Ordinary rain falls down. Storm rain goes sideways and upward, and it attacks details that have never leaked before.
Every year we get calls in September from people whose roofs had never leaked once. The roof was fine in April. It was fine through months of ordinary rain. Then a storm came through and water came in.
The reason is simple and it catches people out constantly: ordinary rain falls straight down, and storm rain does not. Wind-driven rain travels horizontally and even upward, and it gets into laps, flashings and terminations that gravity-driven water would never reach.
The details that fail first
Roof penetrations are the most common failure point we find — pipes, vents, conduit and especially HVAC curbs. These get sealed at installation and then never touched again, and the sealant has usually been baking in Gulf Coast sun for years by the time a storm tests it.
Flashings and wall terminations are next. Anywhere the roof meets a vertical surface is a joint, and wind pressure during a storm can drive water directly up under a termination that has loosened even slightly.
Then there is drainage. A roof that drains adequately in normal rain can be completely overwhelmed by storm volume. Blocked scuppers, undersized drains and low spots turn into standing water fast, and standing water plus wind pressure finds every weakness at once.
What to do before the season
Get the roof inspected while the weather is still calm. That means walking it properly and photographing the condition of every penetration, flashing, termination and drain — not glancing at it from the ground.
Clear the drainage. Scuppers and drains full of debris are the cheapest problem on this list to fix and among the most damaging to ignore.
Then address the details that the inspection turned up. A full waterproofing system reinforces every one of them with fabric and membrane so there is no continuous path for water to travel, regardless of which direction it is being driven.
Why it is cheaper before than after
Waterproofing a roof is a planned, scheduled job at a known price. Repairing a roof plus saturated insulation plus ceilings plus flooring plus whatever was underneath is not.
It also gets much harder to book work immediately after a storm, when every roofer on the coast is booked solid and materials are in short supply. The work is easier, faster and cheaper when it is done on your schedule rather than the weather's.