How much can wood move, how much movement in wood is normal?

We live in a 23-year-old Kampa prefabricated house, timber frame construction.

For example, at the end of September, we freshly painted the bedroom on the upper floor. Now, for the first time, about 2-3 weeks ago, such black "cracks" appeared on the ceiling, exactly where the ceiling meets the side wall. At first, I thought it was mold, but it was clear that these were cracks.

These are now clearly increasing. You can really see it. Also in the bathroom, along this ceiling-side wall edge, actual grooves of 2-3 mm have formed, which definitely were not there before.

We know that wood works, of course. At the moment, it is also really cold.

But is this normal? It seems strange to us. Also, in the hallway, a real crack has formed on the ceiling. That doesn’t just look odd visually...

Cracks in the corners and wall-ceiling joints are absolutely normal.

Photos of the cracks could still be interesting. But basically, that is quite normal, we also have it in certain places. Before we freshly paint a room, you always go over the cracks with acrylic; after painting, nothing is visible anymore.

You must seal these transitions with acrylic before painting. Or, even safer, put a cornice over them.

Here, for example, the bathroom.

We only repainted the bedroom four months ago and actually did not want to repaint it again in just a few weeks. If we now fill it with acrylic putty, will it be very noticeable?

Did you glue a quarter round up there? The way now would be: Wait until no more cracks appear. So be patient until May. Tape the joint closely. Put acrylic on it and work it nicely into the joint with a small damp brush. Let it dry for 24 hours. Then paint over the joint. Of course, you need to have some of the paint for that. After that, hopefully, it will be quiet. These crack joints occur due to drying. There was moisture in the corner, which wanted to get out and forced its way through.