Purpose of the 'floating' slab

[flatbread]

If a person opted to not build a pole barn,

Could they pour a footing/stemwall perimeter without the floating slab (gravel instead)?

Or is the floating slab meant to keep the footing/stem walls from tilting to the inside and outside(resist lateral earth pressure)?

By the way, the site is expansive clay 1500 psf, but the frost depth is only ~ 6'', was pondering about a small one car garage

 

[hilld]

There are many pole barns that don't have a concrete floor, just dirt, so I don't think it is there to keep the poles from moving towards each other. The poles should be 4 feet or so in the ground, don't think they are going anywhere.

 

[flatbread]

extremely fast response, cool!

so are you saying that a garage could be built without a floating slab if the footing/stemwall perimeter were 4' deep

or are you implying that since I am trying to save a few hundred, that I should construct a pole barn?

 

[willymakeit]

If you have expansive soil,with a stem wall you have to go good soil or use cardboard forms under your footings or mono pour.. With pole go to good soil depending on local conditions.

 

[willymakeit]

The cardboard form are also known as void form which deterioate after time leaving a space to expand. Check with your area contractors also as they will usally know what is recommended there.

 

[flatbread]

Footing/ Stem wall:
The pour would be mono, and have gravel under the footings.

using a post hole digger after 18'' you hit the hard clay, use a gallon of water and you can get down to the 2' mark. Do not have access to an auger. Not sure 2' is deep enough for a pole barn. Would have to rent if any locals allow this.

if the voids cause expansion , wouldnt they cause excessive contraction also. Especially in an area that receives no water runoff?

I havent called contractors, because Im not sure if they would want money for recommendations , guess ill call to find out.

 

[flatbread]

so the footing/stemwall will not tilt inwards , outwards, or upheave without a floating concrete slab connecting them. assuming they are designed correctly to withstand 20,000 lbs

 

[wssix99]

so the footing/stemwall will not tilt inwards , outwards, or upheave without a floating concrete slab connecting them. assuming they are designed correctly to withstand 20,000 lbs

Typically, footers are symmetrical or shaped like an upside-down "T" so they don't want to inherently tip one way or another.

In the city, we have issues with footers right up on property lines which have to be "L" shaped. They are relatively complex and can require a lot of engineering to pull off. But... this isn't an issue for you.

Floating slabs are purely non-structural. They "float" on the earth and aren't attached to any other structure. The earth is a 100% free structure for the floor, which is much more economical than building a structural floor or one elevated off the ground. (So, that's why you'll see floating slabs so often on the first floor of buildings.)

 

[Sureshot]

If all you want is a small one car garage on level ground just pour a pad and build it. Make it a little thicker on the outside. Do you have cides there?

 

[joe_padavano]

To get back to the original question, the slab is not intended to reinforce the walls or footers. You can certainly pour just footers and stem walls without a slab.

 

[Kevin54]

There's no reason you couldn't build a pole like srtucture and fill the inside with chrushed gravel. A floating slab is just what it states, it floats at the frost line increases and decreases during the cold season. Way back in time, Bullock Garages, and I imagine some have heard of them, would scrape off some sod, toss down some gravel, call it a floating slab, and then collect something like $13,000.00 from the consumer for a ****** built garage. Then later on they dug down around the perimeter so the concrete was deeper, then built a ****** garage on top of that. One thing Bullock did do was change the rules for how a foundation had to be put in for a garage.

When you get a chance, show us what you're dealing with!!!

 

[flatbread]

I dont get it. Maybe this is what is happening

Im dumb, I guess you guys are suggesting a pole barn, since a perimeter pour would make a ****** garage. I always pick the bad implication(Since I am pessimistic). Im one of them cockeyed country bumpkin poor folks(you know the dumb ones, that shouldnt be breeding).

I asked because I noticed from this map, that my local area soil is different than most of yall's. Maybe this map will help others

http://geology.com/articles/soil/

There are no city codes here besides setback boundaries.
Frost depth is ~5".


Im dealing with a blue area from the map above, with an ~5 " frost depth, ~1500 psf soil bearing capacity, ~5psf snow load. Building site is level with ~5 " gravel on top of Natural Ground Level.


What bumfuzzles me is the lateral earth pressure from expansive soils,and if the "floating slab" would provide support from these expansive soils?

 

[Sureshot]

I think you are way overthinking it. Pour a slab and build the garage. It likely won't even freeze under the garage with the protection provided by the building.

 

[flatbread]

Sureshot, I have been told by a person that used to be very close to me that my problem is that I overanalyze everything. Does everyone else think the same as sureshot, to just slab and build?