Expert: Bruce E. Johnson - 1/6/2010

Question
Hi Bruce,

I am building a pole barn of sorts and using 6 x 6 treated timbers for supports.  I plan to firmly fix each timber in concrete at least 24 inches in the ground.  My question is this:  Laying each one at the exact same height takes a good deal of manipulation in my limited experience.  If I want exactly 8 feet of timber exposed from the ground surface to the roof trusses, this usually means getting a 10 foot timber.  But I do achieve true precision in this.  Handling 10 foot timbers is very difficult, and making adjustments in each hole to get the measurements just right means taking the timber in and out and either adding or removing a bit of gravel each time.  Is it better just to approximate my dirt depth with each one and then achieve precision by cutting all the tops off each one so that I have exactly 8 feet out of the ground?  What would you recommend?  I don't have a lot of extra hands to help me.  And if I do cut off the tops of each timber, how do I get a factory-flush top?  Thanks for your time.  It is greatly appreciated.

Grady

Answer
Hi Grady,
It's possible to get accurate post placement using batter boards and string lines.  By pulling a tight, level string line along the perimeter where the posts will be placed you can measure down from the string line to the proper depth.  In your case I would find the highest ground elevation and use that as the bench mark and set up my level string 6" above the ground at this point.  Once you have your holes dug to the proper depth you then need to set the posts and hold them in place for the concrete pour.  By measuring down from the top of the post 7'-6" and marking the post you would then line the mark on the post with the string line to get your elevation.  I use short pieces of 2x4 on edge that are long enough to span across your post holes by a foot each direction. One on each side of the post running parallel with the string line.  I then cleat the two together with two shorter pieces of wood to make a collar around the post.  Start a nail in the side of the collar and then standing over the post, pull up the post until the mark lines up with the string line and nail the collar to the post.  This will hold your post to elevation while you then brace it plumb.  I am attaching a simple drawing to illustrate.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com