Waterproofing A Roof That Carries Water

How do you waterproof a roof deck that carries a swimming pool?

Waterproofing a structural deck that carries a pool means the membrane has to work under a vessel full of water, above finished rooms, for the life of the building. At Leslie House the deck was waterproofed beneath the stainless vessel before the pool was set. The scope was self-performed by the general contractor, who holds Florida roofing licence CCC1332624.

Why the deck is the hard part

A pool at grade sits in the ground. A pool on a roof has to be carried by the building — and the deck beneath it is doing three things at once: bearing the weight of the vessel full of water, staying rigid enough that nothing below it cracks, and staying watertight for the life of the building. Those three demands do not pull in the same direction. A deck that deflects under load stresses the membrane. A membrane applied to a deck that was not designed for the vessel is the wrong sequence. The structure and the waterproofing have to be designed together, starting at the footings.

The decision to self-perform

Roof waterproofing in Florida requires a licensed roofing contractor. On a deck that doubles as the floor of a swimming pool the membrane is not a finish — it is a structural defence, and there is no practical way to revisit it once the vessel is set. Academia Development Corp holds Florida roofing licence CCC1332624 and self-performed the waterproofing scope. That decision means the same party who carried the structure also held the membrane above it — one signature where the two assemblies meet.

Every roof opening is a penetration

The waterproofed assembly does not stop at the pool surround. Every opening cut through the roof — for skylights, for the glazed lantern, for mechanical penetrations — is a hole through the same membrane. Each one is framed with added steel and detailed at its perimeter before any glazing or equipment goes in. The detailing at those perimeters is where a waterproofed roof assembly is won or lost, and on a roof in the High-Velocity Hurricane Zone the standards for that work are the Miami-Dade envelope requirements.

The vessel and the deck

The stainless steel vessel was fabricated off-site by Diamond Spas, with Watershape Consulting as the pool engineer of record. It arrived on a crane in a single pick and was set into the elliptical basin cut into the roof deck. The waterproofing was in place before the vessel landed. The sequence matters: once a prefabricated vessel is set and the plumbing connected, the membrane under it is no longer accessible. Getting it right before the pick is the only available approach.