Concrete thickness

[mnpeterg]

Excavated and filled with class 5 today for a thickens footer slab (monolithic). The footers are supposed to be 12”x12”. The thickness of the slab I had planned to be 6”. Due to my skill level of the skid steer that I rented Tom Home Depot the thickness definitely varies 6 “ in most to 14 or so in others. Is that normal for diy’ers to have varying thicknesses? Certainly the top of the slab will be level it’s the thickness.

Rebar in the footers and slab.


Slab is for a larger shed.

Issue or simply an additional expense for the extra concrete?

 

[The Cobbler]

Is that normal for diy’ers to have varying thicknesses?

even pro jobs vary . a bit of extra cost in concrete but a small price to pay.
I had a pad poured last fall, it was to be 6" thick, it was from about 6-1/2 to 7-1/2 . close enough

 

[mnpeterg]

The slab is16x30 and had a hard time with the whole dug too deep in one area thing.

 

[Doubled33]

Guys that do grade all day can get within a 1/10 of an inch. When I buy out earthwork the big boys have that number in their contract. I am not buying extra concrete.

Should be fine OK on thicker, but where is your rebar? Is it on the top or bottom of your thick parts or in the middle? My vote is to keep your rebar consistent at say 2” down from the top and maybe add a matt in the thicker part so you don’t have unreinforced concrete that is that thick. Which for your application is probably fine either way, but rebar is somewhat cheap especially compared to your concrete overage.

 

[Renegade1LI]

You're fine for diy, after excavating we go back and do a final grade with approved backfill. That gives a more uniform subgrade which is important for the correct placement of rebar.

 

[NUTTSGT]

You're fine for diy, after excavating we go back and do a final grade with approved backfill. That gives a more uniform subgrade which is important for the correct placement of rebar.

That's what I would do and have done.

 

[ConCretin]

There's really no downside to thicker concrete other than cost but I agree with those that suggest bringing the base to the correct grade with compacted granular fill. It's not hard to do and will just make for a better job. Get a finer material that is easier to move around by hand and set up strings or use a laser to check your grade as you go. Plus or minus 1/4" would be just fine. Even the pro's rely on some hand work to get it that close.

 

[racecougar]

6" to 14" is a pretty huge variation. I'd suggest raising the low areas with compactible fill.

 

[PWC Repair]

I did my 30x48 myself and my concrete varies from 6-8" thick. I felt like that was close enough on the base to pour. How big will this be? 12x12 is a small footer.

 

[Leaflessshadetree]

It will be hard to estimate how much concrete you'll need if the thickness varies that much. Fill and compact the whole area. (IMO driving a skid steer around won't compact well enough).

 

[rayra]

seconding racecougar, that much variance is going to screw up any concrete yardage estimate pretty badly. You should try to get the level corrected to within a couple inches. Otherwise you might need twice as much concrete as anticipated and you might not get it in time because the yard is supplying multiple jobs concurrently and a follow-up truck for your gross mistake might not come in time for your pour. Then you;ll be posting a topic about your screwed up slab / cold joint etc.

 

[Prospecter]

As a DIYer, I usually set up a screed and use sand for the final leveling. But then, with my current project, I hired the work out, so there's that!