Concrete Pad on Grass

[vpate24]

Hi,

Recently I got 11'X11' concrete pad built in my backyard. Some contractor in my neighborhood was working and I got him to build this pad for me. He built it while I was away at work. Later when I checked my security cameras, I saw that he built it on top of grass without digging the grass out. He poured gravels on top of grass then compacted them and then poured about 5" concrete on top of it. I have never heard of anyone doing it this way. Should I be concerned?

 

[JAE]

Depends on what you are putting on the slab I would think.

 

[vpate24]

I am planning on building 10 X 10 storage shed on it.

 

[BridgeSmith]

Since the slab is 5" thick, it's likely strong enough, so the question becomes, is the likely inch or so of settlement going to be a problem.

 

[TigerGuy]

A 10x10 residential use shed is likely to carry a very light load compared to some of the projects we see in the commercial/industrial world. However, if one of us were building it in our yard, we would have a 12-inch thick slab with #8 bars every 6 inches "just to make sure."

 

[hokie66]

TigerGuy,

Not me. I have done exactly as the OP's contractor did.

 

[BridgeSmith]

For a storage shed slab, I'd most likely do a 4" unreinforced slab, or 3" reinforced with mesh on a compacted base of crushed rock. 6" around the edges to embed anchors for the wall. I calculate what's needed, so I can be sure without wasting money.