I was wondering if it is possible to extend a cantilevered beam out to support a gable porch overhang. I know this is getting into the range of engineering territory, but I have seen it in a couple houses and wonder how they structurally support the beam (cathedral ceiling) to prevent it from rolling (seems like a hinge point). I am thinking it is notched into 2x6 studs and overlapped by the top plate. Here are some pictures of what I am trying to describe:
(http://i.imgur.com/u6kuh6o.jpg) (http://imgur.com/u6kuh6o)
(http://i.imgur.com/beh9jKn.jpg) (http://imgur.com/beh9jKn)
(http://i.imgur.com/3xwcDCa.png) (http://imgur.com/3xwcDCa)
Totally doable, definitely want an engineer. If you don't want to pay, you could try to do it in the 3x rule. The overhang of the beam can only be 3x that of the height of it. Ex: 2x8 can overhang 22.5".
With that said, I would add lookouts at 24" OC. Size the rafters based on the span, and at least go 2x4 for the lookouts.
Alternatively, you can cheat by adding a gusset to that overhang.
Those are typically done with glulam beams, the supplier can do the engineering for them.
This calc can give you some sense of the size required if you input the appropriate variables;
http://www.timbertoolbox.com/Calcs/ohangunild.htm
I may be way off here, but in the gable overhangs that I'm familiar with, the lookouts do all the work. I'm not sure how much work such a beam would really need to do. If you do a google image search most such overhangs don't even have a beam like this. Might be more of an issue if you're doing a pole-building.
Either is an acceptable way within their limits.