Minimum thickness for small concrete pad

[LeeG]

I need to add a small 3x6 pad next to my shed. I’ll be hand mixing the concrete. It is going over top of some quarter minus that has been down for several years and is well compacted. It will be used to store an 800 pound piece of equipment.

My question is, can I get by with using 2x3’s (2 1/2”) as forms or is that just asking for trouble?

Thanks,
Lee

 

[nadogail]

I have poured concrete only 1.5” thick over well compacted soil. It stood up to foot traffic.

 

[Leaflessshadetree]

You can use 2x3s to pour thicker pad. I'd dig out to have a thickened edge (5" at least). Just tamp some dirt and/or gravel to fill the gap at the bottom.

 

[chad215]

Just do it right and you won't have to worry about it. I know hand mixing is a chore but honestly it's not that much more in labor or materials for that size. Whats another 3 bags once you've done that much already.

 

[gunguy]

Unless there is a particular reason not too, I'd over-build a little. Using 2x4s for framing, you're talking ten 80lb bags of 'crete with a little left over. A thicker pad gives you a little extra margin of strength.

Just a thought.

Jim

 

[mike93lx]

Is the equipment static or will it be moving on and off?

If static, I'd have no reservations.

 

[Bucko]

Concrete is one of those things I don't try and skimp on. If you do and it goes to **** you will wish you put a few extra bags in the mix. Heck I would be putting a sheet of remesh in there for $21 as well but I do tend to overkill things. If you are trying to use scrap lumber for your forms to save some money you can always do as others above have said and dig it down a little or shore it up with soil.

 

[mike93lx]

Concrete is one of those things I don't try and skimp on. If you do and it goes to **** you will wish you put a few extra bags in the mix. Heck I would be putting a sheet of remesh in there for $21 as well but I do tend to overkill things. If you are trying to use scrap lumber for your forms to save some money you can always do as others above have said and dig it down a little or shore it up with soil.

What is skimping though? What stop at a 2x4?

 

[Bucko]

What is skimping though? What stop at a 2x4?

The general accepted thickness is using a 2x4. As I stated I tend to overbuild things, especially things that will take double the work to fix. I myself would still dig the edges down a few inches and add mesh. Even more reason to dig it down if the slab will be sitting on top of the existing area so you lessen the chance of undermining from water runoff.

We don't really have all the variables either. Is this a 800lb compressor that is covering 4sq' and anchored the pad and will vibrate with each cycle or a 800lb item that is going to be moved on and off on a regular basis. 800lb is not much on the grand scheme of things and my bigger concern would be what the soil is going to do. Is it sandy, rocky, lots of trees surrounding, freeze/thaw climate???? Overkill helps to reduce issues but in the end they always say the 2 things about concrete is its gray and it cracks.

 

[LeeG]

The tool is a sheet metal shear. I have it on a wheeled frame, so it is "moveable". The next time it moves will probably be when I sell it or I move myself.

 

[atch]

I know absolutely nothing about Arizona soil or climate (except for being hot).

That being said here's my experience:

I hand mixed a pad for my air conditioner pad over 20 years ago. I used 1/2 bag of Portland cement per 2 bags of Sakrete; 2x4 forms. I don't know how many bags it actually took but I had to mix more than one batch. I did this entirely by myself. Obviously I was 20 years younger then. I'll not be doing this again in this life. I don't think I put steel in the slab but don't remember for absolutely certain.

This thing has had my A/C unit sitting on it all this time. It's not as heavy as your 800 pounds but there is vibration all summer long when it's running.

No cracks and it still looks brand new.

Note: I had used Sakrete straight out of the bag for previous projects and was disappointed; it just didn't hold up as well as I thought it should have. A friend suggested richening it with Portland and it has worked well. I did a few small projects after this one and always added the Portland. Never had another disappointment.