压型金属板屋面系统中防水材料的选用

Selection of waterproof materials for pressure sheet metal roofing system

随着建筑业的发展，金属板屋面应用范围越来越广泛，由一般工业建筑发展到了造型复杂的公共建筑、功能要求更高的住宅建筑。国家“十三五”规划中，着重强调要研究，推广在各类建筑中应用钢结构的应用范围，做到设计与国际接轨，并完善设计规范和标准，争取到2020年我国钢结构建筑占10%以上。作为钢结构建筑围护系统的重要组成部分，金属板屋面将迎来巨大的发展机遇，金属板屋面防水工程也就成为关注的重点。屋面防水工程质量对建筑物的安全及建筑物的寿命有极其重要的作用。防水工程质量优劣与否，直接关系到建筑材料的耐久性能，以及建筑物的寿命。屋面渗漏会直接影响人们的正常生产、生活质量。对于金属屋面而言，其造成防水工程渗漏的原因很多，其中构造与材料选用不合理是主要原因。

With the development of the construction industry, the application of metal roof is more and more extensive, from the general industrial building to the complex shape of public buildings, higher functional requirements of residential buildings. In the Thirteenth Five-Year Plan of China, emphasis is laid on the importance of research, popularization of the application of steel structures in all kinds of buildings, achieving the integration of design and international standards, and improving the design norms and standards, so as to strive for more than 10% of China's steel structure buildings by 2020. As an important part of the steel structure building envelope system, metal roof will usher in a huge development opportunity, metal roof waterproofing project has become the focus of attention. Roof waterproofing engineering quality plays an important role in building safety and building life. The quality of waterproof engineering is directly related to the durability of building materials and the life of buildings. Roof leakage will directly affect people's normal production and quality of life. For the metal roof, there are many reasons for the leakage of waterproof engineering, among which the unreasonable selection of structure and material is the main reason.

金属板屋面防水主要特点

Main features of metal plate roofing waterproof

金属板屋面与普通平屋面、坡屋面有许多性能及构造差异，其中与本文探讨内容相关、与防水材料选择及防水性能相关的有如下两大特点：

There are many differences in performance and structure between metal plate roof and common flat roof and sloping roof. There are two main characteristics related to the content discussed in this paper and the selection of waterproof materials and waterproof performance.

1、屋面金属板导热系数大，对周围环境温度影响敏感，一天中昼夜有温差，一年四季也有很大温差，使金属板屋面常年存在较大幅度的热胀冷缩变形，易产生因变形而造成的破坏，导致金属屋面出现雨水渗漏。

1. The roof metal plate has a large thermal conductivity and is sensitive to the ambient temperature. There is a temperature difference between day and night, and there is a big temperature difference throughout the year. The metal plate roof has a large thermal expansion and cold shrinkage deformation all year round. It is easy to cause damage caused by deformation, resulting in rain water leakage on the metal roof.

2、金属板吸热快，尤其是夏季暴露在室外，受太阳辐射热的影响，表面温度可达到70-80℃，使整体屋面系统处于高温工作状态。因此，对金属板下的防水材料和保温隔热材料，耐高温老化性能要求比混凝土屋面应高一些。

2. Metal plate absorbs heat quickly, especially when exposed outdoors in summer. Under the influence of solar radiation heat, the surface temperature can reach 70-80 degrees Celsius, which makes the whole roof system in high temperature working state. Therefore, for the waterproof materials and thermal insulation materials under the metal plate, the high temperature aging resistance requirements should be higher than the concrete roof.

金属屋面上应区分防水垫层和防水透汽层的使用

The use of waterproof cushion and waterproof steam permeable layer should be distinguished on metal roofs.

金属屋面板作为金属板屋面的第一道防水，其材料种类、构造类型、细节处理、配套措施等已经为大家所重视，并在技术上不断更新，各项标准纷纷颁布，在工程中也受到较高程度的关注。但作为能使金属屋面达到I级防水的防水垫层和防水透汽层，目前还没有一本相关的规范具体规定其材料种类选择、体现其性能和应用特点。

As the first waterproofing of metal roofing, metal roofing has attracted more and more attention, such as material types, structural types, details, supporting measures, and so on. However, as a kind of waterproof cushion and waterproof and vapor permeable layer which can make the metal roof reach grade I waterproof, there is no specific specification to specify the material selection, performance and application characteristics.

从规范的规定看，防水垫层和防水透汽层是两类材料，其中防水垫层主要指防水卷材类材料，材料厚度选用在3MM以上；防水透汽层是可以让水蒸气透过同时具有一定防水功能的材料，一般采用聚乙烯或聚丙烯材料的无纺布为基材制成，材料厚度一般均小于0.5MM。从材料上看，两者性能差异很大，屋面系统相配套的材料和做法也完全不同，因此也造成实际防水性能有很大区别，工程造价迥异。

Waterproof cushion and waterproof vapor permeable layer are two kinds of materials according to the standard, among which waterproof cushion mainly refers to waterproof roll material, the thickness of which is more than 3MM; waterproof vapor permeable layer is a kind of material which can let water vapor pass through and has certain waterproof function, generally using polyethylene or polypropylene non-woven fabric as the base material. The thickness of material is generally less than 0.5MM. From the material point of view, the performance of the two are very different, and the materials and practices of roofing system are completely different, so the actual waterproof performance is very different, and the cost of construction is very different.

从构造上看：图2屋面构造的保温层通常是玻璃棉卷毡，卷毡的密度小、质量轻，可以直接铺设在檩条上，对底板的要求也只是起室内装饰作用。而图3层屋面构造选用的保温层是硬质保温板，卷材通过粘接或机械固定的方式固定在保温板或底层压型钢板上，因此对基层的要求较高，保温棉要有一定的抗压强度；底层承重用的压型钢板需要考虑上部构造中的螺钉锚固强度，因此对板厚有要求。

From the structural point of view: Fig. 2 Roof structure of the insulation layer is usually glass cotton mat, the density of the mat is small, light weight, can be laid directly on the purlin, the floor requirements only play an interior decoration role. The insulation layer used in the roof structure of the third floor is the hard insulation board, and the coil is fixed on the insulation board or the bottom profiled steel plate by bonding or mechanical fixation, so the requirements for the base are higher, and the insulation cotton should have a certain compressive strength; the profiled steel plate used in the bottom bearing needs to consider the bolt anchorage strength in the upper structure. Therefore, thickness requirements are required.

从铺设方式上看：由于屋面金属板支架都是穿过防水垫层和防水透汽层固定在檩条或系统衬檩上，会形成大量钉孔，存在雨水沿钉孔渗漏的隐患。图2层面的防水透汽层随保温棉铺设，由于防水透汽层材料较薄，搭接处采用专用胶带进行粘连，铺设后会因重力原因有变形，在檩条间有下凹，因此屋面板在有雨水渗漏或板下产生冷凝水的情况下，会产生局部积水，水量大或无法及时排除时，雨水进入到保温棉中的可能性增大。其工序复杂，安装精度高，表面平整，屋面板如有雨水渗漏或板下产生冷凝水，可随屋面坡向导流至檐口。这样设计，可提高屋面板的防水性能。

Seen from the way of laying: because the roof metal plate brackets are fixed on purlins or system linings through waterproof cushion and waterproof vapor permeable layer, a large number of nail holes will be formed, there is a hidden danger of rain water seeping through nail holes. Fig. 2 The waterproof and vapor permeable layer on the floor is laid with insulating cotton. Because the waterproof and vapor permeable layer is thin, special adhesive tape is used to bond the overlap. After laying, it will be deformed due to gravity and there will be concave between purlins. Therefore, the roof panel will produce local water accumulation in the case of rainwater leakage or condensation under the board. When it can not be eliminated in time, the possibility of rainwater entering the insulation cotton will increase. Its process is complex, installation precision is high, the surface is flat, if there is rain water leakage or condensate under the board, can be guided along the roof slope to the eaves. This design can improve waterproof performance of roof panels.

从以上两种屋面构造看，防水垫层和防水透汽层可对金属板构造自身的缺陷有很好的弥补作用。两种材料虽在规范意义上是等效的，但在具体构造中，防水性能还是有很大差异的。因此，在重要项目中，无论是从防水效果还是从保温性能上考量，都推荐使用防水垫层作为第二道防水层的屋面构造。

From the above two roof structures, waterproof cushion and waterproof vapor permeable layer can make up for the defects of metal plate structure. Although the two materials are equivalent in the normative sense, the waterproof performance of the concrete structure is still very different. Therefore, in important projects, whether from the waterproof effect or insulation performance considerations, are recommended to use waterproof cushion as the second waterproof layer roofing structure.

屋面金属板吸收太阳辐射热，造成屋面板夏季温度高，能达到将近80℃，而屋面板下的空间一般是相对封闭的空间，因此屋面板的高温致使其下部空间保持较高温度，对其下侧设置的防水垫层和防水透汽层影响很大，材料的高温老化性能的要求应提高。尤其是咬边连接的屋面板，安装后一般无法再对内部进行维护、维修，对隐蔽工程中材料耐久性要求很高，否则内部材料破坏后，对屋

Roof metal plate absorbs solar radiation heat, resulting in high temperature roof in summer, can reach nearly 80 degrees Celsius, and the space under the roof is generally relatively closed space, so the high temperature of the roof causes its lower space to maintain a higher temperature, its lower side of the waterproof cushion and waterproof vapor permeability layer has a great impact on the high temperature of materials. Aging performance requirements should be improved. Especially when the roof panel is installed, it can not be maintained and repaired, and the durability of materials in concealed projects is very high. Otherwise, the internal materials will be damaged and the roof will be damaged.