@edyj
Box profile is okay so long as you roof when all works on the house are complete..i used the wrong gauge-30 as i was hard pressed for cash and my house still had some works remaining..when the fundis came back for facie boards and other works ,they stepped on the iron sheets thereby flattening the profile ridges,and when we later straightened the ridges,i noticed small holes had developed,and the gaps between the individual iron sheets had lengthened,thereby allowing water to drip onto the ceiling boards..if you can adjust your budget,i would suggest you go for a stronger gauge-e.g 26-28.
Every man is guilty of all the good he didn't do-
Voltaire