Roofs should have a gentle slope guiding water to drains. If the surface is uneven and forms low pockets, water stands there long after the rain stops. Persistent puddles speed up wear on waterproofing layers and increase chances of leaks.
You can often spot this by looking for dirty water rings, patches of algae, or simply by visiting after rain. If water is still sitting in random spots, the slope might be wrong.
A well-sloped roof dries faster and stays healthier for longer.
