Pitched Roof Rafter Sizes

Pitched roof timber sizes.

Pitched roof rafter sizes. This sizing guide for roof rafters will help determine what you need for your small project. Pitched roof timber sizes 1. The pitch and span of your roof will dictate how long of a rafter you ll need use maximum span calculator to help you find your rafter size. Rafter span tables for surveyors roof construction.

Roof pitch between 15 and 22 5 degrees with rafter this diagram illustrates the typical arrangement of a rafter and purlin roof and shows the dimensions referred. For pitched roofs flat roofs and ceiling joists. 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. 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.

The roof pitch should be specified on your technical drawings for the job along with the sizes of the roof timbers. To establish the rafter length we calculate the following. All the figures are based on roofing tiles or slates laid on timber laths over sarking felt. 2 4 x 1 1034 refer to image to the right.

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. Total span ridge 2 individual rafter span. The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.

In this example we have a customer with a building width of 4 8m wide and the pitch of the roof is 25. There are several variables to consider when determining the proper rafter size. If you are deciding yourself on the pitch make sure it is suitable for your roof covering. 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.

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. Surveyors span tables for designing roof rafters. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.