How to paint over mould

Causes of bathroom mould

Mouldy bathroom ceilings have long been a source of concern for homeowners, landlords and Painters & Decorators here in London

Bathrooms that are poorly heated and ventilated and having little or no insulation, will cause the surface of the ceiling and walls to become cold and to remain cold. 

When the warm air from the shower or bath comes into contact with the cold ceiling, the air cools. 
This warm air, which will be laden with moisture, can no longer hold that moisture, therefore it condenses on the cold surface of the ceiling.

Particularly common in London are bathrooms and shower rooms constructed internally of the building envelope.
This therefore means that you have to rely on mechanical extractors to remove or reduce the moisture in the air. 
As these rooms are internal, they are often better heated and insulated, thus producing less mould than a bathroom with external walls and single glazed windows.

At Painters in Central London, we often encounter ceilings suffering from mould and flaking paint.
The ceiling below was above a shower cubicle in a one bedroom flat in Covent Garden. The property was pre- 1930s built, no insulated walls, metal casement windows and a heated by a single towel rail.

Procedure for painting a mouldy ceiling

Surface Preparation

• Remove any loose and failing material by scraping and brushing with a stiff bristled brush until you find a sound edge. 
  
• Remove all visible signs of mould growth and treat all areas with a Anti-Mould Solution. Use in accordance with the manufacturer's instructions. 
• Wash down all remaining surfaces with a hot sugar soap solution to remove any contaminants. 
• Rinse thoroughly with clean water to remove the residues.
• Fill any cracks and holes, sand down, and feather the edges, or fine fill and feather if the paint layers are too thick. 

Priming
Prime all stained, bare and filled areas with one coat of shellac-based primer Sealer in accordance with the manufacturer's instructions.

Decoration
Apply two full coats of an acrylic eggshell finish. 
Dulux Diamond Eggshell is resistant to the levels of atmospheric humidity present in normal interior environments and will withstand repeated washing. It is suitable for use in kitchens and bathrooms.