Roofing
Flat Roofs, Lanais and Pool Cages
Low-slope roofs fail differently from pitched ones. Here is what actually goes wrong.
Limited time offer 4 point home inspection or wind mitigation with any new roof See what is includedFlat and low-slope roofs over additions, carports and lanais fail differently from pitched ones, because a pitched roof sheds water and a flat one holds it. Ponding is the warning sign, most failures happen at the edges rather than the middle, and a lanai roof is really a joint between two structures.
Southwest Florida houses carry a lot of low-slope roof — over additions, carports and lanais — plus screened enclosures that are not really roofs at all. Knowing how they fail helps you spot trouble earlier.
A pitched roof sheds water; a flat one holds it
A steep roof can tolerate an imperfect detail because water leaves quickly. On a low slope, water sits, finds the smallest fault and stays there. So a flat roof depends almost entirely on its membrane and on how carefully it is finished at the edges.
Ponding is the warning sign
Water still standing well after the rain has stopped means drainage has failed — a blocked outlet, a sagging area, a slope that was never quite right. Standing water is both a symptom and a cause: it accelerates whatever is already wearing out under it.
Most failures are at the edges, not the middle
Where the low roof meets a wall, wraps a parapet, or ends at a drain is where the work is. The open field of a membrane rarely fails first. When you inspect one of these, look at the perimeter and the penetrations before the middle.
A lanai roof is a joint between two things
Lanais and carports are usually added onto the main structure, so their roof meets an existing wall. That junction is where the flashing and the counter-flashing live, and it is the most common leak point on the whole assembly — often showing up inside the house rather than out on the lanai.
A pool cage is not a roof
A screened enclosure keeps insects out. It is not weatherproof and is not meant to be. What matters on a cage is the structure and the fasteners: screws into the deck or beam, corroded fasteners near salt air, and panels that have been re-tensioned so many times the frame is working loose. Storm damage here is usually a fastener problem, not a screen problem.
Salt air attacks the parts you cannot see
Near the water it is the metal that goes first — fasteners, flashings, cage screws, drip edges. The visible surface can look perfectly sound while what is holding it down is corroding. That is why the fasteners matter as much as the covering in coastal locations.
LMS installs all of the low-slope systems described here, and we do take on pool cage repair and re-screening. So the lanai, the cage and the low-slope roof over them can be one job with one contractor, rather than three trades to chase.
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