Flat roofs are everywhere in Pretoria East: the modern boxes in Silver Lakes and Olympus, the garages and stoeps added to older Garsfontein homes, the slabs over townhouse units in Equestria and Menlyn. They all share one weakness. Water doesn't run off a flat roof, it sits there. Give it a hot Highveld summer, a hailstorm and a blocked outlet and it finds every crack in the slab.
We do torch on waterproofing Pretoria homeowners and body corporates rely on, plus liquid membrane systems where torch-on isn't the right call. Every job starts with an inspection, because the fix depends on what's actually under the old membrane.
What is torch on waterproofing, and when is it the right choice?
Torch on waterproofing is a bitumen membrane, usually 3–4 mm thick, that is melted onto a primed concrete surface with a gas torch. The seams are overlapped and fused, so the roof ends up with one continuous waterproof skin. Its strengths are durability and tolerance for ponding water, which is why it remains the default for flat roof waterproofing on concrete slabs.
It isn't always the answer. Torch-on needs a sound, dry, primed surface and a trained applicator, because a gas torch on a roof is not a DIY job. On small, detailed areas, parapets with lots of corners, or roofs with foot traffic, a reinforced liquid membrane (acrylic or polyurethane) can be the better fit. We'll tell you which one your roof needs and why.
Torch-on vs liquid membrane: a quick comparison
| System | Best for | Typical lifespan | Typical price per m² |
|---|---|---|---|
| Torch-on membrane (3–4 mm) | Flat concrete roofs, slabs with ponding water | 10–15 years | R250–R450 |
| Liquid membrane (reinforced acrylic) | Detail-heavy roofs, parapets, repairs over sound coatings | 5–10 years | R150–R350 |
| Polyurethane coating | Balconies, roofs with foot traffic, long service life | 15–20 years | R350–R500 |
Typical 2026 South African ranges from published cost guides; your written quote is based on your roof. See our full waterproofing prices Pretoria guide.
How we waterproof a flat concrete roof
- Inspect and measure. We check outlets, falls, cracks, old layers and where the water is actually getting in, then measure the area.
- Prepare the surface. Lifted or blistered membrane is cut out, cracks are filled, and the slab is swept clean. If water ponds, we look at the falls and outlets before anything else.
- Prime. A bitumen primer helps the new membrane bond to the concrete.
- Lay and fuse the membrane. Rolls are torched down with overlapped, sealed seams and detailed up parapets and around outlets and penetrations.
- Protect it. A reflective (silver or aluminium) coat helps against Pretoria's UV, which is one of the biggest causes of early membrane failure.
Concrete waterproofing Pretoria homes actually need
Most "the roof is leaking" calls on flat roofs trace back to a few things: blocked or undersized outlets, cracks where the slab meets a parapet wall, old torch-on that has lifted at the seams, and coatings that have chalked away in the sun. Concrete waterproofing Pretoria work done properly deals with the cause, not only the stain on your ceiling. That's also why we often combine this service with parapet and slab waterproofing and, for active drips, a roof leak repair first.
Field tip
If water stands on your flat roof more than 48 hours after rain, the membrane is working too hard. Fixing the falls or adding an outlet often doubles the life of a new membrane.
Torch-on over old torch-on?
Sometimes. If the existing layer is well bonded and only failing at the seams, a new layer can go over it after repairs. If it's blistered, cracked through or holding water underneath, it has to come off. Stripping costs more up front but avoids trapping moisture that will lift the new membrane within a season or two.
Areas we cover for this service
We do flat roof & torch-on waterproofing across Pretoria East: