If you have almost completed the construction of your house, which already pleases with smooth walls and a solid foundation, it's time to start the roof, which will protect home comfort from the weather and dampness.
But first, you have to design the structure to the last detail. At a height, itβs much more difficult to carry out work, so itβs better to do everything so that after you do not have to redo it. You can carry out the calculation of the rafter system yourself. The whole structure will consist of the following elements:
- Mauerlat;
- ridge beam;
- inclined beams;
- vertical racks;
- crates.
What makes up the foundation
Mauerlat is the foundation of the roof, it is usually made of timber, which is located horizontally and rests on the rafters. To achieve the necessary stiffness (except for the crate), additional details will be needed.
Rafter system calculations
The calculation of the gable roof should include the determination of the parameters of the rafter system. The first step in the design process is to determine the usable area of ββthe attic. It is important to consider how tall the uprights will be. Such a roof quite often has an exploited attic - it is convenient after all.
The main element of the system will be the rafter leg, which carries a lot of roofing and precipitation, as well as wind. The rafters rest on the Mauerlat on one side, and the other on the ridge beam, sagging above them. The roof device provides that the legs should be angled to form a triangle. It is the most stable geometric form with respect to external influences.
The rafters are based on strong boards, the recommended section of which is 50 x 150 mm or 10 x 150 mm. Between these rafters, a distance of 60 to 120 cm should be maintained. This parameter has to be calculated. Here it is important to take into account the rule: the more massive the roofing material, the more often there should be a step.
What else you need to know for calculations
The calculation of the gable roof is also the determination of the angle of inclination of the ramps. If the house has a standard thickness ranging from 6 to 8 m, then the angle of the ramps should be 45Λ. But this will not be enough for living space in the attic. It is better to increase the angle to 60Λ. This option will be the most successful, although it will cost more. In addition, if you make the angle equal to 45Λ and more, you can use any roofing materials.
A gable roof can be asymmetric, which happens quite rarely. But this allows for the availability of space for the arrangement of living space. The angle of inclination of a standard roof is taken into account according to wind and snow loads in the area. It is also important to calculate the snow load, which will depend on the climatic conditions of the area.
The load limits are equal to the limit of 80 to 320 kg per square meter. If the angle of inclination of the roof does not exceed 25Λ, then the coefficient of transition from the snow cover on the roof will be equal to unity. If the slope angle is equal to the limit from 25 to 60Λ, then the coefficient will be 0.7.
Calculation Example
For example, if the snow load of the cover on the ground is 120 kg per square meter, then the load on the roof will be calculated as follows: 120 x 0.7, which will produce 84 kg per square meter. In this case, the angle of inclination can vary from 25 to 60Λ.
The weight of the gable roof cake is calculated by adding up the constant load, which includes the weight of the counter battens, lathing, roofing material, thermal insulation and interior ceilings. The last factor is taken into account in the presence of an attic. The average constant load can be equal to the limit of 40 to 50 kg per square meter.
Design Features
The roof design is made taking into account many factors, for example, the climate in the area. So, if the house is built in an arid region, then the optimum angle of inclination is the limit from 25 to 45Λ. If the amount of precipitation in the region is greater, then the roof can be arranged with a slope of 45 to 60Λ.
The design of the gable roof is also compiled taking into account the prevailing wind. With an increase in the slope, the windage of the structure increases. Roofing materials also affect the angle of slope. So, tiles and slate are used on slopes, where the slope is not less than 22Λ. The design of the project should also be accompanied by the cost of the roof, which depends on the slope of the slopes. The larger it is, the more materials will be needed. This suggests that the construction will cost more.
Construction features: preparation
Gable houses are the most common buildings. If you also decided to follow the experience of the majority and use just such a roof structure, then at the first stage you need to prepare. The design and shape are determined taking into account the project plan of the house. The support points of the rafter system must coincide with the points and lines of the location of the supporting structures.
It is important to take into account the width of the house, as well as the presence of longitudinal bearing walls, which will be located in the center. If you do not plan to use the attic as an additional usable area for seasonal or permanent residence, the roof can be made with layered rafters. In this case, the rafters will be fixed to the ridge run, supporting the racks, which are supported by an internal load-bearing wall.
If you have a question about how to make a gable roof, then you can put hanging rafters in it, which are the most economical and practical option for light buildings. The rafter legs in this case are connected to each other with crossbars in pairs. These elements are horizontal jumpers providing rigidity.
A system with hanging rafters will rest on the side walls. If the width of the house is more than 6 m, then (except for the crossbars acting as the basis for the ceiling), installation of racks and girders should be carried out. The latter are horizontal bars serving as an additional support for rafters. All this together forms a slope of the roof. Installation of runs involves the use of racks that rely on the beds.
Mauerlat installation
Quite often, novice home masters ask themselves how to make a gable roof. If you, too, are among them, then you should familiarize yourself with the technology, which in the next step involves the installation of Mauerlat. It will be located on the longitudinal walls of the house. The harness will take on the pressure of the roofing system and transfer weight to building structures - the foundation and walls.
The foundation can be made of timber, which is treated with protective equipment from fire and decay. In the upper part of the wall, you can install a concrete beam, where the studs are embedded. The distance between them will be 120 mm. The height of the protruding end should be 30 mm greater than the total thickness of the beam and waterproofing.
System work
The gable roof necessarily has a rafter system, which consists of elements combined into a single whole. The rafter system in the form of the letter "A" has rigidity and works on a spreader. If the construction is carried out on a timber house, then the opposite walls must be strengthened with screed from the timber, which are located at the level of the joists. In this case, the walls will not run up under load.
On the ceilings should be lodges - elements of square beam with a side of 150 mm. This system will be the support for the racks, distributing the point load on the floor. If you do not plan to use the attic, you can lay the lodges under the ridge to install the support posts.
The gable roof will have an overlap where the 50 x 150 mm boards are located. You must make a triangle of the necessary height and legs. Elements are interconnected by nails. The structure must be raised upward by installing a rack on the central axis of the ceiling. Elements can be removed during the preparation of the template. So you can change the height of the roof and choose the appropriate option.
Gable decoration
The gable of the gable roof is a continuation of the wall, which is limited by slopes. When installing the rafter structure, it is necessary to install extreme forms that will act as a frame for the gables. The verticality of the structure must be checked by making sure that the elements have the same height.
In the upper parts of the gables it is necessary to install a ridge run, to which the rafter structures are mounted. The pediment can be sewn up after the roofing is completed. However, you can do this at an earlier stage. For this, boards of 50 x 100 or 50 x 150 mm are used, which are installed in horizontal or vertical direction.
Tile Installation
Roofing a gable roof can be done in many different materials, but you can use roof tiles. A strong and rigid rafter system should act as the basis, since the material used is one of the heaviest. The diameter of the rafter bars should be 7.5 x 15 cm, while the rafter step is equal to the limit of 0.6 to 0.9 m. The lathing can be made of square bars, the side of which is 50 cm. You can use bars with a rectangular section , in this case the profile diameter should be 40 x 60 cm.
If the installation of tiles is carried out on top of waterproofing, ventilation must be provided. A few vents should be made, of which there may be two. The first is arranged between the layers of hydro and thermal insulation, the second - between the membrane and the roof covering. Such an installation scheme provides effective ventilation of roofing elements. The first ventilation gap can be arranged using the elements of the crate or by installing boards along the ridge.
Features of truss structures
The rafter system of a gable roof can be equipped with wooden or metal beams. The source material in the first case is a log, board or timber. In the second case, we are talking about a channel, an I-beam, a profile pipe or corner. There are also combined designs, where steel parts are the most loaded, and elements made of wood are less critical areas.
The rafter system of a gable roof (as mentioned above) may consist of iron, which has a lot of disadvantages. Among them, it is necessary to highlight the thermal technical qualities, as well as the need to use welded joints. The remaining rafters most often become part of industrial buildings.
But if private construction is underway, then wood is a priority. Working with it is quite simple, it is warmer and lighter, and also more attractive according to environmental criteria. In addition, the rafters of a gable roof made of wood are connected without the use of welding. The basis most often lies softwood. It can be larch, pine or spruce. The humidity level should not exceed 22%. But wooden rafters of a gable roof have one drawback, which is expressed in the ability of the material to rot.