Aluminum roofing as an alternative to waterproofing

During the monsoon, if there is a lot of rain, and the roof is flat, there is a possibility that water will accumulate on the roof , slowly dripping or leaking in the house.
One way to stop the leakage is by waterproofing the roof of the house. However this can be expensive, and the water proofing is not very permanent, so it has to be repeated every three or four years, which can be expensive.
One alternative is to install aluminum roofing, which is lightweight and durable . The suppliers are claiming that the roofing will last a lifetime. They also claim that the roofing has good resale value.