Concrete Slab for Shed

[icedoc]

I am in the planning stages of a new 12x16 shed to store my tractor, yard tools, and anything else that does not belong in my workshop. I want to do concrete so I won't have any realistic weight restrictions, and also so it will be long-lasting.

The site I have chosen for the shed was an existing garden that has a small concrete pad already beside it. The pad measures roughly 17'x6' and was used to store firewood by the previous owner. I would like to keep the pad and use it for storage BESIDE the new shed. The problem is that the pad is sloped, approximately 1ft drop over its length (runs parallel to the slope of the ground). I would ideally like the new slab to **** up against this pad, but I'm wondering how exactly I should go about doing this, and if it is even a good idea.

I was thinking of cutting forms on an angle and placing them on top of the pad (with lots of back bracing of course) so that there wouldn't be a large gap between the side of the new slab and the edge of the existing pad. However, since the new slab will be level, its bottom edge will nearly be exposed at the back corner. That troubles me, and I was thinking it might be a good idea to thicken the slab edge in that corner. Thoughts??

I've attached a quick rendering of the situation below. The new slab is in grey, the old pad is in blue.

 

[Jhoff310]

Why not just form up around the existing pad and pour over it. You're going to get hit with a small load charge anyways from the cement truck.

 

[K'ledgeBldr]

Don't see a problem with your plan. The corner just needs to be dug deeper- what's the frost line for your area?

I'd construct the slab as a mono-slab, with grade beams running through the middle in both directions.

 

[icedoc]

Why not just form up around the existing pad and pour over it. You're going to get hit with a small load charge anyways from the cement truck.

I could, but I think the extra 2-3 yards of concrete outweighs the partial load fee (I'll double check to be sure). It would also mean putting a step or aggressive slope for the side pad, since I don't want the side pad to be level with the shed floor. Since this will be my first attempt at concrete forming, I'd like to keep things as simple as possible.

Don't see a problem with your plan. The corner just needs to be dug deeper- what's the frost line for your area?

I'd construct the slab as a mono-slab, with grade beams running through the middle in both directions.

Frost line I believe is between 40-48". It is my understanding that a thickened edge slab is not meant to protrude below the frost line, simply "float" on a well-drained subsurface. I would prefer to do a footing below the frost line, but the cost of doing two pours is prohibitive.

I had to look up grade beam - that's a new one for me. Correct me if I'm wrong, but it looks like grade beams are meant to support a slab between point load supports (i.e. piles), as opposed to distributing its load over a broad surface. Since I will be putting down a good compact bed of gravel, are grade beams really necessary?

 

[Joemctag]

Use that black fiber joint material so the slabs don’t touch and one raises or lowers the other. That’s a lot of slope but the outdoor slab should have slope to drain and it’s already there. Slabs cost money. Good you have it. I would think about rain on the existing slab bouncing up and rotting out siding . Maybe use metal. Your new slab appears to be well above the ex. one, which is good. It could even be 6” or 7” above at the door and still work okay. Would not pour the new one right against or on top of the ex. one

 

[kbs2244]

It might make sense to check your local code before pouring any concrete
Putting a shed on a concrete slab often changes it from being a “temp” building into a “perm” one
That changes it from being untaxed to taxable
Ask what the tax increase will be.
The convenience may be worth the increased amount.

 

[Bondo]

Ayuh,.... Why are you postin' to a 4 year old thread,..??

I'm guessin' this shed was built along time ago,.....

 

[kbs2244]

I rarely check the dates
But my advice is timeless