Jǔzhé

Also called juzhe, jǔ zhé, raising and depressing, jujia, jǔjià

The Song method of “raising and depressing” the roof: the ridge is raised by a fixed fraction of the depth (a third for great halls), then each purlin below it is lowered from a straight line by 1/10, 1/20, 1/40… of the rise, giving the concave Chinese roof. The Qing equivalent is jǔjià.