Later on, as tools improved, methods for using thinner boards were developed, and use of kokerabuki, utilizing the thinnest boards, started in the early Heian period.
以後、道具の進化もあり、より薄い板を用いる手法が開発され、最も薄い板を用いる杮葺は平安時代初期には使用されはじめる。