Date Published 29 July 2020
Mould and damp are quite common issues in this country. Many of these issues are related to a change in temperature rather than a defect with the building structure and can be resolved with often minor changes to lifestyle.
The most important issues to address are to maintain a constant temperature within the property and to ventilate adequately. A room left unheated for a significant period of time will be vulnerable to condensation forming on cold surfaces. This is why bedrooms are particularly vulnerable to mould growth during the colder months. Cold surfaces in unheated rooms will not always be limited to window panes; externally facing walls can also be cold enough to allow condensation to form, which is often unseen. The result of condensation forming is however evident once mould spores grow. It is important to maintain a constant temperature to the building fabric above which condensation will not form. This can be achieved by low level heating to rooms even when unoccupied. This will not only help prevent condensation forming, but as it takes less energy to heat the room it can actually reduce overall heating costs.
Ventilation rates will be dependant on a number of variables such as; the number of occupants, the occupant's lifestyle, and construction of the building. What may be adequate ventilation in one property may be insufficient in another. It is for the occupier to ventilate to a degree which will reduce and prevent excessive amounts of condensation and therefore subsequent mould growth.
Below we have listed commonly reported issues together with suggested remedies in green type.
'My bedroom windows have black mould to the base of the glass, around the window frame and to the reveal'
• Mould spores occur naturally and exist in the air in most environments; they can only grow where there is a source of moisture. During colder weather windows and frames will inevitably be colder which can increase the likelihood of condensation forming on them.
Many double-glazed windows have trickle vents already installed; these are situated at the top of windows and are either operated by rotating the ridged opener downwards or by sliding the cover across. The background ventilation provided by these vents can prevent condensation forming on windows and hence prevent mould growth. However often these vents will not clear all the moisture from the air and hence condensation will still form. In this situation increased ventilation is essential and can be achieved by opening fan light windows and / or opening windows to the 'first latch' position. The first latch position allows the window to be opened by approximately 10mm allowing increased ventilation, whilst not being excessively draughty. Windows left in this position overnight have a significantly reduced incidence of condensation and hence associated mould growth. If your property has single glazed windows installed they can still be opened to a minimal opening whilst still restrained on the lower catch.
'I'm not opening my windows with the heating on, that's a waste of money and I'll be cold!!'
Our suggestions are to open trickle vents and open windows to the first latch position (and / or open fan light windows) are intended as a good practice guideline. We would not expect occupants to have windows fully open with very low outside temperatures; this would be a waste of money and you would get cold! Our suggestions are intended to achieve a balance between heating the property, whilst providing adequate air changes to avoid condensation forming. Even on very cold mornings once bedrooms are unoccupied windows can be left in the first latch position, to clear any condensation that may have formed overnight and reduce the likelihood of mould growth.
'I have mould on the back of my bedroom furniture and even to my clothes'
• Bedrooms are often infrequently heated and are subsequently more prone to condensation forming on colder outside facing walls. The measures stated above concerning ventilation rates from windows / trickle vents will help address this issue. However, further consideration regarding the positioning of furniture needs to be considered. Furniture (in particular mattresses / sofas etc) if positioned too close against outside facing walls can trap air. Trapped air will become stagnant and condense, releasing moisture and therefore allowing mould growth.
This issue can be reduced by allowing adequate air flow around bedroom furniture. If possible, position wardrobes / drawers etc against internal facing walls, keep beds / headboards away from external facing walls. Any furniture that is positioned along an external facing wall, try to keep the back clear and allow a gap for air to circulate. If clothes are mouldy / smell musty this indicates a high moisture content to air within the room. For example mould growth can occur to leather items, but only if the moisture content of the air is very high, at around 80%. To reduce this, adequate ventilation is essential to change the air frequently. You may have to consider slatted shelves / an alternative design of wardrobe to increase air flow if humidity levels within the property have not been reduced adequately by ventilation.
'My bathroom has mould growth to the ceiling, external walls and around the bath / shower'
• Use of the bathroom will inevitably increase the moisture content to the air within that room. This moisture laden air will condense on colder surfaces, usually; windows, external facing walls (including window reveals), sanitary fittings, cold pipework and occasionally ceilings.
• Mould growth to the junction of baths / showers to wall tiles is not a defect with the property. It is attributable to standing water usually through use of the bath / shower but can also be caused by condensation on tiled surfaces.
If an extract fan is installed within your bathroom ensure it is used at all times when moisture is being produced. If there is no extract fan, windows should be opened during and after use of the bathroom. Again, as for any other room we are not suggesting a bathroom window be left wide open whilst bathing during the winter or at any time of year, however a fanlight window opened and / or a window left on the first latch position will help to disperse a significant quantity of moisture from the air. Once finished in the bathroom it is imperative the door is kept closed, therefore preventing moisture laden air dispersing throughout the property and condensing on other cold surfaces --- often external facing walls of bedrooms. With the bathroom door closed the extract should be left to run / a window opened sufficiently to quickly disperse the moisture laden air therefore reducing condensation to cold surfaces. By keeping the bathroom door closed after use and opening windows you are rapidly dispersing moisture laden air and preventing the other rooms within the property loosing their heat.
'My kitchen has mould to window reveals and to the back of the units'
• In common with bathrooms, use of the kitchen will inevitably increase the moisture content to air within that room.
If an extract fan is installed it should be used during and after use of the kitchen. If there is no extract fan, windows should be opened during and after use of the kitchen. Again, as for any other room we are not suggesting a kitchen window be left wide open whilst in use during the winter or at any time of year, however a fanlight window opened and / or a window left on the first latch position will help to disperse a significant quantity of moisture from the air. Once finished in the kitchen it is imperative the door is kept closed, therefore preventing moisture laden air dispersing throughout the property and condensing on other cold surfaces --- often external facing walls of bedrooms. We appreciate that it may not always be practicable to close a kitchen door during use for example to keep an eye on youngsters. However if it is closed after use and then well ventilated this will help minimise moisture laden air condensing in this room and dispersing to other rooms within the property.
Cutting down the quantity of steam produced within the kitchen can also help reduce incidences of mould growth. This can be achieved by using lids on pans (which will also save energy), not leaving kettles boiling unnecessarily and ensuring any tumble driers are properly vented as recommended by the manufacturer.
'I have mould spores to the base of my external walls; I've been told the damp proof course must have failed'.
• Failure of a damp proof course is very rare. The cause of mould spores to the base of an external wall is often attributable solely to condensation, however occasionally further investigation is required. Other possible causes include penetrating dampness due to a raised ground level, failed drainage or a defect with the original construction.
'I have double glazed windows installed therefore I should not be getting condensation'.
• Moisture laden air coming into contact with any cold surface will condense. Without adequate ventilation single and double glazed windows will be susceptible to condensation forming which can then lead to mould growth.
'I have mould spores to the under stairs / other storage cupboards with external facing walls'.
• Such areas often do not have an adequate air flow; therefore can smell musty or damp. Stagnant air in these cupboards condenses therefore providing a source of moisture for mould spores to grow. To improve airflow stored items should be kept away from external walls, cupboards not overfilled, slatted shelving used, airflow allowed beneath doors.
This article is brought to you by MGS Surveying on Behalf of Distinct Property Consultants