Wall with black mould growing on it

Black Spot Mould

Black spot mould (also known as Aspergillus Niger) is a common problem in households that down to leaks, moisture in the air and poor ventilation.

Not only does it not look pleasing on the eye but can also damage to furniture and fabrics of your property. There is also the serious issue of the impact it can have on your health.

Both new and old properties are at risk to black mould meaning it definitely something you need to be aware of. Mould can occur in any part of the building where there is a potential for dampness.

Accredited to

Nic Glover

Branch Manager and Waterproofing Design Specialist CSRT CSSW
North East

What is Black Spot Mould?

Black spot mould is a direct effect of condensation. Black spot mould usually appears in areas where there is very little air movement such as window reveals, floor / ceiling and floor / wall junctions and behind furniture that is positioned behind colder walls.

The conditions that black mould needs to develop then are cooler parts of a property where the average relative humidity is 70% or more on a regular basis.

What Causes Black Mould Growth?

One of the main causes for black mould growth is the excess moisture used from everyday living conditions and poor ventilation. A vast majority of households use large quantities of water vapour through cooking or showering.

If the moisture laden air can not escape the property then this will cause mould growth problems. Ventilation is the main cure for stopping mould growth so if there are air vents blocked, double glazing in place, this will cause mould growth to occur.

Areas, where this is particularly important, is where the most water is created such as the kitchen or bathroom.

When the water vapour comes into contact with a surface that is colder than itself then it will start to leave water on the cold surface. Once the water comes into contact with a material such as wallpaper, this area will feel damp and will leave a damp odour.

Once the black mould spores in the air they will start to germinate onto the surface once the surface has reached the dew point.

One should also consider that mould will occur in the non-living areas such as sub-floor voids and roof spaces; in these areas, it often remains unnoticed and can lead to timber decay if it is sufficiently long term and severe.

Condensation black spot mould

The picture above shows black spot mould at the cold spot of the wall / junction as well as mould on the plasterboard finish where the “dabs” holding the plasterboard have created a cold spot.

The “dabs” are the only contact between the plasterboard and the cold wall, therefore the temperature of the cold wall is transferred through the “dab” on to the surface of the plasterboard. This causes moisture trapped in the air to “condensate” out at this cold spot. This is otherwise known as “Cold bridging”.

How Black Mould Affects Your Health?

There is much concern surrounding the effect of condensation mould spores in the air on the health of you and your children.

Generally speaking, mould spores, like pollen, are air-borne and everywhere, and do not affect those in good health. Problems do occur though when mould is allowed to grow and produce spores in great numbers, and these can exacerbate problems in those suffering from asthma, or with respiratory or pulmonary conditions.

There is also the issue of allergic reactions which can be a problem for some people. If a person inhales the mould spores then this can cause the immune system to create an allergic reaction as it is trying to defend itself from an unknown entity entering the body.

How To Spot Signs Of Black Mould

Black mould is quite easy to distinguish. When active the mould will have a black or green. slimy like appearance. If the black mould is in an inactive state it will be powdery and dry. It is important to note that in either of these states black mould can still be a problem.

There is also the issue that black spot mould is not always visible from the start and can be out of plain sight. The mould problem can be in such areas as in the loft, under floorboards or behind the wallpaper.

The tell signs that is often common with black mould is the following:

  • Damp musty smell– When mould growth is active the moulds emit volatile compounds which caused the distinctly ‘musty’ odours associated with dampness. This can be very important in that it is not uncommon to get such a musty smell yet there is no visible evidence of mould growth on walls.
  • Coughing- can be a sign of an allergic reaction
  • Mould- will appear on the window sills, ceiling and walls of the property

How To Get Rid Of Mould

Condensation mould can be treated very easily. Simply washing off black mould and re-painting areas doesn’t work!  The only way to remove all the mould spores is to use a condensation mould eradication kit.

It is though important to reduce the amount of moisture in the air and improve the ventilation in the property (using bathroom and kitchen fans or positive pressure units).

This will reduce the potential for health hazards associated with such growth in domestic properties and with our recommendations a healthy living environment may be achieved.