How Square is Square?

[ARKANSAWYER]

  This is not a trick question but I am interested How Square is Square?  My transit has a variance of 1/4 inch in 100 ft and no matter how you try to square a building it always seems to be off a little bit some where.  And when is plumb plumb?  My level is good but when is the bubble exactly in the middle?  I always treat level, square and plumb as relative terms and try very hard to keep them as close as possible.  But on a very hot day my long tape measures different then on a cold day.  Forms move when pouring concrete and timbers move a bit.
  So when you are building how close do you really try to be perfect?  What do you call close enough?  Is there a spec in the building codes?  When doing a footing I try really hard to be about 1/4 inch of level and when measure from corner to corner I like no more then 1 inch difference, which means there is in reality just about 1/2 inch difference.  It just seams sometimes that no matter how you move or measure things it just does not come in perfect.
  So what is your standard?

[ely]

if i am doing all phases of the work myself, you would be amazed at what i can work with. :D

back when it was my job to lay out a job, we built a building that was 300 feet wide and almost 800 feet long, when we got done on the layout we checked it over and found out we were 1/4 inch long and an 1/8 inch too wide.

the project manager brought in a new survey company because he thought we were blowing smoke. when they got thru they stated the building was less than 1/16th out of square anyway you wanted to check it. we were happy.

in answer to your question, if you are doing the whole job a guy can get away with being out in certain areas.

[ljmathias]

I'm like you Arky, but not nearly as perfect as ely- wish that I was!   

I find that no matter how hard I try, using a bubble level to set or check what the laser level says is flat- they never quite agree to within a quarter inch or so, and you're right- no matter how well you set your grade stakes, stuff happens to throw things off some.  I've taken to putting in footings that are as close to flat and at levels needed but let the forms be too wide- easier for blocks to be laid on wide footings than on ones too narrow.

As I go up, I check and double check to try to keep things plumb, flat and square.  House I'm building now turned out an inch short on width and half an inch on length (36X26) and I deliberately set the outer post and beam supports for the porches in about an inch to allow for "play" during truss setting.  Seems to be working out alright- trusses are going in well and the the extra overhang is easy to cover with soffit.

I had a preacher tell us one time that humans can't be perfect except in their efforts to be- trying is the key, not actually getting there.  How's the old saying go?  "To err is human, to forgive divine-" Alexander Pope (had to look it up), and I think the key is like any happy marriage- better to constantly seek forgiveness.

Lj

[Carpenter]

     I always strive for a 16th of an inch.  Doesn't always happen.  You're right, forms move during the pour and timbers move for the life of the building.  I think a lot of the perfessional level of acceptance does depend on the scale of the job.  I helped raise a timber framed barn that was 70' long and I checked the walls for square, we were an inch out of square on one wall in particular.  The foreman said that wasn't too bad so we pegged it and made a beautiful building.  Had that been a set of cabinets you could never live with an 8th inch out of square.  Nothing we build as humans is ever perfect and we still have to sleep at night.  I don't know that there is any set guidelines saying what is square and what is not.  Interesting question.

[tyb525]

I suppose it depends on how much time and patience you have ;) On a house or large building I think 1/8" accuracy is doing well. On furniture and cabinets, 1/32" would be a better goal.

[Banjo picker]

I know this is in the Timber Framing and Log section, but you have talked about forms moving and footers...Sometimes being fairly square is ok at other times it has to be dead nut as you can get it...Here is as ex



If the forms on the outside move a little bit no worry...as long as I don't have a set of anchor bolts attatched to it...





When the piers with the anchor bolts go in , it had better be right...And that laser in the first pic will get it to 1/8 inch on elevation on 250' or so if my memory is working right...It will get the elevation closer than most will finish the pier...The slab on the bottom really don't matter if its a 1/4 or so one way or the other...in this application...It is going to be covered in limestone as soon as they fire the plant up any way....This job was for Vulcan Materials ...around Searcy Ark.   Done a complete rebuild for that plant...All those piers have to be square with each other for the structure to fit, and that tower has to be square with another tower or conveyer...I poured the concrete for a crusher in Russivelle Al, that had 32 anchor bolts , I think they were 1 1/4 bolts...the holes in the crusher for the bolts were 1/8" oversized...no sleeves allowed...It was one unit all 32 bolts had to go down at once...If it had not been close to perfect, it would not have went down over the bolts....Sorry for being so long winded...I guess I may still miss it a little....Tim

[isawlogs]

 Banjo, I sure can appreciate the closeness of those anchors. I put up a lot of steel and the colums had to fit, burning the holes was frowned apawn big time.
When I put my garage up a few years ago, I kept it to 1/4 on the diagonal, zero on the elevation as I had a car port attached and it would have a beam that would receive the trusses, it all worked out fine.
  furniture, I also try real hard to go with a zero tolerence, makes things fit all the better .

[Coon]

When I worked on building concrete elevators we had 1/16th of an inch per side allowance for error and we would make that allowance up when we yoked the forms together.  The thickest wall in the elevators were 6 1/2" and had rebar inset every 3 square inches.     When the concrete was made water was not used but steam was. We always tried to pour atleast 1 foot per hour of height and it would take about 5 1/2 days just to do the slip pour.