Square
Besides being a shape, square is an extremely important term for anyone interested in doing home improvement. So, what is square? When we "square" something or "check for square," we are referring to a 90 degree angle. If something level is intersecting something plumb this intersection would be referred to as "square." This is because one is perfectly vertical, and the other, horizontal (in regards to gravity) making a 90 degree angle.
Look at the image of the triangle. Lets pretend we're looking at a floor plan. For this example, pretend line C is not there, it's not important. A and B are both walls that we need to install. The small square is to denote the walls are perpendicular. Both sides of this intersection, where the little square is and the opposite side of line B, will be 90 degrees when complete. Which will make the walls square to each other.
So, how do we find square? There are multiple techniques to "square" any two pieces of material. The first, easiest, and least accurate way is by simple using a square (tool). The longer your square (tool) is the more accurate your reading will be. A 6" Speed Square is great for [squaring cuts] or calibrating a Miter Saw, but when your putting up a deck with 108" joists and a 186" ledger, it wont be enough. Getting out your [roofing square] will still probably not be accurate enough. This is where you get into different [Lasers].
So lets say you don't have a laser. Good news all you need is a Measuring Tape, calculator and pencil, and preferably a helper. For this method you will need to know Pythagorean Theorem. I know, that thing we all learned in math and thought we'd never need again, well here it is. Spoken the formula reads: the square root of A squared, plus B squared, equals C. With a calculator this is very easy to figure out. Just take the longest measurement you can on A, then do the same for B. Take these lengths and multiply them by themselves. Example if A=3 and B=4 than A=3x3=9 and B=4x4=16. Then find their sum (addition) 9+16=25. Now the final step is to find the square root of 25. This can easily be done with a calculator. We know 5x5 is 25, therefore, the Square root of C is 5. This means a triangle where A = 3 ft. and B = 4 ft. will only be square when C = 5 ft. This is the commonly used 3, 4, 5 right triangle.
But how does that help you find square? Lets go back to the wall example and imagine we're in an empty room where wall A is built and we are working on wall B. Once we find the point B will intersect with A, we can use our 3, 4, 5 triangle. First we put a mark 3 ft. away from our point of intersection on wall A. Then we make a guess at square, and measure 4 ft. away from A (this will be line B). Now we take our tape along the imaginary line C (see image above), this will run from the two points you just made. This line C needs to be exactly 5 ft for the angle to be square. Move the point representing line B until this is true.
Pythagorean's theorem is the most accurate way to make two things square, but definitely not the easiest. Understand that in most situations, perfect is unnecessary, but you have to be in the ballpark. If not your work will always come out obscure. If you don't want to do the math you can get away with doing the 3, 4, 5 triangle method. The only problems with relaying on this technique are the situations were you don't have 3 or 4 feet to measure. What if you are making a dog house that is 30" (2.5') by 36" (3')? You don't have a 3 foot by 4 foot section so you would have to go back to the formula. 30"x30"=900", 36"x36"=1296" , 900"+1296"=2196" and the square root of 2196" is 46.86". Use a search to find decimals to fractions and round to the nearest 16th. In this case I found that 0.875" is 7/8". I now know my C value has to equal 46 7/8" for my dog house to be square.
Tool Basics
Look at the image of the triangle. Lets pretend we're looking at a floor plan. For this example, pretend line C is not there, it's not important. A and B are both walls that we need to install. The small square is to denote the walls are perpendicular. Both sides of this intersection, where the little square is and the opposite side of line B, will be 90 degrees when complete. Which will make the walls square to each other.
So, how do we find square? There are multiple techniques to "square" any two pieces of material. The first, easiest, and least accurate way is by simple using a square (tool). The longer your square (tool) is the more accurate your reading will be. A 6" Speed Square is great for [squaring cuts] or calibrating a Miter Saw, but when your putting up a deck with 108" joists and a 186" ledger, it wont be enough. Getting out your [roofing square] will still probably not be accurate enough. This is where you get into different [Lasers].
So lets say you don't have a laser. Good news all you need is a Measuring Tape, calculator and pencil, and preferably a helper. For this method you will need to know Pythagorean Theorem. I know, that thing we all learned in math and thought we'd never need again, well here it is. Spoken the formula reads: the square root of A squared, plus B squared, equals C. With a calculator this is very easy to figure out. Just take the longest measurement you can on A, then do the same for B. Take these lengths and multiply them by themselves. Example if A=3 and B=4 than A=3x3=9 and B=4x4=16. Then find their sum (addition) 9+16=25. Now the final step is to find the square root of 25. This can easily be done with a calculator. We know 5x5 is 25, therefore, the Square root of C is 5. This means a triangle where A = 3 ft. and B = 4 ft. will only be square when C = 5 ft. This is the commonly used 3, 4, 5 right triangle.
But how does that help you find square? Lets go back to the wall example and imagine we're in an empty room where wall A is built and we are working on wall B. Once we find the point B will intersect with A, we can use our 3, 4, 5 triangle. First we put a mark 3 ft. away from our point of intersection on wall A. Then we make a guess at square, and measure 4 ft. away from A (this will be line B). Now we take our tape along the imaginary line C (see image above), this will run from the two points you just made. This line C needs to be exactly 5 ft for the angle to be square. Move the point representing line B until this is true.
Pythagorean's theorem is the most accurate way to make two things square, but definitely not the easiest. Understand that in most situations, perfect is unnecessary, but you have to be in the ballpark. If not your work will always come out obscure. If you don't want to do the math you can get away with doing the 3, 4, 5 triangle method. The only problems with relaying on this technique are the situations were you don't have 3 or 4 feet to measure. What if you are making a dog house that is 30" (2.5') by 36" (3')? You don't have a 3 foot by 4 foot section so you would have to go back to the formula. 30"x30"=900", 36"x36"=1296" , 900"+1296"=2196" and the square root of 2196" is 46.86". Use a search to find decimals to fractions and round to the nearest 16th. In this case I found that 0.875" is 7/8". I now know my C value has to equal 46 7/8" for my dog house to be square.
Tool Basics