Disagreements between landlords and tenants occur time and again. One point of dispute is the damage to the apartment walls caused by incorrectly heated and ventilated rooms. Mould stains, mould or damp walls or window panes that are wet inside.
Mould represents a health risk for the occupants/tenants. It is usually a financial burden for the landlord, as the walls often have to be professionally renovated if mould is present. Important: If it can be proven that the mould is caused by the tenant's incorrect ventilation behaviour, the landlord can demand that the tenant contributes to the renovation costs.
Here we explain briefly how moisture can arise and how mould can be prevented by correct ventilation behaviour!
In addition, one has to understand that German flats are very well insulated against heat and cold and are therefore "tight". Very rarely are there ventilation systems or air conditioning systems that provide exhaust air.
So, in every apartment moisture is created. When taking a shower in the bathroom, cooking in the kitchen, drying laundry in the basement or simply by sweating - moisture is created everywhere in the house. In a 4-person household, around twelve litres of water per day are thus accumulated and must be channelled out again through proper ventilation in order to prevent the formation of harmful mould in the apartment. Otherwise the moisture will be deposited as condensation in the coldest part of the room - this is a tasty breeding ground for mould, especially in winter. This is especially true for exterior walls that are blocked by cupboards or other furniture. To ensure that the air in the room can circulate properly between the wall and the furniture, there should always be at least 10 cm of space in between so that the air can circulate.
To ensure an optimum room temperature of 20 degrees and a humidity of between 40 and 60 percent in your home, regular ventilation is necessary. Correct ventilation is just as important in winter as correct heating: only with correct ventilation can moisture problems be controlled and mould prevented.
- All rooms should be heated sufficiently and as continuously as possible.
- At least twice a day, the rooms should be ventilated so that a complete exchange of air can take place (10-15 minutes of airing the rooms at intervals / tilted windows are not sufficient). The tilted position is not suitable for an effective air exchange. Continuous ventilation with the window tilted is wrong.
- For perfect air circulation, open two opposite windows simultaneously. This will draw the stale air outside, as in the case of a suction, and the dry winter air can flow in quickly.
- Do not tilt the windows permanently, as this will only cool the rooms down but not allow air to circulate.
- The air circulation must not be obstructed or even stopped.
- The heat emission of the radiators must not be impaired by coverings or long curtains.
- Doors to less heated rooms should be kept as closed as possible (or to keep the temperature difference between the rooms low)
- Continuous ventilation during the heating period is not permitted.
- Larger quantities of water vapour must be immediately discharged to the outside.
Due to that a pleasant room climate with perfect humidity is maintained.