Claudio wrote:

My advice if you haven't done so already is to have a discussion
with
your
local building inspector. They may have requirements you need to
meet that
would influence the design.

todd

I want to thank everybody specially Todd.

I checked with the building inspector and got not permission to build
a second floor, so I am just going to change the roof. It is quite
old, more than 50 years old metal roof and I am planning to build a
A-Type with shingle and about 9/12 pitch to have some attic space.
In
this way it is pretty simple and I should be able to do it by myself.
Thanks again to everybody.

Claudio