This paper presents a study of the methods by which the inclination of a rafter was determined. Three methods were identified:
1. The inclination of a hien-rafter was determined so that the elevation of the kayaoi could be made higher than that of the kioi.
2. The inclination of a hien-rafter was determined so that the elevation of the kayaoi could be made the same as that of the kioi. (MUTSUTSURE method)
3. The inclination of a hien-rafter was determined so that the elevation of the kayaoi could be made lower than that of the kioi. (KAYATIGAI method)
