The roofline is designed first
Where the new roof meets the old is what the street sees. It gets resolved on paper before the plan is finalised, not improvised in framing.
Materials matched, not approximated
Siding profile, brick blend, window sightlines and trim proportions specified against what is already there.
The join is detailed
Flashing, transition and expansion drawn as a detail. It is the place additions leak, and it is the place they look wrong.