The PuroClean Blog

Mould vs. Mildew – What’s the Difference?

Mould and mildew are very similar fungi, but there are differences between them as well. For example, both fungi grow in damp and humid areas, but they can affect health and properties differently. Knowing the differences between mould and mildew is useful for knowing how to approach a mould infestation problem. Here’s what separates mould from mildew:

Where They Grow

Both mould and mildew can grow in damp areas in homes and outdoors. They need an organic food source, such as drywall, wood, plants, and soil.

Mould can grow on any organic surface in a home. Given enough time, mould can cause materials to rot and destroy the home’s structural components. Mildew grows mostly on plants and can kill them if not removed in time. Mildew is also the name of the plant disease caused by parasitic fungi.


Mould is usually fuzzy or slimy, whereas mildew appears either powdery or downy. Downy mildew is yellow at first and turns to brownish yellow later on. Powdery mildew is white, and then turns yellow and black when it matures.

Mould appears as irregularly shaped spots that can have different colors – blue, green, yellow, brown, gray, black or white. Mildew usually grows in a flat pattern and appears as white, gray, or yellowish patches that turn black or brown over time.

Exposure Symptoms

Mould exposure can cause several health problems such as allergic reactions (sneezing, itchy eyes, runny nose, coughing, wheezing, irritation of the throat, rashes, etc.), respiratory problems (difficulty breathing, coughing, asthma attacks), heart problems, migraines, depression, and more. Mildew exposure poses fewer health risks – coughing, headaches, sore throat, and respiratory problems.


Some moulds are beneficial. For example, Penicillium is used to make antibiotics and can also be used in the production of cheese and tofu. Mildew does not have any known benefits.

Prevention and Removal

As mould and mildew thrive in humid environments, it is important to keep properties dry to prevent growth. A dehumidifier should be used to keep humidity at 30-50%, and appliances should be ventilated. Here are more mould prevention tips.

Removing mould and mildew alone can be difficult and risky. For small infected areas – less than three square metres – on surfaces like walls, mould should be scrubbed with a mixture of household detergent and water. If the affected area is larger than three square metres, the safest and most efficient way to remove the mould is to call a mould remediation company. Here’s why DIY mould removal is not a good idea.

Mildew on plants can be removed by wiping the leaves gently with a dampened paper towel. After each wipe, the paper towel should be freshened. When all the paper’s parts have touched the mouldy surfaces, it should be replaced. Any leaves that still have mould visible on them must be cut off.

Among the many kinds of moulds that can grow indoors, black mould is one of the most infamous. Here are black mould removal tips. The PuroClean team stands ready to provide professional restoration services to any property affected by fire, water or mould damage.

Follow us on Twitter, Facebook, Google+ and LinkedIn to get our notifications!