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04-15-2013, 09:57 AM
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#1
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Do it right.
Join Date: Feb 2008
Location: Amesbury, MA
Posts: 78
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My diagonal measurements say i'm square, but side to side disagree.
I had a concrete slab poured and am now laying one course of cinder block to get the walls off the ground.
I layed out blocks at the four corners and using the 3,4,5 formula figured out my diagonals need to measure 26' 11" which they do. However when I measure side to side I have one side that is 1/2" short and the opposite side is a 1/4" too long.
Of course if I adjust the block to correct those measurements it throws the diagonal measurements out of square. My question is, which measurement is the correct one? I'm assuming the diagonals. Or am I doing something incorrect?
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04-15-2013, 10:03 AM
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#2
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Member
Join Date: Oct 2011
Location: Ohio
Posts: 2,092
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My diagonal measurements say i'm square, but side to side disagree.
You know rectangles have right angles also. Is your slab a rectangle or square?
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04-15-2013, 10:24 AM
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#3
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Do it right.
Join Date: Feb 2008
Location: Amesbury, MA
Posts: 78
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My diagonal measurements say i'm square, but side to side disagree.
Quote:
Originally Posted by hammerlane
You know rectangles have right angles also. Is your slab a rectangle or square?
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rectangle 20x18
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04-15-2013, 10:33 AM
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#4
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Member
Join Date: Sep 2012
Posts: 552
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My diagonal measurements say i'm square, but side to side disagree.
Accuracy isn't too much concern in the manufacturer of blocks so I suggest measuring outside to outside or inside to inside for both dimensions if you aren't.
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04-15-2013, 10:35 AM
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#5
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Member
Join Date: Feb 2012
Location: Utica, NY
Posts: 500
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My diagonal measurements say i'm square, but side to side disagree.
By the way, if you are off by 1/2" or less you are fine.
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04-15-2013, 10:35 AM
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#6
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Maryland
Join Date: Jan 2011
Location: Eastern Shore, MD
Posts: 237
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My diagonal measurements say i'm square, but side to side disagree.
Did you use 3,4,5 to confirm that your four corners are square? If all four corners are square and your footprint measures 18'x20', your diagonal measurement will be correct at just shy of 26'11".
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04-15-2013, 11:17 AM
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#7
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Do it right.
Join Date: Feb 2008
Location: Amesbury, MA
Posts: 78
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My diagonal measurements say i'm square, but side to side disagree.
Quote:
Originally Posted by Pittsville
Did you use 3,4,5 to confirm that your four corners are square? If all four corners are square and your footprint measures 18'x20', your diagonal measurement will be correct at just shy of 26'11".
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I haven't set any block yet, I just set one block on each corner and adjusted until my diagonals were the same. Then I planned to run string off those corner blocks as a guide.
So i'm good as long as my diagonals are measuring correctly?
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04-15-2013, 01:13 PM
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#8
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Member
Join Date: Sep 2009
Location: Chicago
Posts: 8,534
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My diagonal measurements say i'm square, but side to side disagree.
Just a silly idea but why not use a framing square on this project?
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Last edited by sdsester; 04-15-2013 at 01:17 PM.
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04-15-2013, 01:29 PM
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#9
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Member
Join Date: Mar 2005
Location: Welland, Ontario
Posts: 6,014
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My diagonal measurements say i'm square, but side to side disagree.
Measuring diagonals only makes a square IF THE OPPOSITE SIDES ARE THE SAME LENGTH. So make your sides the same length and then measure the diagonals for square.
__________________
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The Following User Says Thank You to joed For This Useful Post:
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04-15-2013, 08:19 PM
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#10
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Do it right.
Join Date: Feb 2008
Location: Amesbury, MA
Posts: 78
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My diagonal measurements say i'm square, but side to side disagree.
Quote:
Originally Posted by joed
Measuring diagonals only makes a square IF THE OPPOSITE SIDES ARE THE SAME LENGTH. So make your sides the same length and then measure the diagonals for square.
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Problem solved.
I should have said I used pythagorean theorem instead of 3, 4, 5
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04-16-2013, 11:01 AM
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#11
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Member
Join Date: Dec 2009
Location: Near Cleveland, Ohio
Posts: 1,322
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My diagonal measurements say i'm square, but side to side disagree.
Quote:
Originally Posted by SubSailor
Problem solved.
I should have said I used pythagorean theorem instead of 3, 4, 5
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In this case, same thing. A squared + B squared = C squared.
3 x 3 + 4 x 4 = 5 x5
I think thats where the 345 triangle came from.
Mike Hawkins 
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04-16-2013, 02:28 PM
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#12
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Member
Join Date: Sep 2012
Posts: 552
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My diagonal measurements say i'm square, but side to side disagree.
Increasing to 6 - 8 - 10 ft. will give you a little more accuracy on a building the size of yours and on larger parcels 60 - 80 - 100 .
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The Following User Says Thank You to Fairview For This Useful Post:
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