31st Jan 2022

Types Of Mould On Walls And How To Treat Them

Insulation mould can be a common problem affecting wall insulation that becomes too moist. Good insulation can help to prevent mould from developing in walls by regulating the temperature of your home. However, insulation can sometimes become mouldy, requiring urgent attention and potentially even removal. 

Damp is another type of mould affecting walls, and needs to be dealt with as soon as possible to prevent further issues developing.

If you want to know how to treat mould before painting, or are concerned that insulation mould may be causing additional problems, here are our top tips for tackling mould on walls.

What Causes Insulation Mould?

Insulation mould is most likely to occur if walls get wet, or in flooded or very humid spaces. For example, insulation mould in an attic could be due to a roof leak or the space being poorly ventilated. Mould can also grow in small gaps in insulation, so it’s important to make sure your insulation is installed professionally to avoid this.

When wall insulation gets wet, the moisture can act as a food for mould, encouraging spores to spread, exacerbating the problem. 

The type of insulation you choose can affect the likelihood of insulation mould developing. Avoid using cellulose insulation in a space that’s at greater risk of becoming moist for this reason; as it’s made from recycled paper sources, this can make it a breeding ground for mould.

Fibreglass insulation is one of the best types of insulation for reducing the risk of mould, especially if it’s installed without backing.

How To Identify Insulation Mould

It’s important to identify insulation mould as soon as possible to help prevent it spreading to the plaster. 

Insulation mould can typically be identified by the presence of spurs, which may be black, brown, white or green in colour - depending on the colour of your insulation material, they may even show as pink or yellow. Sometimes, insulation mould may look like a thin grey or black coating covering the material.

Insulation mould can have a slightly musty smell, and it can potentially lead to respiratory issues if left untreated, which is why it’s so important to spot mould in walls as soon as possible.

Types Of Insulation Mould And How To Treat Them

White mould and black mould are two of the most common types of insulation mould. Read on to find out how to identify and treat them.

White Insulation Mould

White mould can be harder to identify on some types of insulation due to its colour, so you may need advice from a professional if you’re worried that this may be present in your walls. White mould usually takes the form of a white fungus, and it can eat away at insulation material, which could potentially lead to structural damage.

If you find white insulation mould in your property, it’s important to get this professionally removed, as you don’t want to expose yourself to what could be harmful spores.

Black Insulation Mould

Black mould on insulation can be caused by the fungus stachybotrys chartarum, which is most likely to occur in moist spaces. 

If you’re going to try to remove black mould yourself, you’ll need to wear safety goggles, gloves, and a mask that covers your nose and mouth, before tackling the affected area with bleach. It’s also important to address the root of the problem - for example, a leak that’s contributing to the moisture - to prevent black mould from returning.

Damp Prevention Tips

Around 3% of households in England had damp in at least one room of their home in the two years leading up to March 2019, according to data from the UK government. Meanwhile, research published in the same year by Rentokil Property Care found that 5.8 million renters in the UK had experienced damp or condensation issues in their home.

To prevent damp from developing, it’s important to keep rooms well-ventilated to discourage condensation. You can now buy specially designed anti-condensation paint, which can be particularly effective around windows or on walls in spaces that get especially humid. The right kind of insulation can also help with damp prevention.

Nicholas Donnithorne, UK technical manager at Rentokil Property Care, explained: “An average family of four can produce up to 24 pints (14 litres) of water vapour in just 24 hours, and all that moisture has to go somewhere. When the air cools, condensation forms on cold surfaces at what is known as the ‘dew point’.

“Simple lifestyle changes such as drying clothes outside or leaving the window ajar could go a long way in helping to reduce issues and prevent mould growth.”

Damp can cause mould on walls, which typically takes the form of brown, rust-coloured patches that can have a distinctive musty smell. If left untreated, damp can potentially lead to structural problems, as well as health issues.

How To Treat Damp

Sometimes, a damp problem is so severe that repointing is needed to fix external joints that may have decayed over time, exposing them to the elements. This is a problem that typically affects older properties more, but if you have any concerns about the cause of damp in your home, you should always seek professional advice.

However, if you’re trying to remove the stains left by damp that has since been addressed with repointing, or if you know that a wall is stained due to a splash, you can try to remove damp patches yourself. To remove mould on your walls caused by damp:

  • Fill a large bowl with water and washing up liquid
  • Dip a clean cloth into the bowl, wringing out excess water
  • Carefully wipe the mould off your wall, taking care not to spread it around, as this could make the issue worse
  • Use a clean, dry cloth to dab away any remaining moisture from the wall
  • Throw these cloths away to make sure you don’t use them again to prevent the mould from spreading further around your home

How To Prevent Insulation Mould Returning

Insulation mould needs removing as soon as possible to stop the issue spreading. Mouldy insulation may need removing in full, leaving you needing new insulation. The best types of insulation to prevent mould include:

  • Sheep’s wool insulation, which can be one of the best types of insulation for preventing mould, as it has natural damp-fighting properties
  • Fibreglass insulation without backing is another brilliant option for insulating your home without causing any mould or damp
  • Moisture-resistant plasterboard, which has water-resistant properties that make it ideal for rooms with a high humidity level, making it a good option for kitchens and bathrooms

Try to manage the risk of insulation mould developing in the future by:

  • Keep rooms well-ventilated, particularly when cooking, using a tumble dryer, or when laundry is hanging up to dry
  • Use a dehumidifier to remove excess moisture from the air
  • If you notice condensation forming on a window, open it as soon as possible
  • If any condensation has dripped onto the wall or window sill, wipe it away quickly

If you have any questions about fibreglass insulation from U Value or need advice on replacing the insulation on your home, please contact us here.