I have a 1 1/2 car garage that was built in the 1940's (original with house). The slab is level but our yard slopes so that the concrete slab goes from 4" to around 9-10" thick. There is a centerline crack down the middle of it that looks to be all the way through (cracked all the way down through the thickest end. We had a wind storm a few weeks back that racked the garage pretty bad and we would like to replace it since it's so old. Building dept says we must replace the slab because of the crack or have an architect put their stamp of approval on it before they would give us a permit. But before I go to all this trouble, how much would it be to replace this concrete slab and driveway (30'x10'). Is there a calculation I can do for this? I guess I'm trying to get a guesstimate so I can figure out how much money to save. FYI I know absolutely nothing about concrete. Also, are there any ways to fix such a problem that would meet most building codes? And if so, what and usually how much?