Seepage stopped at the slab, under the tiles, where the water gets in.
Bathroom waterproofing done where it works, on the slab and up the walls behind the tiles, with junctions, the floor trap and every pipe penetration detailed, then flood tested before anything covers it up.
- Free site inspection
- Written, itemised quote
- 1-year workmanship warranty
- Same-day callback
At a glance
What does bathroom waterproofing involve?
A membrane applied to the floor slab and up the walls, underneath the tiles. The work is in the detail: coved wall-floor junctions, collars around the trap and every pipe, walls taken to full shower height, then a flood test with the ceiling below watched before the screed and tiles go back on.
When this is the answer, and when it is not.
Sending you to the wrong service wastes your money and our time. This is how to tell.
This is likely right if
- Water is reaching the flat below, or the room on the other side of the shower wall is damp
- The bathroom is being renovated and the wet area should be rebuilt properly before tiles go down
- Tiles are coming off anyway, so the deck is open and this is the moment to treat it
- An older sunken bathroom where the fill has stayed wet and the finish keeps failing at the skirting
Something else comes first if
- The leak is on a pressure line, it drips whether or not the bathroom is used. A plumber has to trace and replace that joint first, because a membrane laid over it simply seals the leak in.
- The stain below sits under a common shaft, a riser or an external wall rather than under your wet area. That's the association's scope to open, and treating your bathroom won't stop it.
- The slab is cracked through, or reinforcement is exposed and corroding on the ceiling below. That needs a structural engineer's opinion before any coating is specified.
What the service includes.
Source diagnosis
We establish where the water is actually coming from before anything is opened: moisture readings on the far side of the wall, the pattern and position of the stain in the flat below, and an isolation check on the supply line to rule out a pressure leak.
Isolation and protection
Water shut off to the bathroom, sanitaryware protected or lifted out, the doorway screened against tile dust, and the route to the lift or staircase covered before any debris starts moving.
Strip-out and deck repair
Tiles and old screed chipped off, saturated fill taken out of a sunken floor, honeycombed patches and cold joints in the slab cut back and made good, and the trap and pipe penetrations fully exposed.
Membrane and junction detail
A polymer-modified cementitious system applied in cross-directional coats, coved fillets formed at every wall-floor junction, collars around the trap and each pipe, and the shower wall taken to full height rather than a splash band.
Flood test and screed to fall
The trap plugged and the floor flooded, with the ceiling below inspected before anything covers the membrane. Then a screed laid to a true fall towards the drain, so water leaves the floor instead of standing on it.
Photographs and handover
The membrane and the tested floor photographed before tiling, since none of it is visible afterwards, along with the specification applied and a written warranty setting out its conditions.
Not included, or quoted separately
- Plumbing work, concealed supply lines, traps, valves and fittings. That's a plumber's scope, and it is finished before we seal anything.
- Tile supply, and matching a range that's no longer manufactured. At inspection we mark the area that has to be lifted, so you know which tiles are at risk. The exact count is only settled once the floor is open, because tiles rarely come off a bonded screed whole.
- New sanitaryware, mixers, shower fittings, exhaust fans, false ceiling panels and the electrical behind them.
- Repair and repainting of the ceiling and walls in the flat below. That's done once the source is fixed and the slab has dried out, and quoted separately.
- Structural repair to the slab or beam, and any work needing a structural engineer's opinion.
The sequence.
Inspection and diagnosis
We look at your bathroom, at the ceiling below where there's access, and at any adjoining wall showing damp. The aim is to name the source, not to start chipping and hope.
Scope and sequence agreed
What comes off, whether a plumber is needed first, how far up the walls the system goes, and what's reinstated by us. The quotation is written against that, with the detail items counted rather than absorbed into a floor area.
Isolate, protect and strip out
Water shut off, fittings removed or covered, dust screening at the door, then tiles, screed and any wet fill taken out and carried down through the route your building allows.
Prepare the deck
The slab cleaned back to sound concrete, defects repaired, corners coved, and penetrations packed and sealed. A membrane only performs as well as the surface it is bonded to.
Apply the system and test it
Coats applied to the specification with the stated overlap onto the walls, allowed to cure, then flood tested with the ceiling below checked before a single tile goes back.
Reinstate and hand over
Screed to fall, tiling where that's in our scope, sealant at the movement junctions, fittings refixed, and a walkthrough with the photographs and the warranty document.
What moves the price on this job.
We do not publish a rate, because it would change once someone measured your property. These are the variables that decide it.
- Whether the bathroom is sunken and how much old fill has to come out, usually the largest unknown until the floor is opened
- Whether existing tiles have to be removed, or the deck is already exposed as part of a renovation
- The number of penetrations, floor trap, WC outlet, geyser and mixer lines, because the junctions and collars carry the labour, not the open floor
- How high the walls are treated: full height on a shower wall against a splash band on the rest
- Whether a plumber has to replace a concealed line before we seal, and how much of the wall or floor has to be opened to reach it
- Access and building rules, the floor you are on, lift use for debris, and the working hours your association permits
Bathroom Waterproofing — your questions.
Can you waterproof over my existing tiles?
Surface products exist, but they're a coating on a finish, not a membrane under it. If water is already tracking to the slab or showing in the flat below, the tiles have to come off, sealing the top of a floor that leaks at the trap changes nothing. Where the tiles are sound and the problem is open grout or a failed junction, re-pointing and sealing is worth trying first, and we'll say so.
The ceiling in the flat below is stained. Is it definitely my bathroom?
Often, but not always. It can be a common shaft, a neighbour's line, or a supply pipe in the slab. We check whether the stain stays wet when the bathroom is unused, take moisture readings, and isolate the supply to see whether it dries. Establishing the source first avoids opening the wrong floor and paying for it twice.
How long will the bathroom be out of use?
It depends on the scope, and we set out the sequence at inspection so you can plan around it. What we won't do is shorten it by tiling over a screed that's still wet, moisture sealed under tiles has nowhere to go and reappears at the skirting or on the ceiling below. If the home has only one bathroom, we plan the strip-out around that.
Will you test the waterproofing before tiling?
Yes. The trap is plugged, the floor is flooded and held, and the ceiling below is inspected before the screed goes down. We photograph the membrane and the test as well, because once tiles are laid nobody can see what was done underneath. If the level drops or anything shows on the ceiling below, we open the detail that failed and treat it again before the screed goes down.
Do you've to break the bedroom wall behind the shower?
Usually not. The treatment is applied from the bathroom side and taken to full shower height, so water that gets through the grout meets the membrane and drains back to the trap instead of soaking into the shared wall. Where salts have already come through and the plaster on the far side is blown, that plaster has to be hacked back, redone and repainted before the finish will hold. That's a separate item in the quotation.
Let us look at your walls first.
Tell us about the property and we will set up a free colour and wall inspection. You get a written, itemised quotation afterwards, with no obligation to go ahead.
- We call you back the same day to get a picture of the property and the surfaces.
- We agree a time and come out for the free inspection.
- You get the written scope and itemised quotation.
- Nothing starts until you approve it.