07 / WATERPROOFING
Bathroom Waterproofing Malvern
Membrane work is the one stage nobody sees and the one that costs the most to redo. This page sets out the sequence we follow in Malvern wet areas — substrate, primer, bond breakers, detailing, fillets, coats, cure, then inspection before a single tile goes on.
The stage that decides the next twenty years
Waterproofing is a system, not a coat of paint. It has to bond to the substrate below it, move where the building moves, and stay continuous through every corner, waste, tap penetration and hob. Most wet-area failures we are called to look at are not membrane product failures — they are detailing failures at a junction, or tiling that started before the membrane had cured.
We carry out waterproofing as an embedded stage inside a full bathroom renovation and as a standalone scope where a shower is being rebuilt but the rest of the room stays. Either way it sits between rough-in and tiling in our twelve-stage process, and nothing after it starts until the membrane stage is signed off internally.
SELECTION LEDGER — MEMBRANE SEQUENCE
Eight steps, in order, every time
01 / Substrate preparation
Sheeting checked for fixing centres and movement, screw heads set, dust and debris removed, floor falls confirmed to the waste before anything is primed.
02 / Priming
Primer matched to the substrate — fibre cement sheet, screed and concrete slab all behave differently, and a primer chosen for one will under-perform on another.
03 / Bond breakers
Installed at wall-to-floor junctions and movement joints so the membrane can stretch across a moving joint instead of tearing along it.
04 / Corner and penetration detailing
Internal corners, floor wastes, tap and mixer penetrations, shower rail fixings and niche returns are reinforced individually before the field coats go on.
05 / Angle fillets
A consistent fillet run at the floor-to-wall junction so the membrane turns the corner on a curve rather than folding into a hard 90-degree crease.
06 / Membrane coats
Coats applied in alternating directions so thin spots in the first pass are covered by the second, with particular attention to hobs, upstands and the waste surround.
07 / Cure time
The membrane is left to cure to the manufacturer’s stated timing for the conditions on site. Nobody works in the room and no screed or tile bed is laid into a soft membrane.
08 / Inspection before tiling
A walk of every junction, penetration and corner, photographed while it is still visible. Only then does tiling begin.
Where the membrane goes
Coverage changes across the room. These are the three areas that decide whether a wet area holds.
ZONE A
Shower floors and wastes
The full shower floor is treated as the wettest point in the house. Falls are set toward the waste before membrane, the waste flange is detailed into the system, and the membrane turns up the surrounding walls rather than stopping at the tile line.
ZONE B
Hobs and hobless recesses
A hob is waterproofed over the top and down both faces as one continuous run. A hobless or stepped-down recess relies on the floor being set lower during framing — that decision is made at design stage, not at membrane stage. See walk-in showers.
ZONE C
Wall heights, in and out of the shower
Inside the shower enclosure the walls are membraned high. Outside it, the treatment steps down — a protected junction strip at the floor perimeter, with extra coverage behind the bath, under the vanity and around any laundry tub in a combined room.
Strip-out reference: workers remove material from an interior. Illustrative stock photography, not a completed local project.
Timber floors and older Malvern homes
Plenty of wet areas around Malvern, Armadale and Malvern East sit on bearers and joists rather than slab. Timber moves, and a membrane is only as stable as the floor under it. Before priming we look at joist spacing and deflection, the condition and fixing of the existing sheeting, whether the floor needs re-sheeting or packing to get a true fall, and how the wet area meets the adjoining hallway or bedroom.
Signs an existing membrane has failed
Drummy or hollow-sounding tiles in the shower floor. Skirting or architrave swelling on the other side of the shower wall. A stain appearing in the next room or on a ceiling below. Grout that stays dark long after the shower is dry, or silicone that blackens again within weeks of being replaced. A musty smell in a room that has no obvious water in it. Any of these usually mean water is getting past the tiles and finding somewhere to sit — which is a shower rebuild conversation, not a re-grout.
What is handed over at completion
At the end of the membrane stage you receive a written record of the wet-area work: the membrane system and primer used, the areas and heights covered, the number of coats and the dates they were applied, along with the photographs taken of every corner, penetration and fillet before tiling covered them.
That record is a description of the work carried out. It is worth keeping with your other renovation paperwork — it tells the next trade, or the next owner, exactly what is under the tiles.
Project references
The projects index explains what a documented project entry contains — suburb, bathroom type, brief, design response, materials and the work completed — and lists the entries that are actually available to view.
If you want to see how waterproofing sits inside a wider scope, the renovation process page walks through all twelve stages from consultation to handover.
QUESTIONS
Waterproofing questions we are asked most
Can waterproofing be done on its own?
Yes, where the scope makes sense — usually a shower being stripped and rebuilt inside a room that is otherwise staying. It cannot be applied over existing tiles, so a standalone job still involves removing the tiling and substrate back to a sound base.
How long does the membrane stage take?
The application itself is short. The cure between coats and before tiling is what sets the duration, and it varies with temperature and humidity in the room. It is planned into the schedule rather than compressed — see the stage timeline.
Do the tiles have to come off to fix a leaking shower?
If the membrane below has failed, then yes — the membrane is under the tile bed and cannot be reached any other way. Re-grouting and re-siliconing can help where the problem is genuinely surface-level, but they will not repair a torn or missing membrane.
How high are the walls waterproofed?
Inside the shower enclosure the membrane runs well up the wall; outside it, the coverage steps down to junctions and splash zones. The exact heights are set for your room and substrate and confirmed before we prime.
Can waterproofing go over a timber floor?
It can, once the floor is stable and correctly sheeted. In older homes that often means additional sheeting, re-fixing, or building up a fall before the membrane system starts. More background in the waterproofing guide.
Tell us what the shower is doing
Send through what you are seeing — drummy tiles, damp skirting, a stain in the next room, or a bathroom you are planning from scratch. Our enquiry form asks for your name, email, phone, suburb, renovation type, budget range, timeframe and project details so we can respond with something useful rather than a generic reply.
RELATED SPECIFICATIONS
Bathroom Tiling Malvern — the stage that follows the membrane
Shower Renovations Malvern — leaks, rebuilds and upgrades
Walk-In Showers — hobless and frameless builds
Full Bathroom Renovations — strip-out to handover
Waterproofing Guide — sequence, detail and failure
All services · Service areas · FAQ
Shower Renovations Malvern — leaks, rebuilds and upgrades
Walk-In Showers — hobless and frameless builds
Full Bathroom Renovations — strip-out to handover
Waterproofing Guide — sequence, detail and failure
All services · Service areas · FAQ