Damp can arise in your home due to structural issues, poor ventilation, or recurring moisture. Learn how to spot damp, the signs, and what type you have.

The signs of damp show up differently in your home depending on the cause. The three main types of damp include rising damp, penetrating damp, and condensation. Knowing how to spot damp and which type you’re dealing with can help determine how serious it is and what to do next.

Rising Damp: What To Look For

Rising damp is defined as the upward movement of groundwater that travels through a wall’s masonry via capillary action, which is the movement of liquid in a narrow space or porous material. The common signs of rising damp include:

• Tide marks (a horizontal band with a visible high-water line)
• Flaking, bubbling, or crumbling plaster
• White, powdery salt deposits on walls
• Musty smell at the ground level

Typically, rising damp is found at the ground-floor level of internal walls, skirting boards, or the base of chimney breasts. It often occurs in houses that are either older or have no damp-proof courses.

If rising damp is left untreated, it can damage the plaster and skirting, and can eventually damage timber in contact with the wall. It’s not especially urgent overnight, but it progresses steadily into a bigger issue without intervention.

Penetrating Damp: What To Look For

Penetrating damp is moisture that leaks horizontally from the outside through a property’s walls, ceilings, or roofs. It can worsen during wet weather and create isolated damp patches in your home. The signs of penetrating damp include:

• Damp patches that worsen after rain on external walls or ceilings
• Brown or yellow stains on walls or ceilings
• Damp patches with irregular shapes
• Peeling wallpaper or paint in specific spots

You’ll find penetrating damp on walls below leaking gutters or downpipes, around window and door frames, on roofs, chimney stacks, or on any wall with cracked render.

Penetrating damp’s seriousness often depends on the source. For example, a blocked gutter is usually an easy fix, but a structural defect can let water in continuously and lead to hidden timber decay. Once patches appear repeatedly, you’ll need to seek professional remediation.

Condensation: What To Look For

Condensation is when water drops form when warm, wet air touches a cold surface. You’ll usually recognise this when you cook or have a hot shower, where hot air hits cold walls or windows. This can lead to black mould that forms in the corners of window frames or on poorly ventilated walls. The signs of condensation include:

• Streaming or heavily misted windows, especially in the early morning
• Musty smell in bathrooms, kitchens, and bedrooms with poor airflow
• Damp patches that don’t correlate with weather

Looking for condensation is usually easy, since you’ll commonly find it in bathrooms and kitchens. But condensation can appear in any room that has poor ventilation or where laundry is typically left to dry.

Condensation is the most common type of damp and is the easiest to manage day-to-day with simple ventilation or reducing moisture. However, if left alone, black mould can grow and lead to respiratory illnesses, especially in children, older people, or anyone with asthma. If condensation continues to return despite changes you make, you’ll need professional help.

When To Call a Professional

After you’ve spotted damp in your home, the first reaction is usually to start with DIY methods like ventilation changes or wiping down wet surfaces. However, some types of damp will require professional intervention, usually starting with a survey.

If you find that mould continues to spread in your home, tide marks keep rising, wet patches start spreading, or timber starts to feel spongy, that’s when you need help.

A professional survey can find the source of the damp as well as understand how to remediate it. Rising, penetrating, and condensation damp each require individual treatments, so treating the wrong type won’t solve the problem.

Kenwood is a PCA-accredited company with decades of experience, reflected in our certified surveyors. If you’ve spotted damp in your home, it’s worth getting a professional opinion rather than guessing. We can identify the source of damp in your home and further provide damp treatments to ensure it doesn’t return.

Book a survey today for a 24-hour turnaround or speak to a member of our team.

Frequently Asked Questions

Can I treat damp myself?

Minor condensation can usually be managed on your own with simple ventilation changes, installing extraction fans or reducing indoor moisture. However, rising and penetrating damp will need a diagnosis first, since surface treatment won’t be enough.

Is black mould the same as damp?

No, black mould is usually a result of condensation or penetrating damp that was left alone. Mould can quickly turn into a complex structural and health risk, so remediation is strongly advised.

What causes damp in a house?

The causes of damp can come from various sources depending on the type that’s occurring in your home. We have created a full damp guide that covers the full scope of damp causes.

Is damp bad for your health?

Persistent damp and mould growth can trigger respiratory illnesses or make existing conditions worse. It can be dangerous in children and older people, especially if there is consistent exposure.

How do surveyors check for damp?

Our surveyors find damp with a visual inspection, moisture meters and identifying the pattern or location of the damp. Our next-day damp surveys are carried out by professionals who rely on real readings and observations rather than single readings.