Here the build roof dialog is being used to set the defaults for manually drawn roof planes.
Framing and roof crickets.
Ok so a four foot wide chimney has a span of 4 foot and half of that is the run which is 2 foot.
Put metal flashing along the sides of the cricket nailed in place to overlap seams with the roof.
This beam will provide the backbone for the cricket or saddle.
2x8 sleepers should be nailed to the roof surface to pick up the ends of the rafters.
The cricket or saddle basically rests on top of the house roof to visually extend the porch roof gracefully into the house roof.
Secure the plywood triangles to the roof decking and cricket ridge with galvanized screws.
This also makes it easier.
Always frame the cricket at the same pitch as the roof and you will be within code guidelines.
Do not check build roof planes.
You will need to use compound miter cuts for the cricket rafters.
In this example a pitch of 12 12 and 1 1 2 x 5 1 2 rafters are specified.