Quick answer
Mould cleaning in a Wellington home is simple for surface mould: ventilate the room, wear gloves, wipe the mould off with a cleaner suited to the surface and dry it completely. Keeping it away is harder. That means cutting moisture every day with extractor fans, steady heating, washing dried outside and a quick wipe of the windows each morning.
Why do Wellington and Hutt Valley homes get so damp?
Cold surfaces meet moist air. When warm, humid air inside the house touches cold glass or a cold external wall, the water in it condenses, and anywhere that stays wet for weeks grows mould.
A damp house in Wellington usually has several of these going on at once:
- Single glazing. Glass is the coldest surface in most rooms, so condensation runs down onto sills and into window tracks on winter mornings.
- Older and weatherboard homes. Villas and mid-century houses often have cold spots on ceilings and external walls, especially where insulation is thin or missing.
- Cold winters. Upper Hutt and the valley suburbs get regular frosts, and the colder a room gets, the more of its moisture ends up on the walls and windows.
- Washing dried inside. A full clothes horse in front of the heater puts a lot of water into the air, and it has to land somewhere.
- Shaded sections. Homes on south-facing hillsides or the shady side of a valley, in parts of Karori, Stokes Valley or Wainuiomata for example, can go much of the winter with little direct sun.
- Steam and gas. Showers and cooking without a working fan add moisture fast, and so do portable gas heaters, which release water vapour as they burn.
How do you remove mould from a bathroom ceiling and other surfaces?
Gently, and without soaking anything. Wipe the mould off with a cloth or sponge and a cleaner suited to the surface, rinse lightly and dry the area completely. The method changes from surface to surface:
| Surface | How to clean it | Watch out for |
|---|---|---|
| Painted bathroom ceiling | Open the window and run the fan. Wipe small sections with a sponge mop or cloth and a mild detergent or diluted mould cleaner, wipe over with clean water, then let it dry. | Don't saturate the plasterboard. Mould that's back within weeks points to poor ventilation. |
| Shower silicone and grout | Scrub grout with a stiff brush and cleaner, then rinse and dry. Treat surface spots on silicone the same way. | Black marks under the surface of silicone won't scrub out. The silicone usually needs replacing. |
| Aluminium window frames and tracks | Vacuum loose grit first, then wipe with warm soapy water. Use an old toothbrush in the corners and dry the rubber seals. | Blocked drainage holes in the tracks, which stop water escaping. |
| Timber window frames and sills | Wipe with a barely damp cloth and mild detergent, then dry straight away. | Bare or soft timber. Stains in the grain may need sanding and repainting. |
| Curtains | Take them down and shake them outside, then wash following the care label and dry fully, outdoors if you can. | Linings that sat against wet glass. Some marks won't wash out. |
| Inside wardrobes | Empty them, vacuum, wipe the walls and shelves, then leave the doors open until everything is dry. | Wardrobes on external walls, and damp shoes and bags. |
Start with the mildest cleaner that works. Warm water and a little dishwashing liquid shift a lot of light mould. If that doesn't, use a household mould cleaner or diluted bleach, following the label, or white vinegar, which won't bleach colours (keep it off natural stone).
Stay safe while you clean
- Ventilate: open the windows and run the extractor fan while you work and for a while afterwards.
- Wear rubber gloves, and add safety glasses and a mask when you're working overhead, since drips and spray fall straight down.
- Never mix bleach with ammonia or with acidic cleaners such as vinegar. The fumes are dangerous.
- Test a small hidden area first, because bleach can lighten paint, grout and fabric.
- Wipe mould while it's damp rather than brushing it dry, so you don't spread it around the room.
- Keep children and pets out of the room until it's aired and dry.
Pick a dry, breezy day for mould jobs so you can open the windows wide and every surface dries quickly.
How do you stop condensation on windows and mould coming back?
Get moisture out of the house every day. Run the fans, air the rooms, wipe condensation off the glass each morning and keep the house steadily warm, because a cold room turns moisture in the air into water on the walls.
Run the bathroom fan for every shower and leave it on until the mirror clears. Use the rangehood when you cook and put lids on pots. Dry washing outside or in a vented dryer, and on wet Wellington days, run a dehumidifier in the room where it's drying (and empty it often).
In winter, wipe the windows each morning with a squeegee or an absorbent cloth and wring it out in the sink. It takes a few minutes and stops water soaking into sills and tracks. Pull beds and couches a hand's width away from external walls, and leave wardrobe doors ajar.
On a fine, breezy day, open the house up for an hour or so; Wellington's wind is good at clearing damp air. Clean windows also make fresh condensation and new mould easier to spot. Our guide to streak-free windows in Wellington weather covers the glass, and our window cleaning service includes frames, sills and tracks.
What do the Healthy Homes Standards say about damp rentals?
Rental homes have to meet the Healthy Homes Standards, which include a ventilation standard and a moisture ingress and drainage standard. Tenancy Services publishes the details for landlords and tenants.
Under the ventilation standard, kitchens and bathrooms need an extractor fan that vents outside, or a continuous mechanical ventilation system that meets set criteria. The moisture ingress and drainage standard covers gutters, downpipes and drains that carry water away, plus a ground moisture barrier under homes with an enclosed subfloor, if one can be installed.
If you rent and mould keeps coming back despite airing and cleaning, tell your landlord or property manager in writing. Tenancy Services can explain what the standards require.
When is mould more than a cleaning job?
When it keeps coming back within weeks, covers a large area, or comes with water stains, soft plasterboard, bubbling paint or a musty smell you can't trace. Those signs can point to a leak or building problem, and cleaning only removes what's on the surface.
Have a plumber or builder check it before you spend money on cleaning. Common causes include a leaking shower tray, blocked gutters, cracked flashings and missing insulation. Fix the cause first, then clean.
For surface mould, Apex offers mould treatment as an add-on to a regular or deep house clean. We target bathrooms and damp corners with eco-friendly products that are safe for children and pets, and we bring all the equipment. It pairs well with a spring clean, and our spring cleaning checklist shows where winter damp hides.
We clean homes across Wellington City, Lower Hutt and Upper Hutt, plus Porirua and the Kāpiti Coast, and every quote is free and fixed before work starts.
Get help with mould cleaning in Wellington
Clean the small patches yourself and fix the moisture behind them. For the rest, call Apex on 022-606-4460 (Monday to Saturday, 8am to 6pm) or ask for a free quote. If anything is missed and you tell us within 24 hours, we'll come back and re-clean it free.
Frequently asked questions
Is bleach or vinegar better for cleaning mould?
Both are common for surface mould. Diluted bleach lightens mould stains but can also lighten paint, grout and fabric, so test a hidden spot first. White vinegar won't bleach colours, but keep it off natural stone. Use one or the other, never both together, and ventilate the room while you work.
Why does mould keep coming back on my bathroom ceiling?
Because moisture keeps landing there. Steam rises, hits the coldest surface and condenses, so a fan that's too weak, doesn't vent outside or gets switched off too early leaves the ceiling wet after every shower. Run the fan until the mirror clears, open the window afterwards and clean small spots before they spread.
How do I stop condensation on windows in winter?
Cut the moisture and keep rooms warmer. Run extractor fans, dry washing outside or in a vented dryer, heat rooms steadily and air the house on fine days. Single-glazed windows will still fog up on cold mornings, so wipe the glass and sills each morning before the water soaks into the frames.
Can Apex clean mould in my home?
Yes, for surface mould. Apex offers mould treatment as an add-on to a regular or deep house clean, targeting bathrooms and damp corners with eco-friendly products that are safe for children and pets. If the mould keeps returning or comes with water stains or soft plasterboard, have a builder or plumber check for a leak first.
Written by the Apex Cleaning Service team
We are a local, family-run cleaning company based in Naenae, Lower Hutt, cleaning homes, rentals and workplaces across Wellington, the Hutt Valley, Porirua and the Kāpiti Coast. More about us
