The Facts About Damp, Mould and Condensation

The cause of damp is often fairly obvious from the symptoms that the different forms of damp present; however, this is not always the case. Usually damp is identified due to the “musty” smell, mould or damp patches that appear inside the home. The most common form within homes in this country is condensation.

Lack of “Breathability” and a build up of water vapour in our buildings not only cause rot, damp and structural failure, it is also a major contributor to sick building syndrome. It has also been heavily linked to the rise of asthma and allergies in this country.

Rising Damp – In a nutshell this is water soaked up from the ground by capillary action and is only a problem when a building has no Damp Proof Course (D.P.C), very common in older buildings(pre 1930), or if the D.P.C has been bridged or damaged. Rising damp only rises about 1m above ground level due to gravity and the capillary forces.

The solution to rising damp – is usually to inject a chemical D.P.C. This may need to be done to various areas and can occasionally need to be done internally as well as externally.

This type of work carries varying guarantee periods but usually between 20 – 30 years. Penetrating Damp – Water penetrating through the roof or walls. This is where water leaks into a building through a fault such as around a chimney stack or windows. Examples of this could also be missing roof tiles or lack of mortar between brick courses. Also look for leaking or missing drainpipes as these can lead to water soaking all the way through the wall. This type of problem is often made apparent internally by the appearance of isolated damp patches.

How do I stop penetrating damp? – In some cases these internal patches will be simply rectified by making appropriate external repairs, for example re-pointing. However if this problem is more widespread internally this will lead to higher moisture content in plaster work, decorative finishes and the home in general. This will then need a more permanent solution. To stop this continuing to be a problem, some form of external weather protection, such as a specialist render system or resin based clear coating would need to be applied.

Condensation – Usually more noticeable in winter, because the building is cold and because windows are opened less so moist air cannot escape. When warm moist air produced by ordinary household activities hits a cold surface it condenses into water droplets i.e. an outside wall or window condensation occurs. This problem is “home made”. Household activities like Cooking, Breathing, Bathing or drying clothes to name a few all are a major source of water vapour within the home.

Preventing condensation

Try not to dry clothes in your home. If this is not practical, keep the door of the room where clothes are drying closed. Open the windows, as this will allow the moisture from the clothes to escape outside and will prevent it circulating around your home. – If you use a tumble drier make sure it is vented to the outside or use a condensing dryer. – When cooking the kitchen should be ventilated. Use an extractor fan if you have one or open a window. Keep the kitchen door closed. – Cover boiling pans with pan lids – this will save money on your fuel bills as well reducing moisture.

- When bathing or washing keep the bathroom door closed. Switch on extractor fan on if you have one. If there is a lot of water vapour in the atmosphere leave the fan on or open a window to disperse the moist air when you have finished bathing. – Keep furniture such as beds and wardrobes clear from the walls to let air circulate. – Keep your house “warm” at a consistent temperature. This will cut down condensation as water does not condense in warm air. Background heating and ventilation will reduce condensation, especially in winter. – Avoid using portable paraffin or bottled gas heaters. They give off a lot of moisture when they burn, as much of 1 litre of water for each litre of fuel burned, so open a window if you have to use one.

Ventilation – Ventilation in the home, if adequate, will allow moisture to escape to the outside. Modern living has led to a decrease in natural ventilation. We have over recent years installed double glazed windows and doors, introduced daily showers and sealed off open fireplaces. The average household in the UK can put as much as 15 litres of water into it’s air on a daily basis!

The simplest and cheapest form of ventilation is to leave a window open whenever possible. In housing built before 1875 they were often built with no D.P.C. and very little protection externally from penetrating damp.

- Use an extractor fan in the bathroom when you bath or shower if you have one. – Open windows slightly after bathing to get rid of the moisture. – Use extractor fan in the kitchen or open a window when cooking. – If you have trickle vents above windows keep them open all the time. – Never block up any air vents or air bricks and if you haven’t got any look into having some fitted. – Heat exchange units are also a good way to encourage air circulation without causing draughts. These units mechanically draw fresh air in from the outside whilst drawing stale air out of the room. This warmer stale air is used to heat the incoming fresh air.

Dehumidifiers – One popular solution to damp and condensation problems is a dehumidifier. These come in various shapes and sizes ranging from small units which will keep a closet or wardrobe dry to large units which are capable of drying out anything from a room to a whole house. Most models have a level switch which will turn the dehumidifier off and sound an alarm when the tank is full.

Insulation – condensation occurs on cold spots, so if you can warm up the cold spots you will help control condensation. Insulating your loft, external walls and draught proofing doors and windows should reduce the amount of cold spots and make your house cheaper to heat. Insulated well, they will remain warmer for longer, reducing the risk of water vapour condensation and therefore reducing the conditions that are ideal for mould growth.

Heating – try to avoid having cold areas within the home. It is better to heat the whole house on a lower temperature than it is to heat one room on a very high temperature. When you get condensation and mould forming, it is often not the room that you are creating the moisture in e.g. kitchen or bathroom but in a room that you don’t often use e.g. spare bedroom. This is probably because this room is not usually heated. Try heating all the rooms regularly. Make sure you are using the heating system and its controls efficiently as this will also save you money. Consistent heating will eventually allow warmth to penetrate walls and ceilings which helps to remove the water vapour. During the cooler months always try to keep the inside temperature at least 5º C higher than the temperature outside.

Moisture – Reducing the amount of moisture in your home will cut down the amount of condensation.

Mould – Is a type of fungi that can grow in a range of areas within the home but only when there is damp present. Although there are many different types of mould they all thrive on high humidity and when growing gives off particles that can cause allergic reactions. If humidity drops suddenly these particles can be in their millions and can cause sneezes. Mould growth within buildings has been heavily linked with asthma and other respiratory conditions especially in children or susceptible adults. Mould spores will only grow in clean water as opposed to the contaminated water from rising or penetrating damp.

Mould usually can be removed with a diluted solution of bleach, following carefully the manufacturer’s safety advice. Always test a small discreet area first before applying it to the whole area. After applying to the affected surface leave it for about 20 minutes then sponge with water. – In more severe cases, to kill and remove mould, wipe down walls and window frames with a fungicidal wash. Follow manufacturer’s instructions carefully. – Dry clean any clothes or affected material and shampoo any carpets. Disturbing mould spores by brushing or vacuuming may increase the risk of respiratory problems. – Mould eradications kits offer the best way to completely remove mould. Kits are available through our offices. – After treatment, re-decorate using a good quality fungicidal paint to help prevent recurrence.


Post time: 04-03-2017