From: Don Bowen KI6DIU <don.bowen AT earthlink.net>
To: homestead AT lists.ibiblio.org
Subject: [Homestead] Responses to preserving poles in the ground
Date: Thu, 01 Nov 2007 12:22:31 -0700
Here is what most of the responses have told me along with some
research. These ideas are based on using timber from the site. If
purchased timber is used, just buy the latest PT stuff and be sure to seal
it off. Forgive the cross posting but I did get answerers from many sources.
Setting a pole for building is easy. It just depends on your climate,
frost line, wood species, load, personal preferences. etc. The problem is
moisture, when wood gets wet the microbes already there and waiting start
to munching. Exposed exterior wood is food for another army of hungry
microbes and insects. In some areas the hungry beasties are so busy and
take no vacations that there is no real cure. No matter what is tried, in
the tropical island of Saipan wood in the ground lasts no more than five
years. Cars have a hard time lasting 10 years before they rust away.
Drainage is the very first line of defense. Make sure that any water
drains away from the poles and none can settle around the pole. Choose
your house site and grading so all water moves away or is channeled
around. Wide eves keep water from splashing and running down the sides.
In the hole use rocks or gravel to insure drainage of any moisture that
does get in the hole. Set the post holes well below frost level then pour
in several inches of coarse river rock. Set the pole and pour in some more
rock, leaving a few inches at the top for a collar. Mound the dirt at the
top or pour a collar of concrete with a peak to drain water away. Heavy
tar treatments and wrapping in plastic may just make a better trap for
surface moisture. In loose soils it may be advantages to pour a collar of
concrete about half way up the hole.
As for the pole, species if very important. Locust and Ceder are often
mentioned as long lasting poles. From personal experience Locust fence
posts out last just about everything but Osage Orange but are much
straighter. Chemical treatments, used motor oil, and tar were frequently
mentioned. Charing the pole was also mentioned several times. Be sure the
pole is completely air dried before use so any checks can be delt
with. One idea was to bore a hole in the base to speed drying, reduce
checks, and allow penetration of what ever preservative used.
If the ground does not drain well, don't bother with poles set in the
ground but use a form and make a cast in place concrete pier. They can be
stopped at grade and steel anchors used to secure the poles.