There Is Mould on My Walls and Ceilings – Where Is It Coming From and How Can It Be Fixed?

Damp and mould are common problems in flats and residential developments, particularly during the colder months.

Many tenants and leaseholders assume that mould must be caused by a leak or defect in the building. Whilst this can sometimes be the case, in our experience the most common cause is condensation resulting from high humidity levels within the property combined with inadequate ventilation, poor temperature control and cold surfaces.

Understanding the cause is important because the correct solution depends on the type of damp present.

The Three Main Types of Damp

1. Rising Damp

Rising damp occurs when moisture travels up from the ground through the walls or floors of a property.

It typically affects the lower section of walls, often up to around one metre above floor level. Signs may include staining, peeling paint, damaged plaster and tide marks.

Treatment may involve repairing or installing a damp proof course, but a proper inspection should always be carried out before any remedial works are undertaken.

2. Penetrating Damp

Penetrating damp occurs when water enters the building from outside or from an internal leak.

Common causes include:

• Defective roof tiles or flat roofs
• Damaged brickwork or pointing
• Faulty gutters or downpipes
• Poor window seals
• Plumbing leaks
• Defective water tanks or pipework

Penetrating damp often appears as localised damp patches on walls or ceilings and may become worse during periods of heavy rainfall.

The solution is to identify and repair the source of the water ingress, allow the structure to dry and then carry out any necessary redecoration.

3. Condensation and Surface Mould

Condensation is one of the most common causes of damp and mould inside residential properties.

Everyday activities such as cooking, showering, drying clothes indoors, boiling kettles and even breathing create moisture. The average household can produce many litres of water vapour every day.

When warm, moisture-laden air comes into contact with a cold surface, condensation forms. Over time this can lead to black mould growth.

Black mould commonly appears:

• Around windows
• On external walls
• In corners of rooms
• Behind furniture
• Around skirting boards
• On ceilings
• In bathrooms and kitchens
• On tiled or other cold surfaces

Condensation-related mould is often worse during winter when homes are colder, windows remain closed and moisture becomes trapped inside.

How Can I Tell If It's Condensation or a Leak?

Condensation is most likely where:

• Black mould is present
• The issue appears on multiple external walls
• Moisture forms on windows
• The problem worsens during winter
• Mould appears behind furniture or curtains

Penetrating damp is more likely where:

• Damp patches appear after rainfall
• Staining is concentrated in one area
• Water marks appear on ceilings
• Paint or plaster is blistering
• There are known defects to the roof, walls or plumbing

If you are unsure, it is important to investigate further as the correct solution depends on identifying the root cause.

The Most Effective Long-Term Solution

Whilst heating, natural ventilation and lifestyle changes all play an important role, one of the most effective ways to reduce condensation is through properly designed mechanical extraction.

Modern extractor fans with humidity sensors or continuous mechanical ventilation systems remove moist air from kitchens and bathrooms before it has an opportunity to condense on walls, ceilings and windows.

Where condensation is a recurring issue, upgrading extraction systems is often more effective than repeatedly cleaning mould or relying solely on dehumidifiers and natural ventilation.

How to Reduce Condensation and Mould

Improve Ventilation

Good airflow is essential.

Where possible:

• Open windows regularly
• Use trickle vents
• Keep internal doors open where appropriate
• Use extractor fans in bathrooms and kitchens
• Keep extractor fans clean and free from dust
• Ventilate bathrooms after showering or bathing

Mechanical ventilation in kitchens and bathrooms can make a significant difference where condensation is recurring.

Manage Heating Properly

Large temperature fluctuations can increase condensation.

Maintaining a steady background temperature helps reduce cold surfaces and makes condensation less likely to form.

Where possible, heat the whole property rather than only one room. A timer and thermostat can help maintain a more consistent temperature throughout the day.

Reduce Moisture Production

Simple lifestyle changes can reduce excess humidity.

Try to:

• Avoid drying clothes on radiators
• Use lids on pans when cooking
• Vent tumble dryers correctly
• Keep bathroom doors closed during showers
• Open windows after bathing or cooking
• Avoid blocking ventilation grilles or vents
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Use a Dehumidifier

A dehumidifier can help reduce moisture levels in the air, particularly where ventilation is limited or condensation is persistent.

This can improve air quality and reduce the likelihood of mould returning.

Keep Air Moving

Mould often forms where air cannot circulate.

Avoid placing large items of furniture directly against cold external walls. Leaving a small gap behind wardrobes, sofas and cabinets can significantly improve airflow and reduce mould growth.

Cleaning Mould Safely

Mould should be cleaned carefully.

Specialist mould cleaning products are available, or a suitable mould treatment may be used in accordance with the manufacturer's instructions.

Always:

• Wear gloves
• Ensure the room is well ventilated
• Follow product safety instructions
• Dispose of contaminated cleaning materials responsibly

Avoid dry brushing mould as this can release spores into the air.

When Should You Report Damp or Mould?

You should report damp or mould where:

• There are signs of a leak
• Damp patches are spreading
• Mould keeps returning despite ventilation and heating improvements
• There is damage to walls, ceilings or flooring
• You suspect a building defect
• The issue affects health, safety or habitability

Photographs and details of the affected areas can help the managing agent, landlord or contractor investigate the issue more effectively.

How Archery Estates Can Help

At Archery Estates, we regularly assist leaseholders, tenants, landlords and directors in identifying and resolving damp and mould issues within residential developments.

Where the issue relates to the building structure, roof, gutters, external walls, plumbing or communal ventilation systems, we can help coordinate inspections and remedial works.

Where condensation is the likely cause, we can provide practical guidance to help reduce moisture levels, improve ventilation and prevent mould from returning.

Need Advice?

If you are experiencing damp, mould, water ingress or condensation within your property, contact Archery Estates for practical advice and assistance in identifying the cause and finding the most appropriate solution.