ᐅ How much can wood expand and contract, and what amount of movement is considered normal?

We live in a 23-year-old Kampa prefabricated house with a timber frame structure.

For example, at the end of September, we freshly painted the bedroom on the upper floor. About 2-3 weeks ago, we first noticed these black "cracks" on the ceiling, exactly where the ceiling meets the side wall. At first, I thought it might be mold, but it was clearly cracks.

These cracks are now clearly increasing. You can really see it. In the bathroom, along this ceiling-to-wall joint, there are also noticeable grooves of 2-3mm (0.08-0.12 inches) that definitely were not there before.

We know wood moves, that’s clear. At the moment, it’s also quite cold.

But is this normal? It seems strange to us. There is a significant crack in the ceiling in the hallway as well. It doesn’t just look odd cosmetically...

Cracks in the corners and at wall-to-ceiling joints are completely normal.

Photos of the cracks could still be interesting.
But basically, this is quite normal; we also have it in certain areas.
Before repainting a room, you always go over the cracks with acrylic. After painting, they are no longer visible.

You need to seal these joints with acrylic before painting, or, even more securely, cover them with a molding strip.

Here is the bathroom, for example.

We repainted the bedroom just four months ago, and we didn’t really want to have to paint it again in just a few weeks. If we fill it with acrylic putty now, will it be very noticeable?

Did you glue a quarter round molding on top there?
The procedure now is as follows:
Wait until no more cracks appear. So be patient until May. Mask the joint tightly with tape. Apply acrylic sealant 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’ll need some of the paint for that. Hopefully, this will stop the issue. These crack joints occur due to drying. There was moisture in the corner that needed to escape and pushed its way out.