edit: TS : there's no such thing as aluminum wiring - they all use copper wires. aluminum just doesn't make sense in electric conductivity

if you use CONCRETE tiles, you don't need the zinc sheet since it's thick enough and is waterproof

but if you use CLAY tiles, you're gonna need the zinc sheets since water may soak / seep into the house

i have never heard of BOMBA not approving those metal sheet layers yet. anyone can confirm?
anyway, additional info:

CONCRETE tile : cheap, easily available // easily stained, not beautiful (about RM 1 per piece)
CLAY tile: beautiful, the color is lasting and not so susceptible to fungus growth // bloody expensive (RM 2 (china made) to RM 15 (italian tiles) per piece)