All the "house keeping" pads I've seen are approx. 3" to 3 1/2" thk. w/some #10 wire or #3 re-bar thrown in. To be honest I believe the thickness is set by the 2x4 framing, BUT this is used only for access by personnel and LIGHT vehicles (golf carts). IF heavy construction or maintenance vehicles is a consideration, the thickness must be increase appropriately. Good Luck! ...Mark
