We are building a small bunkie (8' x 12') at our cottage and are
debating the merits of sinking sono tubes as a foundation vs using
gravel, patio slabs and concrete blocks. We are water access only so
are looking at carrying all materials in by boat and have come to town
to rent an auger to dig holes for the sono tubes but are now finding
we need a HEAP of concrete to pour into 8" tubes.
My cabin is located in a place called Seven Springs(high water table)
Built a 2 story structure on a Sono tube concrete piles with a crawl
space ~10 years ago, no sign of any movement. It'll depend how heavy the
bunlie will be.
You could just rent a helicopter while you're there... :)
Far too little information as others have said for much real help...
If this is intended to be a permanent structure, need adequate footings
that are below the frost line. What "adequate" equates to is the
question and there's no way to tell from here.
Best bet is to talk to somebody local about building conditions and
check on local codes where there are codes. Will give you an idea of
what is considered adequate for the area.
How about concrete block "piers" on the ground (no digging) with screw
anchors to hold cantilevered beams down when the wind blows? A flexible
skirt around the bunkie crawlspace perimeter could keep the ground under
the blocks from freezing, as in a frost-protected warm foundation.
On Tue, 17 Jul 2007, email@example.com wrote:
Tubes with a flared footing at the base, sunk below the frost line of
course is the best way to go but weigh that against the other factors:
Climate, amount of work, what is the final structure? Does it matter if it
shifts or heaves a bit?
Pretty wishy washy answer, but that's what I would go through thinking
Also, have you ever used a power auger? Unless your soil conditions are
ideal thoy are tools sent straight from the fires of hell. Man I hate the
things. I've used a two man auger in ok soil and still almost had the arms
ripped off... what a horrible device!
Best of luck whichever way you go.
On Jul 17, 9:27 am, firstname.lastname@example.org wrote:
Maybe you could call your power company and see if they have any out
of service, too short or used power poles they could part with with.
Since they are heavily treated for ground exposure, boring a hole and
dropping them in shoild be just the ticket. They could be trucked to
the lake side and floated over to your site. Cut to length, a couple
of 20 footers wouls supply all the foundation you need. There might
even be some abandoned railroad timbers in your area. HTH
On Jul 17, 10:27 am, email@example.com wrote:
I'd not mix up concrete, at least not pre-bagged stuff. Not if I had
the aggregate any distance and there were available aggregate locally.
Then, too, any stone smaller in max dimension than the radius of the
tube would be a candidate for inclusion. The "sharper" the stone, the
better for strength.
Check your building codes. Around here, a building of less than 100 square
feet does not need a permit nor formal foundation, and can be laid on
gravel/patio slabs and such. If you don't mind a bit of heave (or a bit
of spring readjustment), why not?
I do, however, strongly recommend assessing the location for wind
strength, and consider some sort of ground anchor so that it can't move
We had an inspector recommend 6" thick footings of gravel and "real"
concrete blocks (not hollow cinder blocks) for the corners, and some sort
of J bolt to anchor our shed. "Recommend" - he couldn't "order" in this case.
We skipped the holddowns because the thing is in a _very_ sheltered location
and wind is almost non-existant. At a cottage on an island, that may
well not be true. We've seen sheds blow away that were in exposed
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