Calculate rafter or joist length to birdsmouth location.
Roof rafter birdsmouth cut.
You should now have a perfect birdsmouth cut in your first rafter.
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.
The ridge cut also called the plumb cut at the top of the rafter the birdsmouth cut which itself comprises 2 different cuts where the rafter meets the building s wall and the tail cut at the base of the 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.
Making a birdsmouth joint.
Here the birdsmouth plumb is 76 37 inches.
This trick worked for me.
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.
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.
With your ridge cut or plumb cut made you are now all set to.
Creating a birdsmouth cut is the classic way to prepare a rafter for a hand cut gable or shed roof.
Use it to make the proper measurements marks and cuts on each rafter.
This is the first stage of the process.
To make it easier before you start to measure mark and cut print these templates fold over some scrap wood same size as rafters and cut through the paper to form the correct plumb and side cuts for common hip and creeper rafters.
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.
How to cut a birdsmouth joint calculating the pitch of a roof and making ridge cut.
If you have never done.
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.
It can be difficult to visualize rafter plumb and side cut angles and how the common hip and creeper rafters all fit together.
When you cut the rafters you ll need to make 3 separate cuts.
