How can I insulate my exterior wall?

Hello,
one room in my apartment is on the outer wall and there it is not only colder but mold also forms. What can I do about it, does it make sense if I try to insulate the wall from the inside? The mold is not only ugly but certainly not healthy, what should I do?

Hello Olaf,

I don't want to spread unnecessary panic here, but mold growth on walls always indicates moisture. That means either moisture is penetrating the wall from the outside, or (as is often the case in new buildings) it is due to insufficient circulation of humidity caused by improper ventilation - however, this can already be noticed if water is accumulating on the window panes. So the very first thing you should do is check, or have checked, where the moisture is coming from, and only then can it be said what you specifically need to do. :-)

Hello, it would certainly be better to insulate the wall from the outside and not from the inside. Furthermore, it is not enough to just stick something on when there is mold, because the mold is already everywhere and spreads with its spores throughout the entire apartment. This is bad for health and can lead to allergies.

Hello,
I also believe that it is pointless if you insulate the wall from the inside. If you live in a rental apartment, it is the landlord's responsibility to take care of it. Besides, it is certainly very cold where you are, and I would consider whether to reduce the rent. Because mold is always a reason to reduce the rent.

Olaf, without a more detailed description of what kind of apartment or even your own house you have, it is difficult to determine the cause. The fact is, mold develops on damp building components, regardless of whether it is due to missing exterior insulation and thus a thermal bridge or due to incorrect occupant behavior. This would at least be the first approach for you to check!

The rooms should always have a certain temperature, both the air in the room and, more importantly, the wall itself, thus the building component. If the room is cold, the air moist, and this then meets the cold wall, it condenses there, and over time mold develops.

In the case of a rental apartment, this would not be a reason for rent reduction but a cause to compensate the landlord for the damage caused due to improper use of the rented property. Not to mention rent reduction at all.

If you cannot identify the cause yourself, get a building expert on site and have the situation that led to the infestation checked before further damage (of course also to your health) occurs.

hello. I read your post and I would be interested to know what solution you found.

my neighbors have a similar problem. the house is a timber frame construction with plaster on the outside. there were many construction defects on the part of the timber construction company, which they have now repaired through longer renovation and remodeling work (after 7 years). but I am skeptical, because now they have a new roof structure, partially new insulation outside, and max boards (I think that's what they are called) on the outside. what only strikes me extremely is that now in the cold season even more condensation is visible on the windows than before! really extreme, I estimate about 15 to certainly 20 cm from the windowsill upwards into the window in the morning. in my opinion, something else is wrong there. and so much moisture in the window areas ..... it also spreads in areas that are not visible.

if it were my house, I would hire an independent expert to investigate the root of the problem and then take action.

what did you do and what is the result?