Modern building roofs are mostly of regular shape, which is also in line with the theory of architecture and aesthetics. In ancient times, many green brick building roofs generally appear to be curved shape, palaces, temples and so on. It has also become a feature of PC imitation stone brick in ancient Chinese green brick building. So why is there such a design?
其实主要的是还是因为曲线看起来更有艺术感，而直线则过于流畅古板，屋顶呈现曲线会更加美观，有古风。如“檐平脊正”正是 对建筑的要求，而装饰艺术则在这个基础上开始运用的。檐宇的线条应该是笔直的，但若做起两端必然运用曲线使它翘起，构成一种曲线美，屋脊本来也是又平又 直，但是运用曲线的结果，是将两端也尽量升起，翘起来，成为曲线美。
In fact, the main reason is that the curve looks more artistic, while the straight line is too smooth and stereotyped, the roof presents a curve will be more beautiful, there is an ancient style. For example, "eaves flat ridge" is the requirement of architecture, and decorative art is used on this basis. The line of eaves should be straight, but if you do both ends, you must use curves to make it warp up, forming a kind of curvilinear beauty. The roof is also flat and straight, but the result of using curves is to raise both ends as far as possible, and to become curvilinear beauty.
The corner ridges on the four sides of the top of the palace and the Xieshan type top also make curves, forming the so-called "pushing mountains". In the roof, the water on both or four slopes should also be flat and straight. These positions use curved surface to adjust the horizontal and vertical slopes to curved slopes. The four corners of the roof are also suitable for the line. The corners of the roof are upward warping. The overall appearance of the roof is very soft and unique.
Throughout the style of Chinese green brick architecture, the reason why beauty is in fact good use of curves to achieve a most harmonious state. And the curves are also shown in columns, bucket arches, beams, piers, paintings, murals and so on, so ancient Chinese architecture is a very artistic knowledge. In fact, the combination of single curve and straight line in Chinese green brick building is very perfect, only one of them will have defects.