If you have almost completed the construction of your house, which already pleases with even walls and a strong foundation, it's time to start on the roof, which will protect home comfort from bad weather and dampness.
But first you have to design the structure to the last detail. At a height, it is much more difficult to carry out work, so it’s better to do everything so that you don’t have to redo it afterwards. You can carry out the calculation of the truss system yourself. The whole structure will consist of the following elements:
- Mauerlat;
- ridge beam;
- inclined beams;
- vertical racks;
- battens.
What is the basis of
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 rigidity (except for the crate), additional details will be needed.
Calculation of the truss system
The calculation of a gable roof should include the determination of the parameters of the truss system. First step in the design processit is necessary to determine the useful area of \u200b\u200bthe attic. It is important to consider how high the vertical racks will be. Such a roof quite often has an exploited attic - it's 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 on the other side on the ridge beam, hanging over them. The roof device provides that the legs should be angled, forming a triangle. It is the most stable geometric form in relation to external influences.
The rafters are based on solid boards, the recommended section of which is 50 x 150 mm or 10 x 150 mm. Between these rafters, a distance must be maintained in the range from 60 to 120 cm. This parameter is to be calculated. Here it is important to take into account the rule: the more massive the roofing material, the more often the step should be.
What else you need to know for calculations
Calculation of a gable roof is also the determination of the angle of inclination of the slopes. If the house has a standard thickness ranging from 6 to 8 m, then the slope angle should be 45˚. But this will not be enough for living space in the attic. It is better to increase the angle to 60˚. This option will be the most successful, although it will cost more. In addition, if you make the angle equal to 45˚ or more, then you can use any roofing materials.
Gable roof can be asymmetrical, which happens quite rarely. But this allows you to ensure the availability of space for arranging living space. The angle of inclination of a standard roof is taken into account by 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.
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 25˚, then the transition coefficient from the snow cover on the roof will be equal to one. If the slope angle is equal to the limit from 25 to 60˚, then the coefficient will be equal to 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 give 84 kg per square meter. In this case, the angle of inclination can vary from 25 to 60˚.
The weight of a gable roof pie is calculated by adding the constant load, which includes the weight of the counter-lattice, batten, roofing material, thermal insulation and ceiling finish from the inside. The last factor is taken into account in the presence of an attic. The average value of the constant load can be equal to the limit of 40 to 50 kg per square meter.
Features of drafting a project
The roof design is made taking into account many factors, for example, the climate in the area. So, if the house is built in a dry region, then the optimal angle of inclination will be the limit from 25 to 45˚. If the amount of precipitation in the region is higher, then the roof can be arranged with a slope of 45 to 60˚.
The gable roof project is also drawn up taking into accountprevailing wind. With an increase in the slope, the windage of the structure increases. Roofing materials also affect the angle of inclination. So, tiles and slates are used on slopes where the slope is not less than 22˚. The drafting of the project should also be accompanied by taking into account 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
Houses with a gable roof are the most common buildings. If you also decide 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 design plan of the house. The support points of the truss system must coincide with the points and lines of the location of the supporting structures.
It is also important to take into account the width of the house, as well as the presence of longitudinal load-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 posts, which rest on the internal load-bearing wall.
If you are faced with the question of how to make a gable roof, then you can base it on hanging rafters, which are the most economical and practical option for light buildings. At the same time, the rafter legs are connected to each other by crossbars in pairs. These elements representare horizontal ribs that provide rigidity.
The hanging rafter system will rest on the side walls. If the width of the house is more than 6 m, then (except for the crossbars that act as the basis for the ceiling), racks and girders should be installed. The latter are horizontal bars that act as an additional support for the rafters. All this together forms a roof slope. The installation of runs involves the use of racks that rely on beds.
Installing Mauerlat
Quite often, beginner home craftsmen wonder how to make a gable roof. If you are also among them, then you should familiarize yourself with the technology, which at the next stage involves the installation of a Mauerlat. It will be located on the longitudinal walls of the house. The strapping will absorb the pressure of the roofing system and transfer the weight to building structures - the foundation and walls.
The foundation can be made from timber, which is treated with protective equipment against fire and decay. At the top 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 more than the total thickness of the timber and waterproofing.
Working on the system
A gable roof necessarily has a truss system, which consists of elements combined into a single whole. The truss system in the shape of the letter "A" has rigidity andworks for a break. If construction is carried out on a timber house, then the opposite walls must be reinforced with timber screeds, which are located at the level of the floor beams. In this case, the walls will not scatter under load.
On the floors there should be beds - elements from a square bar with a side of 150 mm. This system will support the studs, distributing the point load across the floor. If you do not plan to use the attic, the beds can be laid under the ridge to install support racks.
The gable roof will have an overlap where the boards are 50 x 150 mm. You must make a triangle of the required height and leg. The elements are connected to each other with nails. The structure must be lifted up by installing a rack on the central axis of the ceiling. Elements can be removed during template preparation. So you can change the height of the roof and choose the appropriate option.
Gable design
The pediment of a gable roof is a continuation of the wall, which is limited by the slopes. When installing the truss 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 truss structures are mounted. The pediment can be sewn up after completion of the roofing work. However, you can do this at an earlier stage. For this, boards 50 x 100 or 50 x150 mm, which are installed in the horizontal or vertical direction.
Installing shingles
Gable roofing can be done with many different materials, but you can use shingles. A strong and rigid truss system should act as the basis, since the material used is one of the heaviest. The diameter of the rafter beams should be 7.5 x 15 cm, while the rafter pitch is equal to the limit from 0.6 to 0.9 m. The crate can be made of square bars, the side of which is 50 cm., in this case the diameter of the profile should be 40 x 60 cm.
If tiles are installed over waterproofing, ventilation must be provided. Several ventilation gaps 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 roofing. This installation scheme provides effective ventilation of roofing elements. The first ventilation gap can be equipped with batten elements or by installing a board along the ridge.
Features of roof structures
Gable roof truss system 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 a corner. There are also combined designs, where steel parts are mostloaded, and wood elements are less critical areas.
The gable roof truss system (as mentioned above) can consist of iron, which has a lot of disadvantages. Among them, it is necessary to highlight the thermal 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 in terms of environmental criteria. In addition, the rafters of a gable roof made of wood are connected without the use of welding. Most often, coniferous wood is used as the basis. It can be larch, pine or spruce. The humidity level should not exceed 22%. But the wooden rafters of a gable roof have one drawback, which is expressed in the ability of the material to rot.
