Rolled and mastic roofs are often used in urban construction and only to a much lesser extent, in the construction of villas and cottages. Rolled roofs are made of bitumen and bitumen-polymer materials with reinforcing synthetic, cardboard or glass-based, as well as elastomeric. synthetic or glass materials. Mastic roofing coatings are obtained when applied to a substrate (usually concrete) liquid viscous oligomeric products, which, after curing in air, form a continuous elastic film. Mastics have good adhesion to concrete, metal, bituminous materials. In fact, mastic roofing coatings are polymeric membranes that are formed directly on the roof surface. Mastic materials are especially convenient when performing junction assemblies. Mastics can be two-component (actually mastic + curing system), or one-component, cured by moisture, oxygen or CO2 contained in the air.
The allowable roof slope for rolled and mastic roofs is 0-25% and determines the number of layers in the main and additional waterproofing carpet in the case of using rolled materials and the number of reinforced mastic layers in the case of using mastic materials.
There are a number of general requirements for materials for the device roll and mastic roofs . These include such parameters as: heat resistance, strength, conditional elongation, water absorption by weight and flexibility on a timber with a certain radius of curvature at a certain temperature. The maximum permissible parameters for roofing of bitumen-polymer materials are as follows: heat resistance not lower than 55 ° C, conventional strength not less than 1.0 MPa, relative elongation not less than 10%, water absorption by weight after 24 hours not more than 2%, flexibility on a bar with rounding radius (R) 25 mm not higher than 0 ° C. Almost all materials used now have characteristics that significantly exceed the above-listed technical requirements. However, choosing the material from which you are going or you are offered to make a roof , first of all you should pay attention to the compliance of the roofing material with these parameters.
Heat resistance is an indicator that determines whether your roof will melt in a very hot summer on the sunny side of the house. Therefore, the reduced maximum permissible heat resistance of 55 ° C is rather low, because it is known that even in the Moscow region roofs made of bitumen-polymer materials are sometimes heated to 70-80 ° C. The relative elongation of the material should compensate for the seasonal movements of the main structure and, for most of the widely used materials, is 40–60%.
The indicator of flexibility at a certain temperature characterizes the possibility of fracture of the material (for a given bending radius) depending on the ambient temperature. Good bitumen-polymer materials should remain flexible at a temperature of -15-20 ° C. Water absorption by mass after 24 hours for most domestic polymer-bitumen materials on a fiberglass basis is 0.5-2.0%, and for most imported materials with synthetic fibers, water absorption does not exceed 0.5%.
Speaking of imported bitumen-polymer roofs , a number of interesting indicators should be noted. Some materials have properties that prevent the germination of plants, it is especially useful on flat roofs, where over time can grow old foliage and seeds. As a rule, imported materials have full compatibility with old bitumen coatings and very high adhesion to the substrate. In addition, most manufacturers produce a full set of materials for roofing adhesives, sealing mastic, decorative bitumen paints and much more.
Another extremely important property of a roofing material is its durability, in other words, the potential service life. It can be determined on the basis of the flexibility of the material. If we take a decrease in this indicator by about 1 ° C / year, and its change is in accordance with a law close to straightforward, it is possible to easily calculate the potential lifetime of the roof . For some imported materials it reaches 30 years.
But one should not confuse the potential service life of the roofing material with the warranty period provided by the manufacturer and the warranty obligations of the company performing the roof installation work.
Roll materials can provide water resistance even with zero slopes, and the upper limit of recommended slopes is 45-50 °. They can be laid on any solid (wooden, concrete, etc.) base.
There are several main ways of laying roll materials, according to which these coatings are divided into:
The oldest method of laying a roofing carpet is a method of continuous gluing of rolled materials to the base. In some cases it is advisable to lay roofing materials using so-called partial gluing. This excludes the conditions for the appearance of excess pressure due to the formation of an air gap between the roof and the base, which communicates with the outside air along the roof contour or through special exhaust deflectors. Roofs made in this way are called "breathing".
The use of a "breathable" roof not only avoids blistering, but also helps to remove moisture from the base material (about 1 kg / m2 over the summer). The amount of moisture removed can be increased at a fixed cross-section of the air gap due to sprinkling applied to the rolled material during its manufacture.
With a "breathing" roof, its ruptures above the joints and cracks of the foundation are completely excluded, since the deformations of the latter are not transmitted to the roofing carpet.
The disadvantage of a "breathable" roof is the difficulty of determining the location of a leak. If a gap appeared in the roofing carpet, where the water fell, it would spread over all air sinuses and, finding a loose joint at the base, would fall into the interior of the building. The appearance of a leak on the ceiling will not mean that the roofing carpet is damaged just above this place, and finding a real leak is not easy.
A “breathing” roof is necessary for the restoration of old roofing, as there is always moisture inside the old bituminous carpet, which needs to be able to exit. It is also necessary when working in the winter for new concrete surfaces, the humidity of which cannot be brought up to standard parameters.
When using "breathing" roofs in mass construction, it is necessary in the compositions of roof projects to develop schemes for roofing devices with an indication of the layout of the layers and structures of the nodes and junctions.
Partial gluing of the roof to the base can be done by applying for the bottom layer:
Breathable roof systems have long been successfully used in Scandinavia, Germany, Belgium and other countries.
When laying the material by melting or dissolving to comply with the technology, it is necessary to pay attention to the fact that it has a sufficient thickness of the lower coating layer. The minimum required thickness should be consistent with the size of the irregularities (roughness) of the screed base.
Very technological device roofing carpet of materials with an adhesive layer. This method can be used for new roofs, as well as for repairs of old ones, but the base must be prepared with special care. Today, such materials are more likely to be rare for the Russian market and are used very limitedly.
Fig. 18.1. Partial prikleyka roof to the base when used in the lower layer of perforated roll material: | Fig. 18.2. Partial prikleyka roofing to the base when used in the lower layer of conventional roll material: |
Fig.18. 3 |
Laying roll material DERBIGUM (IMPERBEL) in a hot way.
Location and arrangement of expansion joints and expansion joints
Temperature extremes are a serious challenge for the roof. If not to take measures to ensure that the mutual displacement of the elements of the base of the roof and their temperature deformation did not affect the roof, the ruptures of the roofing carpet and leaks are inevitable. In this case, even the use of the most modern and most reliable materials will not help much.
Expansion joints and compensators are designed to reduce the load on the roofing carpet in places of greatest deformations. The idea of installing a expansion joint is to make the deformations in the node normal for this type of roofing material. Needless to say, expansion joints should be made of elastic polymeric and bitumen-polymeric materials, taking into account the mode of operation of the roof.
Expansion joints should always be included in the roof construction in the following cases:
It should be remembered that the expansion joint should first of all protect the roofing carpet from rupture, so you should not direct the flow of water through its structure. It is desirable that the design of the expansion joint provides for the possibility of safe deformation "in volume".
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