This layout tool consists of a long, two-inch wide blade called the body and a shorter, one-and-a-half-inch wide arm called the tongue. The surfaces are stamped with specialized mathematical tables for calculating rafter lengths, stair stringer angles, and board feet. It is an essential instrument for marking out structural cuts in timber framing and general carpentry.
Heard on the job
Use the framing square to lay out the birdsmouth cuts on those common rafters.
Also heard as
- steel square
- carpenter's square
- rafter square
Related terms
Framing hammer
A heavy-duty hammer with a long handle and a milled face, designed for driving large nails into structural lumber.
Birdsmouth
A triangular notch cut into the underside of a roof rafter to seat it securely on a wall plate.
Stringer
A heavy, inclined structural timber that supports stair treads or ladder rungs.