Willow Glen Design Pavers can be set in sand or set in concrete. For big driveways like this one setting it in base-rock and sand allows water to drain and is a much less expensive endeavor. For the garage you can set them on top of your existing concrete slab, however it will significantly change the inside level of the garage floor. Obviously the outside pavers would have to be placed level with the pavers on the inside sloping away from the garage to keep water from pooling.