Property Repair Systems

Removing Black Mould from a Bathroom Ceiling and from Bathroom Walls and What can Cause Black Mould to Form

This project is sponsored by Property Repair Systems

Summary: What are the causes of black mould? This project explains the conditions that can cause black mould on bathroom ceilings and walls to grow and what can be done to try and stop, in most cases, the condensation that causes it. Also find out about methods of black mould treatment and removal and also what you can do to prevent it from appearing again.

Bathroom Mould

The growth of black mould growth on bathroom ceilings and walls is a sign of condensation, and in bathrooms there is generally plenty of that! The warm, air laden with moisture comes into contact with a cold surface and that cools the air so that it can no longer hold the moisture which then condenses on that surface. This is why condensation is typically found on windows and other colder areas. Find out more specific advice on condensation and how to prevent it here.

If there is enough condensation and especially if the environment is slightly warm such as on a bathroom ceiling or wall then black mould can grow.

Black mould on ceiling and walls

Black mould on ceiling and walls – Image courtesy of blackmold.awardspace.com

Bathroom ceilings covered in mould have long been a source of concern for our users. There are three ways to stop the condensation and therefore the likelihood of mould growth:

  1. Reduce the moisture that is created and circulates in the air
  2. Ventilate to remove the moist air before the moisture can condense and cause problems
  3. Heat and insulate your home so that there are less cold surfaces and the air is kept warm enough to hold the moisture so reducing the amount of condensation

There is no avoiding the moist air in a bathroom so it is virtually impossible to reduce the moisture content in the air. Ventilation can be effective and an efficient extractor fan will help reduce condensation enormously and therefore the likelihood of mould growth. Other ventilation such as opening a window may not be practical especially in winter when it will make the bathroom very uncomfortable. Improving heating and insulation may be expensive and potentially unaffordable in the circumstances, but they are an option.

This means that condensation and black mould are most often found in bathrooms, particularly those that are poorly heated and ventilated and especially when insulation properties are poor making the ceiling a particularly cold surface. When this is the case and mould has started to grow it is very difficult to stop it.

How to Stop Mould in Your Bathroom

If you cannot cure the problem by reducing the levels of condensation either by ventilating or using the heating, there is another solution. This is to kill the mould and treat your walls to prevent it's future growth, despite the high levels of condensation.

There are 3 relatively simple steps:

  1. Paint your walls with a mould killer or steriliser to kill off any mould present on the walls and then clean off (following the instruction on the product that you choose)
  2. Paint on a barrier solution
  3. Once the barrier solution has dried you can now paint on your top coat. Mix fungicide additive with any emulsion you choose to stop the mould coming back

For a relatively small cost and effort it is possible to stop mould growing on your ceilings.

Mould Eradication Kits

There are quite a number of products now available on the market that will allow you to eradicate the mould completely. With good fungicidal properties a room of up to 40 square metres can be protected by most available mould eradication kits. A large bathroom measures 4m x 5m which is only 20 square metres.

Mould eradication kit

Mould eradication kit – this particular one is supplied by a company called Property Repair Systems

In most cases the kit will contain all the products that you require to remove and then ensure the black mould does not return.

Application will follow the same process that we have described above; sterilizing the ceiling first, then providing a fungicidal barrier over which you can re-decorate your bathroom. Please follow the instructions and usage directions that will be provided with all products and will tell you exactly how the product should be applied.

Black Mould on Bathroom Ceilings

Understanding what mould is will help in understanding how to get rid of it. Mould is a type of fungus. Threads, like very dense cobwebs, grow together on a given surface and some of them are fertile enough to produce spores. Spores are carried by moving things including air and especially warm air, which is always found in a bathroom.

The warm air travels upwards depositing spores on the ceiling. The spores settle and grow to become mould. The conditions mould likes best are when temperatures are above 70 degrees Fahrenheit and the relative humidity is above 70% and have a guess where those conditions are found ?!

This is important because other than the unsightly stains that the mould causes the spores can also cause respiratory problems. This is why you should never try and scrape away the mould; this will release the spores into the air in the form of a fine dust which can cause breathing difficulties especially if you are prone to respiratory problems.

Black mould that is found in habitable rooms, especially bedrooms, in a much more serious condition, due to the prolonged exposure to the spores that the occupants will receive. The treatment is the same, but much more urgent. Thankfully this is less common

The other thing to understand is that this is a fungus and like many other fungi, black mould will cause a nasty odour; this is a distinctive musky smell.

How to Keep Black Mould in Check

It is possible to keep black mould in check relatively cheaply and easily. There are a number of solutions that will kill mould, although you may have to keep doing this on a regular basis to prevent it returning:

  1. Good old fashion bleach: Mix 4 parts water to one part bleach and apply liberally to the affected area. The bleach will kill the mould but be careful what surfaces that you apply the bleach to as this can damage paint. If you are unsure test it on a small unseen area first
  2. Mould and mildew products: These are generally very efficient at removing the mould stains and killing the mould. They are readily available and will vary in price and effectiveness
  3. Anti bacterial sprays: These are efficient mould killers and will not be bleach based so should not affect the paint work (always read the instructions). These are less effective at removing the mould stains, but are quick and easy to apply so are excellent to ensure that the mould does not return by giving a precautionary spray periodically

In summary, if you can stop the condensation you will stop the mould. This is very often hard to achieve and this is where you have to resort to treating the mould itself. There are a range of solutions that you can employ so you don’t have to have an unsightly bathroom ceiling covered in mould. Other than the aesthetic benefits, there are definitely health benefits from reducing the spores by removing mould from bathroom ceilings.

Don't fancy doing this project yourself? We work with Checkatrade to ensure that we recommend only reliable and trustworthy tradesmen.

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