]DanG wrote:
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I think we would all need more information.


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.