How to Check for Squareness

For carpenters and woodworkers, squareness means the difference between success and failure.
A level is a tool for determing if something is flat or not.A level is a tool for determing if something is flat or not.
If even one frame in a house is not square, it will slightly alter the proportions of the rest of the entire house. When the proportions change, the measurements made by the carpenters become increasingly more complicated as the carpenter has to start measuring for odd numbers and fractions of inches. Squareness is the key to simplified carpenter's measurements. And, luckily, this crucial measurement can be gauged using basic geometry and some common tools.

Step 1

Lay a level across the top of the surface that you are measuring. Then, lay the level across the bottom. Look to see if both the sides are level, if not, the surface can't possibly be square. Make minor adjustments to the top and bottom until they are both level.

Step 2

Take your tape measure and carefully measure vertically 3 feet from the top of one of the sides. Mark the measurement with a pencil.

Step 3

Measure out four feet horizontally with your tape measure from the same corner, across the top of the surface. Draw a mark using your pencil at 4 feet.

Step 4

Line up the end of your tape measure with the first mark and stretch it at a diagonal until it reaches the second mark. Look and see if the measurement reads5 feet or very close to it. Use the Pythagorean Theorem to determine if your corner is a true square.

Step 5

Repeat this procedure on all corners. Make adjustments until all corners equal 90 degrees.

Things You Will Need

  • Level
  • Double square
  • Pencil
  • Tape measure

About the Author

Daisy Buchanan has worked as a staff writer for "The Umbrella," an arts newspaper in Portland, Ore., and as editor-in-chief for "Living Mosaic," an academic journal. Buchanan holds a Bachelor of Arts in environmental studies from Lewis and Clark College.