# Pouring slab for existing wood shed.



## agfrvf (Jun 24, 2019)

Moving to a new place with a nice 24x14 shed. Currently it is up on blocks and has a wood floor. There is now way in hell it will hold my machines. My thought was to lift it and pour a 6" fiber reinforced slab and set the structure down on top. Then drop the structure on the slab. Anyone ever do this?


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## fixit (Jun 25, 2019)

Are you planning to leave the original wood floor? If not it would be possible but a lot of work. If it's a manufactured shed it may be cost effective to sell it & build a new building.


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## cathead (Jun 25, 2019)

Remove the floor, raise it up and prep the floor area, then pour the floor and then lower it on to the concrete.


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## rgray (Jun 25, 2019)

I would also say remove the wood floor first. Unless there is a reason you want to keep it movable.


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## Latinrascalrg1 (Jun 25, 2019)

For a shop of that size and considering the amount of weight you will be loading onto the slab I dont think I would proceed unless i also did a foundation of some type!   IMHO there is Way too much work and money being spent on a project of that size to NOT go that extra distance to ensure a solid structure.


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## Larry42 (Jun 25, 2019)

No experience with fiber reinforcing, I'd be inclined to use #3 rebar @ 24" OC, both ways. Put the bar on chairs to keep it at least 1.5" away from any surface. If your site is solid I don't think adding footings is going to help much in FL.


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## agfrvf (Jun 25, 2019)

Most houses in FL are built without footings. I am also zero risk of frost heaving and on top of a small hill. The current structure has been up about 3 years so the ground is relatively stable. The blocks show no signs of sinking with a payload of lawn tactor and tools.

To gravel or not to gravel seems like the biggest question.

Fiber prevents cracks from spreading and has the strength or rebar.


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## rgray (Jun 25, 2019)

I did the fiber on my last edition (22x36). 
3 1/2" of concrete with 12"x12" outer perimeter.
I did the gravel and vibrating plate compactor to pack it in place.
Along with the fiber I did 4 square wire.
Two 1/8 x 1 1/2 runs of steel used to screed off of. And those remained just below the surface for two lengthwise controlled cracks, so I wouldn't have to have cut lines.
No cracks so far after 2 years. And montana might be a little more hostile to concrete than florida.


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## agfrvf (Jun 25, 2019)

You probably needed the 12"12" perimeter for snow on the roof. If It ever gets that bad at my place your roof would be long past caved in.



rgray said:


> I did the fiber on my last edition (22x36).
> 3 1/2" of concrete with 12"x12" outer perimeter.
> I did the gravel and vibrating plate compactor to pack it in place.
> Along with the fiber I did 4 square wire.
> ...


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## agfrvf (Jun 26, 2019)

To keep costs down do you think using a hand tamper to pack gravel would do?


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## pontiac428 (Jun 26, 2019)

I would never pour concrete on a hand-tamped pad.  Too much investment in the mud, too much time in setup and finishing to risk it.  Compaction should be done with a Rammax or Wacker in lifts of 4-8", depending on soil.  Vibra-plates are for finishing asphalt or paver blocks, or can be used as a finish for concrete after being compacted and tuned up with a more reliable method.  Compaction is everything in concrete work.  It determines the future of your project.  The exception is "gravel" which is for drainage and compacts easily with a vibra-plate, but aggregate base and fill need to be compacted right.


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## rgray (Jun 26, 2019)

If your not disturbing the ground (digging out and filling back up) then compacting is not as big a deal.
But packing that gravel by hand I would consider almost imposible.
I put in 2 inches of gravel and when it is compacted it's very much like walking on any sidewalk. Until you drag a toe or something.
Rental rates around here are cheap as far as renting one of those machines.
I'm no professional contractor or anything. I'm just crowing about how I did it.

My addition previously (9 years ago) I made the mistake of removing to much soil.
I filled it back to the height I wanted with roadmix. I was told it didn't need compaction. So far so good on that addition also.


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## brownac1983 (Jul 27, 2019)

Keep in mind that it may be on blocks for a reason. In some places any structure with a foundation that's over a certain measurement (in my area it's 12' in any dimension) requires zoning and a building permit, and has to either be to code or have approved engineered plans. Once you secure it to the slab it becomes permanent. It's weird, because you can have as large of a shed as you want as long as it's not on a permanent foundation, sort of a loophole.
You may not be in an area where that will matter, but you don't want to go through all that trouble and the county inspector see you and raise a stink. Look into it beforehand.
  -Drew


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## Flyinfool (Jul 28, 2019)

FWIW, I know very little about doing concrete. I am in Wisconsin so we do see real winters here. I poured a deck 35 years ago and acording to the experts I did everything wrong. now it is 35 years later and there are NO cracks at all. I even used it as a parking place for 15 years. I put dowm 4 inches of gravel tamped by stomping it with my size 14 feet. I have rebar around the perimeter and wire mesh across the whole thing. There was no such thing as fiber back then, at least not that I had ever heard of. I poured the whole thing 5-1/2 thick because I did not want to risc any cracks.

Of course YMMV.

As mentioned above, check your building codes, some inspectors get great enjoyment in finding fault with what you do, and a flat out violation, whether you knew you were in violation or not, will really make their week.


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## Tim9 (Dec 30, 2019)

Much of Florida has a kind of limestone ground base which is basically calcinated shells. It is basically a porous limestone. Not like Louisiana marsh. 
  I’d do a biopsy of what’s below your brick wall first. See how deep it goes and is it set on a concrete base. Sort of chain wall.  Best would be if you can pay a contractor or engineer to inspect it for you and give an opinion.


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