The home I moved into has an outbuilding, built before the 90s and maybe as old as the main house (1962). It was a horse barn years ago, then storage and other unknown uses. It's concrete block, no floor, wood framing for the attic and roof, and sheet metal roof. All is in good condition. The concrete blocks show some cracks in the seams between blocks (vertical and horizontal) but a mason who looked at it says it's probably stable at this point and just something to watch for changes over time.

We want to partially-finish at least one room that is already separated from the rest of the barn, and I'm here to ask what to do for the floor. Our idea is to fix for this room to be a workshop for smaller materials: work benches, cabinets, tabletop tools. Here's a few interrelated questions I have about it, followed by photos.

  • There's rebar coming out of the ground, 18" above grade, which I have dug down and found goes over 18" deep. It has some wiggle but cannot be pulled up or pushed down. Friends suggested cutting the rebar a foot below grade and bury it. Any reason not to do that? Any idea what this would've been for? Frost line maps for my area report 32-44"...not sure I want or need to dig that deep if I don't have to! No sign of rebar and electric being connected.

  • The edges of the room show signs of different floor levels. This could have just been stains on the wall from animal bedding. Should I act on these different levels in any way or just ignore them and wash/paint over them if we care to?

  • Electric comes into the room, ran underground. The cable seems good (I'll ask about that in a separate question), but I'll replace the subpanel and all the other circuits in the barn. Anything I should do while getting the floor foundation in place, to ensure the electric is ready for future use? I'm thinking to slide the existing cable into conduit large enough to easily fit over it, then bury that conduit an inch into the fill and close to the concrete wall so that it will be secured to the floor foundation. After cleaning the walls and doing any painting if that'll happen, I'll affix that conduit to the block wall. Meanwhile, the wires will stay taped off until the room is enclosed and I get a new subpanel installed.

Outside view of barn room to be fixed up

Closer view of barn room

Inside view of barn room

corner of room in barn with old subpanel

Close view of cable

rebar sticking out of ground

Closer view of rebar sticking out of ground

My thinking is to add fill and tamp it down, level with the cinderblock 'threshold' entering the room. That leaves 8' from threshold to top of cinderblocks where the ceiling would be. Then I'd add 3" of gravel and level it. I will leave it like that while I finish enclosing the room (add a ceiling, replace windows and door). Once the room is enclosed, I will add a vapor barrier and build a proper wood or earthen floor above that. I envision the floor layers would add one step up into the room, with the floor 7-8" taller than the threshold at ground level (fill to ground level, 3" gravel, vapor barrier, some sort of insulation + subflooring + surface).

Does this sound like a reasonable approach? Any alternatives or cautionary details I should consider about this overall, or specifically about the rebar, level of the fill and gravel, and electric feeder for the barn?

  • 1
    Digging out enough dirt to permit a more level entrance rather than an awkward step at the threshold would be my default approach to this. And the prep will be somewhat different if you want an earthen .vs. wooden final floor, so get that decided. Might want to keep digging and see if the rebar leads to hidden treasure before sealing it away forever. What the bleep that was doing in a horse stall is ???
    – Ecnerwal
    Commented May 29, 2023 at 16:22
  • @Ecnerwal from what I read about both flooring options, the first layers of tamped fill, gravel for drainage, and vapor barrier appeared the same. Do you think that's wrong and the base layers would differ in depth or material?
    – cr0
    Commented May 29, 2023 at 16:24
  • As for level with the main enterance, that does sound good to me, but not knowing much about flooring it is a head scratcher: wouldn't I want any moisture near the door threshold to percolate under a vapor barrier, meaning I would want my vapor barrier to be no lower than the threshold? Or are you suggesting all those floor layers would be below the threshold, so the finished floor is level with or just above the threshold?
    – cr0
    Commented May 29, 2023 at 16:26
  • 1
    A wooden floor does not need contunious support, assuming it's built on wooden framing as usual. The walls and perhaps a few piers in the middle to keep framing spans short are plenty.
    – Ecnerwal
    Commented May 29, 2023 at 16:27
  • Is a concrete floor out of the question?
    – Huesmann
    Commented May 30, 2023 at 13:31


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