"Square." It’s a term you hear often in construction, and it simply means to have two adjacent surfaces that are at an exact 90-degree angle to one another. Sounds simple, but having something square is crucial for everything from wall framing and door installation to cabinets and tile.

Checking that something is square is done with a tool called, not surprisingly, a square. There are all types of squares available, some with a dedicated purpose and some that will do more than one task around the home or shop. So when shopping for a new square, it pays to have some understanding of the function of some of the more common types.

First though, a word about shopping for any type of square. To check a square for accuracy, take any object with at least one straight edge. This could be a piece of plywood, or even a sheet of heavy cardboard. Place one leg of the square against the straight edge of the plywood. Using the other leg of the square as a guide, draw a line on the plywood. Flip the square over so that the same leg is against the same edge of the plywood, but now facing the other direction. Align the other leg of the square against your pencil line, and draw a second line on top of the first. Examine the two lines — they should be exactly on top of one another. If they aren’t, the square is not reading an accurate 90 degrees.

As with just about all tools, a higher purchase price is typically reflected in a better-quality tool that is easier to use and will maintain its accuracy for a much longer time. With any type of square, avoid the temptation to save a couple of dollars by buying a plastic version — metal is much more durable and accurate.


Here’s a look at some of the most common types of squares and their uses:

Framing square: Also called a rafter or carpenter’s square, this is the basic square for use in rough carpentry. Framing squares have one 16-inch edge called the tongue and one 24-inch-long edge called the body, so it is large enough to check framing layouts. It is also stamped with ruler measurements and a number of tables that are used in the layout of rafter lengths and angles, as well as for such tasks as stair stringer layouts. Framing squares are available in steel, aluminum and brass.

Speed Square: This is the trade name for a 12-inch-by-12-inch triangular-shaped aluminum square that is extremely useful for framing and roof-cutting layouts, measuring angles, and marking and checking 90- and 45-degree angles. It also makes a great cutting guide for your circular saw and comes with a comprehensive booklet on roof framing. …CONTINUED

Combination square: Combination squares have a 12-inch-long removable blade with ruler markings on it, and a sliding head that has one 90-degree and one 45-degree side for checking and marking those two common angles. Since the head slides on the blade, it can also be used for measuring inside dimensions, such as the depth of a drawer. Combination squares are available in steel and a less expensive plastic version of questionable accuracy.

Try square: A try square is used for laying out and marking precise 90-degree angles, primarily in woodworking operations. The body of a try square is thicker than the blade, so it rests firmly against the edge of a board and allows the blade to lay flat on the board’s surface for greater accuracy. Try squares are available in a variety of sizes and materials, most commonly with a wood body and a steel or brass blade. Try squares are also available with a blade that is fixed at a precise 45-degree angle for checking miters and saw blade adjustments.

Machinist’s square: This is similar in design and function to a try square, but has an all-steel construction and a smaller size. It is used primarily in metal work and for some types of precision hobby and craft work.

T-square: As the name implies, a T-square is T-shaped instead of L-shaped. The head is designed to rest securely along the edge of the material, and the long, ruler-marked blade is stable enough for use as a cutting guide. In construction, T-squares are most commonly used for marking and cutting such things as drywall, cement board, ceiling tiles and other materials. The most common T-squares are made from aluminum, with a few lower-priced plastic versions available as well.

Layout square: Layout squares are the largest of the squares, often measuring 3 feet and 4 feet on the sides and made from top-quality aluminum. They are used for the layout of such things as tile installations, and are typically triangular in shape to provide the long sides with stability and accuracy. Most also fold up for easier transport and storage.

Remodeling and repair questions? E-mail Paul at paulbianchina@inman.com.


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