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How to get rid of mould and mildew on walls

Mildew and black mould on walls is not only unsightly — it can also be harmful to your health. Fortunately there are ways to stop mould on walls and keep your home healthy. Read on for handy hints on how to clean mould — and keep it from coming back!

Updated By Wiki Tips English Team

aloe vera plant in bathroom against a purple wall

Mould and mildew are the bane of most households, but luckily, it’s possible to use everyday cleaning products to banish and prevent mould from creeping back in again. Mildew, whether on walls or other surfaces, like floors or carpets, is not great news for your health, so it’s also really important to tackle the root cause. Read on for a quick, 3-step guide on how to get rid of mould on walls in your home.

What are mould and mildew and why do they occur on walls?

  • Mould is a kind of fungus that develops from airborne spores. It usually grows in damp, warm conditions without much airflow, which is why household bathrooms and loft spaces often suffer from mould. It is often simply caused by humid conditions and lack of ventilation, but sometimes mould on walls can be due to plumbing leaks, both inside and outside the property. Badly insulated heating pipes can also cause a build-up of moisture behind the walls.

  • Mildew is the name for the most common type of black mould on walls, characterised by spots that can then spread over larger areas if left untreated. To find out if you have mildew on your walls, apply some bleach onto the affected area with a cloth. If the dark colour fades after a few minutes, it’s mildew. If not, the patch is probably just dirt.

Why do I have mould on the walls in my bedroom?

Having mould on the walls in your bedroom can be a real problem. Bedroom mould is usually caused through condensation or high humidity, normally from weather conditions. It can be caused by poor ventilation and moisture in the air. Be sure to check cracks in windows or drainpipes which could be causing a build-up of moisture.

Always follow the instructions carefully when using specially formulated mould and mildew cleaners. Take care to protect yourself by wearing eye protection, gloves, and a face mask, if necessary, and test the product in a small area before continuing.

You will need:

  • Stiff-bristled brush
  • Cloth
  • Chlorine bleach
  • Water

How to clean mould off walls in three steps

Time to learn how to clean mildew and mould off walls! A word of caution: mould can cause allergic reactions and poor health, so if you have an extensive problem with mould on walls, it may be best to seek expert help. If tackling a smaller area, make sure you wear protective eyewear, gloves, and a face-mask, as contact with the spores can be harmful. Open windows or use a fan in the room while working.

  1. Make a solution of chlorine bleach and water

    usually one part bleach to three parts water – or get hold of a household detergent like  with bleach as an active ingredient.

  2. Scrub the blackened area

    Using a stiff-bristled brush, scrub the blackened area

  3. Rinse thoroughly and dry

    Rinse with a cloth and water and leave to dry.

If this doesn’t work, there are products specifically formulated for mould and mildew on walls that may be stronger, but remember never to mix cleaning solutions together as this can cause dangerous chemical reactions. You can find out more about how to use mould and mildew removers here.

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How does a dehumidifier work?

What do dehumidifiers do to reduce humidity at home? The process is fairly simple:

  1. The dehumidifier’s fan mechanism pulls in air from your home

  2. This air is cooled inside the dehumidifier, and the moisture condenses into water

  3. The water is separated off into a different section, and the drier air is lightly re-heated

  4. This air is then released back into the room with much less moisture

  5. The unit will switch off when the room reaches the desired humidity level, or when the water container is full

How to use a dehumidifier:

  1. Different dehumidifiers have different capacities, so factor in the size and humidity of your room before you choose one.

  2. Set up the dehumidifier in the dampest area of the house, like the bathroom or the basement

  3. Consult your chosen dehumidifier’s manual for specific instructions

  4. Set the dehumidifier with your ideal humidity level: this should be between 40% and 60%.

  5. Be aware that the first few cycles that your dehumidifier goes through will be removing more humidity than later cycles: at first, it will be removing excess water that has built up over a certain period of humidity, whereas once it is running regularly it will be collecting lighter amounts of water to maintain an ideal humidity level

How to remove and prevent condensation mould

Spotted some nasty organic 'wall art' around your windows or in your bathroom? It may well be condensation mould. This type of mould appears when moist air clashes with a surface with a lower temperature, leaving nowhere for the moisture to go. Maybe you've seen little droplets of water form by the window or in cold corners? These moist conditions make for an ideal breeding ground for mould, so you'll want to get rid of the condensation and dry out the air as soon as possible.

To remove condensation mould:

  1. First of all, wear a protective face mask, goggles, and gloves while doing this.

  2. Try a bleach-based spray (always try the product on a small part of the surface first before treating the whole of the affected area). You can also try a homemade spray made from one part white vinegar and one part water. Spray the product on the wall and let it work overnight.

  3. Wash off the mould and the product with a damp cloth (you may need some elbow grease here) and use a dry cloth to remove the moisture.

To prevent condensation mould from returning:

  • Increase the ventilation in your home by opening a window. Take a look at your air vents to see if they're blocked.

  • When you're not letting fresh air in, turn up the thermostat a little.

  • Dry laundry outside as much as you can. If this isn't possible, consider investing in a dehumidifier.

How to prevent mould and mildew on walls: our top 6 tips

Once you’ve dealt with a mildew infestation on your walls, the next step is to try to stop it recurring. Here are your options:

  1. Buy a specialised product. An anti-microbial spray, for example, can help prevent the spores from settling again. Anti-mildew paint can also be purchased from most DIY stores.

  2. Consider installing an electric de-humidifier in badly affected areas. This is ideal for long-term mould prevention.

  3. Look into upgrading your home insulation. Sometimes, but not always, bad insulation is the root of the problem. Walls and ceilings that are properly insulated will be less affected by condensation and therefore mould.

The best tips on how to get rid of mould involve cutting out the damp conditions it loves so much:

  1. Keep bathrooms, kitchens, and other humid spaces well-ventilated and as dry as possible

  2. Spread out shower curtains and towels to dry.

  3. Tackle leaks as soon as they’re discovered to prevent moisture seeping into cavities and under floors.

Don’t panic if the mould and mildew on walls return: this is a common occurrence, and you’re now a bit of an expert on how to treat mould on walls!

Originally published