12 x 14 shed...getting frustrated with where to start for concrete floor

[VMS]

Hi Everyone,

Looking to build a 12 x 14 shed (2 x 4 construction, trusses for roof) and want to put it on a concrete slab. My frustration, though is coming from getting the slab done to code...

Here in Hastings, wood walls must be 6" above the level of the earth. So...I am getting myself even more frustrated about how to proceed on a concrete slab.

My original plan is to pour a 4" slab with another 4" deep x 8" wide trough around the edge to keep the slab in place (like a normal floating slab). Is that enough to lay block or to pour a small 6" high wall around the perimeter and on top of the slab without fear of cracking the floor after the shed is built due to the roof load being transferred to the edges of the slab?

Reading other websites is just getting me more frustrated to even get this thing started. Some say best to pour footings, then do block or wall on top of that, then pour the slab inside (like a normal house foundation, but I would not be going down 42" for frost since it is a shed)

I could also build up the corners for the shed with cinder block, build a wood floor, but due to the size of my structure, I would need 2" x 8" framing on the floor for support, putting my floor at 15" above grade (with a 3/4 plywood floor) to make it meet the 6" code requirement.

Please help!!

Steve

[cavalierowner]

A concrete slab is the best way to go IMHO. Just pour a 4" thick slab and thicken the slab to 8" at the perimeter. If you really want to get serious, put a #4 rebar in the thickened slab, although with a shed that small, it's probably overkill. Every 4' to 6' embed a vertical rebar in the thickened slab and let it project about 6" out of the slab; that will get mortared into the block at the perimeter. Then lay a course of 4" block (8" high) around the perimeter to set the walls on; fill the core of the block where the vertical rebar sticks out and add an anchor bolt. That shed will be there for as long as you are alive and beyond!! Oh, be sure the bottom plate is treated.

[MNice]

Anywhere in MN the code says 6" wood earth separation. I wouldn't worry about to much of a thickened slab with the little weight for that shed. Assuming the roof trusses are 12', roof load is 12*14*50 pounds per sq.ft. = 8400# total. Divide that by each supporting wall = 4200# each side divided by the length 14' = 300# per lineal foot. Concrete can easily support that weight on a 4" slab. Your base prep will be more important that the concrete thickness at the edges.

[vikingmeatwad]

I'm about to buy a 10 x 16 shed and just planned to put it on pretty level ground. I imagine long term the concrete will help but what are the other reasons to use concrete for a shed?

Also I'm not positive on the placement yet as I will be building a garage next year so that played into it as well.

[cavalierowner]

This would come under the heading of "Do as I say, not as I do!". I needed a shed about 14 years ago, but it had to be moveable for a number of reasons. It was 8' x 14', stick-built, of 2x4's and T1-11 siding. I built the floor out of treated 2x6's and 5/8" treated plywood and buried the whole thing about half way into the ground. I just used 3" galvanized screws to attach the walls to the floor; my thought was when the final location was determined in 2 or 3 years, I would pour a floor and set the shed on top.

So here I am 14 years later and the shed is still on that wood foundation and the T1-11 is still just a couple inches above the ground. There is no sign of rot or delamination of the T1-11 anywhere and the floor feels as solid as the day it was put in. The ground here consists of about 6" of topsoil, below that is a naturally-occurring sand/gravel mix, so it's very well drained. BTW, I didn't need a permit because the shed was under the square footage where the City would have required a permit. No way this would have passed any inspection!