Questions about concrete round column footings

[thunderskunk]

Howdy,

Bottom line up front: can you build a garage with gravel floor using concrete round column footings? What are some of the wall design considerations?

I’m no stranger to construction. I built a 33x40 that I now live upstairs in. When I did this building, I poured the footer walls first, then built the structure, then poured the slab a year later. This was because carpenters were available in the winter months and it was either-or cash wise at the time. It came out just fine.

I bought a steam tractor. It’s been a childhood dream; essentially a locomotive on tractor wheels. It weights 18,000 lbs, is almost 10’ tall, 8’ wide, and 19’ long. With the stack on, it does not fit through my 9x8’ doors. On top of that, my garage is busy and was never built as a hobby shop. So after some deliberation, I’m rebuilding the 18x24 shed sitting in cinder blocks out back into a garage-esque building. It must be the exact same dimensions and location per zoning regulations, but that should be plenty big enough.

But I spent all my money on a steam tractor! Not exactly, but I’ve calculated about $7800 in materials to rebuild the building and budgeted $10,000 for the project. I don’t want to do a slab with 4-1/2’ footer walls or a floating slab. I would likely need a pump truck to get around the new building and $5k of concrete, plus the groundwork would cost more, etc. Maybe I’ll pour a slab eventually, but not this year if I can help it.

So how about those round columns? I’ve got a guy with a 3-point digger attachment. We cut 6 or 8 holes along the long walls, fill them using cement mixers, and embed those Simpson strong tie mounting plates for beams across the bottom of the structure. Toss in 10” of course aggregate, 6” of staymat, compact between layers; and leave 6” or so for a floating slab pour some day. Use PT pates to seal the building around the outside which is already built up.

It’s probably a dumb idea. Just looking for suggestions.

 

[thunderskunk]

Talked to a buddy: precast piers. Crazy load capacity, no mixers, no cure time, just dig a hole, maybe compact some aggregate down in the bottom, done. I’m debating between a pole-barn design with walls or a beam laid across each side. The idea is to have two doors; the “entrance” 14’ wide so I can park all the way to one side if needed and the other side just for clearance to get a tube brush through the front for regular cleaning. That poses a risk of the walls drifting apart since nothing ties them together at the base of each door, but I’ve seen enough examples I’m not too worried about it.

Here’s the engine.

 

[C-S-H]

Love the steam tractor. Since you are already preparing and compacting an extensive subgrade/subbase/base, why not set the footings at finished floor elevation? I don't understand what the piers are for. They are solving a problem you do not have, and will have to take earth pressure surcharge from the tractor.

 

[ericm]

Congrats on the tractor! Will you have a thread showing it and what you do to it? I think a lot of people here would be interested. For least cost you could do it as a pole barn. Pour the floor and finish the inside later. Pole barns can be built with the poles in the ground, or with concrete pilings and brackets to hold the poles, or precast permacolumns. The poles provide a lot of the stiffness against racking so if you use one of the concrete solutions the poles need to be bolted on well, but that is a solved problem. The concrete solutions cost more but if you have soil that is hard on wood that may be the best way to go.

 

[duneslider]

Post and Beam construction is done this way often. Shouldn't be a big issue.

 

[billconner]

You just need to calculate the live load, presumably the second floor; the snow load if any; and the dead load, the weight of the building. Divide that by the number of piers, and calculate the size of footings based on soil bearing capacity. Maybe 40 psf for live, 30 for snow, and 25 for dead load. 95 pounds X 33' x 40' divide by 8 piers is 15,675 per pier. Don't know what your soil is like but I usually start with 2000 PSF at least and not surprised if it's 3000 or 4000 - sandy gravel. Bed rock more. Whether pier is concrete or wood or other, unlikely it's the weak point.

 

[75gmck25]

What is the brand on the steam tractor? I've seen the Rumeley and a lot of different Avery tractors, but they seemed to be a different design than this one. And where are you located?

 

[thunderskunk]

What is the brand on the steam tractor? I've seen the Rumeley and a lot of different Avery tractors, but they seemed to be a different design than this one. And where are you located?

Engine is a 19-65 Port Huron. I’m in Vermont: I only know of two “running” steam tractors in the state, including mine.

To continue the thread: I ditched the posts. I still individually poured four posts, but tied them into the slab, so I’ve got four corners 4-1/2’ deep to pass the frost line, 16” deep footer bases, and a 4-1/2” slab. All 5000 psi fiber reinforced, which was so hard to work with I burned my kneecaps off, which is a different post. I ground it down a bit after three days, it looks a tad better.

Also: fantastic use for Milwaukee pack outs: a sawhorse that rotates!