Roof Cuts And Rafter Lengths

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.

Roof cuts and rafter lengths.

Rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch. Print full scale rafter plumb cut templates and birdsmouth templates fold template over rafter to mark or cut through. For example if the ridge beam is 1 5 inches thick subtract 3 4 of an inch from the overall rafter length. Marking out the roof rafter lengths onto the timber before cutting step 1.

Roof cuts and rafter lengths hancock s 10th edition is a very popular best selling book. Before you can mark the rafter lengths and layout check the. With the tape measure hooked onto the top end transfer your two rafter lengths onto. Rafter book page 1 created date.

If you are calculating rafter length from the center of the ridge beam as shown below you will need to subtract half of the thickness of the ridge beam from the top end of the rafter. Use our online rafter length calculator to quickly compute the length of the shed roof rafter by entering the measurements of overhead length of roof span pitch or angle. It will help you with plumb and side cuts for hip and rafter down and side purlin cuts and more. See rafter run to outer wall calculator below.

Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. Half building width minus 1 2 ridge thickness. Mark the plumb cuts. Allow for ridge thickness when determining rafter run to outer wall.

The next result is the run. With calculations diagrams and tables. Determine the camber along the timbers length. This is the horizontal measurement from the outside of the wall to the inside of the ridge.

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. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. 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.