Can you install a shelter on the roof to prevent water leakage?

The canopy is too high for rain, and rain will float in. If it is windy, the wind on the roof will be stronger. Because the canopy area is large, it is easy to blow, and it will be more dangerous to blow it down. But if the canopy is too low, workers can't work, the construction is too difficult, and the cost is not low, and the maintenance cost is high. Any worse will leak rain, so it is not cost-effective to install a canopy on the roof.