4 8 2 2 4 for one half of your roof s width b skip this step if you already know what measurement half the width of your roof is.
Rafter sizes for a pitched roof uk.
Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees.
Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees size of rafters in mm roof pitch between 15 and 22 5 degrees with rafter spacing of roof pitch between 22 5 and.
Our roof rafter calculator tools are handy for calculating the number of rafters needed rafter length calculator lineal feet of rafter board feed in ridge and sub facia and the total board feet in the roof.
As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.
To establish the rafter length we calculate the following.
This is the distance between rafter centres.
2 4 x 1 1034 refer to image to the right 2 65.
Roof pitch between 15 and 22 5 degrees with rafter spacing.
Roof pitch refers to the slope which the rafter creates.
Roof pitch between 15 and 22 5 degrees with rafter spacing strength class c16.
For pitched roofs flat roofs and ceiling joists.
2 175m is your rafter length.
Usually 400 450 or 600mm but any value can be used up to 610mm max.
If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.
Surveyors span tables for designing roof rafters.
The full version allows any size.
Roof pitch between 15 and 22 5 degrees with rafter spacing strength.
Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.
Clear span on plan.
Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal.
Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings.
For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2.
You can assess this in two ways either as the roof pitch angles which the rafters make with the horizontal or the proportion between the run and the rise of the roof.
