I have old floors in my flat that creak so much that the neighbours below complain. One room in the flat was fixed by the previous owner and strong boards (the subfloor?) were laid, with carpet on top. They had problems with the old beams but this solved the problem.
I think I need a joiner to to do this, but I'm not sure what the correct category to post in. Or maybe it's a floor specialist? Nothing seems to quite fit this job.