Bird's mouth cut
A birdsmouth or bird's mouth cut is a carpentry or timber roofing term for a small triangular cutout from a beam either at the end or along one side. It is made up of two cuts to remove a triangular piece of timber, the cuts are at 90 degrees to one another but their angle to the edge of the timber being cut will vary depending on the angle of the roof.
Birdsmouths are cut in to roofing rafters at the top to hang onto and be fixed to the ridge beam as well as lower don the rafter on one side to hang over the edge of the wall plate, making the top of the wall frame or lying on top of the wall if masonry of brick. The combination of the two cuts allows the rafter to sit at an angle to the horizontal beams creating the roof pitch.
[edit] Related articles on Designing Buildings
- Beam bridges.
- Beam formwork.
- Bond beam.
- Cantilever.
- Capping beam.
- Chilled beam.
- Collar beam.
- Flitch beam.
- Girder.
- Ground beam.
- Lattice beam.
- Metal web joists.
- Open web beam.
- Post.
- Rafter.
- Rolled steel joist (RSJ).
- Simply supported.
- Timber post and beam construction.
- Types of beams.
- Types of columns.
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
Construction Management, 8 July
NEETs crisis drives interest in trades, but apprenticeships barriers remain.
Passive fire protection webinar
MEP services penetration seals.
Where its at podcast (and video) - The role of the Architectural Technologist as an Expert Witness.
More than 200 remarkable buildings added to SAVE’s Buildings at Risk register.
Government scraps pre-application consultation for Nationally Significant Infrastructure Projects.
Historic England and infrastructure
New projects offer opportunities for the historic environment and local communities.
Construction Management, 2 July
Construction deaths halve in two years.
Green Book changes to drive investment in all parts of UK.
Minimum energy efficiency standards (MEES)
CIAT briefing on response to consultations for privately rented non-domestic properties.
Connect, collaborate, shape the future
Registration now live for UK Construction Week Birmingham.
CIOB announces Saul Humphrey FCIOB as new President for 26/27 term.
A quick, simple, and zero-bills solution to prevent overheating.