ᐅ Independent Expert Assessment for Mold Damage in Older Buildings
Created on: 11 Nov 2025 21:11
J
Jodimaster2k
This has been ongoing since the beginning of 2025.
Exterior wall/corner.
Landlord. (86). They need to ventilate and heat more.
Now an independent court-appointed expert will be involved as a separate evidentiary procedure.
Building protection contractor writes: Clear signs of mold were visible in the lower and upper corner areas of the room, and the wallpaper on the right exterior wall had been removed (according to the tenant, a cabinet had stood here).
At the time of inspection, the room temperature was measured at 21°C (70°F) and the relative humidity at 57%. These values are considered "normal."
A surface temperature measurement of the “exposed” exterior wall at about 1.0 m (3.3 ft) height showed a temperature of 20.20°C (68.4°F).
The temperature measurement in the lower corner behind the bed showed a surface temperature of 17.6°C (63.7°F)! This temperature drop, despite the currently warm weather, is partly due to the corner location (keyword: thermal bridge) and partly due to the unfavorable position of the bed.
As temperatures drop toward autumn and winter, the temperature difference will increase further, inevitably leading to condensation and subsequent mold growth.
The same cause was responsible for the cabinet, now removed, that stood against the exterior wall.
We consider moisture penetration from outside to be ruled out due to the intact two-layer facade.
To verify this, the wall moisture was also measured electrically. The values were within the dry range between 48 and 58 digits. If the room continues to be used as it has been until now, and especially if the furniture position remains unchanged, further mold growth cannot be ruled out!
A structural upgrade of the walls with calcium silicate boards as interior insulation is possible. If interested, we would be happy to provide you with an offer.
Exterior wall/corner.
Landlord. (86). They need to ventilate and heat more.
Now an independent court-appointed expert will be involved as a separate evidentiary procedure.
Building protection contractor writes: Clear signs of mold were visible in the lower and upper corner areas of the room, and the wallpaper on the right exterior wall had been removed (according to the tenant, a cabinet had stood here).
At the time of inspection, the room temperature was measured at 21°C (70°F) and the relative humidity at 57%. These values are considered "normal."
A surface temperature measurement of the “exposed” exterior wall at about 1.0 m (3.3 ft) height showed a temperature of 20.20°C (68.4°F).
The temperature measurement in the lower corner behind the bed showed a surface temperature of 17.6°C (63.7°F)! This temperature drop, despite the currently warm weather, is partly due to the corner location (keyword: thermal bridge) and partly due to the unfavorable position of the bed.
As temperatures drop toward autumn and winter, the temperature difference will increase further, inevitably leading to condensation and subsequent mold growth.
The same cause was responsible for the cabinet, now removed, that stood against the exterior wall.
We consider moisture penetration from outside to be ruled out due to the intact two-layer facade.
To verify this, the wall moisture was also measured electrically. The values were within the dry range between 48 and 58 digits. If the room continues to be used as it has been until now, and especially if the furniture position remains unchanged, further mold growth cannot be ruled out!
A structural upgrade of the walls with calcium silicate boards as interior insulation is possible. If interested, we would be happy to provide you with an offer.
N
nordanney12 Nov 2025 07:28Perhaps a bit of background about the apartment
This rear children's room serves as a sleeping and living area for your father and is furnished with a bed, desk, and television, as well as a wardrobe. The wardrobe is placed directly against the external wall without any gap. The bed is positioned under the window in front of the radiator.
You have been living in this apartment with your parents for 37 years. You first reported mold growth in the bedroom in 2022. Since you did not want to accept inadequate ventilation and heating habits as the cause,
the situation between you and the landlord is quite tense.
Regarding the distance to walls, there has already been some response: “Many experts often refer to DIN/TS 4108-8 ‘Prevention of mold growth in residential rooms’ concerning furniture placement against external walls as well as heating and ventilation. It also includes several tenant obligations for mold prevention. This could seriously backfire in court.”
If I had this kind of stress for years (including other issues in the building, which are documented in other forums), I would rather look for a new apartment than keep confronting the landlord over years, especially if I might be the cause of the problem myself.
This rear children's room serves as a sleeping and living area for your father and is furnished with a bed, desk, and television, as well as a wardrobe. The wardrobe is placed directly against the external wall without any gap. The bed is positioned under the window in front of the radiator.
You have been living in this apartment with your parents for 37 years. You first reported mold growth in the bedroom in 2022. Since you did not want to accept inadequate ventilation and heating habits as the cause,
the situation between you and the landlord is quite tense.
Regarding the distance to walls, there has already been some response: “Many experts often refer to DIN/TS 4108-8 ‘Prevention of mold growth in residential rooms’ concerning furniture placement against external walls as well as heating and ventilation. It also includes several tenant obligations for mold prevention. This could seriously backfire in court.”
If I had this kind of stress for years (including other issues in the building, which are documented in other forums), I would rather look for a new apartment than keep confronting the landlord over years, especially if I might be the cause of the problem myself.
J
Jodimaster2k10 Jan 2026 21:13By the way, the room does not reach 20 degrees Celsius (68°F) at low outside temperatures.
The landlord does not provide any solution.
Radiator type 10.
The landlord does not provide any solution.
Radiator type 10.
N
nordanney11 Jan 2026 11:23Jodimaster2k schrieb:
By the way, the room does not reach 20°C (68°F) at low outside temperatures.
The landlord does not provide a solution.
Radiator type 10. Report the issue in writing (why hasn’t this been done for years?). Reduce the rent. 30°C (86°F) is mandatory.
When it comes to money, things usually happen quickly.
J
Jodimaster2k11 Jan 2026 12:06nordanney schrieb:
Report the defect in writing (why has this not been done for years?). Reduce the rent. 30 degrees Celsius (86°F) is mandatory.
When money is involved, things tend to happen quickly. Due to the mold damage, everything is being thoroughly and continuously documented. There is no customary right in tenancy law. The room is in permanent use (changed usage behavior). But that is what you rent an apartment for. It is designated as a rear children's room, not a storage room.
An expert also needs to answer the question of whether the radiator can adequately heat the room.
The plumbing company is conducting a reevaluation (old measurement). They have taken a very landlord-friendly position here in their defense.
However, from a technical point of view, they can hardly refute it.
N
nordanney11 Jan 2026 14:30Jodimaster2k schrieb:
Due to the mold damage, everything will be thoroughly and permanently documented. There is no customary right under tenancy law. The room is in continuous use (changed usage behavior). But that’s what you rent an apartment for. It is designated as the rear children's room. Not a storage room.
An expert has to answer whether the radiator can sufficiently heat the room.
The plumbing operator is conducting a reevaluation (Altnau). This operator has presented in a way very favorable to the landlord in their defense.
But from a technical perspective, it is hardly possible for them to refute this. Unfortunately, you didn’t respond to my post. Report the defect and reduce the rent. Everything else is secondary. It doesn’t matter why it’s not warm. It’s the landlord’s problem. As long as it is not warm, then you simply do not pay the (full) rent.
J
Jodimaster2k11 Jan 2026 14:32nordanney schrieb:
You just didn’t respond to my post. Report the defect and reduce the rent. Everything else is secondary. It doesn’t matter why it’s not warm. That’s the landlord’s problem. As long as it doesn’t get warm, there simply won’t be full rent payment.Due to the mold damage, the tenant has been paying rent under reservation for many months now.
The plumbing company has recalculated the heating requirements (for an older building) for the room.
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