Poor Cantilever Roof Framing
It's not uncommon to find poor cantilever roof framing
joist or even floor framing joist for that matter. If you live in a home
that has a situation like this and you don't have any problems with it,
I wouldn't worry about changing anything.
The costs for making these repairs could be enormous. In the picture above, they removed the damaged roof joist and replace them with new ones. They didn't bother to correct the cantilever problem and this is usually what happens when most home repairs are made, anyway.
Good cantilever framing extends one third from the building and goes back two thirds into the roof framing. In other words, if we look at the two arrows in the picture above, this is the area that the cantilever is extending from the building.
If the measurement between these arrows is 3 feet, the roof joist should extend at least 6 feet into the roof framing. In the picture above, it almost looks like it's the same distance.
Home Repair Tip: If you wanted to fix the roof (and I'm not recommending that you do, if you're not having any problems with the roof, I don't recommend making unnecessary repairs.) because you're having problems with it.
You would need to remove the all of the roof joist and reframe this entire section using the one third cantilever and the two third back framing method.