Roof Slab & Box Gutter Waterproofing in Erasmuskloof, Pretoria

Location: Erasmuskloof, Pretoria
Service: Roof Slab Waterproofing & Box Gutter Repair

A flat concrete roof slab is only as good as its waterproofing membrane, and once that membrane starts to crack and lift, water finds its way in fast. That’s exactly what was happening on this family home in Erasmuskloof, where years of sun exposure had left the roof slab and box gutters in need of professional concrete slab waterproofing.

The problem with the existing roof

The existing waterproofing on the roof slab had delaminated and cracked in multiple places, with joints starting to separate under UV and thermal movement. Once a membrane loses its bond to the substrate like this, every crack becomes a potential entry point for water, and the damage tends to spread quickly across the surface.

The box gutters and flashing sections told a similar story. Water was leaking around the gutter joints and flashing details, and one of the roof outlets had become partially blocked, restricting water flow off the slab and adding extra hydrostatic pressure exactly where it wasn’t needed.

The Eco Seal solution

As an approved SealPro applicator, Eco Seal approached the project as a complete waterproofing renewal rather than a patch job, working through it in clearly staged steps:

1. Open and correct the outlet. The blocked roof outlet was cleared first, restoring proper waterflow off the slab before any coating work began.
2. Prep and prime the substrate. The full roof slab and box gutter areas were cleaned and primed to give the new system a sound base to bond to.
3. Reinforce the vulnerable joints. Cracks and delaminated joints were strengthened with a StretchSeal membrane, bridging movement points that would otherwise crack straight through a standard coating.
4. Waterproof the slab with the ArmTec system. The full roof slab was renewed and waterproofed using the ArmTec HyperFlex system, applied in coats to build a seamless, flexible membrane across the entire deck.
5. Seal the box gutters and flashings. The gutter and flashing sections were closed off and waterproofed separately using the StretchSeal system, with a fibre cement section added and sealed at the flashing detail to shed water cleanly.

The result

The roof slab now carries a continuous, fully bonded ArmTec membrane with no more delaminated patches or open joints, and the box gutters drain freely with the outlet restored and the flashings properly sealed. The finished surface gives this Erasmuskloof home a watertight roof deck that’s built to handle Pretoria’s summer storms and UV load — the same standard we bring to all our roof repairs and waterproofing.

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

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