Concrete pad with footings for shed foundation?

   / Concrete pad with footings for shed foundation? #1  

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I live in northern Ohio, with a 3' frost line. I have been wanting to build a 12x20' shed for some time. I plan to use 1/4 of it for a chicken coop and the rest will be a small work area that I can heat easily in the winter when needed. The site is on a slight grade with 10" fall over the 20' length. I had intended to dig post holes and sink 8 6x6 posts below the frost line, then place treated beams and floor joists a couple feet elevated off the ground. I would use a treated plywood deck too, and use conventional lumber above that. This would solve my grade issue, and give the chickens a place to hide under it. The new lumber treatments and the cost of treated lumber and stainless steel hardware is making me rethink this.
Can I pour a 12'x20' concrete slab with built-in 8"x8" footings and build a shed on it, disregarding full footers and frost? Will a slab with footing support a shed that size and float with the frost heaves without crumbling? By my estimates I can pour the slab and add a row of of concrete blocks to start the wall for the same cost as the elevated treated deck style. The slab is appealing since the shed would outlast me as long as it didn't crack and move too bad.
Does anyone have experience using slabs with footings in the north, for buildings this size? When pouring slabs with footings, do you cut joints or leave it as one solid piece?
 
   / Concrete pad with footings for shed foundation? #2  
This size I would build on skids on top of the ground.
 
   / Concrete pad with footings for shed foundation? #3  
I live in northern Ohio, with a 3' frost line. I have been wanting to build a 12x20' shed for some time. I plan to use 1/4 of it for a chicken coop and the rest will be a small work area that I can heat easily in the winter when needed. The site is on a slight grade with 10" fall over the 20' length. I had intended to dig post holes and sink 8 6x6 posts below the frost line, then place treated beams and floor joists a couple feet elevated off the ground. I would use a treated plywood deck too, and use conventional lumber above that. This would solve my grade issue, and give the chickens a place to hide under it. The new lumber treatments and the cost of treated lumber and stainless steel hardware is making me rethink this.
Can I pour a 12'x20' concrete slab with built-in 8"x8" footings and build a shed on it, disregarding full footers and frost? Will a slab with footing support a shed that size and float with the frost heaves without crumbling? By my estimates I can pour the slab and add a row of of concrete blocks to start the wall for the same cost as the elevated treated deck style. The slab is appealing since the shed would outlast me as long as it didn't crack and move too bad.
Does anyone have experience using slabs with footings in the north, for buildings this size? When pouring slabs with footings, do you cut joints or leave it as one solid piece?

You can easily pour a slab on grade for this size building. That is actually my preferred way to do post frame building because it keeps the lumber out of the ground.

Just pour whatever thickness of slab you want with a 12" minimum. thickened edge.

Not sure what you mean by 8'' x8'' built in footings though?

I would place one control joint in that slab.
 
   / Concrete pad with footings for shed foundation?
  • Thread Starter
#4  
You can easily pour a slab on grade for this size building. That is actually my preferred way to do post frame building because it keeps the lumber out of the ground.

Just pour whatever thickness of slab you want with a 12" minimum. thickened edge.

Not sure what you mean by 8'' x8'' built in footings though?

I would place one control joint in that slab.
The 8"x8" was the thickened edge. Everything I've seen called this a slab with a built in footing. I planned on using a 4" slab with a 8"x8" thickened rim, or something similar. Are you saying the rim should be 12" minimum depth or width? Maybe a 10 or 12" deep rim, with a base 8" wide tapering up and in to the 4" slab? I like the idea of keeping the lumber off the ground with a row of blocks too.
 
   / Concrete pad with footings for shed foundation? #5  
The 8"x8" was the thickened edge. Everything I've seen called this a slab with a built in footing. I planned on using a 4" slab with a 8"x8" thickened rim, or something similar. Are you saying the rim should be 12" minimum depth or width? Maybe a 10 or 12" deep rim, with a base 8" wide tapering up and in to the 4" slab? I like the idea of keeping the lumber off the ground with a row of blocks too.

I got ya now.

Yes I was referring to a 12" x 12" footing but really on the that small of a shed a 8'' x 8'' would be plenty.
 
   / Concrete pad with footings for shed foundation? #6  
I live in northern Ohio, with a 3' frost line. By my estimates I can pour the slab and add a row of of concrete blocks to start the wall for the same cost as the elevated treated deck style. The slab is appealing since the shed would outlast me as long as it didn't crack and move too bad.
Does anyone have experience using slabs with footings in the north, for buildings this size? When pouring slabs with footings, do you cut joints or leave it as one solid piece?

The results of your price comparisons are interesting. We have a 4' frost line, and I have dithered over the same question but never got around to getting out the calculator. I have never been a fan of lumber in the ground either - even though I am pretty sure it would outlast me :D

I think your chickens will be fine on concrete if you put enough bedding down, maybe 8"-10" deep. It will provide some residual heat and protect their feet. You might think about going one block higher in that portion of the shed to keep the bedding off the wood walls. It can get pretty deep by Spring and depending on how many chickens, can have quite a load of ammonia in it - as you probably know.
Dave.
 
   / Concrete pad with footings for shed foundation? #7  
I got ya now.

Yes I was referring to a 12" x 12" footing but really on the that small of a shed a 8'' x 8'' would be plenty.

Chickens attract critters.

Critters that like to dig.

They like to dig under shallow footings and make a maze of tunnels.

I'd be concerned about having a 'rat wall' footing around it.... Deep enough to keep the critters out.

--->Paul
 
   / Concrete pad with footings for shed foundation? #9  
Can't help you with the frost line part of your question but out here in California the rule on saw cutting the slab is 1/4" per 1" depth of of slab. The most reactionary area of concrete is in the upper 25% of the slab. A common residential pour being 4" in depth would get a 1" deep saw cut. An easy way to check the depth-the top edge of a quarter (two bits-.25 cent piece) placed in the cut will be in equal plane with the finished slab. The saw cut width is wider than the quarter so retriving it isn't too difficult!
 
   / Concrete pad with footings for shed foundation? #10  
I live in northern Ohio, with a 3' frost line. I have been wanting to build a 12x20' shed for some time. I plan to use 1/4 of it for a chicken coop and the rest will be a small work area that I can heat easily in the winter when needed. The site is on a slight grade with 10" fall over the 20' length. I had intended to dig post holes and sink 8 6x6 posts below the frost line, then place treated beams and floor joists a couple feet elevated off the ground. I would use a treated plywood deck too, and use conventional lumber above that. This would solve my grade issue, and give the chickens a place to hide under it. The new lumber treatments and the cost of treated lumber and stainless steel hardware is making me rethink this.
Can I pour a 12'x20' concrete slab with built-in 8"x8" footings and build a shed on it, disregarding full footers and frost? Will a slab with footing support a shed that size and float with the frost heaves without crumbling? By my estimates I can pour the slab and add a row of of concrete blocks to start the wall for the same cost as the elevated treated deck style. The slab is appealing since the shed would outlast me as long as it didn't crack and move too bad.
Does anyone have experience using slabs with footings in the north, for buildings this size? When pouring slabs with footings, do you cut joints or leave it as one solid piece?

I don't think chickens and a wood floor would be a good mix. Why not build the shop floor out of wood and leave a dirt floor in the coop portion?
I would close off the area under the shop. Just think how much fun it would be retrieving a dead chicken from under there. Plus like Rambler mentioned, chickens attract critters. You don't want to give the critters a hidden area to chew their way into your shop.
Pouring the slab you described should work. Where I live the "footing" would have to be 16" below the bottom of the slab. Check your local building code.
One thing that worries me about pouring a floating slab and heating part of it is the frost could heave the end with the coop more than the heated end.
You'll absolutely need to reinforce the concrete. At the bare minimum you'll need 6x6 reinforcing wire in the slab and two rows of number 4 re-bar in the footing.
 
 
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