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I'm going to be remodeling my attached garage into a living space. The garage is graded from 0in to ~4.5in below the homes slab foundation height and so that will need to be leveled to meet the existing slab. Most leveling compounds can't be used deeper than ~2in, not to mention being far more expensive. So for the lower end I'll need to use something else below the leveler to raise it.

If I poured a few inches of concrete (on top of a bonding agent or after prepping the slab as necessary) and used a leveler for the last inch or less, would that concrete need to have rebar? FWIW The homes foundation is ~3 years old and has rebar installed per code.

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    You'll want to create a subfloor that is softer to walk on and better insulating than concrete, so why not correct the grade with that material now instead of adding more concrete?
    – jay613
    Dec 21, 2023 at 12:55
  • Most concrete can't be used less than 2", so you're probably going to have to double up—concrete in the section that's >2" deep, leveler in the section that's <2" deep.
    – Huesmann
    Dec 21, 2023 at 17:07
  • Adding a top level comment for anyone in this situation. I found out that concrete leveler is crazy expensive ~70$/cuft. Leveling a 2in x 20ft x 10ft area would cost > 1500$. So while I think that is still a great option in theory, it's just not cost effective compared to framing a wood floor, which should be half that price. Dec 24, 2023 at 16:06

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Reenforcing is not required.

Reenforcing is a relatively inexpensive optional add-on that greatly increases performance of relatively expensive concrete that you're planning to buy anyway.

Fibers might make more sense than rebar if the section is only 3"-4" deep at one end of the wedge, though some steel mesh or bar at that deep end would be a very minor incremental expense in the cost of the whole project.

But it's your call, entirely. I would do fibers at minimum.

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    (Accepting this since it answers the question but for anyone reading I am also going to consider simply framing the floor with 2x4s / 2x6s as mentioned below) Dec 21, 2023 at 14:42
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Frame Challenge:

Instead of pouring concrete, self-lever, whatever, consider laying 2x4 pressure treated (or a plastic vapor barrier then non-treated 2x4) joists to raise the height.

  • The 2x4s (3.5" tall, actual) should get you the height you need (taking into account subfloor & floor on top) while providing just a bit of give to make the floor more comfortable for walking on. Use 2x6 if necessary.
  • They'll also provide space for some additional insulation (was there any insulation under the original garage floor pour?) to make the room more comfortable.
  • They are easy to cut at an angle to accommodate whatever change in grade is necessary to make a flat and level top surface for whatever final flooring you're installing. They're also easy to cut curves in as necessary to work with any variations in the existing floor.
  • They're probably cheaper than concrete and rebar, and are far easier for most DIYers to work with than concrete (there's a definite art to finishing concrete well).
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  • That's a great point that I will consider! I don't think any of the slab has insulation now, and adding might ease the extra load on my HVAC. It might also make it easier to frame new inner walls, which would otherwise need to be anchored in concrete. I'd have to be very careful to get the level exactly right, but even considering some re-cuts, its still less risk than a bad pour. Not to mention that I have done all sorts of framing work and almost no concrete work. I assume it would still be a good idea to pour a stem wall on the outer edge to raise the wall off the ground? Dec 21, 2023 at 14:36
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    That's a totally different question, @TheShoeShiner and you should ask a whole new question.
    – FreeMan
    Dec 21, 2023 at 14:39
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    The advantage of this approach is that is more easily reversible. Dec 21, 2023 at 23:39
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You do not need rebar.

I have done this to a couple of homes to convert garages to living spaces. (concrete slab homes) It is a good plan and allows flooring to be installed so it can flow directly into the new room.

The only issue I came up against was the exterior door. ( side door, not overhead). I opted to purchase a shorter, manufactured home door.

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I wouldn't be using rebar but would use some steel mesh at least in the deeper sections of the pour.

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