Mold in the house: what builders and homebuyers can do

Mold in the house: what builders and homebuyers can do

For a long time, mold was considered a problem that only owners of old buildings are plagued with. This has meanwhile changed: the gray not only thrives in musty flats and ailing old buildings, but increasingly also in new buildings. The Association of Private Builders estimates that about every second new building is already affected during the construction of mold. Actually, the property should therefore not even be purchased.

Causes of mold

The typical causes of mold in new buildings include: lack of construction control, moisture and ubiquitous mold spores. If these three factors come together under certain conditions, then the pest can spread. Moisture and moisture during construction are the main causes of mold damage in new buildings. Construction sites may be open for months, even in winter. During this time it rains, floors and ceilings get wet and the mold spores make themselves comfortable. If this problem is not discovered in time and the construction is not systematically closed, large-scale damage occurs that can only be eliminated later on.

Winter construction sites a big problem

If a construction site is carefully covered in winter, it is itself then mold infestation is a rarity. Especially key contractors, who are committed to speed, are ideal for a construction project in winter. But beware: you usually do not charge a time cushion for construction interruptions. Protective measures and tarpaulins are also rarely included in the budget. In the event of a sudden snowfall, the construction site can be open for several days or even weeks. Snow and Rain runs over the ceiling opening into the unfinished building, water is in the cellar on the floor and moisture drips into the walls. Wet stones are the ideal breeding ground for mold later. In cold weather, the water expands in the wet rock additionally still. The stone bursts, rips and parts shear off.

During interior installation heat Another cause of mold in new buildings is unheated construction sites. The interior work begins as soon as the roof is covered and the windows have been installed. The interior fittings include the screed and interior plaster

. Both materials contain relatively much water. Accordingly, a long drying time must be given. During this time, which lasts several weeks, the construction site must be well ventilated - heated in the winter as well. Insufficient heating and ventilation leads to mold. When dry heating but can go a lot wrong. A typical problem: the screed is poured, inside the house is plastered and put the underfloor heating in operation. However, the attic hatch remains open to the uncombed attic

. The effect is devastating: The wet warm indoor air from the lower levels accumulates and is sucked up through the open floor hatch. There she meets the cold inner roof surfaces, where she condenses and dries timber. The result: Molds are formed.

Mold damage is expensive Such building damage should not only be detected as quickly as possible, but also taken seriously. Around 100 of the 100,000 existing mold species endanger the health of the residents. If such mushrooms have settled in the new building, then only one thing will help: Renovate or replace all affected components

. The current case law provides that this is a matter for the contractor. However, this only applies if the damage was discovered in time. Builders often do not notice such damage, but the black pores are in the initial stageonly recognizable by trained eyes

. If the mold is not detected, it disappears under the disguise and does not appear until years later.

Gather evidence Anyone who discovers or suspects mold on their site should act promptly and consult an independent surveyor. This can confirm the mold and secure the evidence


  • Checklist: How to prevent mold
  • Keep construction site as dry as possible
  • Have construction site covered in winter
  • Allow rainwater and snow to penetrate
  • Check walls and floors for moisture in spring
  • if construction site is wet, do not continue building
  • ensure adequate drying when ventilating

systematically breathe, do not tilt windows