Podium & Car Park Deck Waterproofing

A podium deck is one of the most demanding waterproofing environments in construction. It is a roof, a floor, and a car park all at the same time — it has to carry vehicle loads, it has to resist the thermal movement of the structure, it has to drain water away, and it has to do all of this without a single point of failure. When a podium deck leaks, the water comes through into the spaces below — the car park, the retail units, the offices — and the damage is often extensive before it is even noticed.

The first thing we do is understand the structure of the deck. We need to know the falls, the drainage, the movement joints, the penetrations, and the condition of the existing waterproofing. We also need to know what is going to be on top of the deck — a wearing course, a screed, a tiled surface, or a planted area — because the waterproofing system has to be designed for the traffic and the loading that it will carry.

For podium decks we use traffic-rated membrane systems that are designed to carry the loads of vehicles and the movement of the structure. The membrane is applied to the prepared concrete, it is detailed at the drains, the upstands, and the movement joints, and it is protected by a screed or a wearing course that is designed to the traffic. The system is tested with a flood test before the wearing course is installed, so we know the deck is watertight before it is covered.

The movement joints are the most critical part of a podium deck. The deck moves with the temperature and the loading, and the joints have to accommodate that movement without breaking the waterproofing. We use movement joint systems that are designed for the specific movement of the deck, and we detail them so that the water is carried away from the joint, not into it.

The result is a podium deck that is waterproof, that carries the traffic, and that protects the spaces below. We document the system, we test the deck, and we stand behind the installation with a warranty. If the deck leaks, we will come back and find out why.