Four inches for a garage floor? A sidewalk maybe. I would not have anything less than 5 inches of compacted Quarry Process, #4 rebar, or at least No. 10 reinforcing wire, and 5-1/5" of 3400PSI Concrete for a garage floor.( 2 x 6 Forms)
As far as a spec goes the others are right. Asking for proposals from contractors without a proper specification is asking for trouble, because things might get left out in order to be low bidder.
In many cases the best way to do this type of thing is to negotiate with a contractor who has gotten good references, and listen to what he has to say.
You say fully prepared. To me, fully prepared means cleaned out leveled, Quarry process in place and vibra-plated, properly formed level, with vapor barrier in place.
What does it mean to you?
" A lot of men build things, and a lot of things fall down "
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