How to remove mould and damp

Project overview

Not only does mould look ugly, but if it’s not treated properly it can impact your health causing asthma, respiratory infections or allergies. Mould is a reasonably easy problem to tackle so long as you identify the problem and try not to cut corners. So here’s our guide to removing, fixing and preventing mould infestations.

Print Version

What causes mould?

Before you can stop black mould from growing, you need to understand what causes it in the first place.

Mould is the result of excess moisture which can usually be attributed to either structural problems or ventilation problems.

Excess moisture can be caused by leaky pipes, rising damp in basements or ground floors, rain entering through crevices or damage to roofs or windows. It can also be a problem with new build houses which have been constructed before ground water has dried out. If your home is a new build, damp can be a harder problem to fix so you should consult a professional.

Mould is also the result of a build-up of condensation. Condensation is formed when there’s too much moisture in the air and hot air comes into contact with a cold surface. This can be caused by simple everyday tasks like showering, cooking, ironing and drying clothes indoors.

Condensation is easy to prevent.

How to stop condensation

Stopping condensation doesn’t require much effort.

  • Open windows or put on the extraction fan when you’re showering or bathing
  • Put lids on saucepans and use the extraction hood
  • Regularly ventilate your home and leave doors open to let air circulate – Opening your windows for 15 minutes each morning is a good way to start.

Once you reduce the moisture in your home, the chances of black mould growing is slim.

How to clean mould off a painted wall

You should only remove mould if it’s caused by condensation and covers an area smaller than one metre squared. If the mould is caused by sewage or contaminated water, call in a professional.

Before you start, wear goggles, long rubber gloves and a mask that covers your nose and mouth to protect you from the mould spores. Open the windows for added ventilation but keep the doors shut to avoid spores spreading.

  1. Fill a bucket with water and a mild detergent like washing up liquid. Or use a dedicated mould remover to make quick work of it. 
  2. Dip a cloth in water and wipe the mould off the wall. Don’t brush it as this can release mould spores.
  3. Once you’ve removed the mould, use a dry rag to remove the rest of the moisture.
  4. Throw away the cloth and vacuum the room to make sure you’ve removed all of the spores.

If you have mould on soft furnishings like clothing or soft toys, they should be shampooed or professionally dry cleaned.

Top tip: You can use this same process to clean mould off wallpaper as well as painted surfaces. If you’re removing it off wallpaper, don’t use too much water or the surface will bubble.

How to prevent damp in a bathroom

Damp and mould are most common in bathrooms because of regular excess moisture. The best way to prevent it from building up is to keep the room well ventilated by opening a window or switching on the extraction fan every time you shower or bathe.

If you have poor ventilation in your bathroom, there are still some steps you can take to reduce condensation.

  1. After you’ve had a bath or shower, use a squeegee to a remove the excess water from the walls. This will help cut down the amount of extra moisture in your bathroom by as much as three quarters.
  2. Seal the grout with a standard sealer to stop moisture from leaking through once a year.

How to treat damp walls before painting

Before you treat damp, you need to address the source of the problem first. Identify what it is that’s causing mould to develop and fix it. If it’s condensation, follow our recommendations above.

The good news though is that treating a damp wall is really easy and will take next to no time at all.

  1. Remove the mould from the wall following the above steps.
  2. Let the area thoroughly dry out before you begin treating it.
  3. Use a specialist damp seal to prevent mould from growing back. Follow the instructions on the packaging. Some may require you to paint an area around the damp and other may require more than one coat.
  4. Once the seal is dry, touch it up with paint.

This should stop damp from coming through a wall.

How to paint over mould

You should never ever paint over mould. It won’t tackle the source of the problem and can often make it look worse. Whether mould is in your bathroom, kitchen or living room, It’s much better to get rid of it first and then treat the area.

Once you’ve treated the affected area, use a specialist anti-mould paint to finish the job. If you’re painting a bathroom or kitchen, make sure the paint you’re using is mould resistant for extra protection.

Damp stains can be painted over with a suitable paint, so long as the damp has dried and the source has been treated. Some damp sealants can be applied directly onto a wet surface, so check the instructions before you begin.

Share article