What is The Difference Between Rising Damp and Condensation

The Differences Between Rising and Condensation Damp

By Ruth MacEachern

Product Manager

While different types of damp might appear similar in your home, it is vital to be able to tell the difference between them if you want to remove the problem.

The different types of damp

There are two causes of damp in a home:

• Damp which is caused by moisture from within the house.
• Damp which is caused by moisture entering from outside the home.

Damp from external sources includes rising damp from the ground, rainwater leaks, poor drainage, or defective plumbing.  Condensation damp is caused by the humidity in your home due to the moisture released into the air from activities such as cooking, bathing, and breathing.  In our homes, condensation damp is more of a problem during periods of cold weather as the water vapour carried in the air is more likely to condense on walls and windows.  Damp caused by exterior sources of moisture such as rising or penetrating damp are generally worse in wet weather.

You can often tell what is causing damp by its appearance.  Condensation tends to form patches of mould on walls and ceilings away from an obvious source of moisture, whereas rising damp will normally be found as a stain rising about 1 metre from the floor on the ground level of your home and penetrating damp will form around its source – such as a leaking window frame, a broken pipe, or a hole in your roof.

Why damp is a problem

Damp is the cause of a variety of problems in your home and the causes need to be removed as quickly as possible.  Without action, damp issues affect the fabric of your property.  Plaster will start to crumble, wallpaper and paint will start to blister and peel away, and wood skirting boards, window frames and furniture will start to rot.  Wherever damp is present, mould and dust mites can thrive.  These can cause numerous health problems including allergies and fatigue.

What causes rising damp

Rising damp is caused by the ingress of water from the ground into the walls of your home.  Modern buildings include a damp course layer – a plastic barrier in the walls – which is designed to stop bricks from sucking the water up from damp ground.  In buildings without a damp course, or where soil and other matter has built up around the walls to a higher level than the damp course, the capillary action of small cavities within bricks and cement draws water out of the ground like a sponge and holds it in the structure of the building material.

The capillary action in your walls is limited and rising damp will only form up to about 1.2 metres above ground level before gravity prevents it getting any further. This limit means that when rising damp is present, there will usually be a clear pattern with staining on your walls..

In the damp conditions of an affected wall, mould spores can gain a foothold and you will often see the growth of mildew or dangerous black Stachybotrys Chartarum mould in affected areas.  This needs to be treated quickly as it is a major health risk.

Condensation damp

Condensation is caused when warm air with a high moisture content comes into contact with cold surfaces like walls and windows.  As the temperature goes down, the amount of moisture that the air can hold falls and tiny drops of water form on the surface and create the patches of condensation that you see in the morning.

The air in your home is naturally moist, but the amount of moisture is increased by the release of water vapour from cooking, bathing, and showering and even respiration.  If condensation is allowed to sit on walls for long periods of time, it can penetrate the outer layers of your walls and seep into furniture where it becomes a longer-term problem, causing mould to grow.

What you can do to reduce condensation

Condensation damp is highly preventable, and there are small changes in behaviour that help to immediately reduce the risk: 

• Dry clothes outdoors
• Close the kitchen and bathroom doors during use
• Ensure that you use extractor fans and pan lids when cooking
• Use an extractor fan when bathing
• Leave windows open during warmer weather
• Ensure that furniture is placed at least 2 inches away from external walls
• Avoid overfilling wardrobes and cupboards

Read more about ways to stop condensation >>

If your home suffers from persistent condensation problems and unsightly damp patches, then you may need to review your current ventilation system to ensure that it is sufficient to allow for good airflow.  Extractor fans play an essential role in ventilation but older devices do need to be replaced every 5 to 10 years as their motors can wear out and they can become clogged, which makes them less effective at removing humid air.

Treating condensation and damp

Treating the condensation that can lead to damp in your home might be easier than you think.  Installing filterless extractor fans in your bathroom and kitchen that automatically adjust their power levels depending on humidity can reduce condensation problems quickly. 

Find out more

Almost 1 in 5 UK homes have a problem with condensation that can lead to damp and mould, but by taking the right action, you can resolve issues with condensation forever.  Arrange a free home survey from one of EnviroVent’s local specialists who can advise you about how proper ventilation can benefit your indoor air quality and reduce damp.  Enter your postcode below to find a ventilation specialist near you.