Roof construction: simple about complex

No one will argue that the roof is one of the most important building structures. It takes on most of the negative impacts of the environment, is experiencing very serious stress. Therefore, for the well-being of residents, the design of the roof of the house plays an important role. What does the roof look like in a section and about its correct device - in this article

The roof of the building, through its elements, transfers the load from its own weight, snow or wind flow to the supporting structures of the house itself - whether it be walls or columns. Therefore, special attention is paid to its proper design.

Inaccurately calculated do-it-yourself roof rafters, slopes or roofing material can quickly damage themselves and cause damage to other building structures. Theoretically, the calculation of roofs should be carried out according to SNiP II-26-76 (1979) - "Roofs".

However, the last changes were made to this standard in 1979, when many of the modern coatings were not yet in nature.

Therefore, the design of roofs and their construction in terms of insulating materials and directly roofing material is now mainly accepted either by analogy with replacement materials, or based on the specifications of their manufacturers.

There are many forms of roofs, since each region has its own climatic features and traditional roofing materials.

However, apart from various exotic projects, where each component was carefully calculated and made by hand, all roofs can be typified according to the following features:

• bias
• roof shape
• The number of rays
• Type of supporting structure
• roofing material

However, all these types have common elements:

• top floor covering
• load-bearing roof structure
• roofing cake - a larger or smaller set of layers that provide insulation of the building from precipitation, wind chill

In terms of such roof pitch, the roof can be flat (symbol, a slope of at least 3% is necessary for any roof to drain precipitation) or pitched.

Some flat roofs are made with a "reverse" slope - they have a drainage system located inside the building, for this they install special storm risers, and receiving funnels on the roof.

Slopes, respectively, are made towards the funnels. Although seemingly complex, it is sometimes easier and cheaper than creating a complex system of gutters and pipes outside the building.

For flat roofs, in the vast majority of cases, the base of the roof is the ceiling of the last floor of the building, although there are also structures with an attic, but this is rare - usually a technical floor is arranged instead.

To create the desired slope for drainage: with an external discharge system, sometimes one side of the floor slab of the last floor is raised, with both systems, the slab is installed evenly, and the required slopes are set using cement screeds.

flat roof structure

Important information! A flat roof is the simplest of the roof construction options. It has the smallest surface of all possible, therefore, provides the lowest consumption of materials. However, due to the low slope, it requires an excellently functioning drainage system, which means careful design and execution.

Flat roofs are divided into:

• Non-ventilated - such a roof does not have access to air from the external environment. Modern insulating materials make it possible to pack the insulation almost hermetically: from below it is a vapor barrier that prevents the penetration of moisture from the ceiling, and from above - waterproofing. However, with this method of organization it is necessary that:
  • The insulation is guaranteed not to have residual moisture when laying
  • Layers of hydro and vapor barrier were laid without any flaws
• Ventilated - this is a variant of the roof, in which, with the help of special gaskets, the insulation is separated from the waterproofing vertically. This allows air to freely blow through the heat-insulating layer and remove moisture from it.

• Inverse - here the reverse order of the insulating layers is used: the waterproofing layer is laid first, and the thermal insulation layer is laid on top of it. Non-absorbent (for example, polystyrene foam), a protective layer of gravel is made on top. If necessary, an additional protective layer is laid.

Inverse roofing has a number of advantages over other options: here, if necessary, it is not necessary to use a concrete screed, which dramatically reduces the weight of the roof, waterproofing is reliably protected from mechanical stress, exposure to heat, frost and ultraviolet radiation.

Also, roof structures with small slopes are divided into non-exploited ones - where people are allowed to stay only for the purpose of servicing the roof itself (dumping snow, leaves, repairs, etc.), and exploited - terraces are arranged on them, recreation areas and sports grounds are placed, plants are planted .

This is a very reasonable use of empty space, both for an urban high-rise building and for a cottage. However, such a roof is much more complicated both in terms of the equipment process and in terms of its structure. Several new layers are added to it.

pitched roofs

The most diverse group of roof structures is pitched. This is not surprising - after all, only one plane can be arranged, and inclined ones can be combined endlessly.

Such roofs are very beautiful, especially due to the combination of slope angles.

Advice! When choosing a roof for a house, you should not get carried away with too complex shapes.The more angles the roof has (especially concave ones), the higher the cost of its construction and operation, and the more pretentious project will not be reflected in the construction time in the best way.

To understand what differences are in question in different types of pitched roofs, you need to know the terminology. At the same time, there are two levels - load-bearing structures and directly roofing - each has its own set of standard elements. .

Since roofs are classified according to their appearance, and it manifests itself in the form of a roof, the first thing is what is what on the outside:

The main classes of roofs are single-pitched, gable, four-pitched (hip and half-hip) and multi-gable (having more than 2 gables and a complex roof configuration). Also, any of the types of pitched roofs can have a straight (even on each of the slopes) or a broken roof.

Pitched roofs are those where, within one or more slopes, the angle of its slope changes.In this case, the fracture can be both in the direction of increasing the slope, as in the classic mansard roof, and in the direction of its decrease, as in half-timbered houses.

Since the roofing lies on the supporting structures - the truss system, it is clear that the more complex the configuration of the roof, the more difficult this system will be.

This leads to an increase in the volume of work, an increased consumption of materials and an increase in the load on the supporting structures of the entire building. On such roofs it is more difficult to implement a drainage system. Also, the area of ​​materials that are used to organize the roofing carpet increases manifold.

truss system

The rafter system serves as the skeleton of the roof. It takes on the load from the roofing material (its own weight, the pressure of snow accumulated in winter, wind load) and transfers them to the supporting structures of the building.

The purpose of the main elements of the truss system:

• Rafter legs are used to fasten and hold the roofing material
• Tightening - a horizontal element that does not allow the rafters to part
• Run (sleight) - a beam based on racks and puffs and running along the roof slope, perpendicular to the rafters. Serves to evenly distribute the weight of the roof between the rafters
• Rack - an intermediate supporting vertical element that transfers the weight of the truss system to the internal load-bearing walls or floor slab
• Lying - a beam running along the floor creates a stiffening belt together with a run and racks, and also distributes the load from them evenly along the supporting structure of the building
• Mauerlat (rafter beam) - strapping along the top of the bearing walls, to which the lower edges of the rafter legs are attached.Transfers the load from the rafters to the external load-bearing walls

There are two main types of rafter systems: hanging rafters and layered. The difference between them is in the principle of transferring pressure to supporting structures.

Sloped rafters rest on the outer load-bearing walls from above, through the mauerlat, exerting pressure on the walls from top to bottom. If necessary, additional supports are installed inside the roof.

Depending on the width of the building, there may be one or two such supports. In this case, the maximum distance between the points of support of the rafters on the outer walls can be 14 m.

In this design, the rack works in compression, if necessary, struts are also installed, and they keep the rafters from deflecting or breaking in the middle. With a long span, the rafters are additionally reinforced with puffs.

In the case of a roof structure with hanging rafters, the system, on the contrary, works to break. They are called hanging, because the rafters rest only on the external load-bearing walls, without supports inside the house.

The task of tightening here is to prevent “the spreading of the rafter legs, it is installed here at the lower ends of the rafters. With an increase in span, an additional screed, or crossbar, is placed at some distance from the upper edge of the rafters.

With even larger spans, a vertical headstock with struts is installed in the center. It works like this: the rafters tend to break the lower puff.

In this case, the force from them is transmitted to the headstock (from top to bottom), and through it - to the puff. Thus, there is a "reverse thrust" - a compression force that bends the puff, and pulls the ends of the rafters to the center. The struts help to transfer the pressure of the middle part of the rafters to the same puff.

Advice! The roof follows the configuration of the main load-bearing structures of the building, at least the external walls. Since roofs with complex terrain will require an appropriate truss system, it is worth calculating the gains and losses even when drawing up the layout of the future home. Often it is more expedient to refuse architectural excesses. Even a simple canopy over the well works more reliably.

The rafters are installed, depending on the design loads, every 600-2000 mm, while either each pair of them, or at some intervals, are connected by additional elements - the same crossbars. Such bundles are called trusses. With large roof sizes, this is a complex and lengthy job if done on site, right at the time of installation.

To improve dimensional accuracy and increase construction speed (as well as reduce costs), factory-made trusses are used, manufactured in an industrial way.

The end is the crown

And all these difficulties are necessary in order to place the last detail on the roof of the building - a roofing pie. It is he who protects the entire interior of the house from rain, snow and wind. The pitched roof is blessed with the fact that any kind of roofing can be laid on it.

This, really festive for any homeowner, looks like a cutaway cake as follows:

• Bearing beam structure
• Vapor barrier layer
• insulation
• Rafter
• crate
• Waterproofing
• roofing material

Since the supporting structures had to be taken care of in advance, the main thing was to maintain the correct order of the layers. The principle here is this: the closer the layer is to the external environment, the higher its moisture permeability to the outside should be.

The vapor barrier unilaterally releases moisture from the house, but does not let it in. But then follows a layer of insulation, which loses its properties when wet.

Therefore it follows:

• Install reliable waterproofing with the passage of vapors of insulation to the outside
• Ensure good ventilation of the roof space

Naturally, if the roofing material is not installed correctly, then the roof will leak very quickly, so special attention should be paid to its installation.

With the right calculation and arrangement, any roof structure works well and lasts a long time. However, you should take into account the features that each of them has - and the house will always be warm and dry.

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