squaring concrete pad


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Old 05-09-06, 07:28 PM
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Angry squaring concrete pad

OK.... so I'm forming up my pad w/ 2x4's and I know there is some sort of formula to make the whole thing square. If I put a string line along the 2x4 that is there and go ???ft past it and then go back diagnally ???ft and stay ???ft from the end of the 2x4 that is there it should be square. The string forms a triangle, right??? If anyone has any idea what the heck I am talking about could you please fill in the blanks??????? Want to get this project going.
 
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Old 05-09-06, 09:05 PM
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Measure from corner to corner diagonaly this should be the same, use a tape measure a string will stretch depending on how hard it is pulled or use the 345 method. Measure 3' on one side from the corner then 4' the diagonal will be 5'.
Frank
 
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Old 05-10-06, 05:11 PM
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The 3-4-5 method is the best. If you are squaring a larger area, you can use multiples of that formula.
 
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Old 05-10-06, 05:22 PM
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the 3:4:5 method establishes one square corner, and theoretically, if you can read a tape measure, you can figure out the other sides off of that. Due to human error, you'd still want to measure the diagonals.

So, what Frank99 stated holds true. If you measure from corner to corner of any square or rectangle, the opposite diagonals should measure exactly the same in order for the whole thing to be square.
 
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Old 05-11-06, 04:41 AM
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The others are right. But if it's a small pad, just use a framing square. No muss, no fuss.

Pecos
 
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Old 05-11-06, 02:07 PM
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thank you

Thanks everyone. Got it done. The pad is 24x34ft so I used the 3,4,5. Looks good. I am about 1 inch off from diagnol to diagnol. But I made the pad 2 inches big on each side for this reason. I was scared I wouldn't get it square. A garage will sit on top of the pad w/ footings underneath. Is that 1 inch going to be a big problem? Should I adjust this before I pour? This would require a lot of work now that it is formed.
 
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Old 05-11-06, 02:32 PM
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That is close enough that you can square your sill plate before you attach it to the pad. It just means your sill will hang 1/2" over each side on the diagonal that is 1" too short.

Usually when a building is going on a pad, you want the pad to be perfectly square, which is why most of us recommended measuring the diagonals. The sill plate is meant to go to the exact edge of the pad and the sheathing usually hangs over the edge of the pad to act as a drip edge.

If the pad is bigger than the building, that presents a problem with water sitting on that ledge, making the potential for the sill plate, sheathing, and siding to constantly be sitting in water. Flashing the bottom edge of the building over the concrete with a z-flashing and keeping the sheathing and siding above that level would be the only solution in that case. (or make the sill plate overhang the pad as mentioned above.) I guess you could build the garage to match the pad, but that'd be a pretty poor solution.
 
 

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