Rafter Sizes For A Pitched Roof Uk

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal.

Rafter sizes for a pitched roof uk.

In this example we have a customer with a building width of 4 8m wide and the pitch of the roof is 25. 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. Roof pitch between 15 and 22 5 degrees with rafter spacing strength class c16. To establish the rafter length we calculate the following.

Roof pitch between 15 and 22 5 degrees with rafter spacing. The full version allows any size. Surveyors span tables for designing roof rafters. Rafter slope min 15 max 45 degrees.

For pitched roofs flat roofs and ceiling joists. 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. Roof pitch refers to the slope which the rafter creates. 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.

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. Often you express roof pitch as the ratio between the rise and the run in the form of x 12. 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. Clear span on plan.

2 175m is your rafter length. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. 2 4 x 1 1034 refer to image to the right 2 65. 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.

This is the distance between rafter centres. 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. Usually 400 450 or 600mm but any value can be used up to 610mm max.