Once the heating goes on, mould tends to come back in the same places: the bathroom ceiling above the shower, the cold corner of a back bedroom, the wall behind a wardrobe. For homeowners and landlords, the real question is not whether to paint over it, but how to have it treated so it stays gone. This guide explains what a proper mould repaint involves, which anti-mould paint suits which room, and what to check before booking an interior painting service for the job.
Why painting over mould on walls fails
Mould is a living growth, not a stain. Painting over mould on walls without treating it first seals the spores under a fresh film, where the damp plaster keeps them alive. After a few weeks of cold, damp weather, black spots show through again, often in the same pattern as before.
Even before it grows back, the old staining shows through ordinary emulsion. Mould leaves a grey or brown shadow in the old paint and plaster, and that marking bleeds back through a standard topcoat.
Most importantly, paint does nothing about the cause. Condensation mould forms when warm, moist air from cooking, showers, drying clothes and breathing overnight meets a cold wall or ceiling. The SEAI’s guide to home ventilation explains how good ventilation lowers the chance of condensation forming. A repaint that ignores ventilation buys a few clean weeks, not a clean winter.
Condensation or damp: what has to be fixed first
Not every patch of black mould on painted walls is condensation. Where and when it appears shows which problem you have:
- Condensation: high corners, ceilings, window reveals and walls behind furniture, usually worse on winter mornings and in bathrooms and bedrooms. This is the type a mould repaint, paired with better airflow, can solve.
- Penetrating damp: patches that spread after heavy rain, often below a leaking gutter, around a window frame or behind cracked render. The water is getting in from outside, so the exterior needs repair first, and often a weatherproof exterior paint system.
- Rising damp: a tide mark low on ground-floor walls, with flaking plaster or white salts. That calls for a damp specialist before anyone paints.
Painting over penetrating or rising damp hides the warning sign and wastes the money spent. A good painting contractor will tell you when a wall is not ready for paint.
What a professional mould repaint involves
A lasting job follows the same sequence every time, and it is worth checking that a quote covers each stage.
Inspection and protection
The painter identifies the cause, checks that extractor fans and window vents work, and protects floors and furniture with dust sheets and protective coverings before any treatment starts.
Treating the growth
A fungicidal wash goes on the affected area and beyond its visible edge, is left to work, and the surface is then rinsed and allowed to dry fully. Household bleach lightens the staining, but it is no substitute for a proper fungicidal treatment on porous plaster.
Sealing the stain
Flaking paint is scraped back, the surface is lightly sanded and filled where needed, and a stain-blocking primer or sealer goes over the marked area so the shadow cannot bleed through the finish.
A mould-resistant finish
Two full coats of a mould-resistant topcoat follow, in a sheen suited to the room. Usually the whole ceiling or wall is repainted rather than a patch, so the finish matches. The job ends with a clean-up and a walkthrough to check for snagging.
Choosing anti-mould paint for each room
On a mould job, the topcoat should be a mould-resistant formulation, specified by the painter, in the sheen that suits the room. Choosing anti-mould paint in Ireland then comes down to how each room is used.
- Bathrooms: steam settles on the ceiling every day, so a finish that sheds moisture and wipes clean outperforms flat matt, and that is the sheen to ask for in mould-resistant paint for bathrooms. As examples of those finish types, our interior wall paint guide points to Fleetwood Extra Plus Vinyl Soft Sheen, a soft sheen that is Irish-made and good value where walls get wiped often, and Little Greene Intelligent Eggshell, which is moisture- and stain-resistant and goes on woodwork as well as walls.
- Kitchens: grease joins the steam, so the same wipeable finishes apply, and extraction over the hob does as much work as the paint.
- Bedrooms: mould here usually comes from overnight condensation on external walls and behind wardrobes. Where a flat look matters, ask for a washable matt in a mould-resistant formulation.
Anti-condensation paint is a different product. It adds a thin insulating layer that keeps a cold wall’s surface slightly warmer, so less moisture condenses on it. It can help on one stubborn external wall, but it does not replace an extractor fan or regular airing.
What shapes the cost of a mould repaint
Every quote depends on the property, so there is no fair flat figure. The main factors are:
- how far the mould has spread, and whether ceilings, walls or both are affected;
- how many rooms are involved, and how high the ceilings are;
- whether whole surfaces need stain sealing to avoid a patchy finish;
- work outside painting, such as a new extractor fan or a gutter repair;
- the grade of paint specified.
Paint grade matters more than it seems. Premium paint brands typically cover better, often needing only two coats where a budget paint might need three or four. A cheaper repaint that skips treatment usually has to be redone the following winter.
For landlords: the rented-housing standards
There is a legal side for landlords too. With some exceptions, such as holiday lets, the Housing (Standards for Rented Houses) Regulations 2019 require rented homes to be kept free of defects caused by dampness, with adequate ventilation in every habitable room and ventilation in kitchens and bathrooms to remove water vapour. Mould that keeps returning in a rented property is usually a sign that the ventilation needs attention as well as the walls.
FAQ
Can you paint over black mould on walls?
Not straight away. The growth has to be treated with a fungicidal wash, the wall left to dry and the stain sealed before a mould-resistant topcoat goes on. Paint applied directly over black mould traps it, and it usually returns once condensation does.
Does anti-mould paint stop mould for good?
It resists growth on the paint surface, but it cannot remove the moisture that feeds mould. Combined with proper treatment and better ventilation, it keeps walls clean far longer than standard emulsion.
Is anti-condensation paint worth it?
On a single cold external wall, it can reduce how much moisture settles on the surface. It works best alongside an extractor fan and regular airing, not instead of them.
Get mould-affected rooms repainted properly
Mould keeps spreading while the heating season runs, and a small patch now is a quicker, cleaner job than a whole ceiling in January. Request a quote from our house painters in Dublin or our Wicklow house painters. Tell us which rooms are affected and when the mould appears, and ask for the quote to set out treatment, sealing and the finish for each room.
