"69roadrunner" wrote in message
...

I am planning to build a porch roof attached to the back of my house. . .
.
What I need to know is what size each of the beams spanning the sides
need to be to support the roof. There will be a 16" overhang . . .

This requires a building permit (in most jurisdictions.) The municipal
or county office that issues building permits can probably answer your
question (without charge.)

--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)