A Study on the Formation of Eight-Grades Values in Yingzao Fashi

Yingzao Fashi (A Treatise on the Construction Methods) introduces an ingenious adaptable building system that leverages the application of cai (carpentry system of measurement). This system seamlessly integrates architecture design, work limits, and rules for material usage in timber structures through meticulously crafted proportional relationships. This integration facilitates universal and precise budget management. Within this adaptable framework, eight grades of the cai-fen modular system hold significant structural and computational importance. However, the specific values assigned to these grades remain somewhat enigmatic, lacking a widely accepted explanation. This paper endeavors to analyze these designs within Yingzao Fashi from the perspective of budget management. It delves into grade standards of buildings, the numerical relationship between fen and cai, the choice of sixth grade as a benchmark, and the proportional relationships among the various grades. By examining the text of Yingzao Fashi, the surviving buildings in that era, and the editing background and purpose of the document, the paper concludes that these designs are deeply rooted in the practical building knowledge of the time. Furthermore, they are specifically tailored to meet the need for convenient computation, thereby enhancing the effectiveness of budget management.