What to expect
| Typical duration | Terrace 1–3 weeks including falls · wet room 3–5 days |
|---|---|
| Cost band | Figures live in the cost index |
| Permit required | Not usually |
| Seasonal constraint | Application needs dry, moderate conditions — not August surface temperatures |
The build-up, in the order that matters
The specific product matters far less than the sequence. Almost every failure we are called to is a sequence failure, not a product failure.
- Falls formed in the screed. Not in the adhesive bed, not by lipping tiles. A minimum meaningful fall to the outlet, and it is checked with water rather than a spirit level, because water finds the flat spot a level does not.
- Primer, then membrane, continuous. Every upstand, every penetration and every internal corner detailed before the main areas, not after.
- Upstand height at abutments taken well above the finished level, dressed properly, and protected by a flashing rather than relying on a sealant bead.
- A separating layer between membrane and finish, so movement in the tile does not tear the membrane.
- Outlet at the true low point, plus an overflow above it. An overflow is not an optional extra — it is how you find out a gutter is blocked before the water finds out for you.
- Movement joints in the finish carried through to the substrate, at perimeters and at any change of direction.
Why the island is harder on this than most places
- Thermal cycling. A dark terrace surface in July can be extremely hot by afternoon and cool sharply overnight. That daily expansion and contraction is relentless and it is what tears badly detailed systems apart.
- Wind-driven rain. Winter storms drive water horizontally and upwards. A detail that works against vertical rain fails against rain arriving at forty-five degrees, which is why upstand height matters more here.
- Occupied space below. Because so many buildings here are terraced into a slope, a terrace is frequently someone's ceiling. A leak is not an inconvenience, it is damage.
- Salt. Salt crystallisation in a porous finish accelerates surface breakdown and opens paths for water.
Cave houses are a different problem entirely
A yposkafo does not need waterproofing in the conventional sense — it needs the opposite. Sealing the inside of a cave traps the moisture that arrives through the rock and forces it to condense behind the finish.
Cave moisture control is about surface-water routing above the vault, vapour-open internal finishes and designed ventilation. It is covered properly on cave house damp proofing, and it is worth reading before anyone applies a membrane to the inside of a cave wall.
What this trade covers
- Terraces and flat roofs, including forming falls and rebuilding the outlet arrangement.
- Wet rooms and bathrooms, coordinated with tiling so the sequence is correct.
- Below-ground and retaining structures, including tanking where it is genuinely appropriate.
- Balcony and upstand detailing on caldera-facing elevations.
- Leak investigation — establishing where water is actually entering rather than where it appears.
- Remedial work on failed systems, including the strip-out that honest remediation requires.
- Cistern waterproofing, which is a different specification again. See water cisterns.
Questions people actually ask
Can you apply a coating over my existing terrace to stop the leak?
Sometimes, and only after finding out why it leaks. Coating over a failed system with the water still tracking underneath moves the leak rather than stopping it, and then you have two failed systems to remove.
How do I know where the leak is coming from?
Rarely from directly above the wet patch. Water tracks along falls, through voids and along service runs. Investigation before repair is not a delaying tactic — repairing the wrong place is the most common waterproofing expenditure on this island.
How long should a terrace waterproofing system last?
That depends entirely on the detailing and the exposure, which is why we are wary of quoting a figure. What can be said honestly is that failures here are usually detail failures within a few years, not membrane failures at end of life.
Can I tile directly onto the membrane?
Not without a separating layer. Bonding a rigid finish directly to a membrane means every bit of movement in the tile is transferred straight into the waterproofing.
When is the best time to do this work?
Spring or autumn. Applying a liquid system to a surface at peak August temperature, or in a winter storm window, both produce poor results — and the second one is how remedial jobs get done badly, because they are urgent.