Concrete slab & balcony waterproofing
Flat concrete slabs and balconies protected against thermal cracking and ponding with the reinforced ArmTec HyperFlex system.
Flat concrete roofs and balconies are the hardest-working waterproofing surfaces in Bloemfontein. Concrete expands in the afternoon heat and contracts overnight; on a highveld winter day the surface can swing through more than thirty degrees. Rigid coatings cannot survive that cycle — they crack, water finds the crack, and the leak appears somewhere else entirely inside the house, following the slab's reinforcing steel.
Ponding makes it worse. Most older slabs in the established suburbs have settled low spots where stormwater stands for days after rain. Standing water degrades coatings faster and finds every weakness.
The answer is a reinforced flexible system. ArmTec HyperFlex embeds fibreglass mesh in an elastic membrane so the waterproofing bridges existing cracks and absorbs new movement instead of splitting over it.
The SealPro systems we use
- ArmTec HyperFlex system — the fully bonded, seamless reinforced system: the correct primer (Penetrar on porous concrete, UltraBond WP on sealed surfaces), ArmTec coated fibreglass mesh shaped over the full surface, one coat of HyperFlex pressed through the mesh to lock it to the substrate, then two coats of HydroSeal HF liquid rubber as the final seamless waterproof membrane.
- Penetrar / UltraBond WP primers — matched to the slab's condition so the membrane bonds into the concrete, not just onto its dust.
- HydroSeal HF liquid rubber finish — two coats of seamless liquid rubber membrane, UV-stable and fully bonded, complete the assembly at a dry film thickness of 1–1.5 mm.
- Tiled balcony option — sound tiled balconies are waterproofed directly over the tiles: Posi Screed in open joints, UltraBond WP over the tile face, then the full reinforced system — no stripping needed.
How the job runs
- Inspect & quote — we identify cracks, ponding areas, failed screeds and every outlet and upstand detail.
- Prep & repair — cleaning, crack routing and repair, ponding correction where practical, primer application.
- Seal & reinforce — membrane coats with ArmTec mesh over the full surface, with extra detail at edges, parapets and outlets.
- Topcoat & sign-off — UV-stable topcoat, water-test where appropriate, walkthrough and documentation.
Common questions
My slab leaks but the damp shows up in a different room. Is that normal?
Very. Water travels along the slab's reinforcing and cracks before it drips, so the stain is often metres from the entry point. That is exactly why patching where the drip shows fails — the whole slab surface needs to be sealed as one system.
Can you fix ponding water on my flat roof?
We correct ponding with screed repairs where practical and detail the membrane for standing water where re-screeding is not economical. The inspection tells you which applies.
Do balconies need a different system to roofs?
Balconies add foot traffic and tiled finishes into the equation. The membrane system is similar, but details at door thresholds, balustrades and drainage are where balconies fail — we treat those as first-class parts of the job.