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Reviewed by Tom Reilly — Senior Editorial Reviewer — Roofing, Carpentry & General Contracting

Who to call · Painter

Mildew growing on painted walls: call a painter — or fix it yourself

Dark spots or fuzzy patches on painted interior walls — especially in bathrooms, kitchens, and basements — indicate mildew growth caused by excess moisture. A painter can kill the mildew, apply mildew-resistant primer, and repaint with mold-inhibiting paint, while recommending ventilation improvements to prevent recurrence.

Is this your problem?

Symptoms to look for

  1. 01

    Dark spots or fuzzy patches on walls — black, green, or gray

  2. 02

    Musty smell that persists despite cleaning

  3. 03

    Paint discoloration in corners or near windows

  4. 04

    Condensation frequently forming on the affected walls

Who to call

Painter

A painter applies an anti-fungal system properly; a damp specialist or insulation contractor fixes the cold wall that condenses moisture in the first place.

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Fix it yourself

How to fix mildew growing on painted walls

Mildew growing on painted walls

easy 1–2 h

Tools: spray bottle, sponge, gloves and mask, brush and roller · Materials: 1:10 bleach solution or a fungicidal wash, mould-inhibiting paint or additive, primer

Steps

  1. Ventilate and wear gloves and a mask; wash the wall with a bleach solution or fungicidal wash and leave it 20 minutes before rinsing.
  2. Let the wall dry completely — a day with the window open or a dehumidifier running.
  3. Find the moisture source: a cold outside wall, furniture pressed against it, a bathroom without a fan, or drying laundry indoors.
  4. Prime with a stain-blocking primer and repaint with a mould-inhibiting paint or an additive mixed into the paint.
  5. Keep furniture 5 cm off the wall and ventilate daily; mildew is a humidity problem before it is a paint problem.

Stop and call a pro if

  • the mildew is behind the paint film (paint flakes off with black underneath) — moisture inside the wall
  • it covers more than a square metre or returns within weeks
  • the wall is cold and wet to the touch in winter — an insulation or damp problem

What a pro does that you can't

A painter applies an anti-fungal system properly; a damp specialist or insulation contractor fixes the cold wall that condenses moisture in the first place.

DIY cost: $15–50 for wash, primer and paint

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FAQ

Frequently asked questions

Who should I call for: Mildew growing on painted walls?

Call a licensed painter. Painters have the specialized training, tools, and insurance to diagnose mildew growing on painted walls safely and stand behind the fix. Most offer free quotes and can visit the same day or the next.

Can I fix this myself?

Often, yes: the guide above has 5 steps (easy, 1–2 h, $15–50 for wash, primer and paint). Stop and call a painter if the mildew is behind the paint film (paint flakes off with black underneath) — moisture inside the wall.

How fast can a pro come out?

Most painters offer same-day or next-day visits for non-emergency issues. True emergencies (burst pipes, gas smell, no heat in winter) are typically handled within 1–4 hours.

How much does it cost to fix?

Costs vary by severity and your location. Submit a free quote request to get real pricing from local pros in your area.

What are the signs of: Mildew growing on painted walls?

Dark spots or fuzzy patches on walls — black, green, or gray. Musty smell that persists despite cleaning. Paint discoloration in corners or near windows. Condensation frequently forming on the affected walls.

Who to call

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