Title: How to Cut a Birdsmouth Joint | Fixing Rafters and Joists to Wall Plates | DIY Doctor
Headings: Birdsmouth Joint – How to Cut a Birdsmouth and how to Cut and Install Roofing Rafters and Joists
Birdsmouth Joint – How to Cut a Birdsmouth and how to Cut and Install Roofing Rafters and Joists
What is a Birdsmouth joint or Cut?
How and Where is a Birdsmouth Cut Used?
How to Cut a Birdsmouth Joint
Calculating the Pitch of a Roof and Making Ridge Cut
Calculate Rafter or Joist Length to Birdsmouth Location
Making a Birdsmouth Joint
Making the Tail Cut

Content: What is a Birdsmouth joint or Cut? The Birdsmouth Joint (also called the birds beak cut or birds beak joint) is a small triangular shaped cut out at the base of a roofing joist that allows the joist to sit nicely on top of the wall plate (top of the wall before the roof starts). As I’m sure you have gathered, the name “Birdsmouth Joint” refers to the fact that the joint itself looks a little like a birdsmouth when viewed from the side. Birdsmouth joints cut into roofing rafters and mounted in place on top of the wall plate
If is wasn’t for this joint, a rafter or roofing joist would only balance on top of the wall plate, making fixing difficult not to mention the fact that there wouldn’t be any solid connection between the roof and the supporting walls below. The addition of this joint allows the top of the rafter to sit solidly down on top of the horizontal area of the plate, whilst the vertical front edge butts up to the vertical exterior side edge of the wall plate. This both allows for a solid fixing and also for any forces to be successfully transferred from the roof, down into the supporting walls and then down to the foundation. To ensure a secure fix for the rafter to the wall plate a fixing process known as “Toenailing” is normally used, whereby nails are driven in to each side of the rafter at an angle and down in to the timber that forms the top of the wall plate. The act of toenailing (or sometimes it’s also called skew or side-nailing) ensures that both timbers are securely fixed together to form a solid joint. It’s also possible to use joist hangers, rafter tie down straps or any other suitable steel engineered fixings that are made specifically for this job. In terms of the cut itself, both the horizontal and vertical cuts that form the birdsmouth joint have their own names;