How to Prevent Damp and Mould

Mould is more than just unsightly – it produces allergens, irritants and, sometimes, toxic substances, and can lead to quite serious issues in those of us that suffer with asthma, allergies and eczema. So it’s important to eliminate damp and mould from your property, and stop it coming back.

Not only is mould unsightly, but it’s damaging to our health, too.

What causes damp and mould?

Damp and mould are caused by excess moisture in the air. The warmer the air is, the more moisture it can hold – which also means the colder the air, the less moisture it can hold – which is why keeping your property warm can help to reduce damp and mould.

What causes excess moisture?

Excess moisture can be caused by leaking pipes, rising damp, rain seeping in through gaps in the roof or around windows. This kind of water ingress can be quite sudden and shocking, and most of the time you’ll be able to pinpoint the cause (if not, you might need a water ingress investigation).

In addition to these external factors, excess moisture can also be said to be caused by our lifestyle. For example, whether we dry our clothes indoors, keep windows closed when we shower and cook, and don’t keep our homes warm, condensation will form.

What happens is that the moisture from the clothes/cooking/shower, etc. gets held in the air, and when the air cannot hold any more moisture, droplets of water form on the coldest surfaces – this is why we see condensation running down windows, which are one of the coldest parts of a property. It’s also why damp and mould are most often spotted on external walls, rather than internal walls within a property.


How can damp and mould be prevented?

The first step is to find out what could be causing the excess moisture within your property. If you keep windows closed while drying your clothes, then be sure to open them. You could invest in a tumble dryer, which can either vent the excess moisture which causes damp and mould straight outside, or can collect the water in a container to be poured down the drain instead. When you see the amount of water that comes out of a condenser tumble dryer, you’ll realise why drying clothes indoors leads to damp and mould!

Here’s a list of quick changes to you can make which will reduce the amount of moisture in the air, and therefore reduce the chances of your property becoming damp and mouldy:

  • Ventilation is essential; open windows in all rooms as much as possible.
  • Provide positive ventilation by means of a fan in the bathroom. If condensation issues are very bad then you can install a humidistat (this is like a temperature thermostat, but it turns on when it senses high humidity, rather than low temperature).
  • Top tip: you can check an extractor fan is working by placing a sheet of paper against it. If it stays put, it’s working!
  • Install a cooker hood and fan, to vent externally, in the kitchen.
  • Do not dry clothes within the property, or if you do, make sure it’s in a warm, ventilated room, or use a tumble dryer or dehumidifier to keep moisture out of the air.
  • Ensure adequate background heating throughout the day. As mentioned above, the colder air is, the less moisture it can hold.  
  • Close the bathroom door after taking a shower or bath to allow steam to be taken away by the fan.
  • Use fungicidal paint (you can find some good options on the Rawlins Paints website) in areas where persistent condensation occurs.
  • Clean condensation residue regularly, before mould has the chance to grow.
Damp can even cause paint to flake off walls.

What if you can’t work out what’s causing the damp and mould?

If the cause of your damp and mould isn’t so obvious, then a damp and water ingress inspection might be required. During one of our preliminary visual inspections, we’ll take a look at the sealants around windows and doors, check the render and pointing for cracks where water ingress could be occurring, and inspect the roof externally and internally to check for any points where rain could be entering your property.

Our structural reports always provide conclusions as to the cause of the issue and recommendations for how to fix any water ingress which may be occurring. For example, we might recommend that the external brickwork is repointed, the flashings around chimneys are fixed, or the sealants around windows are raked out and replaced. If the repairs needed are quite extensive, we can also prepare a schedule of works for the repairs, and manage the whole project.  

For example, the resident of the flat below called us to investigate the damp staining on her living room ceiling. From our inspection, we worked out that damp staining coincided with the balcony door of the flat above, and we concluded that the lead tray was most likely to blame – either there were holes in it, or it hadn’t been installed at all. Installing a new cavity tray should fix the problem.

damp staining caused by a leaking cavity
Damp staining caused by a faulty or missing cavity tray in the balcony door above.

How to remove mould

Now you know what’s causing the damp and mould and have worked out a plan of action to prevent it in future, the next step is to remove the mould. Luckily, it’s pretty simple to remove mould from walls and ceilings, and you can probably do it yourself using washing up liquid and water. But if the mould covers an area of more than 1m x 1m, it’s probably best to get a professional in to remove it.

Don’t forget to protect yourself from mould spores – we recommend using goggles, long rubber gloves and a mask.

To remove mould, wipe the affected area with a rag dipped in a bucket of water and washing up liquid. Keep dipping and wiping till all the mould is removed from the surface, then grab a new rag to remove any remaining moisture from the wall. Make sure to throw the rags away and clean the bucket well – those mould spores like to linger!

Now that you’ve got a nicely cleaned surface, a good idea will be to paint over it with fungicidal/anti-mould paint, which should help to prevent the issue occurring in the future. This approach, combined with our suggestions for reducing condensation within your property, should mean you’re mould-free from here on out.

Good luck!

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