I hired a contractor to make me a shed foundation from concrete for a tuffshed. I wanted a 10x20 foundation but instead of making it a rectangle he made it as a parallelogram. When tuffshed got here they said it was too far off to build. It's about 10 inches off. I considered allowing the contractor to fix it by cutting concrete and pouring additional concrete. However, that would mean the new concrete on the edge, right were they will need to put bolts in to secure the shed to the foundation. Would that make the concrete crack? and is this generally a bad idea?

He seems totally incompetent and hasn't offered a solution on his own as he doesn't seem to understand the problem.

I've considered using rebar or some kind of adhesive but I'm not sure that will be sufficient since the bolts from the shed will be so close to the new pour.

The last thing I considered was just starting over. What do you guys think?

shed foundation

  • 11
    Did you have a contract? If not, then you had "some random worker" and it's notoriously difficult to hold them to the standards of an unwritten contract, even when they are obviously incompetent...if you had contract, you'd have terms and specs to make them correct the work at their expense. If they are a "licensed contractor" in your area you might have some recourse through whoever licenses them, but expect it to be frustrating and disappointing.
    – Ecnerwal
    Aug 6, 2022 at 22:18
  • 2
    Have you paid the contractor yet?
    – JACK
    Aug 6, 2022 at 22:56
  • 2
    He is willing to try to fix it but I'm not sure how to fix it sufficiently
    – Bryanzpope
    Aug 6, 2022 at 23:22
  • 4
    he doesn't seem to understand the problem ... get a cardboard box ... cut off the top and bottom ... stand it on the floor ... square it up ... tell him this is what I asked for ... skew it ... this is what you built
    – jsotola
    Aug 6, 2022 at 23:26
  • 1
    A builder who doesn't understand right angles isn't going to get very far. I reckon you'll need to get someone competent to fix it, and hope to recover something from the useless one
    – Chris H
    Aug 8, 2022 at 10:39

1 Answer 1


I am not going to get into payment/ legality/ recovery discussion. Obviously the guy messed up and you will have to deal with that as best you can.

Removal and redoing the slab would certainly be first choice- if someone else is paying for it. I tend to think this will probably not happen. Here is a idea to fix what you have. While not optimal it is probably the easiest solution to get your shed up.

Add concrete to one end of your slab (see drawing) but enough to have the ability to bolt down your shed walls and be secure. You could pour greater than 12" and have a slab that you could use on the other side which would be outside the shed. Care should be taken to seal the shed with caulking and possibly flashing against the concrete where it sticks out beyond the shed. This has a high potential for water leakage.

If you are stuck with the job as is and don't want to pay to redo this is a feasible alternative.

enter image description here

  • 10
    Agree, but better to dig the new edge much deeper than the old slab, so you get a "thickened edge slab" (google for drawings). Be sure to epoxy lots of rebar dowels into the old slab (w/ Simpson set-XP, for instance). Aug 7, 2022 at 0:21
  • 4
    Absolutely right on the thickened edge- I guess I assumed (wrongly) that was the case already- thanks for adding that...
    – Kyle
    Aug 7, 2022 at 3:01

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