Traditional Soviet-style wooden roof

In Soviet-style buildings with five purlins, seven purlins and nine purlins, their brain rafters, (upper and lower) flower rafters and eaves rafters are often overlapped with nails, but some early buildings are also directly staggered without overlapping. In order to distinguish the two methods of folding rafters, some people call them "folding palm" and "folding palm" respectively.

Grinding rafters used in modern antique buildings.

Comparatively speaking, it is more common to lap with nails.

In the previous investigation, the overlapping position of the rafters is also worthy of attention. "Construction Law" records that "every purlin is sewn and nailed obliquely". Sometimes, different buildings, "for sewing" and then "oblique approval" are different. The work of nailing rafters is also done by carpenters in ancient buildings.

Rafters decoration

Although the rafters are small, the ancients decorated them carefully, and different buildings in different times also applied different decorative styles, which is also a point that needs special attention in the investigation and design of ancient buildings and learning to imitate them.

For example, Ming-style architecture, with obvious flying heads and rafters, is a typical official architectural style of Ming Dynasty. At the same time, in exquisite buildings, especially religious buildings and some folk buildings, eaves and rafters exposed to the air are often painted with colors, not only to decorate or show the architectural purpose, but also to paint for anticorrosion and waterproofing.

In buildings in the south, rafters are often connected with the roof wood structure to facilitate ventilation and anti-corrosion, while some houses and masonry in the north can directly surround the rafters, which may also make it difficult to replace or repair the rafters. At the same time, the southern dwellings are mainly round rafters, while the northern dwellings are used to square rafters.

Color paintings are rarely used in southern dwellings, but the carvings are often more exquisite than those in northern dwellings, and the wooden frame shapes are also diverse, which is one of the characteristics of southern dwellings.

Zheng Xuan Suzhou Humble Administrator's Garden

Number of wing angle rafters and rafters

In northern dwellings, purlins are generally singular, rafters are even and rafters are even. For example, there must be four rafters in three rooms, and the rafters cannot be singular, which is also a long-standing folk custom. However, according to the investigation of historical buildings, many wing rafters are singular, but many are even. For example, the wing rafters of Tiananmen Gate Tower and Forbidden City Corner Tower are even.

Wing angle rafters are a group of eaves rafters that are both punched out and raised. When calculating, the rafter near the corner beam is the first wing angle rafter, and the rafter near the body is the last wing angle rafter. The formula of "punching triangle, four corners and half angles" is applicable to corner beams and head rafters, but not to wing rafters. In the design, it is generally set out according to 1/3 of rafter diameter.

Wing rafters are square and round. Round wing rafters are mostly used in large buildings such as palaces and temples, while square wing rafters are mostly used in garden buildings, such as verandahs and pavilions. In order to combine the wing rafters with the corner beams, it is necessary to cut the tail into wedges and the head of the square wing rafters into different diamonds.

Luo Guo-rafter and the roof of the rolling shed

Generally, large buildings have joists on the roof purlins, and the rafters are dug out to put them. At the same time, roof purlins must be made into upper and lower gold plates to maintain stability. Underside or back of purlin, where it overlaps with other components (pads, joists, tows, etc.). ).