However; mould caused by excessive condensation is another matter, condensation is usually caused by poor ventilation, and this could simply be due to tenants not opening windows.
Here’s what you need to consider as a Landlord
What is Condensation?
Warm air contains more moisture, when it comes into contact with air or surfaces at a lower temperature water is released to form condensation.
Condensation is generally noticeable where it forms on non-absorbent surfaces such as windows or tiles, but it can form on any surface and it may not be noticed until mould forms.
Conditions for Condensation
Condensation in property is mainly a winter problem, particularly where warm moist air is generated in living areas and then penetrates to the colder parts of the building.
Water vapour is produced in relatively large quantities from normal day to day activities. Moisture can also be drawn from the structure of the building into the internal air.
Problems with the structure of the building can mean that its moisture content is unnecessarily high. This can either be due to the method of original construction or as a result of structure failures.
Properties have become more effectively sealed, keeping in moisture produced within the house and providing better conditions for condensation to occur. Ventilation is only effective if consistent throughout the whole of the property. Condensation is encouraged by poor air circulation and the first evidence is often the appearance of mould growth.
Homes often remain unoccupied and unheated throughout the day, allowing the building to cool down. The moisture producing activities are then concentrated into relatively short periods (morning and evening) when the structure is relatively cold, while the building is still warming up.
To control condensation
First of all, you need to ensure that the amount of moisture in the air is not excessive.
Check the structure of the building:
• Check that the walls are not suffering from rising damp.
• Ensure that there is damp-proof course and that it is not damaged. A new damp course can be installed.
• Check that all airbricks are clear, consider fitting additional airbricks to ventilate under suspended floors.
• Consider applying a surface finish to outside walls to prevent rain penetration.
• Check the roof, make sure that it is sound and directing rain into the guttering, not the structure of the building.
• Check the guttering and down pipes, make sure that they are carrying the water away and that they are not damaged/blocked causing the external wall to become soaking wet.
• Check solid floors to ensure that damp is not coming up through it, if it is, you may need to introduce or replace a damp proof membrane or fit a more suitable floor covering.
• Check that there are no leaking water pipes or tanks within the house.
Condensation will almost always occur with single glazed windows.
• Simple secondary glazing can be fitted at relatively low cost. If installed allow for some ventilation. Although secondary or double-glazing is unlikely to eliminate all condensation, they should reduce it to an acceptable amount.
• Alternatively new double-glazing windows can be considered. Although more expensive there are cost saving benefits as they are virtually maintenance free.
• If walls are decorated with many layers of paper this can act like blotting paper. Consider stripping and re-papering with single layers.
• Lining the wall with thin expanded polystyrene (normally available from your wallpaper stockist) before you hang new wallpaper could be considered.
• Ceilings under the roof should not suffer from condensation providing adequate roof insulation is fitted. If there is no or little roof insulation, additional insulation should be installed (financial grants may be available). Additional insulation will not only reduce condensation, but also reduce energy loss, reducing utility bills.
• Solid floors are often cold due to their large thermal mass (they take a long time to warm up). Even vinyl floor tiles tend to be cold, however there are a number of 'warm' flooring options available such as cork or cushion tiles. Thin wood flooring can be fitted on most existing solid floors.