Slab for 12x20

[mike93lx]

I need a shed and think I've settled on 12x20. It will be right off the driveway, so keeping the floor at existing grade would be quite nice.

I want to keep the footprint to the shed dimensions, so I was thinking I'd have a slab placed and then either add a course or two of block or form up a short curb (under 12" ?) and then building on top. any other ideas/things I am missing?

 

[markzrt1]

Good plan. I did one row of block.

 

[Prospecter]

I just used 2 layers of PT 2x lumber Ramsetted to the slab and attached my panelized walls to that. Not "correct" but it works well and no problems in Maine 20+ years on. Quick and easy. However, I was not dealing with the current lumber prices.

 

[driftpin]

I did a slab that size a few years ago, I used a thickened-edge slab with #5 rebars in it, and #10 6" X 6" WWM in the field. I had ordered a Hardi-Board 10' X 20' building w/a steel frame, standing-seam steel roof, and PT 2x8 footer board, which was fastened to the concrete with HILTI threaded tamp-in pins. I used a thick double-bead of silicone under that board. For power to the building I had below-grade PVC and wire from the main service entry panel, and above that, below grade, I did a PVC run for a data cable. The trenches/PVC come above-grade next-to the slab, not in it. I have a 100 amp service panel, and 120 V outlets 4 ft around the perimeter done in MC cable, and multiple 20 amp and 30 amp 240 V for a welder, 60 gallon air compressor, and saws. A lot of the stuff inside is on dollys or casters, so things can be moved. I used 4 ft LED double-bulb FEIT lights daisy-chained below the ridge beam, and I have wall shelving above your head at the workbench, with Gladiator 8,000 lb capacity rack shelving on one wall. I use masonite on-top of the Gladiator wire shelf surface, to make it easier to slide on/off whatever is stored there. The outside has LED lighting luminaires on motion detectors. I also have one 120 V GFCI outlet in a weatherproof box on the outside, next-to the overhead roll-up door.

 

[mike93lx]

I just used 2 layers of PT 2x lumber Ramsetted to the slab and attached my panelized walls to that. Not "correct" but it works well and no problems in Maine 20+ years on. Quick and easy. However, I was not dealing with the current lumber prices.

even with crazy lumber prices, a second piece of PT is cheaper than the concrete work, and a lot cheaper.

I'm probably overthinking it with a curb or block wall, and it would be easier to stand the walls if there wasn't one

 

[Leaflessshadetree]

even with crazy lumber prices, a second piece of PT is cheaper than the concrete work, and a lot cheaper.

I'm probably overthinking it with a curb or block wall, and it would be easier to stand the walls if there wasn't one

Maybe overthinking, maybe not. If the slab will be above the surrounding ground and it stays dry I wouldn't do the curb.
If close to the ground and likely to be wet or moist for periods of time the curb will provide some defense against rot.
It also will depend on siding/sheething, interior finish and intended use.
It also can add to height which may be a factor for some people.
On a simple shed I most likely wouldnd't do the curb. If I was creating a finished and conditioned space I'd be more likely to.

 

[mike93lx]

Maybe overthinking, maybe not. If the slab will be above the surrounding ground and it stays dry I wouldn't do the curb.
If close to the ground and likely to be wet or moist for periods of time the curb will provide some defense against rot.
It also will depend on siding/sheething, interior finish and intended use.
It also can add to height which may be a factor for some people.
On a simple shed I most likely wouldnd't do the curb. If I was creating a finished and conditioned space I'd be more likely to.

The slab will be right at grade, to allow a smooth transition to the driveway.

I am think lp siding and trim for the whole thing. No regular wood on the exterior.

The space is planned as a storage shed and possibly a place for welding and maybe a little woodworking. No plans for conditioning, but a window a/c is not out of the question.

I have an attached two car garage, but it would be nice to get some of the noisy and dirty work out of the house.

 

[Daniel Dudley]

I wouldn't make a permanent foundation for a temporary building unless I could turn it into a parking pad later..

 

[mike93lx]

I wouldn't make a permanent foundation for a temporary building unless I could turn it into a parking pad later..

Why is a shed a temporary building? Besides, what is permanent? Not like removing a 12'x20'x4" concrete slab would be all that hard.

My intention is to have this shed be there at least as long as I am, which could be 20 years. After that, I don't care what happens to it.

Even if that mattered to me, the pad will be right off the end of my driveway, so it could be an extension, but it won't match the finish of my driveway at all

 

[65ranchero]

Why is a shed a temporary building?

For one thing it shouldn't be taxed if it's temporary and in most places no permit will be needed but may need to run it past zoning if in town

 

[mike93lx]

For one thing it shouldn't be taxed if it's temporary and in most places no permit will be needed but may need to run it past zoning if in town

Taxing of shed vary greatly. I want the right building independent of what it does to my taxes.

A building on skids might save a few dollars every year, but isnt what I want

 

[Stuart in MN]

I'd put in a course of block. It keeps the wood up and away from ground moisture, as well as snow (but that may be less of an issue for you.) It probably helps prevent termite infestation too.

 

[mike93lx]

I'd put in a course of block. It keeps the wood up and away from ground moisture, as well as snow (but that may be less of an issue for you.) It probably helps prevent termite infestation too.

Snow is (finally) not a problem for me, but moisture always is. If I could get a brick veneer that matches the house, doing a stem wall in that could look nice. I definitely don't want exposed block, so it would have to at least get parged or stucco'd