sonotubes under a concrete slab

emg0fnv

anybody ever heard of pouring a concrete slab over a sonotube enclosed area. Such as a 24 x24 garage. Place sonotubes around the perimeter and then pouring the concrete slab. The sonotubes would maybe act as a frost wall. Ok heres your chance to tell me im an idiot

concretemasonry

You would need a thicker structural slab that is reinforced with rebar. The thickness and spacing of rebar will depend on the slab size and the Sonotube spacing.

What part of the world are you hiding in (no location provided in the profile). The climate has something to do with the answer.

Dick

TarheelTerp

tsk... you say that like you've never heard it before.

what wheel are you trying to reinvent here?
or did a hundred or so sonotubes fall off the back of a tuck?

joed

I have seen sidewalks over unstable soil done similar to the sink a few sonos in critical areas to act as foundation and pour the slab.

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jomama45

I've only done this once, and it was a building that housed bovine. I wouldn't suggest it, especially if you have a building dept. to answer to.

mae-ling

DO it all the time for attached garages. Thicken the edge of the slab.

emg0fnv

Im in the north east. I dream this stuff up and wonder why not. No I didnt get a hundred sonotubes. I guess I should of given more information. I was thinking of building a pole barn type of building. And using sonotube to construct the pole barn on. With this building there is no center wall, all open. I was wondering how I would pour a cement slab in the middle of this thing.

joecaption

And what's going to keep the walls from swaying if the post are not sat into the ground?
The inside area is going to have to be back filled enough so the siding is at least 6" above the grade. SO the siding does not come near the grade.
Anytime I've seen or built a pole barn we use 6 X 6's set in the ground at least 2' (below the frost line) holes get back filled with concrete, A trench gets dug out around the outside even with the post to form a berm so the slab will be thicker on the outside edges, form boards get screwed to the outside of the post so the center of the slab will be at least 4" thick.
You should lay 6 mil. plastic down before the pore as a vaper barrier. If it's to be heated you could also lay foam down.
Personaly I think this is a job for a pro concrete finisher not a DIY. It's a one shot deal, done wrong and there's going to be low spots, cracks ect.
Once that truck shows up there is no going back.

mae-ling

Are you saying a concrete slab as in a garare type with sonotubes filled with concrete around the edge under the slab then build a pole barn on top of that?

Pole barns sink the poles in the ground and have no concrete piles or concrete floors usually (around here anyway). As soon as you are doing all that concrete work anyway you may as well build a frame building, it will actually be easier and cheaper.

pafred

I'm not building a pole barn, only a covered patio. do sono-tubes require footing? (42" below fg)

mae-ling

In some areas yes they do.

Red Squirrel

My fear would be that the slab's movement would counter the sonotube movement, and you'd get cracking. For example if the sonotube concrete pillars are pushed because of the frost, you'd get a bunch of bumps in the slab with cracks. Best to keep it uniform. Now if the pillars are strictly holding the entire slab up with zero dependance on the ground, then you'd be ok, but that would be more involved to build. Then again, I'm no expert here, maybe I'm way off.

COLDIRON

Why not dig a perimeter trench about 8" wide down below the frost line and pour a monolithic slab with the plates right on the perimeter of the slab.

If you have the right height if not go to plan B.