Be Bold with Black Mould – A Case Study on Mould Diagnosis

Have you ever wondered what happens during one of our typical black mould diagnosis jobs?

On a wintery Monday morning, our York branch was called out to a multi-occupancy household with initial reports of mould growing in several areas of the property. The inside temperature of the home was 9 degrees Celsius, a good 10 degrees below the ideal room temperature for living.

In this short description, we have already encountered numerous risk factors which create a perfect environment for black mould growth.

There are 6 things that are generally required for black mould to thrive:

1. Firstly and most importantly, moisture within the property. For our case in York, this was certainly an issue.

Households with more people are significantly more likely to have mould growth due to increased activity in the house. More showers, more baths, more cooking and more clothes to dry. This paired the lack of central heating during winter due to the cost of living crisis, creates a solid foundation for mould spores to grow and black mould to spread.

Now for the technical and science bit:

Water vapour in the air from the activity within the household cools when it hits cold surfaces, such as a window in winter. The temperature at which the vapour returns to liquid is referred to in the industry as ‘dew point’. When this is achieved, we see condensation on walls and windows.

Mould spores can be likened to plant seeds, which require a ‘watering environment’ to grow. Built up and undisturbed condensation leading to damp can provide this.

2. Secondly, the mould spores need organic matter to grow on. Not all materials are prone to mould growth, but those which can provide an organic material to feed on such as wood, leather and paper are typical. For the property in York, the plaster on the walls provided the perfect fertile environment.

3. Next, you need the correct temperature for black mould to thrive. Unfortunately for this property and all our homes, room temperature is preferred, as mould does not thrive in hot or freezing temperatures.

4. Lack of disturbance to the area is another contributing factor. Those surfaces that are wiped, trodden on or cleaned regularly are more likely to have prevented mould growth.

5. Sunlight can often help control mould spores, so dark and gloomy corners that do not get sun light are most at risk of growing black mould. This is why you can see mould has grown in ceiling corners that sun light cannot reach. Linked to earlier comments, sunlight can help to warm rooms and potentially dry moist areas with condensation.

6. Substantial lack of air movement to carry spores is the final contributing factor to the perfect environment of mould.

For our property in York, there was an inadequate extractor fan was installed in the bathroom. Good extraction of moist air (especially in bathrooms and kitchens) can greatly help mould prevention. With it also being winter, people often prefer windows to be left shut, containing the moisture within the property too.

Good extractor fans which are activated via light switch, will continue extracting for 10-15 minutes after you have left the bathroom and turned the light/ fan off. Those that do not, tend to do a poor job at extracting the vapour from the room.

Final diagnosis:

Our expert technicians completed a detailed risk assessment and inspection of the property and came to the conclusion that black mould had grown due to excessive moisture, and inadequate ventilation of the property.

Of course, it’s important to note that damp could have also been caused by a leaking pipe or another source of moisture, but thankfully on this property this was not the case. For more information on this, please see our Trace and Access service page.

As part of our service, our technicians will provide recommendations to the owner of how to remediate the root of the cause and help to reduce conditions conducive to black mould growth.

This customer was recommended to improve heating within the property, control moisture sources we identified and, in particular, look at improving the ventilation system situated in the bathroom to deter the problem from returning.

As well as carrying out mould inspections in properties, we also offer mould removal services too. Mould removal is beneficial due to the harmful nature mould potentially has on your health.

If you have mould on walls, mould on ceilings, mould in your bathroom or any other room, our Mould Remediation services can help, contact your local Rainbow branch, email enquiries@rainbow–int.co.uk or call the Rainbow helpline on 01623 42248.