Flat Roof Slab Waterproofing in Steyn City, Johannesburg

Location: Steyn City, Johannesburg
Service: Flat roof slab waterproofing with outlet repositioning

This double-storey home in the Steyn City estate had a large flat roof slab sitting directly above a bedroom and bathroom below. Two old drainage outlets on that slab were positioned awkwardly and had started to let water track back into the roof structure, leaving the homeowner with a slow leak that only showed up during heavy Highveld storms. Eco Seal was brought in for a full flat roof waterproofing renewal, correcting the drainage layout and re-waterproofing the entire slab from scratch.

The problem

From above, the roof looked deceptively fine — a smooth grey membrane with a tidy line of cabling running across it. Up close, it told a different story. The existing full-bore outlet had been let into the slab at a low point that collected standing water rather than shedding it, and years of ponding had worn through the surrounding waterproofing. Around the outlet itself, the membrane had cracked and lifted, exposing a dark, water-stained hole straight down into the substrate. Every rain event was pushing moisture past the old seal and into the bedroom and bathroom ceiling below.

The Eco Seal solution

As an approved SealPro applicator, Eco Seal worked through the following steps to solve the drainage problem permanently rather than just patching the symptom:

1. Close and rescreed the old outlet. The existing full-bore outlet was sealed off and the surrounding slab rescreeded to bring it back to a sound, level surface — removing the low point that had been collecting water.
2. Reposition drainage to the outer wall. Two new 80 mm outlets were installed on the outer wall, moving the discharge point to where it could shed water efficiently instead of pooling on the slab.
3. Prep and prime the full 35 m² substrate. The entire slab was cleaned, degreased and primed to give the new waterproofing system a clean, stable base to bond to.
4. Apply the ArmTec waterproofing system. A flat-slab ArmTec membrane was applied across the full area, reinforced at the new outlet points and roof edges where water movement is greatest.

The result

The slab now drains cleanly to the two new outer-wall outlets instead of pooling in the middle of the roof, and the ArmTec HyperFlex system gives the homeowner a durable, seamless waterproof layer with no more weak points around the drainage. The bedroom and bathroom below are protected from the leak that had been slowly working its way in, and the roof is now finished with a clean, uniform coating that will hold up through Johannesburg’s summer storm season — the same concrete slab waterproofing we install across Gauteng.

Contact Eco Seal for a free inspection and quote: 083 309 8164 · www.ecoseal.co.za

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