Roof Slab Waterproofing: A Flat Roof Case Study
Concrete roof slab maintenance and waterproofing (ArmTec system) — installed as a complete SealPro system by BloemGuard.
A flat concrete roof slab is only as good as the membrane protecting it. On this project, that membrane had reached the end of its life. The old coating had gone brittle and discoloured, water was ponding around the outlets, and moisture was starting to work its way into the structure below. The owner brought in a SealPro-approved team to strip the failing system back and rebuild the waterproofing properly.
The problem
Years of sun and weather had taken their toll on the existing waterproofing. The coating had delaminated and cracked across the slab, lifting away from the substrate in sheets that could be peeled off by hand. Where the old membrane had let go, water had nowhere to go but down into the concrete.
The drainage made things worse. The roof outlets sat too high and had silted up, so rainwater puddled in front of them instead of draining away. Standing water is the enemy of any flat roof, and here it was pooling exactly where the waterproofing had already failed. Left alone, this combination leads to internal damp, blistering and long-term damage to the slab itself.
The solution
As an approved SealPro applicator, the team installed the ArmTec waterproofing system, a reinforced build designed for flat concrete slabs that flex and move with temperature.
- Strip and prepare. The old delaminated coating was removed and the slab was cleaned back to a sound, stable surface, then primed with Penetrar to lock in the substrate.
- Correct the drainage. The blocked outlets were opened up and reset so water flows to the drains instead of ponding on the slab.
- Reinforce the weak points. Cracks, joints and the roof flashings were strengthened with Flex and StretchSeal membrane, sealing the areas most likely to move and split again.
- Build the reinforced membrane. HyperFlex was applied and embedded with ArmTec mesh across the slab, creating a tough, flexible layer that bridges hairline movement.
- Seal and finish. The whole roof was topcoated with HydroSeal HF, leaving a seamless, UV-stable grey membrane that sheds water and stands up to the sun.
The result
The slab now carries a clean, continuous waterproof membrane from parapet to parapet, with the outlets draining as they should. No more peeling coating, no more standing water, and no more moisture finding its way into the structure. The finished surface is neat, hard-wearing and built to give the owner many more seasons of reliable protection.
If your flat roof slab is showing the same warning signs — ponding water, brittle or peeling coating, damp patches inside — it's worth having it inspected before the next rainy season. BloemGuard is an approved SealPro applicator serving Fichardt Park and the greater Bloemfontein area.
Contact BloemGuard for a free inspection and quote: 072 933 0162 · bloemguard.co.za
The work, step by step
