jǔjià 舉架

Note

Jujia is the method of positioning the purlins, layer by layer, in order to determine the pitch of the roof. The term mainly appears in the Gongcheng zuofa (1734) and Yingzao suanli edited by Liang Sicheng, so it can be considered part of the official practice of the Qing dynasty. Different from juzhe 舉折 described in the Song dynasty Yingzao fashi (1103), jujia is the process of determining the height of the roof ridge based on the heights of the purlins as calculated from the bottom (eaves) to the top (ridge). Here jugao 舉高 refers to the height that a purlin is lifted relative to the one below it. The jugao of each purlin is determined by the percentage of the distance of bujia 步架, the distance between two adjacent purlins. For instance, “65 ju” ( 六五舉) means that the height of jugao is 65% that of the bujia 步架. The first step is to determine the height between the top of the neighboring pillars, guazhu 瓜柱 post, or tuodun 柁橔 brace. Then add the appropriate height of pingshui 平水, and this will result in the appropriate position for the purlin. As outlined in the Yingzao suanli, the calculation of jugao differs according to the number of purlins in a given building. Few actual buildings correspond exactly to the method of jujia outlined in the Gongcheng zuofa and Yingzao suanli, indicating that the height of the purlins could be increased or decreased according to specific circumstances rather than always rigidly following a single standard that was documented in these texts.

The practice of jujia explained by modern scholars is different from that outlined in the Qing Gongcheng zuofa. The description in the Gongcheng zuofa refers to a construction process involving prefabricated components. In comparison, the practice of jujia explained by modern scholars focuses on the general principles of jujia, and aims to understand the method of determining the final positions of the purlins. Furthermore, the precise method used for calculating the positions of the purlins is still a matter of scholarly debate.

Since juzhe (the method of determining the pitch of the roof in the Song dynasty) and jujia (the method of determining the pitch of the roof in the Qing dynasty) differ significantly, scholars who study architecture in the Ming Dynasty are interested in understanding the development from juzhe to jujia (Guo 2005; Zhu 1983). The possible reasons juzhe developed into jujia remain the subject of active debate in published literature (Zhang 2005; Zhu 1983) as well as in current courses at major research institutions, such as Southeast University, Nanjing (2022). 6

舉架是通過柱、梁把桁條（小式建築中稱為檁條）層層上舉的方式獲得屋架折線的方法。該術語在文獻中主要出現於清工部《工程做法》和梁思成編訂的《營造算例》，可認為是清官式做法。與宋代《營造法式》記載的舉折不同，舉架是從下往上逐次確定桁條位置。首先确定进深方向竖向构件上皮（柱，瓜柱，柁橔）相对于前一构件上皮抬起的高度。，該高度以桁條間的水平距離為基準按一定規則計算。繼而加上平水的高度（等同於墊板高度），即得到桁條下皮的高度。(梁 1981；王 1995，18）在實例中，沒有嚴格符合《工程做法》或《營造算例》中規定的舉架做法。 7

現代學者所闡釋的舉架的做法與《工程做法》的描述逻辑有所不同。《工程做法》的描述方法符合构件預製後進行安裝的施工过程。而現代學者所描述的舉架做法，着重定義舉架的一般性原則，以直接確定桁条的位置为目标，強調靜態的結果。不同學者確定桁條位置的基準點和举架的起算点也不同（梁 1981，2006；孙 2009，251-278；马 1991，7；潘编 1993）。 8

Related concepts

jǔzhé 舉折

Broad Match: building frame