Can't you use screws? Time an issue??No screws for some reason,possibly could work themselves lose after a few days of ground movement,God knows.the company has set procedures and 6 inch nails it is.Time not the issue its the fact that trying to hammer in nails with all sorts of cables and water mains in the way makes for a right laugh while tryin to balance 3m lengths of wood
So basically some fanny in a suit has said a screw will work its way out before a nail. Architects eh..???