The most obvious reason is for their aesthetic appeal curved lines on the roof of a home allow for a more organic design.
Why are korean roofs curved.
The tiles usually shaped to represent bamboo create their own curved surface further confusing the evil spirits.
Temple roofs were curved because buddhists believed that a curved shape could ward off evil spirits which were thought to only move in straight lines.
Curved roofs can also be used as an alternative to a flat roof or a skillion roof and may allow for greater indoor areas or extra floors where height restrictions are a concern.
The upturned roof design appeared during the han dynasty 206 bc 220 ad and were the standard type used until the song dynasty 960 1279.
This happens because in summertime the sun is more directly overhead while in the winter it only gets about 35 degrees above the horizon at noon.
Asian roofs are gently curved out at the corners in order to allow more light to enter the windows in winter and provide extra shade in the summer.
The roofs are concave for aesthetic purposes and the eaves also gently curve upwards cheoma.
The upturned eaves on roof corners are the most identifiable mark of chinese roof architecture.