squaring my building

my building is going to be 30x40, when run the strings to set the posts should the width be 1.5 in shorter on each sides and front and back for the 2x4's

It depends on what you want. If you are building a pole framed building and want the exterior measurements to be 30x40 you should allow for the 2x4 (1-1/2") as well as the exterior sheathing thickness.
Determine the spacing of your poles and then try to square to the outside corners with your string.

Most people measure their buildings to the outside of the girts.

Strictly from personal experience here, having measured several thousand buildings, there are very few that measure exactly even. Most run about 4" wider or narrower than the even foot. Surprisingly, the older houses and buildings are often a little closer to even than newer ones. Even manufactured and factory fabricated housing is not exactly to the even feet advertised. (A 28x40 may be 27' 8" by 40' 3", etc.)

I am usually surprised when I measure something and it turns out perfect. Always makes me smile, because I know how hard someone had to work to get it that way. My own contractor built barn? 30' 4" x 40' 4".

I don't know if there is an advantage to being exactly on the even foot other than siding may be easier. Trusses will still fit, might take a few more 2x4's, a few extra shingles. Cost wise I don't think it's that great a difference, but you might want to ask wherever you are buying materials from to see what they recommend.

Steve

<font color="blue"> my building is going to be 30x40, when run the strings to set the posts should the width be 1.5 in shorter on each sides and front and back for the 2x4's
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By your post it is safe to assume your putting up a pole barn. Pole barn metal is generally 3' in width. On the 30' side you'll be 3" short if you don't allow for the 1 1/2" girts. On the 40' side your going to end up ripping the last piece. I've always tried to make pole barns widths and lengths divisible by 3. That way you can put all the wall metal on without having to rip any. Instead of 30 x 40 have you considered 30 x 39 or 30 x 42?

But none of that has anything to do with "squaring a building".

To square anything there are 3 methods. The most popular is measuring diagonally from corner to corner and adjusting until you get the identical measurement. Another method is utilizing the 3-4-5 method. That is where you measure in one direction 3' and 90 out in the other direction 4'. The distance between the 3' mark and the 4' mark will be 5' if its square. You could use any multiple of this formula ie: 6-8-10, 12-16-20, etc. Probably one of the most underused but most accurate methods is the Pythagorean Theorem - the square of the length of the hypotenuse of a right triangle equals the sum of the squares of the lengths of the other two sides. The formula being in long ahnd because I don't know how to get the 2's in their proper perspective is: A squared plus B squared equals C squared.

Thanks for all the help! It is a 30x 40 pole barn, sorry about the confusion

<font color="purple"> A squared plus B squared equals C squared. </font color>

a² + b² = c² [img]/forums/images/icons/smile.gif[/img]

Good advice about making your final dimension match a 3' interval if using metal. If you use ply/osb etc just make everything a little UNDER a multiple of 4'

I always think it is easier to cut off a bit than to cut and then nail up a 2" or so piece. My luck I might run out of the color I bought and have to nail up 2" of contrasting siding...embarrassing! [img]/forums/images/icons/grin.gif[/img]

About squaring a building with a string. Don't!

One of the many reasons buildings end up out of square is that the string stretches. Even fiberglass tapes at long distances stretch more than I like. Try to use a steel tape for the final adjusting.

I try to use two tapes (not neccessarily steel) to get the rough layout. One is used to measure a wall length (or length plus offset to batter boards) and the other to measure the diagonal. You place a pin where the two tapes cross with the correct numbers.

An example: Yo want a 30x40 OD building. Place two pins either 30 ft apart or 40 ft apart to delineate one wall. Anchor a tape at each of these pins and find the location where the one tape indicates the "other wall length" and the other indicates the diagonal. The previously mentioned referrence to Pythogoras tells us that the diagonal is 50 ft. So if we first put down two poins 40 ft apart and anchor a tape to each pin we then want to see where the two tapes cross with one reading 30 ft and the other 50 ft. This is a corner of the building. repeat this to establish the 4th corner.

You can do it with one tape by a process of successive approximations and multiple iterations but it takes longer and is way more frustrating. After you have located the 4 corners. Measure the diagonals with a steel tape (if you didn't use steel to start with) and make any minor corrections needed. If yo use two steel tapes to start with you do it one time, RIGHT and you are through. Most of us don't have a problem with stretching in a steel tape.

You need to establish level as well and I suggest a water level. A water level will produce results as good as any commercial LASER level and is dirt cheap. You can use a length of garden hose (50 ft min for a 30x40 bld) with a few feet (2-3 works good) of clear tubing added to each end. If you don't find sufficient info on water levels via google.com or other resources, return here and I can tell you (or probably any number of others) the simple procedure to use. You can DIY the clear tubing and attachments or buy a premade kit at some builder supply places.

Best of luck in your adventure,



[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

First I draw up on CAD the outside dimensions of what I want to make. Then I draw in square the poles set back the appropriate distance from the metal siding (1.5"). Then on a drawing layer I set the diagonals for pole centers, stake them after measuring diagonals and corner to corners. Drill holes and clear dirt. Put laths and string line in set the outside dimensions of poles. Move string along line horizontal lathes to square in the building again measuring diagonals and building sides. As pointed our earlier use a metal tape only! I recommend two people to make the measurements.
By projects are always square within a 1/2". Could to do better but I consider that good enough.
Certainly this is not the only way but just any example of how someone else does it.

See PDF attachment for 16x20 tractor shed post layout

metal tape suggestion is good. I use metal tapes. but hey... to give advise on the 1 1/2" allowance... YES... you have to or your trusses wont fit... if you make the poles at 30 x 40, your trusses will not extend out to the edge of the headers as they are supposed to. they will stop at the pole edge. I believe this is more important than having to rip steel. I am currently writing a book on pole barn construction if anyone has any hints or tricks... im all ears... this book is a start to finish pole barn guide... so any tricks throw em my way. I might like em... and use em i guess! ha!

Regards,
Mike