In need of good expert advice.... Our new home has 34 year old zincalume roof. (late 80s). No leaks. After applying the gurney, the roof looks good and feels strong. I've been told that older zincalume sheets were made even more durable than modern ones, having a lifespan, if cared for, of up to 70 to 100 years! Is this true?

We are thinking of keeping the sheets and replacing the rusted ridge cap, screws, and to insulate with new blanket and batts. The roof has no gutters and in need of fascia upgrade. We'd like to repair wooden fascia & wrap in colorbond metal, add new colorbond gutters and aluminium mesh leaf guard. We are also going to add skylights, and solar array down the track. Is it crazy to add all this new stuff to 34 year old Zincalume roofing sheets?

It feels more sustainable and better budget wise to use the old sheets if they have 30 plus years left in 'em. But if not, we would just get new Zincalume roof sheets. (Does zincalume have the same thermo insulating properties as colorbond? But even so, we feel zincalume doesn't scratch as easily as colorbond and is more durable)

Please help :o)