Roof Rafter Birdsmouth Cut
Once you ve cut the top end of the first rafter you can calculate the position of the bird s mouth based on the height and width of the roof then use that rafter as a pattern to cut the others.
Roof rafter birdsmouth cut. Here the birdsmouth plumb is 76 37 inches. With your ridge cut or plumb cut made you are now all set to. If you have never done. Use it to make the proper measurements marks and cuts on each rafter.
A bird s mouth cut lets a rafter sit squarely down on the top of the wall rather than resting against it at an angle. This is the first stage of the process. For the rafter to fit correctly you need to cut the bird s mouth exactly where the rafter will meet the wall. This trick worked for me.
Calculate rafter or joist length to birdsmouth location. Birdsmouth plumb if you study the diagram carefully you will see that there is an indentation in the roof rafter where it meets the exterior wall of the building. Making a birdsmouth joint. Because a roof requires many rafters to frame it speeds things along if you use the first rafter as a pattern or template for the other rafters.
How to cut a birdsmouth joint calculating the pitch of a roof and making ridge cut. The actual indentation or cut is known as the birdsmouth while the birdsmouth plumb is the depth of the cut out. You should now have a perfect birdsmouth cut in your first rafter. Please consult a professional before making any cuts i am not a professional framer or roofer nor do i claim to be.
First off the plumb cuts are better left until all of the rafters are in place on the roof using a chalk line to get the plumb cuts in a dead straight line making the fascia board fit nicely. Second even if the plumb cuts at the rafter s lower end have already been made small variations in rafter length and effects of bowed or arched rafters will throw off your birds mouth location. Creating a birdsmouth cut is the classic way to prepare a rafter for a hand cut gable or shed roof. It can be difficult to visualize rafter plumb and side cut angles and how the common hip and creeper rafters all fit together.