Why are there black and greyish spots and patches on my walls?

What is it?

Mildew and other fungal growth cause patches or spots on walls.

What are the possible causes?

  • High humidity and moisture in spaces such as bathrooms, kitchens and laundry areas encourage microbial growth.
  • Using oil based paints or low quality water-based paints,
  • Applying paint on a surface or coating which already has mildew or from which mildew has not been completely removed.

How can I fix this problem?

  • Confirm that the problem is indeed mildew by applying a few drops of bleach. If it whitens, it is likely to be mildew.
  • Scrub the entire mildewed area with a solution of one part bleach and three parts water – clean till all mildew is gone. Use rubber gloves and eye protection.
  • Thoroughly remove all dirt or organic matter on which mildew can feed. Use a power washer if necessary.
  • Use a top quality water based paint as it is likely to have more mildewicide.
  • Look for a paint that has anti-microbial properties to prevent further formation of mildew.
  • Install fans in high moisture areas.