


#1




Any construction folks out there ? Need help please
Is there a pretty much fool proof way to get pin point measurements?
I need to dig four or five footers, 2' x 2' and go down maybe a foot max. No frost line in SC and most houses don't go down more than a foot from what I have seen. I want to enlarge my deck. I want to measure 16' off from the back of my house. I want to make sure that the footings' centers are 90* or perfectly perpendicular to the house. I could use string, measure, the trick of 3, 4, and 5, et cet., but wondering if anyone has used a laser device or other contraptions? Been a while since I frammed or worked in this realm and wanted to see what folks actually use these days. Deck will be 16' x 20' 
#2




Hi Mark,
I understand you don't worry about frost but be sure to get down to soil that is good bearing, meaning not too much organic material in it to deteriorate and let your footing settle. Also building so it could be shimmed later would be a good though too. 1. Pick your points for the outermost portion of your deck on each side, then 2. establish where your two outer corners will be (assuming the deck is rectangular) and put in a temporary stake or marker then measure the diagonals from the point on the house. 3. then adjust your stakes until the diagonals are equal. It should be square at that point, meaning 90 degree angles at each corner. If the deck is irregular you can start this way then measure off the strings tied from corner to corner to establish points inside the perimeter. Its not hard, just dig in and it will become apparent.....easy compared to the mechanical adventures you do all the time on our mercedes diesels. Feel free to pm if clarity is not immediate.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. 
#3




yes, rectangle, but the problem is that I have 10 x 10 deck in the way ... lol

#4




I will see if I can work with it .... thanks Tom

#5




You'll figure it out.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. 
#6




Measure out from the house the distance you want to go, then measure diagonally from corner to corner. The diagonal measurement will confirm perfect 90˚ corners if your measurement from the house is known. We did this recently when pouring a slab for a gazebo and turned out a perfect 20x25 slab.
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'11 Honda Accord EX  "The Daily" 70K '83 500SL Euro  "The Money Pit" 116K '91 350SD  "Diseasel Jr." 173K '94 BMW 525i  "The Red Car" 180k 
#7




Doesn't the measure diagonally assume that your first "line" is already perpendicular? That is, If I start on the left side and measure out 16' and try to eye ball it, then go to the right side and do the same thing, I am assuming I will be somewhat close. Then, if I take a diagonal measurement each way (a giant X from above looking down) wouldn't I still need to make sure that my first side I started with was 90* to start with?
It just stopped raining here so I am thinking I will try my measurments and markings tomorrow. I got some steel stakes and string. 
#8




No. If you measure out from the house, the diagonals will make you adjust so you get a perfect square. If you mismeasure one side, then it cannot by definition be square, that is a perfect rectangle.
Don't overthink it; is simple. I do this almost every Saturday for Habitat. 
#9




So, in other words, if I go from the exact spot I want to start, measure out 16' and do the same on the other side, I just go back and forth with a diagonal measurement until each arm of the "X" is the same?

#10




Exactly right.
__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. 
#11




I can't get a good picture in my mind of what you mean by the deck in the way but it might be easier to first establish one perpendicular line.
Perhaps the 5, 12, 13 triangle would work. Or you could use any numbers. You want to go out 16 feet. Say you have 6 feet you can use easily going parallel to the house. 16^2 + 6^2 = 292. Square root of that is 17.09, or about 171/16. Maybe get a 16 foot wire arrangement (stretches less than string), pull it out from the point and play with moving it side to side until you get the 17 foot mearsurment from the 6 foot spot. I could imagine that using diagonols on both sides from the start could be lot of moving around. If you establish one perpindicular, will be quicker to use diagonols to get the other one and then check it against itself. Also, consider that an equilateral trapezoid will have matching diagonals. To avoid that you would also need to make sure that BC = AD. Using diagonals would be easier, I'm thinking, on laying out a rectangular form as you have the four sides of your rectangle in place, in that case BC will = AD. In your case, the line BC is sort of floating at this point, assuming that the line AD is the wall of your house.
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#12




Located this book on my bookshelf, it appears to be very informative on this subject.....
https://www.amazon.com/DecksPorchesPatiosRepairImprovement/dp/B0074CXPWC/ref=sr_1_1?ie=UTF8&qid=1524941636&sr=81&keywords=time+life+decks+porches 
#13




Checking the diagonals is where it's at for square.
As to plumb, that's a whole different issue!
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#14




Quote:
Hey, thank you ! Right now, I have a 10 x 10 deck. I need to tear it down and replace it but I am replacing it with a 16 x 22 deck. I do not want to remove the current deck until I dig the "footers" (12 x 12 concrete going down maybe 12" to 18" max). Using 6x6 posts vs. 4x4. I can dig and put in place the side ones and the ones on the 'outside.' By keeping the old deck in place, I am not getting yelled at by my family for not having a deck. Once the footers are in place, cured for a week or two. I can set those posts on metal plates although not 100% permantly  I can make fine tuned adjustments. I can do the tear down in half a day and do the clean up and probably the other half of the day install the outside perimeter. Having the footers on the money will make this painless for me. 
#15




Quote:
Did some string magic over the weekend, and figured out what Tom (and others) are talking about. 
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