One option to gain headroom in the garage could be to set a floating slab floor below the level of the footer. This would involve excavating the garage floor to a lower level than the footers, then pouring a new concrete slab that sits on top of the soil. The slab would not be attached to the walls or footers, allowing it to "float" independently of the rest of the structure. This would effectively lower the floor level and increase the ceiling height in the garage.

However, it's important to note that this solution may require additional excavation, grading, and drainage work to ensure that the new slab is stable and does not create any water infiltration issues. Additionally, it may be necessary to obtain new permits and approvals for the revised plans, which could cause delays and add to the overall cost of the project.

Another option could be to explore other design modifications that would comply with the height restriction while still achieving your desired level of functionality and aesthetics. This could include adjusting the layout of the basement or reconfiguring the ceiling heights in other areas of the home. Consulting with your architect or a structural engineer could help you determine the best course of action based on your specific situation and goals.

In any case, it's important to work closely with your contractor and any relevant professionals to ensure that any modifications to the plans are safe, compliant with local regulations, and meet your expectations.

Does it ever happen that the contractor has to dig up the footers and put them in at the right depth because they F'ed up literally the first thing they did, and that now affects everything else from here on out? Curious about this.

It was a good practice run, now let's build it correctly. Someone needs to correct their error and make the owner whole.

If the driveway slopes to the garage, check the math that you’d be able to drive the car under the garage door opening. (we had such a situation, and when we bought a minivan, had to get one without roof racks, otherwise they would have struck the top of the garage opening when the car leveled out at the opening.)

Who owns the lot?

Thanks folks. I own the lot. The height restriction is dictated based on the historic elevation of the land prior to excavation — in short, not an option to go up. I’m interested in the idea of digging down, contractor says there really should by 4” of floor slab over the footer. I can ask our engineer if pouring below the footer is an option, but want to respect our contractor’s final word. Has anyone needed to reinforce floating concrete floor w piers?

Krista Deng

Kudos for the Open Ai reply!

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want to respect our contractor’s final word
Buy him/her/them a new tape measure.
I knew a custom builder who pulled up half a poured foundation; the (real) architect paid for her mistake.

Excavating below the bottom of existing footings raises the possibility of undermining them and you would need an engineer's design to underpin them. But you should be able to align the bottom of the slab-on-grade with the bottom of the footings.

Is the floor above the garage concrete on metal decking? Perhaps it can be reduced in thickness.

It's difficult to be helpful without a drawing. The place to start is with a local engineer. Talking to contractors, strangers and bots is interesting but not very helpful.

Have you asked your contractor what height garage door will fit? It might be possible to lower top of slab to top of footing, but most footings are not finished.

"but want to respect our contractor’s final word."

How does that reconcile with:

"told me there’d been a miscalculation"

A 9' basement pour, especially in a basement with occupied rooms, in this era of house building is as important an amenity as having an ice maker. So I'm trying to read between the lines, and not sure if: you are resigned to the mistake; don't know who made the mistake; wasn't too keen on a 8'+ ceiling height to begin with; or don't have the appetite to pursue what was designed.

Did the:

- construction documents mislabel elevations;

- excavator do the math wrong;

- concrete contractor skipped over that part

- site conditions didn't allow it

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Pouring the slab next to the footing, if you can do so, will reduce your interior footprint because of a shelf made by the footing projection.

A slab that would want to be supported on piers means the substrate (soil) is not adequate for bearing, so the slab would need to be a 2-way slab (meaning designed to support itself wholly instead of relying on resting on soil). If that was the case, a raft slab would be chosen. Not sure how this relates to your situation.

Appreciate the input. We’ve looked into the issue further. It turns out the engineer did not account for the 8” depth of the gravel/insulation/tinging/etc slab for radiant heat we are using under our concrete slab. The contractor misjudged the dog only by about 4”, but the combo makes up 12” variable. It’s a bummer, but it looks like it’s one we’re going to live with :/

Dig, not dog.

"We are up against a height restriction in our code, so can’t go higher."

There is a REAL GOOD CHANCE nobody is going to measure it.

I have a real good story about building height that I can not tell publicly.

It's one of those first world problems. Eight feet is not short.

That contractor and engineer are certainly a well-matched pair!

Expecting professionals to adhere to their contracts is so petty when somewhere in the world children are going to bed hungry.

This is a pretty significant mistake.  I don't know that I could accept 8' ceilings and applaud you for being as calm as your are about the situation.  I would still let the builder and engineer know you aren't happy and ask if they are willing to give you some sort of credit towards other costs.

If the top of the slab is poured level with the top of the footing and the thickness of the floor structure above is somehow reduced by another 4", the ceiling height might be 8'-8" which should be fine. Even a height of 8'-6" is a huge improvement.

Make sure the garage door can work whatever the ceiling height.

The longer you wait the harder it will be to remove the footings.

If all those things were known and spec'd - I would require a do over.

8' is okay - but mark my words - it won't stay 8'. There will be additional conpromises that will have to be made. HVAC will have to cross joists. Is your basement wide open or to you have rooms / walls? If so that will be a lot more HVAC ducting that will have to be further into the space making bulkheads "everywhere" - which will bring your effective ceiling height down to 7'

Using a basement for bedrooms is a compromise. Having a low ceiling height is one of the things that people dislike about basements. This is a significant devaluation in your home, IMO and should be corrected.

I don't know how much money you are spending on this house - but this is a really big miss.

I also know this is easy for me to say - so ultimately you know your situation the best and what other factors are at play.

Its not possible to offer real solutions without full knowldedge of the actual structure so it would help if you posted a wall section drawing with dimensions.