Yes, Swisstrax tiles can be installed directly over cracks with no height differential. The only time a red flag comes up is if there is a crack that can be about ¾” in height differential and depending on where the crack falls in accordance where the vehicle is being driven. Many companies such as Ford, GM, Barrett Jackson and many others use our floors in parking lots during events with vehicles driving over or parked on them. Haven’t seen a garage floor as bad as a parking lot floor yet!