What are the three causes of damp

What are the three causes of damp

By Ruth MacEachern

Product Manager

Damp is a common problem that can seriously affect the fabric of your home and lead to problems with mould that can be damaging to your health. But did you know that not all damp is the same, or forms for the same reason. There are three main types of damp: condensation, rising damp, and penetrating damp. Each of them has different causes, symptoms, and solutions. In this blog, we will explain how to identify and treat each type of damp in your home.

What causes rising damp

A phrase that can put the fear into any homeowner or buyer is “rising damp”.  Rising damp is a problem that can be very expensive to repair and affect the value of your home. This type of damp occurs due to moisture rising from the ground through the walls or floors. In most cases, it happens due to a problem with the damp-proof course or membrane, a barrier that prevents water from entering your home.  Rising damp only occurs on the ground floor of your home and is characterised by stains rising to about 1 metre above ground level.

The most common signs of rising damp in a property are:

• A brown or yellow tide mark on the wall, above the skirting board
• A white, powdery substance on the wall, left by soluble salts dissolved in the water
• A damp or musty smell
• Crumbling or peeling plaster or wallpaper
• Rotting or warped woodwork

If it is not dealt with by a professional, who will need to repair or replace the damp proof course in your walls and replace the affected plaster, rising damp can weaken your walls and floors, and create an unhealthy environment for you and your family.

What causes penetrating damp

The second most common form of damp, penetrating damp, is caused by water entering the property through walls, or through internal leaks.  If you have discovered damp patches in your home on walls or ceilings, it may be due to one of the following:

• Cracks or gaps in the external fabric of your home
• Faulty roofing, guttering, or pipes
• Leaking pipes behind walls or in the ceiling

The most common indicators of penetrating damp in a home are as follows:

• Damp patches on walls or ceilings that may grow larger after rainfall
• Blistering or flaking paint or plaster
• Mould growth on walls or ceilings or around windows where water is leaking
• A wet or rotten smell

If the cause of penetrating damp in your home is not addressed, the problem will continue and could lead to damage to plaster and mould growth that will be damaging to your health.  To prevent penetrating damp, you will need to fix the source of water ingress, whether this is by sealing gaps or cracks in your walls, repairing broken roof tiles, or replacing internal pipes in your home. 

What causes condensation damp

By far the most common cause of damp in the UK, and affecting up to one in five homes, condensation damp can be difficult to stop, as it is caused by the humidity in our homes.  Activities such as cooking, bathing, and even breathing release water vapour into the air.  When humid air meets a cold surface such as an external wall or window, the water vapour will condense and form droplets on the walls that can soak in and create damp patches.

Condensation damp may not have an obvious cause nearby such as a leak, but it can be treated.

If you have noticed condensation forming on your windows and walls overnight or discovered mould or mildew patches on walls and ceilings, then it is likely that condensation damp is to blame.

The most effective way of stopping damp as a result of condensation from becoming a more serious problem is to improve the ventilation in your home.  Helping the air to circulate more effectively and ensuring that moisture laden air from bathrooms and kitchens is expelled will prevent it from escaping into other living areas.

Modern extractor fans should be fitted in rooms with sources of water such as bathrooms, WCs, kitchens, and utility rooms.  These should be run during cooking or bathing.  Fans such as the EnviroVent Cyclone 7 have a moisture sensor which adjusts their power level to reduce humidity more quickly and help to prevent condensation from building up.

You should also avoid drying clothes indoors or leaving towels on radiators and use pan lids when cooking to reduce the amount of steam released into your home.

If you have found patches of condensation damp away from sources of water – such as in bedrooms or your lounge, it may be that whole house ventilation is more appropriate.  Positive Input Ventilation (PIV) systems can be retrofitted into a home and provide a constant source of fresh filtered air via a loft mounted unit.  This fresh air from outside your home displaces the humid or stale air to stop condensation.

Find out more

If you have discovered condensation damp in your home, our local ventilation specialists can help.  Request a free home survey by entering your postcode below.  An EnviroVent expert will visit your property, identify the sources of condensation, and provide you with advice about the best things you can do to stop condensation and mould for good.