Related article: Choosing a roof for homeMember of the International Academy of Architecture Jean Verzhbitsky in his book "Architectural Culture" wrote: "The specifics of architectural works is that the material (functional and technical) and spiritual inseparably fused in them, accounting for integrity, which has properties that are not inherent in every part of the in isolation. " Builders also share this view, believing that the presence of a complex roof can be justified as an aesthetic and practical point of view.
"Complex roof, usually high, in the case of private construction: its height shall be two-thirds the height of the facade, - says Alexey vouch Foreperson of" Illeonstroy. " - This, along with the presence of a number of different design elements, gives it a grandeur. And at the same time allows better use of attic space, usually as an attic, for which the cost per square meter of the area is lower than the main floor. "
According to him, if the design of facades made to adhere to a rectangular shape, then leave for roofs wildest fantasies. They make hip, pyramidal, mnogoschiptsovymi, hipped, domed, conical and even univariant. The most popular in this series are hipped roof, giving two mutually perpendicular sections of the front triangle and a trapezoid. If the foundation of the house square, the hipped roof is transformed into a pyramidal hipped.
"The roof, formed by the intersection of the two slopes of varying heights, called mnogoschiptsovoy - adds Desyatun Basil, head of roofing systems Metal Profile Group, Russia's leading manufacturer of roof and faÇade systems. - It has a very attractive appearance, good for homes complicated layout, with extensions. "
However, experts advise not to forget that the more complex configuration of the roof, the more detailed and careful calculation it requires.
One of the most problematic in terms of the design and operation of any places of the roof are the internal angles between the rays, known as "the valley", in common parlance - valley sheet. And the more complex mnogoskatnaya roof, the more her of "bottlenecks".
Winter snow accumulates in the valley, which puts additional pressure on the slopes below them. For example, the snow load for the middle band is on average 180-240 kg/m2 for a horizontal surface. On the slopes of the roof, it will be less due to their bias. And here in the valley, in contrast, can reach 500 kg/m2 or more. And the more complex the roof, the steeper slopes of her, the more her bag of snow.
At the same time for the slopes with a gradient of 60 ° pressure of snow in general can not be ignored. "The snow is something he is not terrible, but it's windy, high roofs susceptible effect sails with wind power, creating a pressure of 35 kg / m ², - warns Roman Ustimenko technician of" Krovmarket. " - The bombing of a water-proof blanket roof, concentrated pressure in the valley combined with the flat on the opposite side can damage the roof. " That is why there are cases when hurricanes destroy complex roof, characterized by large areas of waterproofing carpet. Therefore, many experts believe that the standard for the maximum wind speed of 100 km / hour, which is set to calculate the roof, should be increased in the design of roofs complex configuration.
In addition to the snow and the wind, there are heavy rains. For a simple gable roof, they are completely safe. But the more valleys, the greater the impact of water flow on the roof. Thus, with rainfall of 50 mm on the roof area of 60 m2 per hour will fall to 3 tons of water which swept into the valley. In moments of peak rainfall the water level in the valley sheet may reach 10-20 centimeters. If a strong shower water often spills over into the gutter valley, resulting in leaks. Avoid such hassles help correct design of the roof system and reliable waterproofing.
Features of the design and installation of complex roofs
Specialists in one voice say that the complex roof design requires careful consideration. Build them on the eye - is dangerous. Even if you do not take into account the variables of snow, wind and rain loads, only a qualified designer can accurately calculate the force constant pressure trusses, rafters, purlins and roof of the pie in mauerlat. As for the weather, causing the variable components due to the vagaries of weather, there are complicated calculations. "The roof mnogoskatnoy all interconnected. Rafters must withstand the constant and variable load. In many ways, the design features also depend on the choice of roofing material, "- says designer Andrew Kostikov.
For example, if the roof covering, due to their physical and chemical properties, can lose flexibility, the roof may leak. The reason is that the designs are always laid mnogoskatnyh maximum allowable deflection of rafters, which should not exceed 1 cm to 2.5 m in length. In other words, a six-meter ramp, even reinforced by internal struts can bend by 2.5 cm, and it may be building codes. Thus, the roofing must accept these variations, that is to have sufficient flexibility to bend.
It's time to recall the bituminous coatings, including shingles, for which, on the one hand, the typical monolithic carpet, and on the other - glazing (complete loss of elasticity) in the cold. Sag under the weight of snow skates caps or by the impact of the squally wind deprives bituminous carpet rigid support and carries him away. It is like a fragile glass bend. As a result, the integrity of the coating may be compromised, and it will lose resistance to water and wind. The principal drawback of this lack metal and cement-sand tile.
However, cement-sand tiles and natural require installation on crate powerful waterproofing, such as weld roofing substrates: the only way to protect these types of leaks in the roof valley. But roofing felt, again, is a bitumen-based and, like shingles can be damaged by hard frost.
Thus, to completely avoid these problems will help metal. "In this case, the role of internal drainage on the intersections of rays will play the bottom rod valley with the edges of 300 mm in both directions. Proper sealing between metal sheets and strips valleys by using self-adhesive porous seal and secure all elements of the cover is made with galvanized screws with colored head and EPDM gasket "- explains Basil Desyatun (GC Metal Profile).
However, no roofing, including metal roofing, not a 100% guarantee against leaks. More so when you consider what could be fraught with the deflection under the influence of the snow or wind loads. And the condensate formed on the back surface of the sheet metal, as well as rainwater from the top, going into the valley. Therefore, they are still high-risk areas and require particularly robust under-roof waterproofing.
With this in mind, even with reliable waterproofing membrane under the valley of mount lapped in 2-3 layers. If a lot of valleys, this complicates the installation and greatly increases the amount of material. Therefore, for complex roofs are preferred more effective solutions, such as diffusion membrane Dörken DELTA ®-VENT N three-layer non-woven polypropylene, connected in layers at the molecular level, ultrasonic welding. "Thanks to the high strength and a three-layer structure of the membrane DELTA ®-VENT N can be laid in a single layer, even in the most problematic areas of roofs: a valley, contiguity, the nodes pairing, ie in places where conventional waterproofing membranes and films stacked in 2-3 layers, "- said Valery Nesterov, General Director of" Dirk. "
The easier it is - the stronger
Complex roof automatically implies a complex truss: for mauerlatov fixed frame consisting of cobwebs rafters, puffs, posts, struts and beams. Often it is the scheme of many triangles, realized from timber and planks. For example, a three-meter radius of the spire and four-meter is about eight rafters, and tapered design of their number could rise to 24. Question than cover these towers, is the main thing.
Natural or cement-sand tile in this case is not suitable in the best way, except that the form of "beaver tail", and that with the use of a large amount of manual labor on her cut. If the tower is crowned by a roof, it will enhance the whole truss construction. After the weight of tile is 40-70 kg / m ², which means that the above tower with a surface area of 19m ² with the weight of the rafters "pull" of about 1.5 tons. If used as a roofing metellocherepitsu (4-5 kg / m ²), then the weight of the structure is only 200 pounds.
But we have considered only one tower, which, generally speaking, can be several. According to Alexei vouch (company "Illeonstroy"), complex roof always incomparably greater surface area than the simple Gable. This means that the light roofing materials are preferable, especially in areas with snowy winters. In addition, by reducing the value of the constant load on the truss system is released reserve strength to resist alternating stresses. The result is the same truss, covered, for example, metal, survive much harsher impact of elements, rather than in the case of natural tile.
Complex roof - a responsible choice that requires a professional approach to the design and installation. But if done correctly, then the house will not only fashion "hat", but also durable, reliable protection from the elements, and its inhabitants - the extra storage space, which allows to increase the living space.
Material courtesy of Group Metal Profile