How did the chuandou building system differ from the tailiang system?

The tailiang and chuandou systems represent two distinct engineering approaches to supporting roofs in traditional Chinese architecture.

The Tailiang System

Also known as the "beams-and-columns" system, tailiang relies on a post-and-lintel frame. It utilizes a stepped-up series of elevated tie beams that are sequentially shortened to support the roof purlins and the main roof beam. This system is characterized by its standardized nature and the use of column-top bracketing to support the structure.1

The Chuandou System

Primarily found in southwestern China, the chuandou system employs tall, thin columns that extend from the roof purlin to the ground along the full length of the gable end. Unlike the tailiang system, horizontal tie beams penetrate these timber columns directly. This method allows for greater geometric flexibility in the gable wall design. Instead of column-top bracketing, chuandou architecture uses slanting wooden struts that extend diagonally downward from the eaves purlin to the columns for support.1