Rafters showing through the ceiling

I’ve got a friend that says she can see her rafters every 24" on the inside of her drywalled ceiling. What would cause this? Moisture? She says there’s no sagging, just lines on ALL of her rafters that weren’t there before.


Sounds like ghosting. Do a search on the board for “ghosting.” There are many posts regarding this condition.





From many things I have read it only takes as little as 1/10 of a degree to cause ghosting .
A 2*4 does not have the same insulating value as 4 inches of insulation .
Smokers or candle burning helps this to happen faster .