Notching Roof Rafters

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.

Notching roof rafters. R802 7 cutting and notching. In general never make notches in the middle third of the joist where the bending forces are greatest. Other rules in compliance with the international residential code irc r502 8 and r802 7 are. Simple jig to cut your birds mouth notches.

Click here to download a full notching and boring guide for joists and studs from the wwpa. Notches in solid lumber joists rafters and beams shall not exceed one sixth of the depth of the. Since the webbing in the truss is vertical it is considered by building inspectors to be ok. Structural roof members shall not be cut bored or notched in excess of the limitations specified in this section.

To lay out a common rafter you need the pitch of the roof expressed in units of rise per foot of run in the gable roof example shown here a rafter with 6 in 12 pitch rises 6 in. More truss makers are switching to drop gables where the only notching is on the 2x6 outrigger itself. 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. The number of rafters needed will be determined by the length of your roof.

Up here notching the gable end truss is common it is done to support the lookouts and fascia on the end of the gable. Rafters are commonly spaced about 24 inches 61 cm apart. This trick worked for me. For every foot.

I noticed that the lumber don t know whether to call them joists or rafters comes down from the peak and they had to notch it. All roof rafters should be identical so follow the same steps to measure the plumb cut tail cut and birdsmouth cut.