How to Use a Framing Square

You don't have to be a professional carpenter to use a framing square. Even if you're a carpentry hobbyist, the tool can come in handy.

You will need

  • Framing square
  • Lumber
  • Marker
  • Circular saw

Step 1 Hold the framing square Hold the framing square in your hands. Note that it is made of one flat sheet of metal with two arms positioned at right angles to each other.

Step 2 Observe the tongue Observe the shorter arm, called the tongue. It is 1 1/2 inches in width and from 14 to 18 inches in length. Now observe the longer arm, called the blade. It is 2 inches wide and 24 inches long.

Step 3 Examine the graduated scales Examine the graduated scales on each arm. The face of the square, the side where the manufacturer’s name usually appears, has a scale broken down into 1/8th and 1/16-inch intervals. The scale on the back is broken down into 1/10th- and 1/12th-inch intervals.

Step 4 Cut a board Cut a board. Place the blade against the edge of a piece of lumber that you wish to cut at a right angle. Mark a line along the edge of the tongue and cut at the mark.

Step 5 Layout a roof rafter tail Place the framing square flat near the end of a board you want to use as a roof rafter. Align the blade with the bottom edge of the board and the tongue with the roof pitch. Then mark the cut. This will be the tail end of the rafter, and the cut will be horizontal when the rafter is installed onto the roof.

Step 6 Mark the vertical end Slide the framing square along the length of the rafter board, keeping the blade at 12 inches and the tongue at roof pitch until you reach the end of the rafter’s span. Mark the vertical cut where the rafter will connect to the ridge board.

Step 7 Cut the rafter Cut the laid-out rafter with a circular saw. You can now use this rafter as a template for any others you cut.