What size timber do I need for a roof?
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 |
What is the maximum span for a 2×6 rafter?
What is this? A 2×6 rafter can span 14 feet 8 inches when spaced 16 inches apart with No. 1-grade southern pine lumber on a roof with a 3/12 slope or less with a maximum live load of 20 pounds per square foot and a dead load of 15 psf.
How do I calculate roofing timber?
Equation:a2 + b2 = c2 Already having the rise will make it easy to determine the rafter length by loading the numbers into the equation chart. For example, a roof with a span of 20 ft and a rise of 7 feet needs rafters that are the square root of 400 + 49 = 21.2 feet.
What size of rafters do I need?
Generally 2″×6″ rafter can span upto 10 to 15 foot, 2″×8″ rafter can span upto 13 to 19 foot, 2″×10″ rafter can span upto 16 to 23 foot, 2″×12″ rafter can span upto 18 to 27 foot and 2″×4″ rafter can span upto 7 to 9 foot based on normal weight condition, spacing between rafter, species and grade of timber and pitch or …
Can I use 4×2 for 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. If you have a simple gable shed roof, then using 2×4 rafters makes more sense unless you have a very large shed.
How far apart should rafters be?
But they do tend to space rafters in one of several industry-standard increments, typically either 12, 16 or 24 inches apart. These spacing intervals are measured “on center,” meaning that the measurement is taken from the center of one rafter’s horizontal surface to the center of the next rafter.
What size timber do I need for a flat roof?
The joists should be sized using either the TRADA span tables or BS EN 1995. The sizing and spacing will depend upon the loads imposed on them and the required span. Wherever possible, joists should span the shortest distance. Common joists sizes are 200 x 50mm, 175 x 50mm, and 150 x 50mm.
How do you calculate rafter length and Birdsmouth?
On the rafter, you want to cut, measure its overall depth, and divide it by 3. Using this figure, measure and mark two points on each side of the vertical line, which indicates where the birdsmouth will be cut.