Mould and Fungus After the Monsoon: Removing It So It Does Not Return

By late September, Pune and Pimpri-Chinchwad homes are at their most humid, and the black spotting appears — bathroom corners, the back of the wardrobe, the north wall of the bedroom, the underside of the kitchen platform. Most households scrub it, paint over it, and meet it again next August. This guide explains why that happens and what actually ends it.

First, work out which kind you have

Getting this right is the whole job. Treating leak mould with a dehumidifier is futile, and treating condensation mould with waterproofing is money spent on the wrong problem. If you are unsure, a moisture meter reading behind the growth answers it in seconds.

The removal sequence that actually holds

1. Fix the water source. Leak, seepage, rising damp or ventilation — whichever the diagnosis showed. Everything below is wasted without this step.
2. Dry the wall completely. Weeks, not days, for a saturated wall. Air movement and patience; a fan pointed at the wall does more than a heater.
3. Remove all blown or hollow plaster. Tap the wall — a hollow note means the plaster has lost its bond and must come off. Growth lives behind it.
4. Apply a fungicidal wash to the exposed surface and leave it the full dwell time stated on the product. Do not rinse it off early.
5. Replaster where needed, then let the new plaster cure and dry properly before any coating.
6. Prime with an anti-fungal primer, then finish with a washable emulsion. On external walls, an elastomeric or water-repellent finish is the one that lasts.

Room by room: where it starts in a Pune home

• Bathrooms. Corners, grout lines, the ceiling above the shower. Cause is almost always ventilation, sometimes a leak from above. Run the exhaust during and for fifteen minutes after every shower.
• Wardrobes on external walls. Back panels and the clothes touching them. Cause is a cold, sometimes damp wall with no air movement. Leave a 50–75 mm gap and use vented backs.
• Kitchen platform underside and the wall behind the sink. Cause is usually a slow plumbing leak or a failed sink seal, not humidity.
• Window reveals. Cause is condensation on the coldest surface in the room, or failed perimeter sealant letting rain in.
• Ceiling corners on the top floor. Cause is the terrace, and no amount of interior treatment will help.
• Behind the refrigerator and the washing machine. Warm appliance, still air, cold wall — a reliable trio.

Prevention that costs nothing

• Cross-ventilate for thirty minutes a day, ideally in the driest part of the afternoon.
• Run bathroom and kitchen exhausts past the end of use, not just during.
• Dry clothes outside or in a ventilated utility, never in a closed bedroom — a single load releases litres of water into the air.
• Keep furniture off external walls.
• Leave wardrobe doors ajar in the worst weeks.
• Wipe the shower walls down after use. Unglamorous and extremely effective.

When it is a building problem, not a housekeeping one

If mould returns to the same place every year despite good ventilation, if the wall reads wet on a meter, if the plaster sounds hollow, or if the pattern spreads in a direction rather than speckling evenly, stop cleaning and get the wall investigated. Recurring growth in one location is a moisture path, and moisture paths are traceable. In Pune and PCMC the usual culprits are external wall seepage on the monsoon-facing elevation, a bathroom above, or rising damp at plinth level — see how wall seepage is treated for what each involves.

Leakproofs by Betterwork treats the moisture rather than the stain, which is why the wall stays clear the following monsoon.

Frequently asked questions

How do I permanently remove mould from my walls?

Permanently means removing the moisture, not the stain. Find and fix the water source, dry the wall fully, remove any blown plaster, treat the surface with a fungicidal wash, then finish with an anti-fungal primer and paint. Cleaning alone brings it back within one season.

Is black mould on walls dangerous?

Prolonged exposure to indoor mould is associated with coughing, wheezing, nasal irritation and worsened asthma, and matters most for children, older people and anyone with a respiratory condition. Treat it as a health issue and a building issue at the same time.

Why does mould keep coming back after cleaning?

Because the moisture that fed it is still there. Bleach removes the colour from the surface but does nothing to the damp inside the plaster, and the growth returns from the substrate.

Does bleach kill mould on a wall?

It decolourises surface growth but does not reach hyphae inside porous plaster, and the water it adds can make things worse. A proper fungicidal treatment on a dried wall is what works.