I have bird feeders my uncle made out of cedar... They might not "rot" but they have split with time every place he put in a screw or nail. He was a proper carpenter, so I think they were done with good technique. They lasted about five years before they were split enough to leak to the point the seed was always wet.
On my screen porch, I have cedar covering the posts on the outside. It holds the screen in place. It has never been stained or treated. It is screwed on. Maybe it is better quality, or thicker, or ? than the bird feeder cedar, as it has been on there at least twenty five years and has not split or had any other problems. Has even been taken off twice, new screen put on the porch, and the wood put back up.
