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 and news
Licensing construction; looking back to look forward
Voluntary to required contractors (licensing) schemes.
A contractor discusses the Building Safety Act
A brief to the point look at changes that have occurred.
CIOB Construction Manager of the Year award
Shortlist set to go head-to-head for prestigious industry title.
HSE simplified advice for installers of stone worktops
After company fined for repeatedly failing to protect workers.
Co-located with 10th year of UK Construction Week.
How orchards can influence planning and development.
Time for knapping, no time for napping
Decorative split stone square patterns in facades.
A practical guide to the use of flint in design and architecture.
Designing for neurodiversity: driving change for the better
Accessible inclusive design translated into reality.
RIBA detailed response to Grenfell Inquiry Phase 2 report
Briefing notes following its initial 4 September response.
Approved Document B: Fire Safety from March
Current and future changes with historical documentation.
A New Year, a new look for BSRIA
As phase 1 of the BSRIA Living Laboratory is completed.
A must-attend event for the architecture industry.
Caroline Gumble to step down as CIOB CEO in 2025
After transformative tenure take on a leadership role within the engineering sector.
RIDDOR and the provisional statistics for 2023 / 2024
Work related deaths; over 50 percent from construction and 50 percent recorded as fall from height.