Expert: Bill-C - 1/6/2010

Question
Hi Bill,

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,

To do this accurately and easily then proceed as follows if you can get an auto level or laser level ;

Excavate your foundation box trench  to 28 inches below the finished ground level , check with level,
Pour  4 inches of levelling concrete to pre levelled pegs set within the foundation to the checked height to form a subase foundation , this will set your heght for the post assuming they are accurately cut to the 10 feet dimension.
You can do this in stages by doing one then moving to the consecutive one or do the four corners separately then cast your post in and stringline the post tops to acheive your level,you can use timber formwork pegged into the ground stretcher fashion to position your posts until the concrete sets.
Ensure you establish a ground level (benchmark)where your finished level will be taken from at onset.
I have previously used steel rebar or heavy nails in the base of the post to ensure it gets secured, If the posts are wet they dry and shrink slightly with a tendancy to move.

hope this helps

regards
Bill