How To Work Out Roof Rafter Lengths

See rafter run to outer wall calculator below.

How to work out roof rafter lengths.

Divide this in half and the result is 7 feet. 2 4 x 1 1034 refer to image to the right 2 65 2 175m is your rafter length. Print full scale rafter plumb cut templates and birdsmouth templates fold template over rafter to mark or cut through. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal.

Using the appropriate roof pitch table in a rafter cutting guide such as 4 12 determine the length of each rafter based on the correlating measurement shown for 7 feet. In this example the shorter walls are 14 feet long. To establish the rafter length we calculate the following. 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.

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. Position your level against the roof until the bubble of the vial sits between two lines. Marking out the roof rafter lengths onto the timber before cutting step 1. With the tape measure hooked onto the top end transfer your two rafter lengths onto.

Mark the plumb cuts. Take a measurement of 12 inches using a level. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. Select a roof pitch.

Includes result for hip valley factor slope factor and the roof slope in degrees. The length of the rafter is given from the long point of the ridge cut at the top down along the top edge the board to the same plumb cut on the rafter s notch. Rafter length calculator calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. Rafter length using angle v r 2cos a rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch.

Determine the camber along the timbers length. Before you can mark the rafter lengths and layout check the. Determine a thickness for the ridge and use the drop down to select it. The results are automatically fired as soon as any of the values are entered or altered.

Half building width minus 1 2 ridge thickness.