Flat Roof Slab Waterproofing: A Case Study
Flat concrete roof slab waterproofing (ArmTec System) — installed as a complete SealPro system by BloemGuard.
A leaking flat roof slab is one of the most damaging problems a home can face. Water finds every crack, pools where the fall is wrong, and slowly works its way through the concrete into the ceilings and walls below. In this case study, a large flat slab had stopped shedding water the way it should, so the homeowner called in a SealPro-approved applicator to strip it back, correct the falls, and rebuild the waterproofing from the substrate up.
The problem
The existing slab had lost its fall in several areas, leaving flat spots where rainwater sat instead of draining away. Standing water is the enemy of any flat roof: it forces itself into hairline cracks, breaks down old coatings, and eventually reaches the reinforcing steel and the rooms beneath. The surface was weathered, stained, and porous, and the old system had reached the end of its life. Simply painting over it would have trapped moisture and failed within a season.
The solution
Working as an approved SealPro applicator, the team rebuilt the slab as a complete, monolithic waterproofing system rather than a quick patch:
- Screed to correct the falls. A new screed was laid across the slab to re-establish a consistent fall toward the outlets, eliminating the flat spots where water had been pooling.
- Prepare and prime. Once the screed had cured, the entire surface was cleaned and primed with Penetrar to seal the substrate and give the waterproofing a sound, dust-free surface to bond to.
- Detail the joints and upstands. Flex was worked into the critical joints, edges, and upstands with StretchSeal reinforcing to strengthen the areas most prone to movement and cracking.
- Reinforced membrane. HyperFlex was then applied across the full slab with ArmTec mesh embedded into it, creating a seamless, reinforced membrane with no weak seams.
- Final waterproof coat. The system was finished with HydroSeal HF, a flexible, UV-stable top coat that seals the whole slab against summer downpours and harsh sun.
The result
The finished slab is a smooth, seamless grey membrane that drains cleanly to its outlets and looks as good as it performs. Every joint is reinforced, every flat spot is gone, and the concrete below is fully protected against water ingress. The owner now has a flat roof they can trust through the rainy season, backed by a full workmanship guarantee.
Whether your flat slab is leaking, ponding, or simply overdue for renewal, a properly installed waterproofing system is the difference between years of protection and a recurring headache. BloemGuard is an approved SealPro applicator serving Langenhoven 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
