Your project is certainly doable but you need to give a whole lot more
information particularly what is the ovehead span going from the doorway
to the house plus the load factor for your area (snow can be awfully heavy)

But a bigger deal will be getting by any local building authorities.
They will have definate ideas of what standards you should be following
and who should be resposible for those standards. Read: get a structural
engineer to sign off on them.

You are not likely to get a definite answer on the internet, most of the
folks who could accurately calculate the beam size will not stick their
necks out and give you a solid answer. Or at least not without seeing
the actual installation.

cj wrote:
i have an enclosed sunroom attached to the side of my house. i can enter
the room through a standard size doorway but i would like to open the
entrance considerably, about 10 feet or so.i guess the way to go would
be to put in an i beam header to support the weight. what size i beam
would i use? the i beam would be part of an exterior load bearing wall.
thanks, cj