Humidity in basement apartment

always and always this fairy tale..strange that we have NEVER had problems with mold. We NEVER air out briefly and like to dry the laundry inside (makes the air so nicely humid).

No sorry..but that is just dirt! To cause mold yourself...you really have to be very stupid..

You again fortunately your view is not the rule.

I would be surprised if that in the pictures was caused by incorrect ventilation. At most it might have been favored; but not the cause.

I would not make the tenant crazy now and wait for the examination by the expert.

Today the expert was here. He said that the following steps should now be taken:

- Leak detection and pressure test in the heating system. The tenant said that some time ago the heating system had lost pressure

- if that doesn't help, digging around the building should be done and the insulation should be checked

- only if nothing is found then should we deal with ventilation

In any case, instead of the woodchip wallpaper, a rough plaster should now be applied as it does not mold as quickly there

So what it is caused by..... no idea as of today!!

Well, in summer he doesn't have to heat, he has over 19°, but warm air carries a lot of moisture and that has to be regularly removed.

Have you ever paid attention to the humidity outside in summer? That way you bring in more moisture rather than preventing mold with three quick ventilation sessions a day...

Even though I rarely agree with Steffen80 - this time I completely do. The myth of incorrect ventilation by tenants is outdated nowadays.

Is the house "airtight"? How old are the windows? What is the year of construction of the house? Are there plenty of openings for heating pipes, etc.?

Does the tenant live alone and is rarely at home [then he brings in little moisture]?

For the time being, I share the opinion that it is rather not due to ventilation (or too little ventilation). The expert also points in that direction ...

Through a drilling, the expert should be able to determine whether the wall in the middle is wet or not. Then you can see where the wall is damp.