Image © Margarethe Holzer

茅草屋顶：建筑的历史、性能和可能性
Thatched Roofs: History, Performance and Possibilities in Architecture

由专筑网邢子，小R编译

乍一看，Dorte Mandrup对Wadden海洋中心的设计似乎是在模拟风景。其低矮的高度，水平的线条，尤其是材料，使其成为与当地自然完美和谐的现代建筑。但实际上这座建筑与环境的联系也包含了该地区的建筑遗产，更具体地说，它使用了在附近收割和干燥的稻草覆盖建筑。这是一种极其传统和历史性的建筑技术，但很少被用于当代建筑。在这篇文章中，我们将介绍这种天然材料的历史，特点和一些使用实例。

At first glance, Dorte Mandrup's design for the Wadden Sea Center seems to mimic the landscape. Its low height, its horizontal lines and, above all, its materiality make it a modern building in perfect harmony with the local nature. But its connection also encompasses the built heritage of the region, more specifically because of its covering with straw, harvested and dried close to the land. This is an extremely traditional and historic building technique, but which is rarely attributed to contemporary buildings. In this article we will rescue some of the history of this natural material, its constructive characteristics and some examples of use.


Image © Adam Mørk

研究茅草屋顶的使用历史是相当具有挑战性的。不像石头，甚至是简陋的水泥，由于它是一种天然的和可生物降解的材料，在古老的建筑中很少有使用它的痕迹。然而，研究人员发现，茅草结构可以追溯到人类脱离游牧民族后致力于发展农业的时代。有研究表明，茅草在阿兹特克帝国和现在所说的欧洲的第一批建筑中被使用，以及在欧洲、英国和墨西哥等地都有对其使用的研究。

茅草屋顶是一种传统的方法，包括使用干燥的纤维，如稻草、芦苇、棕榈树和其他天然纤维来创造一个屋顶覆盖物。这些纤维被分组并以一定的方式交织在一起，形成一个表面，通过连续的重叠变得防水，老鼠和害虫几乎无法穿透。屋顶自下而上安装，顶部是最注重维护的地方，因为它是水渗入的薄弱点。坡度较陡的屋顶会使水流得更快，防止潜在的渗透问题。但这并不意味着这种材料限制了设计师的创造力，因为它是灵活的，所以可以很容易地实现有机的形状，就像Porky Hefer Design设计的The Nest一样，在这个项目中，茅草材料包裹着屋顶和大部分墙壁。

Researching the history of the use of thatched roofing is quite challenging. As it is a natural and biodegradable material, there are very few traces of its use in old constructions, unlike stone structures or even rudimentary cements, for example. However, researchers point out that the thatched structures date from the time when humans stopped being nomads and dedicated themselves to agriculture. There are indications of their use in the Aztec empires and in the first buildings of what we now call Europe, as well as research on its use in Europe, the UK and Mexico, among many others.
Thatched roofing is a traditional method that involves using dry fibers such as straw, reeds, palm trees and other natural fibers to create a roof covering. These are grouped and interwoven with a certain tension to form a surface, which through successive overlaps becomes impermeable and almost impenetrable to rodents and pests. The roof is mounted from the bottom up and the top is where more care must be taken and more maintenance must be done, as it is a weak point for water infiltration. Roofs with a steeper slope will make the water run faster, preventing potential infiltration problems. But this does not mean that the material restricts the designers' creativity. Because it is flexible, organic shapes can be easily achieved, as is the case with The Nest, by Porky Hefer Design, in which the material surrounds the roofs and most of the walls.


Image © Katinka Bester

由于多种空隙和表面不规则性，这种材料组成在干燥和压实的情况下具有良好的绝缘性。如果应用得当，稻草还具有非常好的抗风性。茅草也相对较轻，这为屋顶的支撑结构减轻了压力。还有一个必须考虑的问题是它的防火性能，作为一种干燥和高度易燃的材料，必须采取预防措施，以防止燃烧，同时能让人尽快控制住火情。目前，有一些公司在使用含有阻燃剂的合成纤维来加强这一性能。

The material composition, due to the multiple voids and surface irregularities, provides excellent insulation when dry and compact. When applied correctly, straw also has very good wind resistance. Thatch is also relatively light, which means the roof support structure can be less robust. One issue that must be taken into account is its behavior in the event of a fire. As a dry and highly flammable material, precautions must be taken to prevent combustion and control flames as quickly as possible. Currently there are some companies that work with synthetic fibers with flame retardants, for example.


Image © Stefano Mori

由于它是一种既廉价又相对简单的材料，其应用通常集中在农村地区。换句话说，我们很难在曼哈顿或圣保罗市区看到茅草屋顶。而当有材料和劳动力可以使用时，这种建筑技术的结合就特别有趣。这就是Anna Heringer工作室为津巴布韦的一所幼儿园所做的项目，它是津巴布韦生态文化教育中心的一部分，设计来源于自给自足的理念，用木材、稻草和石头建造。正如项目描述所指出的，“利用这些当地技术，该项目遵从团队精神、技能知识、自信和富有尊严的过程进行建设。由于气候环境和当地条件的影响，除非是用玻璃和钢铁建造的建筑，否则不会永远存在，但这也是这个项目想要探索的技术，同时考虑其可持续性。……这就是我们认为这个项目主要是用现有的材料进行先进的建筑构造，然后这些材料以后可以成为田地里的肥料的原因。”

As it is an inexpensive and relatively simple construction, its application is usually concentrated in rural areas. In other words, we will hardly see thatched roofs in Manhattan or downtown São Paulo, since the incorporation of this constructive technique is especially interesting when materials and labor are available to do so. This is the case of Studio Anna Heringer's project for a kindergarten in Zimbabwe, which is part of a Permaculture Education Center in Zimbabwe and is designed within the philosophy of self-sufficiency, built in wood, straw and stone. As the project description points out, “With these local techniques, the project aims to build with a process that reinforces solidarity and team spirit, skills and knowledge, self-confidence and dignity. Due to climatic contexts and local conditions, buildings, unless constructed of glass and steel, will not last forever, but it is essential that the know-how to maintain and rebuild them is kept alive and passed on to succeeding generations. (...) That's why we see this project primarily as training in advanced building techniques with existing materials that can then become compost from the kindergarten's fields.”


Image © Stefano Mori

同样，在Morison工作室的Mother Pavilion项目中，方法也是类似的。“其形状是对点缀在这个乡村的非凡干草砖的诠释。……墙壁和屋顶由当地的稻草制成，其屋顶是由一位工匠大师按照传统风格制作的，他曾经作为学徒的第一份工作就是在这个地方收割干草堆。”

At Studio Morison's Mother Pavilion, the approach was similar. “The shape is an interpretation of the remarkable hayricks that dotted this countryside. (...) The walls and roof are made of local straw, the roofing of which was made in the traditional style by a master craftsman, whose first job as an apprentice was to harvest a haystack on this very spot.”


Image © Charles Emerson

在印度的一座房子里，传统的技术被融入了更多的动态形式，为屋顶带来了其他的功能，那就是收集雨水。“茅草屋顶的形状像一个倒金字塔，向院子内侧倾斜，庭院兼作雨水收集器”。

In this house in India, the traditional technique was incorporated with more dynamic forms, to bring a primary function to the roof, which is to collect rainwater. "The thatched roof is shaped like an inverted pyramid that descends inwards towards the courtyard. Not only focused as the central concentration, the courtyard also doubles as a rainwater catchment."


Image Cortesia de Pragrup

如前所述，屋脊是稻草屋顶最令人担忧的地方（事实上，这些是所有屋顶的重要部分）。在Tåkern游客中心项目中，Wingårdh Arkitektkontor AB通过加入天窗解决了这个问题。正如建筑师所指出的。“该建筑用稻草覆盖，像观鸟者的幕帘一样形成伪装，将其内容隐藏在周围的自然世界中，陡峭的色调使其具有长久的生命力。茅草屋顶最脆弱的屋脊部分，被改造成了玻璃天窗”。

As previously mentioned, the ridge is the most worrying point of a straw roof (in fact, these are important parts of all roofs ). In the Facts Tåkern Visitor Center project, Wingårdh Arkitektkontor AB solved this by incorporating a skylight. As the architects point out: “The building is clad in straw, camouflaged like a birdwatcher's curtain, hiding its contents from the natural world around it. The steep tone gives them longevity. The gable, where a thatched roof is most vulnerable, is transformed into a glazed skylight.”


Image © Åke Eson Lindman

稻草也可以在现代性和传统性之间创造一种对比。在Sandellsandberg的Synvillan Eriksberg酒店和自然保护区，茅草屋顶与笔直的形状和抛光的金属覆层形成对比，后者的反射特性给人一种建筑溶入景观的错觉。

Straw can also work to create a contrast between modernity and tradition. At Sandellsandberg's Synvillan Eriksberg Hotel & Nature Reserve, the thatched roof contrasts with the straight shapes and polished metallic cladding, whose reflective properties aim to give the illusion of a house dissolved into the landscape.


Image © Åke Eson Lindman