DanG wrote:

I think we would all need more information.

The major issue here is ending up with a header to carry the load
over head once you remove the material in the proposed opening.


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.

--Goedjn