I have a pretty old/tight 2 car garage with a completely shot foundation and I'm sure the roof is 20 yrs old (house roof is on its last legs as well).

My goal is to end up with a place we can use as a gym/play space as a primary with parking cars secondarily. We have a smaller house and with growing kids, we are trying to find more room.

I'm considering doing a rebuild/upgrade to it and I have no idea what these things should cost?

Ideally I want to do the following:

1. Repair foundation (I think the last quote I got was $5k for this work).
2. Raise the height of the overall garage with a goal of more interior space + storage space
3. Insulate the walls and put in a mini-split/ductless AC unit to control the temp in the room.
4. spray a nice surface on it to walk on.
5. Add an attached room on the side that would be fore storing Oil/mower/etc. Not accessible from the main garage.

My SWAG says at least $50k, but wanted to see what yall thought as I try to figure out what to do next?

I'm no help, but am wanting to do something extremely similar to mine as I face similar problems. So good luck!

IMHO and with that Spartan budget (these days ... old days you got a 1500sf new house!!!)

1. Repair foundation (I think the last quote I got was $5k for this work).
NO - the repairs warranty are only good for 2 years, so let it go to h**l and demo much later on in life
2. Raise the height of the overall garage with a goal of more interior space + storage space
NO- money better spent elsewhere, TMI to come
3. Insulate the walls and put in a mini-split/ductless AC unit to control the temp in the room.
YES YES, mineral wool cheapest, moisture dries out - unlike most others - sound proof, fire proof
4. spray a nice surface on it to walk on.
NO spray, this would one of those floating floors, where the budget money works best, e.g. eng.wood
5. Add an attached room on the side that would be fore storing Oil/mower/etc. Not accessible from the main garage.
STORAGE SHED w/ramp since it's on blocks, no flooding
All metal exterior good for 40+ years
Pre-built, delivered, leveled on blocks
Treated plywood flooring
As close as you'd like it to be "attached"

You may have missed that the foundation is already shot. Major cracks and sloping. It would not be usable for the purpose I want from it without addressing it.

If you want to raise the roof height, then that would be cheaper to tear down and rebuild, but I'm not certain you are contemplating a tear down are you?

The Fife said:

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The garage sounds like a complete redo, including removal and replacement of the slab. No clue what that will run you though.

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This is kind of where I am. It's an unfinished, uninsulated garage with a broken slab, so beyond the breaker box, for the garage, there's not much to it.

I'm fine tearing it down or salvaging, honestly depending on what is cheaper.

I just have no idea what to think about cost wise to see if I should call someone in to fine to it.

Now that others have weighed in to clarify your situation, it WOULD be best to inviate a 5-star rated, remodeling-only home builder to give his 2-cents and solutions.

As I began, don't stack a lot of coins on top of a rocky foundation and build to suit as best as can within present limits ,,,, there's not much salvage savings afoot.
Otherwise, demo & build new ... maybe $100 of salvage might be gleaned ... if YOU do it moonlighting and then they accept it all

You know, they make pre-built houses, garages and truck them in pronto .... google me if need leads

Don't know real budget or thoughts on a loan, but my thoughts are the best way to accomplish what it sounds like you want is to demo existing instead of sinking good money after bad and rebuild with a garage apartment above.

After just building a patio with a slab and raised roof (no AC, insulation, etc.) that is close to the size of a garage, I'm going to say you're between 75-100k min. You need to consider electrical upgrades, maybe new service for the garage only, and possible EV down the road. All of it adds up quickly. A slab alone will run you 15k new, and the structure probably 50-60k min.

I would also recommend you subbing it all out yourself if you want to be cost conscious and have the time. I couldn't get a GC to bid my job bc I think the scope didn't give them the profit they were looking for - had one tell me they're chasing 300-500k jobs and mine wasn't there.