How to Use a Framing Square

A framing square is made of steel or a lightweight material like aluminum. It has a 2 in. wide arm called a blade and a 1-1/2 in. narrow arm called the tongue. Framing squares are used to cut stairs, rafters, or any project requiring several square or angled cuts. Using a framing square is easy once you learn a few simple measuring techniques. And whether you are a math wiz or not, soon you'll be using a framing square for all your more complex framing needs.

Things You'll Need

• Framing Square
• Sharp Pencil

Instructions

Use a Framing Square

1. Figure out the height and distance of your project. If you are building stairs decide how high you want your steps. Put the framing square on the edge of a 2 by 12. Put a mark on the left hand side for the rise. Put a mark on the right hand side for the run.

2. Using the top edge of the square, mark the L shape made in the board, move up the board with the square, repositioning it until it is in another L shape at the top of the first one. Repeat the process until you have a series of L shapes running the length of the 2 by 12. This should give you the beginning of your stair stringer. This is also the way to cut your roof rafters.

3. Put the square diagonal across a board to make a roof pitch. Where the square crosses over the board on each end, trace the end of the square on its diagonal at the number of your rise to run; these are the numbers found on the square. This will be the peak of the roof rafter where it will sit on the wall.

4. Determine span, determine run, determine pitch, layout rafter, cut, and test. All measurements are to be performed using the top edge of the framing square.

Tips & Warnings

• On one side of a framing square are charts for calculating different types of rafters. It also gives the angles of the side cuts of hip and valley rafters and the differences in length of hip and valley jack rafters 24 or 16 in. on center, so you only have to measure the first one and not every one.

• You must adhere to numerous building codes when constructing stairs and other building projects. Framing squares are extremely helpful in making sure all your angles and cuts are to code.