Brian,
It kinda depends on where in Michigan. Building Code in Southern MI ( I'm in
Livingston County) requires the the top of footings for pole building and deck
footings to be at least 42" below final grade. Northern MI would be deeper.
You can look up the normal frost line in your area on the internet. The top of
your footing can be at that level, but your county probably has a minimum
depth. You can make it less than that, but you should then expect things to
move up and down with the frost, break, and in some case to eventually "pop
out of the ground". A slab in Michigan requires a 36" (it might be 24" or so -
it's been a while) deep "Rat Wall" below final grade. The "rat wall" is to
keep the moles, rats and skunks from burrowing under it and causing problems
for your floor. My pole barn (24' x 40' 2 Story) has the 42" deep footings for
the poles and the 36" rat wall. The 5" to 6" floor is in 4 quadrants with
welded wire mesh and is poured over a 2 foot tamped sand
base. There are three centerline poles to support the second floor. I
originally planned to do automotive work in it, but have since turned to
building a few small boats. Today I would put in a 3" floor with wire mesh or
a wood floor.
I bought a one person gas powered auger and bored 48" to 50" deep 8" dia.
holes below final grade and put in concrete to make the top of the footing at
the 42". The 4" x 6" poles went in after that hardened, dirt was tamped
around the poles so that the bottom of the poles didn't move around and they
were stablized with framing, The rat wall and floor were poured on top of
tamped sand as a single pour. That fills in around the poles and everything is
solid. My wife and I built all of the barn (with some help from friends)
except the concrete floor work that we had professionaly done.
The only problem I have is because the service door is next to one of the
poles and the floor moves up slightly in the winter due to frost causing the
door to jam. I may move the door so that both sides are on 2" x 4"s supported
from the floor and that should solve the problem.
If I were building the "same" barn today, I would pour an exterior wall
foundation (48" deep x 16 or 18" wide) with interior pilings and install a
suspended wood beam floor on the pilings. The whole barn would be stick built
rather than a pole barn. It would have been a lot easier than dealing with the
poles when they started to twist as the whole structure aged. It's about 8
years old now. In my area it is almost impossible to get 4 x 6 poles that are
not twisted. The wood floor would have turned out to be about the same cost as
the concrete floor over sand and it would better suit my needs today for
nailing braces for boat forms. It would also be a heck of a lot easier on the
feet.
Just my thoughts and how I did it. Good luck with it.
John
_______________________________________________
Support Team.Net http://www.team.net/donate.html
Shop-talk mailing list
http://autox.team.net/mailman/listinfo/shop-talk
http://www.team.net/archive
|