You are going to cut out triangles that will cover the apex of each set of rafters.
How to notch out a 2x4 for a roof.
So roughly 7 8 long for a 2 4.
Layout your sheet of plywood on sawhorses.
For the rafter to fit correctly you need to cut the bird s mouth exactly where the rafter will meet the wall.
Access the roof using an extension ladder.
For this example a section of roof is 20 feet wide.
Measure out the span of your arch on a sheet of your plywood and cut a piece of string to the same length represented in the images as the line which connects a to b.
The roof rafters provide integral structural support to the roof.
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.
Find the center point of your first measurement on the plywood and draw a line at a 90 degree angle from that center point until you reach the desired height of your arch.
If you re framing a gable roof on a new house or building a shed or even a doghouse with a gable roof you ll need to cut a number of roof rafters.
Birdsmouth joint how to cut a birdsmouth and how to cut and install roofing rafters and joists.
This video will show you how to figure length and cut a common rafter for a gable roof using a framing square.
Measure each section of the roof from side to side parallel to the line of the fascia board.
Each side of the gusset will be 8 long but only 8 tall.