The Membrane Is Failing From Underneath
This is the thing about Sea Point that most quotes miss entirely.
Reinforced concrete protects the steel inside it chemically. The cement alkalinity forms a passive layer on the reinforcement that stops it rusting. Break that protection and the steel corrodes, and corroding steel expands to several times its volume, cracking the concrete from within and pushing it off in flakes.
Near the sea, the thing that breaks the protection is chloride. Salt carried on the wind penetrates the concrete over years, reaches the reinforcement, and destroys the passive layer directly, even where the concrete is otherwise sound. This is chloride-induced corrosion, and Sea Point, sitting directly on the Atlantic with a dense stock of concrete-framed blocks built from the 1950s onward, is a textbook case.
The result on a roof is that the slab surface is delaminating. You can lay a flawless torch-on membrane on it, and within a few years the membrane lifts, not because the membrane failed but because what it was bonded to came away.
This is why blocks here get waterproofed repeatedly and keep leaking. Each contractor addresses the membrane. Nobody addresses the slab.
Parapets are worse than the roof field. They are exposed on both faces and on top, they take the full force of winter fronts, and they typically have thin cover to the reinforcement. On most Sea Point buildings we survey, the parapets are further gone than the deck.
Flat Communal Roofs and Who Is Responsible
Sea Point building stock is predominantly multi-storey blocks with flat concrete roofs, which creates a specific set of problems.
The roof is common property, so a leak into a top-floor flat is a body corporate matter rather than an owner matter, and the decision to spend runs through trustees and a budget. That process takes time, and meanwhile the water keeps coming in.
Flat roofs on older blocks have lost their falls. Decades of slab deflection, patched screeds and relocated outlets mean water sits rather than draining. Standing water on a chloride-affected slab accelerates everything.
Outlets and overflows. Many older blocks have too few outlets for the roof area and no overflow provision, so a blocked outlet during a winter front puts water over the upstands.
Plant, aerials, satellite dishes and later service runs all penetrate the membrane, usually fixed by whoever installed them with no waterproofing detail at all.
Balconies are a second front. Every balcony on the building is a small flat roof over somebody living space, with the same chloride exposure and the same spalling. Most inter-unit leaks in Sea Point blocks are balconies, not the roof.
Salt, Wind and the Promenade Front
The exposure gradient across Sea Point is real and it matters for specification.
Buildings on the Beach Road and Promenade frontage take direct salt spray and the full force of north-westerly winter fronts off the Atlantic. Buildings a few streets back, toward Main Road and the upper slopes, still sit in salt-laden air but without the direct spray loading.
Winter fronts arrive from the north-west at 50 to 65kph, driving salt water horizontally onto the seaward elevations. Exposure is therefore not even across a building. The seaward parapet, the seaward balconies and the north-west elevation deteriorate visibly faster than the sheltered sides of the same block.
The summer south-easter is dry and does not put water in, but it lifts poorly bonded membrane edges, abrades exposed surfaces with wind-carried particles, and works at anything already loose.
Everything metal corrodes faster here, including gutters, brackets, fixings, balustrade posts and handrail bases. Balustrade fixings penetrating a balcony surface are a frequent leak point and a frequent corrosion point at once.
What We Do Differently on a Sea Point Building
Survey the slab, not just the surface. Delaminated concrete sounds hollow when tapped, and it looks completely sound. Mapping it before quoting is the difference between a repair that lasts and one that repeats.
Quote concrete repair separately. Trustees need to see what is structural repair and what is waterproofing, because the two have different lifespans and different implications for the building reserve fund.
Survey the whole roof, not the leaking corner. Visible spalling is usually the leading edge of a larger affected area that has not flaked yet. Pricing only the visible damage means coming back.
Written reports with photographs, suitable for presenting at a trustees meeting.