Shower rebuilds and waterproofing
Leaking shower repairs and full shower rebuilds in Narre Warren 3805, with new waterproofing to AS 3740 and tiling. Honest advice on when a repair is worth it.
A leaking shower is the most common reason a Narre Warren household starts looking for a renovator. The membrane sits under the tiles and the screed, so once it fails nothing reaches it until the tiles come off. Surface work delays that. A rebuild from the substrate up ends it.
How to tell the membrane has gone
The pattern in the older houses here is consistent enough to be diagnostic. Silicone has pulled away where the shower base meets the wall. Grout is cracking in that same corner and along the bottom course. Out in the hall, on the far side of that wall, there is a damp patch on the carpet, or the skirting has swelled, or paint is bubbling at the bottom of the wall in the next room. Often the smell of damp carpet arrives before anything is visible.
Other signs worth acting on: tiles that sound hollow when tapped low on the shower wall, a base that flexes underfoot, a floor waste that drains slowly, efflorescence in the grout, and a ceiling stain in the room below an upstairs shower.
Australian shower membranes mostly reach the end of their working life between 10 and 15 years, and somewhere between 55 and 65 per cent of showers in this country leak. Those two figures set the expectation for anything over 15 years old: the membrane is at or past its life, and a clean looking shower is unproven rather than sound. The symptoms are covered further on signs your shower is leaking.
Why a re grout is not a repair
Grout is a cementitious filler between tiles. It is porous by design and it was never the thing keeping water out of the wall frame. The membrane behind and beneath the tiles does that. Re grouting a shower whose membrane has failed changes how the shower looks and stops nothing. The same goes for a silicone reseal, a clear surface sealer rolled over the tiles, and a grout colour seal.
One narrow case makes surface work honest. Where the shower is under about 10 years old, the tiles are sound, the base does not flex, no damp shows anywhere beyond the shower, and the only defect is perished silicone in a corner, replacing that silicone is reasonable maintenance. On a 40 to 50 year old bathroom in the Narre Warren brick veneer belt the case does not apply, and we will not quote it as though it does.
What a rebuild involves
- Assessment on site, taking in the wall and floor outside the shower and the ceiling below where the shower is upstairs.
- Written fixed price quote against a written scope, stating what happens if the frame or the floor turns out to be damaged.
- Sampling the wall sheeting where the house predates 1990, before anything is pulled off.
- Removal of the screen, tiles, screed, base and wall sheeting across the shower area.
- Inspection of the frame and floor structure once it is open. Rot in a bottom plate or a stud is repaired before anything goes back.
- New wet area wall sheeting, new floor substrate, and a screed that falls to the waste.
- Waterproofing to AS 3740, applied in the coats the product data sheet specifies, with the cure time it requires.
- Tiling, grout, screen install, silicone and handover.
Step 5 is why a rebuild cannot carry a fixed price for the hidden parts until the shower is open. The quote covers the known scope and states the rate for structural repair if it is found, so no surprise invoice turns up at the end.
The standard the work is built to
AS 3740, current edition 2021, governs waterproofing in domestic wet areas, and the National Construction Code calls it up. Victoria has been on NCC 2025 since 1 May 2026. A shower wall is waterproofed up to 1800 mm measured from the floor substrate, and that figure sits in the ABCB Housing Provisions rather than in the standard itself.
A membrane is a system, not a single tin: primer, bond breaker at the movement joints, reinforcing at internal corners and at the wall to floor junction, the right number of coats at the right wet film thickness, and a correct puddle flange detail at the waste. Miss any one and the result passes a look and fails in service. The coats are photographed and a flood test is done before tiling starts.
When the rebuild should become a full renovation
| Situation | Sensible scope |
|---|---|
| Shower failed, rest of the room is under 10 years old and sound | Rebuild the shower only |
| Shower failed, bathroom is 18 to 27 years old, layout still works | Same footprint strip and rebuild of the whole room |
| Shower failed, bathroom is 40 plus years old with asbestos sheeting | Full renovation, because the sheeting comes out anyway |
| Water has reached the frame, the floor or the room next door | Open it up first, then scope |
| Tiles are discontinued and cannot be matched | Full retile at minimum |
Those rows track the two housing eras in postcode 3805 almost exactly. In the newer estates south of the freeway the shower has failed while the room, the service runs and the window positions all remain fine, which is the textbook same footprint rebuild and the reason that suburb prices so predictably. The older single storey half gives a different answer: at 40 to 50 years the membrane has gone, the fibreglass base is finished, and the wall lining is coming out under controlled conditions regardless. Rebuilding one wall and leaving half century old tiles on the other three rarely makes sense once the room is already open. See Narre Warren for that stock and Narre Warren South for the newer half.
What we will not claim
We do not offer a lifetime or a ten year waterproofing warranty of our own. A promise like that is worth whatever the business behind it is worth, and plenty of the businesses that made it are no longer trading. What the job carries instead is the membrane manufacturer’s own product warranty, the statutory protection that attaches to Victorian domestic building work, and the certificates the licensed trades issue and lodge.
Rebuilding a shower between its existing walls rarely raises a permit question, though the value of the job can raise others. Both tests are set out under what the law requires, along with the certificates you should end up holding.
What it costs
Waterproofing supplied and applied runs $50 to $85 per m2, wall tiling $75 to $165 per m2, floor tiling $90 to $190 per m2, and a new screen $1,200 to $3,500. A shower rebuilt on its own is quoted from those components plus demolition, substrate and plumbing. Where the assessment says the whole room should go, the bands are $10,500 to $21,000 for a small or budget bathroom and $21,000 to $36,750 for a standard one, as set out on full bathroom renovations and in the cost guide. Attach photos of the shower corner and of the damp patch when you use the quote form.