Moisture in properties whether they are houses, bed sits or flats is something that affects lots of people each year. Often property owners or tenants think there is something major wrong with their property, but in many cases the problems are not major and are caused by the activities of daily living and with some simple changes can be dealt with an improved. However for others, moisture will be caused by a failure of the building fabric and identifying these early on and taking remedial action will reduce any ongoing damage to the property or its contents.
This simple guide is designed to give premises occupiers some initial information to help them ascertain whether any signs of moisture are likely to be caused by a building fabric issue (leak/Rising Damp), or by matters that can be addressed by the property occupier (Mould/Condensation).
MOULD
Mould typically looks spotted or speckled and black in colour. Condensation forms at the coldest position in the room and then mould starts to form. It is due to a large amount of moisture in a room/flat which can be produced from all sorts of things such as basic breathing, drying washing, lack of ventilation, cooking, using a washing machine, using a bath or shower. The only way to stop the development of mould, is is to:
- clean with something that will stop the mould growing.
- to reduce the moisture content in the room/flat by stopping the activity,
- by increasing ventilation by opening the windows, using window trickle vents, installing an extract fan or using a dehumidifier.
Condensation and mould is not as a result of an issue with the building fabric, roof or any ingress of moisture from outside and hence can not be resolved by any work on the building fabric.
Condensation can also be made worse by:
- cold internal room temperatures from lack of heating
- lack of adequate ventilation
- poor thermal insulation
Managing a healthy internal temperature of 21C in a living room and 18C in other rooms can assist in managing condensation.
You may think that you don’t produce much moisture but on average, a property of two adults on average can produce up to 24 pints of water a day from normal daily living activities.
The moisture (percentage relative humidity) in the air can be measured with a device called a hygrometer and a comfortable relative humidity is around 40-55%. Properties with a relative humidity above 60% are at much higher risk of having condensation issues and hence mould.
There is a much higher incidence of condensation and mould in properties currently due to the very poor weather outside and unprecedented amounts of moisture in the air and in our properties.
CONDENSATION RESULTING IN MOULD
Mould caused by condensation will not resolve itself, it needs to be cleaned off. The best way to do this is by using a specialist mould and mildew cleaner that is available at most larger supermarkets. A couple of examples are below, lots of other manufacturers products are available as well.
WATER INGRESS/LEAKS
Water ingress though a failure of the building structure such as roof, pointing, cracks or sealing around a window looks more stain like in nature.
This type of staining indicates water is entering the property either directly from outside, or possible from another room or flat, depending on where it is. Often water can enter at one point in the property and reveal itself somewhere else as water travels both through gravity and capillary action through any void or crack.
Water can pass through the fabric of a building from any angle and can happen for a range of reasons. The water often moves through the building in waves, so often different shades of the saining can be seen as it progresses. Also white salt like deposits can be left behind.
Some common causes of water ingress are:
- Roof leaks or missing tiles
- Chimney leaks
- Leadwork on roofs and chimneys that has cracked, or has been stolen
- Missing pointing
- Bricks or stonework that has become porous
- A breach of the cavity, or poor cavity wall insulation.
- Blocked downpipes or gutters
RISING DAMP
Rising damp is the movement of moisture from the ground up through the walls of a building and this can happen where there is a breach of the damp course, or if a damp course has not been fitted. The damp course is a layer (of a plastic or felt like material) put between a course of bricks or blocks usually just above the ground level to stop water moving up through the building.
Risg damp is usually dark brown in colour and will normally be at the base of walls on the ground floor. It does not normally rise to more than 1 metre in height from the ground level. Rising damp can take a long time to gradually work its way up the walls of a property and hence does not usually suddenly appear.
Gary Hepburn
Sirius Property Services Ltd
(last updated September 2023)
