How To Birdsmouth A Roof Rafter

Also known as a bird s mouth joint or sometimes a bird s beak notch this type of cut is typically used to securely connect a rafter to the top of a supporting wall with the help of a wall plate.

How to birdsmouth a roof rafter.

When you cut the rafters you ll need to make 3 separate cuts. Step 3 cutting out the bird s mouth. Measure or calculate the height of the roof from the top of the wall to the top of the ridge plate and multiply that number by itself. This notch allows the beam to rest flush onto the top plate.

Among the most important individual components is the birdsmouth joint. Before you cut your boards you ll need to measure the width of your building and calculate the exact length of each rafter. Rise is the vertical distance from the top plate of. The result of this equation represents the.

From the marked point draw a line at the same angle as the pitch of the rafter up and make a mark at 1 1 2 inches. Due to the width. In my photo above the green rafter line length is from the plumb cut face or ridge board face to the plumb cut face of the bird s mouth notch. From that line across the rafter draw a perpendicular line at the 1 1 2 inch mark out towards inside part of the rafter.

Calculate pitch of roof use roof pitch to cut ridge cut use ridge cut as point of reference to form birdsmouth make tail cut. Calculate the pitch of your roof. This 90 degree angle forms the bird s mouth. When it comes to laying out a rafter it s essential to understand the basic building blocks of framing.

Multiply your pitch by 24 to determine the rise per foot of run. Pitch rise run x 2. So to summarise the full process is as follows. Measure along the top of the rafter the distance that you calculated in the previous step.

How do i know where to cut the bird s mouth in a rafter. Make one rafter that has the bird s mouth cut in place and extends out past that for your roof overhang test fit it in place and mark it pat for pattern rafter to use in cutting its sisters. A birdsmouth cut involves taking a notch shaped like a bird s mouth out of each rafter where it meets the top plate. How to cut bird s mouths in rafters step 1.