I recently installed rafters on an L-shaped roof, about 280 sq ft- It was my first time and I took the advice of a YouTube video that said as long as all the rafters were facing the same direction, they could be installed crown up or down- I chose down, and realize that EVERYONE else insists on crown up- what can I do about this?
When framing walls all the crowns can go in or out, but on a roof they all need to go up. Only way to fix it is to redo it.
Sheet the roof twice the second layer of sheeting should smooth it out
Add a stiff-back under rafters at half the span. Support with posts over end walls, and interior walls if any.