Like they said, yard layout is the first question. I only had enough room to go 24' wide on my property so I went 40' deep. 40' deep is kinda a weird depth, it's more then enough for 1 vehicle but not quite enough to work on anything with 2 vehicles deep.
From my experience I wish my garage was 40' wide x 30' deep. 30' deep is a great depth for vehicles pulling in. 40' wide will give you the ability to go 3 bays wide. And go a min of 12' ceilings. I wish my 10' ceiling was 2' higher.
I agree with Jamie's first paragraph.
I went with a 10' ceiling, I wish I would have stopped with 9'. The extra height just drives the costs up (you will spend MORE money than you expect to and want to) and the building is a touch out of scale with the house. Scissor trusses for the possible lift addresses the height issue.
You have lots of options:
Depth Length SqFt
25 48.00 1,200
26 46.15 1,200
27 44.44 1,200
28 42.86 1,200
29 41.38 1,200
30 40.00 1,200
31 38.71 1,200
32 37.50 1,200
33 36.36 1,200
34 35.29 1,200
35 34.29 1,200
36 33.33 1,200
37 32.43 1,200
38 31.58 1,200
39 30.77 1,200
40 30.00 1,200
What do you want to use the garage/shop for?
I based my size (42' x 23.75' = 997.50sf) on two things. (1) The vision I had for a race shop and (2) resale at some point in the future.
I was stuck with 1,000sf after getting the township to increase the max size for "accessory buildings" from 600sf! I wanted room for four cars; one 16' door and two 9' doors with reasonable room between four vehicles and along the sides (shelving and/or workbenches and/or machine tools).
The 16' door (parking spots one and two) is where primary race car work takes place. The second race car is in the "third" parking spot and the "fourth parking spot" is an open area for fabricating, working on stuff, parking another car, etc.
I could have gone deep with three stalls, but I thought that would have held back future salability. I could have gone wider, but that would made getting around the front and back of the 17' race cars difficult. My 23.75 depth (with 6" walls) is about the least I would go. If I were working on Suburbans, extended cab pickups, 50's and 60' Cadillacs, hearses, and other long vehicles ... I would have gone much deeper and hit the local town board much harder to get a max size of 1,200 or even 1,500sf.
If you want more size and have the room for more size, consider going to the municipality and proposing an increase in the maximum size for accessory building. You'll probably find as I did that the municipalilty's appetite for a "variance" or "conditional use permit" is almost
ZERO. But they were receptive in considering an increase in the max size. When looking at the other restrictions that could limit the size of your building (side yard, rear yard, distance between buildings on your property) are likely not to change, but if you need those to be smaller, consider asking for that too ... but don't be surprised these measurement are not on the table.
Hope my thought process helps!