Tony,
Roof flaps do not change the contour, they are flush with the top.
Vic,
Where did you get the 35% from?
DW
Dan, I should have been a little more clearer, I wasn't referring to the flap itself but the 50 or so rivets that hold the flap box to the roof that change the contour of the roof and the gap (break in the roof line) that is created from the recessed flap hinge.
I think Vic was anticipating a possible new rule.
Its an RMR thing.
Tony