Do yourself a favor and spend some time researching on the Garage Journal forum. I found out about that forum after I built the garage at my old house and made a bunch of mistakes.
https://www.garagejournal.com/forum/ What where you mistakes we can learn from?
The architect convinced me that 1/8” per foot slope of the slab was code. When I asked the building department, they agreed. Turns out it was BS. There is no code saying anything about the slope of a slab, at least not here (Northern CA). I ended up with a garage with a very sloped floor, which made jacking up cars precarious at the worst, a pain in the butt at least. I found out after it was done that the slope thing was BS. I did insist on 14’ of flat area at the back, so at least I had a space for benches, my toolbox and an area where I could build an engine.
I also had mine built as extra wide and deep 2 car (26’ x 36’). It sounded good and looked good on paper, but in reality, it wasn’t ideal. I should have built it 36’ wide and 26’ deep with three bays, with one dedicated to a lift.
We sold that house 7 1/2 years ago. My garage now is much smaller and even though my garage at the old house wasn’t ideal, I miss the space (approx 900 sq ft)
The moral of the story is do a lot of research and don’t jump into the project like I did.
