Case Study: Double-Layer Torch-On Flat Roof Waterproofing with Protective Screed Overlay

Location: Durban CBD, KwaZulu-Natal

Project: Flat Roof Waterproofing Over Parking Deck

Issue:Unprotected and aging roof surface above a parking deck required a durable waterproofing solution to prevent water ingress and allow for structural loading from vehicle traffic above.

Overview:

This project involved the installation of a heavy-duty waterproofing system on a flat roof located directly above a parking deck in the Durban CBD. Due to the high risk of water penetration and the structural demands of vehicular traffic, the client required a robust waterproofing solution with added load-bearing protection.

Problem Diagnosis:

The existing surface was exposed and vulnerable to moisture ingress, especially during heavy rains. The roof served as a load-bearing slab for vehicles, so the waterproofing system not only had to be watertight but also capable of withstanding pressure from above. Without intervention, water ingress would compromise both the slab and the parking deck below, leading to structural damage and safety hazards.

Solution Implementation:

Target Roofing & Waterproofing deployed a double-layer torch-on waterproofing system, a proven solution for flat roofs requiring long-term water protection. The scope included:

  • Thorough surface preparation and screeding for evenness and adhesion.

  • Application of a dual-layer bitumen torch-on membrane system to ensure complete waterproofing redundancy.

  • Protection of the membrane with a concrete screed overlay, enabling the surface to carry the load of parked vehicles safely and efficiently.

While asphalt was considered as an alternative top layer, the client opted for a concrete screed due to its affordability, durability, and better compatibility with the site’s requirements.

    Outcome:

    The project was successfully completed with a clean, uniform finish and a highly resilient waterproofing system. The concrete screed now protects the membrane from physical damage and environmental wear, while providing the necessary structural support for vehicle loads. The parking deck below remains completely dry, and the client has peace of mind knowing the system is built for long-term performance.