Seal between wall and ceiling

[Gjutjärn]

Onestrike does not handle movements very well, it becomes like rock-hard foam plastic when it dries.

Ok, but are there really that many movements there? The house is from '72. And there will be a trim in front of/against the joint too!

 

[Gjutjärn]

Don't know Onrstrike but if it's a lightweight filler, it's not very effective. It's much better with gypsum plaster. The only function backing rod / tightly packed insulation has with soft sealing is to prevent the seal from collapsing over time.

https://www.bauhaus.se/one-strike-filler-rep-spackel-250ml Says it fills up to 70mm. Ah okay. And since there will be a list in front, it shouldn't be a problem?

 

[Oldboy]

The problem with hardening mtrl is that it cracks over time. Wooden houses move with the seasons (RH), regardless of when they are built.

Even cheap latex caulk cracks. That's why I always use draught strips now, and never use caulk if I can avoid it.

With a list, I see no reason for filling or similar beyond the draught strips, unless maximum soundproofing is important. In that case, you should carefully follow Björn's advice.