[misfit41]

Dont worry about the test weight of the concrete,3500 lb test is more than sufficient for a garage floor,and if you ever want a car hoist,a wood floor will support that,it is so distributed that thickness is not a factor,,4 inches is plenty with a good back fill,make sure it is sawed properly,this is the life of concrete,if it is done right, and the joints filled with silicone you will have little to no cracking.but I agree with the have it done theory,,,Tim