Rafter Span

Richard from Georgia asks: Concerning rafter span; If I have a center ridge board and measure to the outer wall, that is the span, but if the wall is two feet wide and has a support on the inner wall up to the rafter, would not the span of the board be on the inner wall of the 2 foot wall?

Roofing expert Jeremy from Apollo Primm says: My understanding is the clear span of a rafter is to the outside edge of the wall if you are using span tables.