Home Front logoQ. I am a landlord and I noticed just a couple of weeks after my tenants moved in whilst dropping something off to them that they did not seem to be ventilating the apartment at all and it felt rather damp in there and there was noticeable condensation on the windows. Now after being away for two weeks they have reported black mould growing on the walls. What do you suggest I do, as I am pretty sure this will be down to condensation in the property, and having had the place for seven years know that this has definitely never been the case with previous tenancies?

A. Having dealt with this first hand I can tell you that this black mould is almost 99% the result of poor ventilation. Condensation is one of the most common problems in homes. Condensation occurs when warm moist air meets a cold surface. The water in the air settles as water droplets on the surface. One of the most common visual effects of condensation – apart from water being deposited on cooler surfaces – is that of mould growth. This will often look like ‘black spots’ (although it will completely cover a surface when conditions are right). Mould tends to appear on surfaces where condensation takes place regularly. In order to have condensation, moisture must be present in the air (water vapour) and this can come from a number of sources within a house. Condensation can occur naturally as a result of changes in temperature or artificially by the actions of people themselves. Water vapour is produced in relatively large quantities from normal day to day activities. A normal household puts about 10 kg of water into the air every day simple things like breathing, washing and cooking are all things that contribute. There are three main areas that will need to be managed if you are experiencing condensation and mould issues. They are water vapour production, heating/insulation, and ventilation. Suggesting that they make some simple changes to the way they live can have significant effects on condensation and mould growth. Ventilation, suggest that they open all windows throughout the home every day for 5 – 15 minutes to get the air circulation through. Keeping some heat on during winter months and try to avoid drying clothes inside rather in a dryer or outside if possible. Make sure extractor fans are working too. Sometimes there could be inherent issues with the property that could be the cause but it does not sound like it in this particular case.