ᐅ Indoor humidity as high as outdoor humidity

Hello,

I’m not a home builder, but I thought if anyone can help me, it would be here.

My wife, my 6-month-old daughter, and I moved into an end-terrace house two months ago. Now we have the following problem:
We have very high indoor humidity levels. In the living room, it is always around 55%, and in the bedroom and office about 60-65%. We ventilate regularly by fully opening the windows for about 10 minutes (shock ventilation), including cross-ventilation, but the humidity hardly decreases, only by about 5%.
The house was built in 2000, so it should have good thermal insulation standards. I even checked the walls for moisture with a building moisture meter, and the values were between 2-5%, so it’s probably not coming from the walls. Are the windows not sealed properly, allowing the same high humidity from outside to enter the rooms? The indoor humidity does decrease on sunny days.

Before this, we lived in a 3-room apartment (3-bedroom, kitchen, bathroom) built after World War II (1953) in Hamburg, where indoor humidity was always around 30-40%, so this situation is surprising to us.

What could be causing this?
How can we reduce the humidity?

Thank you very much,

Martin

Uh, wait a moment. Please stay calm and get informed first. You have the perfect humidity level. Ideally, it should be around 50-60%.

30-40% is far too low and unhealthy. That can already cause problems with the mucous membranes.

Humidity only becomes critical at around 80% in combination with cold walls (dew point...).

So everything is great!

Yes, that is correct, but it is not normal for the humidity in the room not to decrease after ventilating. Is it?

Your indoor humidity levels are fine. How could they drop significantly if the outdoor air isn’t much drier?

So everything is normal and good.

It depends on the indoor and outdoor temperatures. If it is colder outside than inside, the humidity should be lower after ventilation than outside; if it is warmer outside, the humidity will increase after ventilation.

On the one hand, the humidity level is not concerning. However, for this time of year, I find it quite high. As already mentioned, the indoor moisture will only be lower than outside if heating is used indoors.