No we don't. The OP doesn't know what the walls are made
of, what's inside them, or even how to measure them, and is therefore
manifestly not competent to be tackling this job by himself.

Thanx for your help.

I'm not pretending to know what i am doing, otherwise i wouldn't have
posted. I was just asking for a little advise.

Right, and the advice I'm giving you is that this job has structural
implications that you're not up to coping with, and you should
find a professional to deal with it. There will be enough things for
you to fix without messing with collapsing headers.