Roof Rafter Layout Framing Square

I marked it in red to make it easier to spot.

Roof rafter layout framing square.

The standard two foot framing square also referred to as a carpenter s square and historically as a steel square is an l shaped tool that is used to mark angles for cuts used in building framing particularly roof rafters stair stringers and many other cuts or angles other than 90. Framing square guides are small inexpensive metal attachments to the framing square that are locked in position on the square s edges at the pitch and run dimensions to define the roof angle and make the repeated marking of the rafters much more efficient. On the framing square blade face using the common rafter length per foot run line in the table look along the blade under the inch number 18 we see 21 63.