placed at 400mm centres but no more than 600mm centres.
How far can 2×8 ceiling joist span?
Span is determined by species, grade, dimensions, spacing, use, and load. 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. Based on all factors though, a 2×8 joist span is 7′-1” to 16′-6”, and a rafter 6′-7” and 23′-9”.
How far can a 4X8 beam span without support?
Dimensional Lumber Deck Beam Span Chart
| Joist Spans | ||
|---|---|---|
| Douglas Fir-Larch, Hem-Fir, Spruce-Pine-Fir, Redwood, Cedars, Ponderosa Pine, Red Pine | 4X6 | 6′-2″ |
| 4X8 | 8′-2″ | |
| 4X10 | 9′-8″ | |
| 4X12 | 11′-2″ |
What is the maximum span for a 2×8 ceiling joist?
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”.
What is the maximum span for a 2×12 ceiling joist?
15 feet and 10 inches
A 2×12 with an E of 800,000 psi and Fb of 790 psi also works, since it can span 15 feet and 10 inches. Given a design span of 15 feet 1 inch and a 16 inch joist spacing, first determine which size lumber will work.
