Hi,
I need some advice. In our house (3 years old, solid construction, 36.5cm (14 inches) Poroton blocks), there is mold forming in one room at the corner where two walls (both exterior walls) and the ceiling (upper floor under the flat roof) meet. There is no mold anywhere else in the house, and we ventilate the room daily.
I had the roofer check the site, and they removed the roof down to the concrete layer, but everything is dry there.
Now we’re really stuck... Everyone is puzzled. What could be causing this problem?
Thank you and best regards
I need some advice. In our house (3 years old, solid construction, 36.5cm (14 inches) Poroton blocks), there is mold forming in one room at the corner where two walls (both exterior walls) and the ceiling (upper floor under the flat roof) meet. There is no mold anywhere else in the house, and we ventilate the room daily.
I had the roofer check the site, and they removed the roof down to the concrete layer, but everything is dry there.
Now we’re really stuck... Everyone is puzzled. What could be causing this problem?
Thank you and best regards
Ah yes... the good old heating/ventilation debate.
Those who understand the connections immediately recommend more heating and ventilation.
Others look for problems in the wall construction, etc.
The issue, as always, is a thermal bridge. Call it what you want. The fact is the wall is colder (and possibly more humid) than the rest, and for this reason, moisture in the air condenses there.
Humidity levels around 70% are not "healthy." Ventilation helps, but either with mechanical ventilation or the well-known shock ventilation method. Well, this apparently does not apply in leaky houses (older buildings, etc.).
However, the room’s air moisture absorption must be increased. Because to be able to ventilate large amounts of moisture out in a short time (shock ventilation), these quantities must also be available to be transported away.
Exaggeratedly speaking, you could leave the window open all day without higher temperatures, and nothing would change.
The house is only 3 years old. If it has always been ventilated and heated minimally, and the thermal bridge has always been present, then construction moisture may still be there at that spot and the occupant is only ventilating the additional moisture introduced. As a result, the wall will never dry out.
Those who understand the connections immediately recommend more heating and ventilation.
Others look for problems in the wall construction, etc.
The issue, as always, is a thermal bridge. Call it what you want. The fact is the wall is colder (and possibly more humid) than the rest, and for this reason, moisture in the air condenses there.
Humidity levels around 70% are not "healthy." Ventilation helps, but either with mechanical ventilation or the well-known shock ventilation method. Well, this apparently does not apply in leaky houses (older buildings, etc.).
However, the room’s air moisture absorption must be increased. Because to be able to ventilate large amounts of moisture out in a short time (shock ventilation), these quantities must also be available to be transported away.
Exaggeratedly speaking, you could leave the window open all day without higher temperatures, and nothing would change.
The house is only 3 years old. If it has always been ventilated and heated minimally, and the thermal bridge has always been present, then construction moisture may still be there at that spot and the occupant is only ventilating the additional moisture introduced. As a result, the wall will never dry out.
P
Pluto197721 Nov 2019 09:08Thanks for all the responses. I see I need to ventilate more often and heat more (the room was below 20°C (68°F) since it’s only used as a bedroom).
By the way, the room is on the 1st floor (1st story) in the south/west corner.
What still puzzles me: the wall itself is dry everywhere (measured by professionals – “34” whatever that means). Only at the top corner is it really damp (“136” whatever that means) and 2.5°C (4.5°F) cooler.
Is this a thermal bridge? Can anything be done about it, or should you just live with it and make the best of it?
Best regards
By the way, the room is on the 1st floor (1st story) in the south/west corner.
What still puzzles me: the wall itself is dry everywhere (measured by professionals – “34” whatever that means). Only at the top corner is it really damp (“136” whatever that means) and 2.5°C (4.5°F) cooler.
Is this a thermal bridge? Can anything be done about it, or should you just live with it and make the best of it?
Best regards
H
HappyDee4521 Nov 2019 09:17Roof insulated? Insulate the ceiling of the upper floor?
Pluto1977 schrieb:
live with it and make the best of it? You can also repaint it every quarter of a year so you don’t see it.
Our fully renovated apartment always had problems with mold stains in the corners of the living room and bedroom toward autumn and winter (whether the external thermal insulation composite system has an effect or not, I have no idea). We couldn’t get the issue under control in the corners, which was really frustrating. Since we had a separate entrance door at that time, we could easily do cross-ventilation. So, it couldn’t have been caused by ventilation. We repainted every six months because nothing else helped!
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