Are Mould and Mildew the Same Thing?

Are Mould and Mildew the Same Thing?

By Ruth MacEachern

Product Manager

Discoloured patches on your walls or a musty smell as you enter your home could be a sign that you have a problem with mould or mildew.  In the autumn and winter, colder temperatures typically mean that condensation becomes more common in UK homes, and with this, we often see an increase in the prevalence of damp, which in turn creates the ideal conditions for mould and mildew to grow.

Both mould and mildew are found in homes, and thrive in similar conditions, but the two organisms are quite different, and understanding the difference between them is helpful in treating the problem and preventing it from returning in the future.

What is mould?

There are thousands of different mould species that exist around the world, and not all of them are found in homes.  Moulds are a primitive organism that shares characteristics with both fungus and bacteria.  Moulds spread by way of microscopic spores that are carried on the air, and once they arrive in suitable conditions, they develop into a large organism.

Mould typically grows inside a material – inside the plaster of your walls, and the dark patches that form on the surface are the fruiting bodies that release the spores for the mould to spread.  In most cases, the moulds that grow on walls and ceilings because of high moisture levels will appear slimy and black or dark green.

While the sight of mould can be upsetting, it is the spores which cause health problems.  Many people have allergic reactions to mould spores that include difficulty breathing, skin irritation and streaming eyes.  Some moulds such as Stachybotrys Chartarum (toxic black mould) release chemicals called mycotoxins that can affect your nervous system.

What is mildew

Mildew is a subspecies of mould that spreads and develops in a similar way.  Mildew is quite easy to distinguish from household moulds.  Rather than having a slimy black appearance, mildew is normally white or light grey and has a more powdery of fluffy texture.

Mildew often grows on softer surfaces or in the backs of cupboards.  While mould doesn’t have a strong odour, you will often know that you have a mildew problem before you see it because of the musty odour it gives off.

What causes mould and mildew

Both mould and mildew thrive in damp conditions and in the home.  Damp patches form when moisture is allowed to saturate a material over time.  Damp can be caused by several factors including water leaking in through holes in the ceiling, leaky pipes, and being drawn up from the ground into the lower parts of your walls (rising damp).

The most common cause of damp in homes is from condensation.  The air in our homes carries water vapour from activities including cooking, bathing and drying clothes indoors.  The amount of water that the air can hold depends on temperature.  When it is warmer, the air can carry more water vapour, however when the temperature drops at night, that water vapour is released onto surfaces where it forms droplets of condensation that will soak into permeable surfaces.

Where damp patches form, mould will quickly follow.

Removing and preventing mould and mildew

If you have discovered mould or mildew in your home, it is important to clean it as soon as possible.  Household bleach diluted with water, or a fungicidal cleaner can be used to kill off the mould, and then it can be wiped away.

When cleaning mould you should always wear eye protection and mouth coverings as well as rubber gloves to reduce the chances of ingesting mould spores.  Dispose of any cloths or brushes that you have used to remove the mould so that you don’t spread spores to other areas of your home.

Wash any clothes and fabrics where mildew has grown in a hotter wash to kill off the remaining mould and ensure that they dry fully before putting them back in a cupboard or wardrobe.

Unfortunately, simply cleaning mould away will not stop the problem from coming back.  It is necessary to remove the conditions that allowed the mould to grow in the first place, and this normally means reducing the humidity levels in your home.

Take steps to reduce the amount of steam released when cooking on the hob by using pan lids and ensure that your extractor hood is working properly.  Avoid leaving bathroom doors open when using the shower and turn on your bathroom extractor fan.  Do not dry clothes indoors or put towels on the radiator as this can release large amounts of moisture into the air.

If you have found mould growing away from an obvious source of moisture, whole house ventilation could help.  Positive Input Ventilation systems (PIV) such as EnviroVent ATMOS draw in fresh, filtered air from outside your home to displace the humid air and this stops condensation for good, which prevents mould from returning.

Find out more

Improving the ventilation in your home will stop mould and mildew for good.  Our local specialists can visit your home to carry out a free survey that will identify the causes of condensation and they can provide you with advice about the best way to deal with the problem.  Enter your postcode below to find an expert in your area.