Very interesting high skill installation. For domestic use colours seems impractical 3 ton volume unlikely. 70mm rockwool tween rafters 50mm sarking dual purpose board over =120mm insulation total. Can VMZINC membrane go over direct & zinc roof covering finish fix direct into sarking? Zinc weight reduction factor+structural improvement of sarking board attractive. Height restriction problem + batten & ply bit high. If can't utilize this excellent material purpose made metal plaintile panels possible alternative but more expensive than tiles & short guarantee period. The offer of advice on domestic projects generous impressive! Proliferation of this material justifable less structural weight long life recycles & 50 year gurantee superb. Now what's the cost?