Top Causes of Damp in Your House and How to Treat it

Top causes of damp and how to treat it

Damp – one syllable that will strike fear into the heart of any homeowner. Damp is just excess moisture in your home that can’t escape, but that moisture can cause plenty of issues. Damp can make a room feel cold, clammy, and unpleasant, and left unchecked, it can even cause structural issues. But luckily, there’s plenty you can do to prevent damp and even fix it once it occurs. From spotting the tell-tale signs of damp in a house to the most common causes, our guide on how to treat damp will make sure your home stays warm, cosy and welcoming.

In this guide:

Signs of damp in a house

As you’d expect, damp is at its worst in autumn and winter, rainy, windy seasons with long wet spells. You can usually smell damp in the winter, so look out for the unique musty smell – but there are some key warning signs of damp you should keep an eye out for year-round.

Damp in walls

If your walls feel cold or wet, it’s a sure sign of damp in the house. Keep an eye out for small black or grey spots, which can be mould caused by the moisture in the wall. If there’s a spot where paint is bubbling or flaking, or where wallpaper is bulging or peeling, it could also be a sign of damp in the house.

Damp on ceilings

The corners of your ceilings can be one of the first places you spot damp in your house. If you notice browning in the corners of your rooms or where the chimney breast runs behind the wall, it can be an early warning sign.

Damp in the bathroom

Bathrooms are high in moisture thanks to steam from the shower and bath, so keep an eye out for signs of damp in your bathroom. Check the sealant on windows and the edges of baths and showers for black mould in the grout, one of the signs of damp.

Damp in the kitchen

The chances are you’ll notice any obvious signs of damp in your kitchen, but you might not think to check inside your cabinets to make sure there’s no damp coming in from the walls. If you have furniture against the walls or in corners like dressers or built cabinets, check that there’s no mould growing behind them too.


Windows are one of the worst culprits for letting water and moisture into your home. As part of winter-proofing your home, be extra vigilant about windows. If you notice lots of condensation on windows, or pooling water on windowsills, it’s a sign that moisture is getting into your home. Check the sealant to make sure it’s not pulling away, and that no black mould is growing in the grouting.


Damp can hide behind furniture, especially larger items that you don’t move very often like sofas and wardrobes. If your home has a damp problem, mould can start growing on soft furnishings like sofas and chairs, so make sure that you move them away from the walls to let air circulate.

Basements and cellars

If you’ve ever been in a dank and musty cellar, you’ll already know that damp can be very obvious in basements – and can be the first place you’ll spot penetrating damp. As these spaces are usually unheated and already prone to damp since they’re beneath ground level, check the walls for staining, and if anything is being stored in the basement make sure there are no mould or mildew spores growing on cardboard boxes or soft fabrics.


What causes damp in a house?

There are plenty of causes of damp in a house, which can come from both inside and outside. Water and moisture are persistent and can cause damage slowly over time, so you might not notice until it’s a serious problem. If you know what’s causing the damp, you’ve got a better chance of diagnosing and treating damp walls and ceilings.

Here are some of the main causes of damp in houses:

Penetrating damp

Penetrating damp is one of the main causes of damp in homes. When the exterior of your home lets in water, even a small crack can become a big issue. Old houses especially can face issues like weathered flashing and mortar pointing that’s falling away, allowing rainwater to pool and trickle in. Leaking gutters are also a top cause of damp, especially if your gutter is blocked and water is pushing against brickwork, causing erosion.

Poor ventilation

There’s plenty of moisture inside your home too. Every time you run a shower, leave laundry to dry, cook or wash, you’re introducing a little bit of moisture into your house, which is a top cause of damp. This moist air needs a way to get out, or it will build up and cause condensation. Modern homes are designed to be watertight, which is great for stopping penetrating damp, but sometimes can hinder ventilation.

Lack of waterproofing on old homes

If you have an old house (like many people in the UK) you might unfortunately be more likely to have damp. Old period properties weren’t designed with waterproofing in the same way a modern home would be, so moisture is more likely to pass through your ceilings and walls. Some period features, like chimneys, also make damp more of an issue. If a chimney isn’t fully blocked off, water can trickle down, causing issues in rooms even if they don’t have a fireplace anymore.

Rising damp

Most houses have a damp-proof course, which is a kind of space built into the walls of your house to prevent damp from spreading through the walls. Older properties might not have these courses, or they might be less effective – which means that moisture can rise from the ground below the house and move into the house and the floors above. If your floors and rooms are cold and smell musty, and if this gets worse the closer you are to ground level, you may have rising damp.

How to treat damp

When it comes to damp, prevention is better than a cure. It can be hard to know how to stop damp in a house, but there are things you can do to keep your home warm and cosy. Repairing damp-damaged walls and ceilings can be done, but if you can stop the moisture from getting into your home in the first place, it’s a lot easier.

Treating damp walls

Damp in walls is an unpleasant (and unsightly) problem, but it can be treated. You can easily remove black mould spores and spots from walls with warm soapy water. But if you have a significant case of rising damp, treating damp walls might need to be handled by professionals who can replaster and dampproof internal walls, to remove the damage and prevent it reoccurring.

Make sure you’ve got ventilation

Plenty of modern homes have extractor fans in the bathroom and kitchen to filter excess moisture out of your home. If you don’t have these and you’re noticing that rooms stay damp for a long time (for example, after the shower’s been running), then it might be a good idea to invest. If you can’t install extractor fans, something as simple as keeping windows open a little when you shower can help to keep your home ventilated and well-aired.

Remove the excess moisture

If you’re seeing some of the issues from poor ventilation, one solution is a dehumidifier. These machines are relatively inexpensive, and pull moisture out of the air, and they’re ideal if you have one room like a basement or attic room that has a specific problem with damp.

Keep your house warm

Make sure your heating is running for at least some of the day, especially in winter, and try to keep a constant temperature. Sudden drops in the temperature of your home and cold spells in your house could cause condensation, especially around windows.

Make the most of your central heating

Invest in double-glazed windows if you don’t already have them, and make sure you have loft and wall insulation to keep the heat inside your home. As a bonus, this will also mean that your central heating costs stay low!


Damp can be a pain to deal with once it gets a hold in your home, but by following this guide on how to treat damp, you can keep your house fresh and warm. By learning to recognise the tell-tale signs of damp in houses and understanding the causes of damp, you can prevent it taking root and causing major issues, helping your house to hold its value and remain cosy and welcoming. For more guides on how to care for your home and property advice, check out the Good Move blog.


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