Regrout, reseal or retile: what your shower tiles actually need
Mouldy silicone and dirty grout can be fixed for a fraction of a retile. Loose tiles, swollen skirting or stains in the next room mean water is behind the tiles, and only a new membrane fixes that. How to tell which one you have.
By Bathroom Renovation NZ
Key takeaways
- Regrouting and resealing fix surface problems: stained or crumbling grout and mouldy, peeling silicone, with the tiles still solid.
- Tile paint and resurfacing change the colour, not the waterproofing. They suit a dated wall, not a wet shower floor.
- Loose or hollow-sounding tiles, swelling at the skirting or door frame, or stains on the other side of the wall mean water has got behind the tiles. That needs a retile with a new membrane.
- Retiling an existing shower with the plumbing left where it is runs $1,800–4,000, and Superior Renovations states that excludes waterproofing.
- None of the three needs a building consent in an existing home; all of them still have to meet the Building Code.
If the tiles are solid and only the grout and silicone look bad, regrout and reseal: it is a day or two of work and a fraction of the cost of retiling. If tiles are loose or sound hollow, the skirting or door frame is swelling, or there are stains in the room next door, water is already behind the tiles and the membrane has failed. Regrouting over that hides it for a while. The fix is a retile, with the old membrane stripped and a new one laid and photographed before the tiles go back on.
How do you tell a grout problem from a membrane problem?
| What you see | What it usually means | Usual fix |
|---|---|---|
| Dark or stained grout, tiles solid | Surface dirt or mould in porous grout | Deep clean, or regrout and seal |
| Black, peeling silicone at corners and the tray | Silicone at the end of its life | Cut out and reseal |
| Cracked or missing grout in places | Movement, or grout past its life | Regrout; watch for the signs below |
| Tiles that sound hollow when tapped, or move | Adhesive has let go, often from water behind | Retile, with a new membrane |
| Swelling skirting, door frame or vanity base | Water escaping the shower into the framing | Retile, and check the framing |
| Stains, mould or peeling paint on the other side of the wall | Water behind the tiles | Retile, and check the framing |
Cracked grout is not a cosmetic issue in a shower. In MBIE Determination 2024/054, the tiled showers failed Building Code clauses E3.3.4, E3.3.5 and E3.3.6 because cracked grout let water into the concealed space behind them. Grout is not waterproof on its own; the membrane underneath is what keeps the wall dry, and grout cracks are how water gets to it.
When is regrouting and resealing enough?
When the tiles are firmly stuck, there is no sign of moisture outside the shower, and the problem is the look of the joints. A regrout rakes out the old grout, fills it fresh and seals it; a reseal cuts out old silicone at the internal corners and where the tiles meet the tray, and replaces it. Silicone is the part that goes first in most showers, and the joint between the wall and the tray takes the most movement, so a reseal is normal maintenance, not a repair.
It is worth having moisture readings taken before you spend money on either. A non-invasive meter reading around the shower, the vanity and the door frame is quick and tells you whether there is water in the wall that a regrout would only cover up. Our measure-and-design visit includes them.
What about tile paint, resurfacing or tiling over old tiles?
Tile paint and professional resurfacing change the colour of a dated wall, and they can be a sensible short-term fix in a laundry or on bathroom walls outside the shower. They do nothing for waterproofing, and on a shower floor they wear quickly underfoot. Tiling over old tiles saves the strip-out but hides whatever is wrong underneath, adds weight and thickness, and leaves the old membrane, whatever its condition, in place. If the reason you want to change the tiles is a leak, none of these is the answer.
What does a proper retile involve, and what does it cost?
The tiles and substrate come off, any rot in the framing is priced and repaired, new wet-area substrate goes on, and a waterproof membrane is applied to the system's instructions and photographed before tiling. Superior Renovations puts retiling an existing shower with the plumbing left where it is at $1,800–4,000, excluding waterproofing, and a new tiled shower at $1,550–8,250 across New Zealand. A whole-room retile is $15,000–35,000 excl. GST in CheckMyBuilder's mid-range band. If the budget is tight, an acrylic unit at $900–2,000 installed is the cheapest way to replace a failed tiled shower properly.
Questions
Can I regrout a leaking shower?
You can stop water getting in through cracked grout, but if the membrane behind has failed, or there is already water in the framing, regrouting only hides it. Look for loose tiles, swelling skirting and stains on the other side of the wall before deciding.
How often should shower silicone be replaced?
Whenever it is mouldy, peeling or pulling away, which in a well-used shower is every few years. It is the joint that takes the most movement, especially where the walls meet the tray.
Is tile paint a good idea in a bathroom?
On walls outside the shower, as a short-term cosmetic fix, it can be. It does not waterproof anything, and on a shower floor it wears quickly.
Does regrouting or retiling a shower need consent?
No, in an existing home. Work on internal linings and finishes is exempt under Schedule 1 clause 12, and MBIE Determination 2024/054 found that includes the membrane under a tiled shower. The work must still meet the Building Code.
Sources
Published 19 October 2026, last updated 19 October 2026 by Bathroom Renovation NZ. Every figure and rule on this page is quoted from a source we read in full on the checked date. See our editorial policy.