Your Guide on How To Paint Over Mould

Mould can be found on interior or exterior surfaces such as bathroom walls and ceilings. If you are painting over mould or stains it is important to kill mould before painting. This step by step guide will show how to kill mould and prime walls in a single step.


Evaluate the quantity of Mould Killing Primer you need depending on the size of your project. A typical coverage of such a primer is about 10SQM per litre.  Read the product labels before using any product to have an understand drying time of primer and any PPE required. Mould builds up on walls and ceiling because of excessive moisture and the source of moisture must be removed before preparing the walls for painting. Source of moisture could be water leakage from a pipe or rising dampness due to high water table etc.

Tools & Products You Will Need

  • Mould Killing Primer
  • Stain Blocking Primer
  • Brush
  • Roller Kit
  • Rags

Preparing Mouldy Walls For Paint

Step 1: Preparing the surface

Clean the wall to remove any loose growth of mould from the surface. If you have a Mould Killing primer go the step 2. If you don’t have a Mould killing primer you can use bleach solution to get rid of any mould growth on dry wall surface. Ensure the surface is dry before applying bleach on dry walls. Apply carefully saturating mould with bleach solution and gently rubbing with a soft scrubbing pad. We strongly recommend use of a mould killing primer over using a traditional bleach solution to kill mould growth on walls and ceiling completely.

Step 2: Apply the mould killing primer

Stir the primer well before use with a flat timber stick to get a uniform composition. Apply a coat of Mould Killing Primer generously with a good quality cutting in brush around the corner. Then use a good quality roller to apply mould killing primer on entire wall to ensure entire wall is covered. Areas which have water stains may be spot primed with a stain blocking primer to ensure all stains are sealed in.

Step 3: Apply the protective top coat

Ensure the mould killing primer has dried completely before painting. Always use a good quality interior paint with mould defender’s additives to ensure there is no mould growth in future on paint surface. Apply two coats of the interior paint to finish the walls in your desired colours Our Picks


  • Zinsser Mould Killing Primer
    Zinsser BIN