How to Identify Signs of Damp in your House

Houses across the UK are subject to changes in weather, humidity, temperature and over time these can have an impact on your home. You might notice damp patches, musty smells or mould growth for the first time, and wonder what has caused the problem. 

Damp can affect any building new or old, but typically it can be attributed to a lack of
property maintenance, porous building materials, poor ventilation or the absence or failure of an existing damp proof course. Moisture can enter your house through upwards movement of moisture known as rising damp, through moisture migrating into the fabric of the building caused by penetrating damp, or by excessive moisture within the property, known as condensation. Sometimes damp problems are caused by plumbing leaks, or leaky appliances like washing machines.

Our expert guide explains the most common signs of damp in the home, and solutions to prevent the problem returning. If you are unsure about what to do next, we can arrange a damp survey by a trained professional who will provide advice and recommendations to help treat damp in your home.

Damp is the presence of unwanted moisture in a property either entering the building from external sources or because moisture has condensed on surfaces internally. It can cause unwanted or unpleasant problems such as musty smells, deterioration of plasterwork and paint, and mould growth. It can even lead to health concerns in some circumstances. Rising damp, penetrating damp and condensation are the three main types of damp that affect properties in the UK.

There are three main routes that cause damp, and these differ depending on the type of damp.

• Rising damp is caused by moisture rising upwards from the ground through walls by capillary action. If a damp proof course fails, there is no longer a waterproof barrier to prevent this.
• Penetrating damp is caused by defects in the building fabric, such as damaged masonry or pointing, damaged roof tiles, blocked gutters or high ground levels.
• Condensation is caused by warm moist air inside the building condensing on cold surfaces, which can often lead to mould growth.

These are the main types of damp affecting houses, and each type has tell-tale signs that can be used to confirm the type of damp. Sometimes the damp problem can be complex, so a damp survey by an experienced and qualified surveyor may be required to get to the root cause of the problem.

If you have a damp problem its very important to fully understand the root cause in order to correctly treat the issue. Unless the source of moisture is addressed the problem could return in the future.

There are telltale signs of damp in houses, which can be used to confirm your next steps.

• Beads of moisture on cold surfaces like windows, tiles and cold walls
• The appearance of black mould on walls, behind furniture or in cupboards
• Mildew (mould) forming
• Increased humidity levels
• Walls that are cold or wet to the touch
• Damp smells
• Rotten wood
• Stained walls, peeling wallpaper or flaking paint

Condensation is caused by excess moisture and will condense on cold surfaces.

• Damp patches on external solid walls
• Damp stains on walls or ceilings
• Peeling or bubbling wallpaper and paint
• Wet and crumbly plasterwork
• Rotten wood
• Black mould isolated to one specific area
• External damp patches in the same area
• Musty smells

Damp penetration can affect any level of a property, so may appear on walls, ceilings, and on any floor within your property.

• Damp patches along the ground floor
• Tide marks up to a metre high, above skirting board level
• White powdery salt deposits known as efflorescence
• Peeling and blistering paint and wallpaper
• Deteriorating Plasterwork
• Rotten skirting boards
• Musty smells

Rising damp will only ever affect ground level walls, up to a metre. If you notice damp problems elsewhere this indicates it is not rising damp.

• Damp patches or water marks on walls
• Yellow or brown stains
• Salt stains or efflorescence
• Moss and algae on walls
• Vegetation growth in gutters, drains or on chimneys
• Blocked drains 
• Cracked, crumbling or missing mortar or masonry
• Evidence of broken or damaged tiles

You first need to understand what is the source of the damp. You can get a better understand of this by:

If you are unsure or would like a second opinion from a professional expert, you should request a damp survey to be carried out.

The most effective way to stop condensation in your home is to ensure the property is sufficiently ventilated, cold surfaces are insulated and you use regular heating.

If your home does not have adequate levels of ventilation, moisture levels in the air will increase, condensation will form on cold surfaces and mould growth will begin to form. Simply wiping away condensation and mould is not a long term solution, as it will come back if the root cause is not addressed.

In order to stop penetrating damp, you must find the source of the moisture ingress and fix the building defect causing the problem. Regular maintenance can prevent penetrating damp from occurring in the future, and often small remedial repairs from a local builder can fix issues such as broken guttering and areas of mortar that need repointing. Sometimes high ground levels may require elements of structural waterproofing.

Rising damp is prevented by the installation of an effective damp proof course that creates a waterproof barrier to prevent moisture rising upwards from the ground. If you have noticed signs of rising damp, this means there is either no damp proof course in place at the property, it is bridged or it has become defective over time.

The most cost effective solution to stop rising damp is the installation of a chemical damp proofing course. This involves an injection of a waterproofing cream at regular intervals into the mortar course, creating a water repellent barrier stopping moisture from rising up through the walls and potentially carrying hygroscopic salts with it.

We would recommend a damp specialist is engaged to confirm the problem is rising damp, and then provide recommendations for an effective solution. This may include replastering if existing plaster has been deteriorated by salt migration.

If you are unsure about the type of damp affecting your property, and would like professional advice, Peter Cox are here to help.

If you book a damp and timber survey with Peter Cox you can expect a thorough and detailed survey from a trained surveyor, with all findings detailed in an easy to understand report, backed by photographic evidence. We have CSRT/CSTDB qualified surveyors located across the country from our network of local branches. The survey report will detail any issues found and recommendations for further treatments, but only when required.

We are a Which? Trusted Trader and we’re rated ‘Excellent’ with over 2,500 independent reviews on Trustpilot.

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  What makes a house feel damp?

  One of the main reasons a house will feel damp is because of excess moisture creating a humid atmosphere. This is caused by everyday tasks such as cooking and cleaning, but unless there is adequate ventilation for the moisture laden air to escape, it will simply remain in the atmosphere, or condense on cold surfaces. The lack of ventilation and humid air makes areas of the house feel damp and cold, and over time can lead to mould growth.

  Damp walls caused by problems like rising damp or penetrating damp may cause a room to feel damp and cold, as these surfaces are no longer able to retain heat, as their thermal efficacy drops and if you do heat the room, the damp wall will absorb it.

  To make a house feel less damp you will need to address the root cause of the problem, and may require a professional survey to fully understand the dynamics of the property.

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  Does damp smell?

  Yes, damp has a persistent musty smell that is noticeable after a while if you have a damp problem. It is similar to when you leave clothes in the washing machine too long, or they have not dried quick enough. Other problems associated with damp, such as fungal decay, may leave an earthy smell similar to rotting wood or mushrooms. This could indicate a more serious problem in your home. 

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  What are the symptoms of damp air?

  When you have damp humid air in a property you will notice damp patches on cold surfaces, like the inside of windows or the surface of tiles and mirrors. It may even lead to mould growth on walls and ceilings. This could lead to health symptoms associated with mould growth including respiratory issues such as coughing, wheezing, and shortness of breath. Some people may have allergic reactions with symptoms like sneezing, a runny nose, watery eyes, and skin rashes, and a general feeling of unwellness including headaches, fatigue, and sleep disturbances

  Associated with the damp, lack of ventilation and air circulation means the moist stale air may contain mould spores, dust mite allergens and volatile organic compounds (from cleaning products, hair spray, deodorant and scented candles), which can also contribute to asthma symptoms.

  These problems are more likely to affect people with weakened immune systems, small children, and older adults.

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  Can damp go away on its own?

  No. Typically damp problems will not go away on their own, as they are caused by building defects or the presence of moisture within a property from day to day living. This means that in order to prevent the problem you will need to make remedial repairs, or find ways to control moisture creation. The first step is to identify the cause and determine the type of damp that is affecting the property. If you are unsure you should contact a professional who can provide specialist advice for your damp and mould problems.

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  Is it unhealthy to live in a damp house?

  If possible, you should avoid living in a damp house, particularly for an extended period. Homes that are fit for human habitation are considered to be free from damp and mould that could cause significant harm. This is particularly true for people with underlying health conditions such as allergies or asthma or specific age groups, which put them at increased risk from damp and mould that may trigger reactions or make breathing more difficult. Any concern about symptoms they are experiencing should be discussed with a healthcare professional.

  Even if visible mould is not present, dampness alone can increase the risk of health problems for certain people. Damp and mould should always be addressed promptly to protect occupant health from long-term exposure. The occupant has a responsibility to control moisture production and ensure there is adequate ventilation to remove excess moisture and airborne pollutants or direct concerns to their housing provider or the Housing Ombudsman service.