Question:
I am wanting to build an extra garage because mine is full. I am
thinking of building a pole barn type with 2 garage doors. Probably
30x30.
I have been fighting with the idea of building it myself. I have a
tractor with a bucket available to me as well as an auger for the
tractor.
Any advice? How far are posts, trusses spaced? How do I ensure the
building is square?
Answer:
I own a couple of much larger pole barns, dirt floors, but when it
came time to build my 30x34 two story shop, I opted to use post
and beam construction on a foundation and slab floor instead.
epending on climate, soil type, and the EPA, pole barns have a
number of unfortunate issues having to do with setting the poles
directly in the soil. If your climate has frost heave issues, the walls
will quickly become wavy as the poles heave differently. The poles
may deteriorate fairly quickly too, depending on soil chemistry and
your ability to get properly treated poles (the EPA now requires
creosote treated poles to be handled from cradle to grave as toxic
waste).
Replacing a bad pole can be a real problem. Usually it isn't
practical to remove the bad pole, you have to sister another
pole in next to it. But when you do that, nothing fits, so you have
to patch the girths and trusses too. A real nightmare. You can't
really seal a pole barn either.
Post and beam in a shop size building is about as conservative of
materials (ie low cost) as pole barn construction, yet it avoids most
of the problems of the pole barn. The wooden posts (6x6) are set
on 8 foot centers on a floor plate (2x6) bolted to the concrete.
Nothing wooden touches the soil or is exposed to the elements.
The outer sheeting, and the foundation, totally seal the building.
Three rows of girthing (2x6) are run, bottom, middle, and top around
the outside of the posts (same as a pole barn). The "tin" screws to
these (I actually used high strength baked on enamel finished sheet
steel guaranteed not to fade or rust for 20 years, but people in the
trade still call it "tin"). Use of screws, not nails, with rubber washers
under the heads is a must. These won't loosen, and they won't leak.
On the interior side of the posts, 2x6 girths are run at top and bottom.
These, with their matching girth on the outside, form the load beams
for the structure, and also provide a place to attach any interior panels.
If you want a really rigid structure, add 2x4 crossbucks between each
pair of posts (cut to fit interior so they don't interfere with the girths).
The beauty of this style of construction is that you can lift and handle
all the pieces by yourself (though a helper makes installing the girths
a lot easier). No problems with frost heaves. No wood is exposed to
the elements. The building can be really sealed (helps keep dust down,
and is a must if you want to heat or air condition the space). And if you
do ever need to replace a post or beam, you can do it a lot easier
than replacing a pole in a pole barn.
