How to waterproof a terrace or roof (stop leaks for good)
A leaking terrace ruins the ceiling below. Here is how to prep, treat the cracks and corners, and coat a terrace with SUMO Terraceguard or Weatherguard for years of dry seasons.
ON THIS PAGE
Terraces take the full hit of sun, rain and thermal movement, so their waterproofing has to be both watertight and UV-stable. Most terrace leaks trace back to untreated cracks, weak corners, or a coating applied too thin.
This guide covers a durable exposed-terrace method with SUMO Terraceguard or Weatherguard: preparing the slab, treating cracks and the parapet corners, and building crossed coats that flex with the slab.
What you’ll need
Step by step
Clean and prepare the slab
Remove dust, moss, loose screed and old flaking coatings. The surface must be sound and clean — a coating is only as good as what it sticks to.
Cut out and fill cracks
Open up cracks, clean them, and fill with a repair mortar gauged with SUMO SBR Latex for a flexible, well-bonded repair. Cracks left untreated will telegraph straight through the coating.
Reinforce corners and the parapet junction
Bed reinforcing tape or fabric into the coating along the slab-to-parapet corners and around any drains or pipes. These junctions move the most and leak first.
Apply the first coat
Brush/roller a full first coat of SUMO Terraceguard or Weatherguard across the whole slab and up the parapet to the required height, working it in with no dry misses.
Apply the second coat crosswise
After the first coat has cured enough to over-coat, apply the second at right angles for complete, pinhole-free cover. The crossed coats give an unbroken, flexible film.
Cure and check ponding
Let the coating cure, then check after rain (or a hose test) for any ponding. Standing water shortens the life of any terrace coating, so improve falls where you can.
Care, tips & what to avoid
- !Coating over untreated cracksLive cracks reappear through the film. Cut out, fill and reinforce them first.
- !Skipping the parapet cornersThe slab-to-parapet junction is the classic leak point. Reinforce it.
- !One thin coatThin film means pinholes and early UV breakdown. Apply two crossed coats to spec.
- !Ignoring ponding waterStanding water shortens coating life. Improve falls to the drains.
