There are other factors that you didn't mention that can impact the cost. Will the space be insulated and heated? Does any siding/brick, etc. have to be removed from the existing house to attach the new garage? Will you be using regular shingles on the roof or will they be architectural shingles? That's just a few of the things that you need to decide.

In addition to that construction costs are vastly different in different geographical areas and permit costs also vary. Some areas require architectural stamped drawings and some you can sketch it on a napkin. What I could build the same garage for in Kentucky might be vastly different from what it would cost you.

Start with what you need and what you want in the garage. Then check with the local jurisdiction for requirements to obtain a permit. If detailed plans are required have those prepared and then get quotes from at least 2 or 3 contractors. Talk to your new neighbors and find out who they have used before and their satisfaction level.

Good luck and enjoy your new home.

don't not add a swing door, either front or rear or side, they really are worth adding. every time i wanted to get a clippers or something out of the garage, i had to raise an overhead door.

When we were thinking about adding another 1.5 car garage onto our existing 2 car, our builder told us he could build a standalone 2 car garage cheaper than a 1.5 attached. This was due to the work tying the new into the old rooflines etc. And it did end up being less expensive and more functional. Its just a thought but maybe you could get a bigger garage for the money if you offset a standalone one behind your house?

1.5 is good. You have room for a car and bicycles, toys, camping equipment, or a workshop. I'd put a smaller access door for the storage garage, and a 1-car door for the car area.