Help with concrete slab poor

I am about to pour a concrete slab for a shed. My yard has some slope . I leveled the forms and I end up about 4 inches low on one corner. I put some stone in and leveled the inside of the forms. I am concerned with the outside of the forms whenI do the pour. The stones went under the forms and I am
Concerned what will happen when I remove the forms.

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You need alot more fill then that. You can’t just let it stop right at the form line. And it ahold have been class 5 ao you could compact it. You also don’t want that slab perfectly level, which I’m doubting it is. But it should drop 1/2 inch from house to out side edge

Thank for the reply. If I add more fill to the outside of the form do you think I will be ok? This is just for a shed I won’t have anything to heavy in there.

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Just make sure the corner doesn’t wash out other wise that slab will crack in no time at all

I did a 16×20 slab for a shed 20 years ago. Filled in with class 5 compacted by hand. Major point is use rebar. I put a lot in. 20 years later zero cracks. Do not buy the story that some material in the concrete mix means it won’t need rebar.

David Bollig wrote:

I did a 16×20 slab for a shed 20 years ago. Filled in with class 5 compacted by hand. Major point is use rebar. I put a lot in. 20 years later zero cracks. Do not buy the story that some material in the concrete mix means it won’t need rebar.

First off, this 4 inch clay doesn’t need rebar lol. And the concrete your talking about is a batch with fiberglass mesh. Rebar is recommended in 6 inch thick plus slabs and slabs that cars and equipment will be on. Driveways for regular cars and trucks are 4 inch with wire mesh. Absolutely 0 reason the put rebar in it. And the joints cut in concrete are where the cracking is, it’s controlled. I’ve been in concrete all my life and I can only guarantee you one thing. All concrete cracks

Bearcat89 wrote:

You also don’t want that slab perfectly level, which I’m doubting it is.

I’m not sure what he means but if you are putting a building on the slab yes the slab needs to be perfectly level across the entire surface. As far as rebar yes no matter what type of soil you are on rebar will improve the performance of the concrete. I would suggest a 3/8″ #3 rebar mat 2′ OC. I consider them like rubber bands if the concrete cracks which it will it keeps the slab from seperating.

supercat wrote:

<div class=”d4p-bbt-quote-title”>Bearcat89 wrote:</div>
You also don’t want that slab perfectly level, which I’m doubting it is.

I’m not sure what he means but if you are putting a building on the slab yes the slab needs to be perfectly level across the entire surface. As far as rebar yes no matter what type of soil you are on rebar will improve the performance of the concrete. I would suggest a 3/8″ #3 rebar mat 2′ OC. I consider them like rubber bands if the concrete cracks which it will it keeps the slab from seperating.

I assumed it was a patio slab so I figured it needed to be sloped. I missed the part it’s for a shed. and wire mesh is more then sufficient for that small slab.

Thank you all for the replies. Im just concerned about the washout. Any tips on that?

I would get your fill dirt around your forms. If your gravel washes out you will have problems.

If it’s a shed you should have probably dug the other corner down rather then building the other up. But keep fill around it. Problem will be the rain washing it away.

A perimeter of rebar will go a long way in strengthening those corners/edges. The slab looks awfully thin. Thin concrete breaks easily. It’s probably worth your time to make sure it’s thick enough to endure the assaults of time and tool.

duh queen wrote:

A perimeter of rebar will go a long way in strengthening those corners/edges. The slab looks awfully thin. Thin concrete breaks easily. It’s probably worth your time to make sure it’s thick enough to endure the assaults of time and tool.

Looks like a typical 4 inch slab pour

I would get a load of dirt to build up the area, perp is the most important part of any job, weather its building a shed or painting a car.

IMO Pour the slab and backfill the next day and get some grass growing that will help with soil stabilization. To me the slope is not that steep.

supercat wrote:

IMO Pour the slab and backfill the next day and get some grass growing that will help with soil stabilization. To me the slope is not that steep.

Exactly!