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What’s the difference between damp and mould?

Are you worried about early signs of damp, mould or condensation in your home? It’s important to know that some types of damp are more serious than others. Learn the difference between damp and mould, plus find out how to treat them, with our simple guide.

Are you worried about early signs of damp, mould or condensation in your home? It’s important to know that some types of damp are more serious than others. Learn the difference between damp and mould, plus find out how to treat them, with our simple guide.

Written by
Anna McEntee
Home, pet and travel insurance expert
Last Updated
15 APRIL 2024
10 min read
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What are the different types of dampness?

The three main types of dampness you might find in your home are condensation, rising damp and penetrating damp. Each has different causes and each needs to be treated in a different way. 

  • Condensation is excessive moisture inside a property caused by inadequate insulation, heating or ventilation.
  • Rising damp is caused by groundwater travelling up into walls and floors.
  • Penetrating damp is caused by structural problems, such as leaking gutters and roofs.

All of these can lead to mould forming.

What’s the difference between damp and mould?

In simple terms, damp is the accumulation of moisture, while mould is a type of fungus that grows in moist environments. Although mould growth often results from damp, the two issues can exist independently.

What causes dampness in a house?

Damp in a house is caused by an excess of moisture on internal walls and surfaces that has no way of escaping. The most common form of dampness in a house is condensation.

While condensation can be easily wiped away, other causes of dampness in a house can be more serious and difficult to treat. Examples include leaking pipes, rising damp in cellars and on ground floors, or water seeping in through a damaged roof or window frames.

If you spot any wet patches or dampness in your home, it’s vital to take action before the problem escalates.

What is condensation damp?

Condensation forms when warm air inside a building comes into contact with a cold surface.

It could start from something simple, such as steam build-up from hot showers, drying clothes indoors or cooking on the hob. If treated properly, condensation can be remedied without it causing lasting damage.

Spotting condensation 

The first sign of condensation is usually moisture drops on walls, mirrors or windows.

While these small droplets of water may not be troublesome right away, the effects of condensation can worsen over time.

Does condensation cause mould?

If there’s no way for excess moisture to escape, condensation could eventually lead to mould growth on walls, ceilings and furniture. 

Mould typically appears as a cloud of little black spots, usually in corners and poorly ventilated spaces, such as behind cupboards and wardrobes.

How to treat condensation on walls

If caught early, condensation mould can be easily treated at home using a cloth dipped in soapy water or with an antifungal spray that will kill the fungus. Remember to dry the area after you’ve cleared the mould. You could also treat the area afterwards with a mould-resistant paint to help prevent the issue reoccurring.

Here are some simple steps you can take to help get rid of condensation mould in your home and keep it away for good:

  • Invest in better ventilation systems, such as extractor fans or dehumidifiers in particularly damp rooms like your bathroom and kitchen.
  • Close the door and open windows when you’re using the kitchen or bathroom.
  • Use pan lids when you’re cooking.
  • Dry your clothes outdoors.
  • Place furniture a couple of inches away from external walls.
  • Leave your windows open to let your house air when the weather’s good, especially during the colder months.
  • Air your wardrobes and cupboards occasionally and keep clutter to a minimum.
  • Make sure your tumble dryer vent is outside.

Does home insurance cover condensation damp?

Most home insurance policies don’t cover damp caused by condensation. However, condensation can be managed and prevented at home. If you do this, it shouldn’t cause lasting damage.

Did you know?

While you sleep at night, you’ll breathe in and out thousands of times. On a cold night, the moisture from your breath can form condensation on your bedroom windows. These droplets of water could eventually pool on the window sills and seep into your walls and frames.

To help prevent damp patches and condensation mould in your bedrooms, wipe down your windows and open them up each morning to let in fresh air.

What is rising damp?

Rising damp can look a lot like condensation, but it has a very different cause.

As the name suggests, rising damp starts at ground level and rises upwards, climbing your walls from the floor. It can cause more damage than condensation, so it’s important to be able to tell the difference between the two.

Rising damp is more commonly a problem in older properties, where the damp proof course (DPC) – the barrier installed in the building’s structure to keep moisture out – is either damaged or missing.

Without this barrier, water is drawn up from damp ground into the cavities between bricks and cement like a sponge, by a process called capillary action.

What does rising damp look like?

Much like condensation, rising damp produces dark mould patches on your walls, but there are a few tell-tale rising damp signs you can look out for too.

Peeling paint or wallpaper, along with mould growth on skirting boards and loose flooring, could all point to rising damp. You may also notice tide-like marks and a white powder that looks like salt on the walls.

Rising damp originates from moisture under the ground, so can usually be found rising from the floors or skirting boards. You won’t usually find rising damp higher than a metre from the ground. It also mainly affects external walls.

Is rising damp dangerous?

If left untreated, rising damp could cause serious health problems for you and your family. The growth of mildew or black mould from excess humidity could trigger respiratory problems, allergies and asthma. 

As well as health dangers, rising damp can also weaken the structure of your property and damage plaster, wallpaper, floors and skirting boards. It might lead to wet rot, which is a fungus that can damage wood. Or, even more seriously, it could cause dry rot, another fungus that spreads through wood very quickly and is sometimes referred to as ‘building cancer’.

How to fix rising damp

Fixing a rising damp problem will probably mean quite a lot of work. The damp will need to be treated and the affected area damp-proofed to prevent reoccurrence. But the faster you can spot the signs of damp in your house and treat it, the less expensive the work is likely to be.

Rising damp treatment may include repairing or replacing the damp-proof course, but it’s a good idea to call in a damp surveyor to find out the exact cause of the problem before any work begins.

Rather than installing a physical DPC, there are now chemicals and gels that can be injected into walls to create a damp-proof membrane. A DPC injection is normally a much simpler process than trying to retrofit a physical DPC into an existing wall.

Is rising damp covered by insurance?

It’s worth checking, but most insurance policies won’t cover you for damage caused by rising damp. Be aware that if your home has rising damp, you’re obliged to tell your insurance provider about any damage to the property. Failing to do so could risk invalidating your home insurance in the future.

Author image Anna McEntee

What our expert says...

“Condensation might be the most common cause of damp, but it’s also the most treatable. Reducing the amount of moisture in your home is the best way to combat condensation before it becomes a problem. Simple things like opening windows, using fans while cooking and making sure tumble dryers aren’t clogged with dust could help to eliminate damp and mould.”

- Anna McEntee, Home, pet and travel insurance expert

What is penetrating damp?

Penetrating damp is caused by water from the outside of a building leaking through the walls. The most common causes of penetrating damp are leaking pipes, ageing brickwork and poor guttering.

This type of damp should be assessed and treated immediately to help minimise lasting or irreversible damage to your property.

Penetrating damp signs

Signs of penetrating damp include dark patches on the walls that won’t go away – they might even grow or darken when it’s wet outside.

Cold rooms, a reoccurring black mould that grows over time and a noticeable damp smell may also indicate that you have penetrating damp.

From the outside, signs of leaks or cracks in your guttering or roof tiles may point to an issue. It’s important to stay on top of maintaining the outside of your property to save yourself from lasting structural damage.

How to fix penetrating damp

You’ll need to identify how the water is getting into your property and fix the source of the problem. Otherwise, any repair work you do on the inside will only be a temporary fix.

If you can’t find the source of the leak yourself, you might need to hire a builder or a plumber to help. If your home insurance policy includes trace and access cover, it may cover the costs of this. Once the source of the problem is fixed, you can begin to assess the damage on the inside.

The problem with penetrating damp is that a lot of the damage might be affecting the inside of the walls, so might not be visible. It’s advisable to get a qualified damp surveyor in to investigate any damage that might be out of sight.

Does home insurance cover penetrating damp?

Depending on the source, you might be able to claim for at least some damage in the case of penetrating damp.

For example, while deteriorated piping would be considered ‘wear and tear’, if the source of the leak that caused the damp was a defective boiler, you may find that you could claim at least for damage directly caused by the leak.

If you’ve identified penetrating damp, contact your insurance provider for more guidance. Remember, you’re obliged to tell your insurance provider about any issues relating to damp, whether your insurance covers you for the damage or not.

What causes mould on walls?

Condensation and damp issues, if left untreated, could result in mould growing on the walls of your home. Mould spores thrive in damp and humid conditions. That’s why they’re often found in poorly ventilated bathrooms and kitchens.

Mould grows rapidly and will continue to spread over walls, ceilings, skirting boards and even furniture until it’s removed and treated. It can be a serious health risk, so take action as soon as you spot the first mould patches forming.

Signs of mould

Mould is typically black or green in appearance. Not only does mould look unsightly and smell unpleasant, but it can also release toxins if left untreated.

Mildew is a type of fungus that is often found in bathrooms and cellars. It’s typically white with a fluffy appearance.

How to get rid of mould

Mould needs to be treated with a specialist product that will kill the fungus. While antifungal products are widely available to buy, it may be best to call in the professionals if your mould problem is widespread.

If you decide to treat mould yourself, make sure you wear protective goggles, rubber gloves and a facemask to protect you from the mould spores.

If mould has affected your carpets and can’t be removed, it may be best to rip them out and throw them away altogether.

Mildew can be easily removed with a scrubbing brush and an over-the-counter cleaning product.

Does home insurance cover mould?

As most home insurance policies exclude damage caused by damp and condensation, it’s unlikely you’ll be covered for mould problems. The best way to protect your home from mould is to prevent it from growing in the first place:

  • Let in as much natural light as possible during the day
  • Clean, vacuum and dust regularly to prevent fungus from growing
  • Keep rooms well-ventilated to ensure moisture can escape
  • Ensure your home is well-insulated to help keep humidity levels low during the winter
  • Consider buying a dehumidifier to help remove excess moisture from the air.

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Frequently asked questions

How do I know if my home has a damp-proof course?

You can check if your house has a DPC by looking at the external walls. Close to the ground, between 8cm and 60cm up, you should see a thin dark line running horizontally between the brickwork all the way around the external walls.

If your home was built in the past 150 years or so, it probably has a DPC. Historically, builders used slate, but in more modern buildings it might be a plastic membrane.

What are the health risks of damp and mould?

According to the NHS, you’re more likely to suffer from respiratory problems, allergies and asthma if you live in a house that has damp and mould. Vulnerable people, including babies, elderly people, anyone with skin or breathing conditions and those with a weakened immune system, should avoid spending time in a damp and mouldy house.

What is dry rot and how do I identify it?

Dry rot is a fungus that destroys wood and timber. It infects moist and damp wood, but it can also move through other building material. It could cause serious structural damage to your property, so you should identify and treat it as soon as possible.

Here are some signs of dry rot to look out for:

  • Wood and timber start to shrink, darken/turn grey and crack
  • There’s a damp or musty smell
  • Timber becomes brittle to the point where it crumbles in your hand
  • Large mushroom-like fruiting bodies start to form
  • Patches of rust-coloured spore dust form around the mushroom-like growths.

What causes damp in bedrooms?

Moisture built up from breathing and sweating while you’re asleep can cause condensation in bedrooms. Lack of ventilation will typically steam up your windows and eventually cause black mould to develop.

If there are damp patches on the walls or ceiling of your bedroom, it’s likely that water is penetrating its way through from the outside.

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Anna McEntee - Home, pet and travel insurance expert

Anna’s all about delivering fantastic insurance products at a great price. Value is the most important thing for Anna, as she cuts through the jargon and finds what’s most important and worth your hard-earned money.

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