Previously, we went over how rendering your walls is important because it will lead to ‘penetrating damp’ / ‘lateral damp’ that causes black mould to grow and spread using its spores (here is a link to the previous article:   )

In this blog post, we will go over how to get rid of black mould.

The first thing to do is find the cause of the excess moisture in buildings so you need to locate the brick wall there the penetrating damp first occurred or have a look in the basements, ground floors, leaking pipes etc. In a newly-built home, damp can occur while the building is still drying out.

Next, you need to reduce or prevent moisture and damp building up in places like kitchens and bathrooms by covering pots and pans during cooking and keeping the windows open to properly ventilate the kitchen and bathroom after a shower or bath, ensure your home is well-insulated to ensure heat is not transferred outside your house and to prevent damp coming in, heating your house to prevent condensation etc.

You may be able to remove the mould yourself by wearing goggles, long rubber gloves and a mask to cover your nose and mouth from breathing in the mould spores. When clearing up rooms containing black mould, open the windows but keep doors closed to prevent spores spreading to other areas of the house.

There are a variety of substances that can be used to kill black mould when they are diluted with water; these substances are: ammonia, bleach, vinegar, baking soda, Tea tree oil, hydrogen peroxide and borax. Note: read the instructions carefully on the hazards of using ammonia, bleach, vinegar, baking soda, Tea tree oil, hydrogen peroxide and borax, do not swallow these substances, avoid getting these substances into your eyes or skin, do not inhale fumes given off by these substances, wash using clean and cold running water the affected eye/ skin area if the substances have entered your eyes/ skin and seek medical attention immediately if you have swallowed/ are suffering from skin irritation/ suffering from eye irritation and pain due to these substances.


Bleach (sodium hypochorite) contains hypochlorous acid which reacts and inhibits black mould growth, vinegar contains ethanoic acid which reacts and inhibits black mould growth, baking soda (sodium bicarbonate) is an alkaline substance



Note: Only remove mould yourself if it’s caused by condensation and covers an area less than one metre squared (1×1 metre or 3×3 feet) and on’t try to remove the mould yourself if it’s caused by sewage or other contaminated water.

If this all sounds like too much work and you don’t want to personally clean up the black mould, seek a professional to remove it.





What happens to unrendered walls?

Walls act as the foundations for the roof of a building and they shelter the occupants from the weather when it rains, snows, becomes windy etc. Hence, walls are important and need to be maintained.


If walls are not given a render coat, they will be damaged by frost and wind.

Pic A – porous brick

Pic B – what the porous brick looks like on close inspection

Notice that most bricks have small holes in them (they are called porous bricks) and it is these small holes that allow water from rain to penetrate the brick which leads to erosion. When water enters the interior of the brick and is subjected to extremely cold temperatures during Winter, the water solidifies and becomes ice which expands and makes the small holes bigger until the holes are large enough to form cracks and break the brick apart (see Pic C for a visual aid of th).


Pic C – weathering of brick by erosion

Pic D – a cracked brick wall due to erosion

Rendering is the application of a plaster coat to the walls of a building; it is a building technique used countless times.

Applying a coat of render requires the coating to be made out of a mixture of cement, sand, water and sometimes lime.

Rendering differs from plastering in that rendering involves applying a render coat of plaster to the external walls of a building while plastering involves applying the plaster coat to internal walls of a building. Another key difference is that rendering uses a more coarser type of sand compared to the more smoother sand used for plastering.

Rendering is used for a variety of reasons such as making the walls of the external building water proof and resistant to weathering and erosion, improving the value of the the property, hiding the damaged bricks of the property etc.

There are a variety of render coats to choose from: K Rend render has additives (polymers – self-repeating chemical compounds) added to the render mixture which makes the render coat water-resistant and strong possibly due to the polymer additive repelling the water away from the surface of the render, which prevents erosion and weathering of the brick layer) and the polymer additive may ensure the render coat sticks to the underlying brick layer strongly and prevent the render from cracking.

Pic A – a house that has been rendered in Greece; note how smooth and aesthetically pleasing the render coat has made the property appear


Pic B – diagrams to explain what a  polymer is and what it is made out of; note – the plastic shopping bags you use are made from a type of polymer obtained and processed from crude oil


Pic C – A diagram to show how render coats are applied to a brick wall