The use of a mansard roof during construction is very popular. There are a number of advantages for this, one of which is an increase in the living space in the house. Installation of such a roof occurs in stages. At the same time, the roof truss system of an attic roof requires special attention and accuracy, since this is the most difficult stage of work.
Schematic of the truss system of a broken roof of the attic.
Attic is a dormitory-style dwelling. Its construction can be carried out on an already constructed building, without disturbing its foundation, but only by removing its old roof. The truss system of the attic plays the role of the skeleton of the entire roof. When building it, it is necessary to observe some nuances.
The skeleton of the roof construction is mounted on wooden beams with a section of 100x100 mm. Under them, a waterproofing layer of roofing felt or roofing material is laid. The presence of beams is necessary in the event that the overlap is made of reinforced concrete slabs. If the overlap is wooden, then the timber is not needed, since in its quality beams of overlap act.
Knots of fastening of rafter system.
The rafter system is made of coniferous varieties of certain moisture, which should not exceed 18%. In this case, all the material must be well dried and oskkuren. In no case should wet wood be used for the construction, as this may further lead to its deformation and destruction of the roof itself.
Attic roofs can be of several types: symmetrical or asymmetrical, broken or triangular. They can be installed both on the same level and two-level. During the construction of the roof, it is important to correctly perform the angle of its slope, which depends on the climatic conditions of the area and on the material with which the roof is covered.
The slope of the attic should not exceed 60 0 , since this reduces its usable area. And it should not be less than 30 0 , because it can lead to the destruction of the roof due to the accumulation of rain on it. When designing a mansard roof for better comfort, consider the size of the living space.
For greater convenience, the height inside should be at least 220 cm, and 300 cm wide. Regardless of the shape and design of the roof system, its layout is carried out and carefully studied before starting work.
Schemes of fastening of struts.
The first step in assembling the roof construction is to install a subrafter system. First, markup is made for racks made of a wooden bar with a section of 100x100 mm, at a distance of no more than 200 cm from each other. Then they are installed in the same plane on the laid beams.
Racks must be strictly vertically, which is checked with a plumb line.
In order to exclude their oscillation and vertical shift, they are reinforced either with braces or braces. Since the vertical racks are the basis for the attic walls, they must be covered on both sides with a covering material, for example, plasterboard, plywood, fiberboard, etc. Next, insulation is laid between the cladding plates. After that, the upper bar is mounted, the cross section of which is 100x100 mm. It is attached to racks with nails or metal brackets.
Connection of rafters in the ridge.
The next stage of the work is the installation of the mauerlat, to which the entire roof of the attic will be subsequently attached. For this, boards with a minimum thickness of 40 mm or a wooden bar, whose size is 150x100 mm, are used. The material treated with antifungal agent is laid horizontally on the walls with a level.
To prevent moisture from the walls from falling on the mauerlat, a layer of waterproofing is laid under the board. Fixing the material with the wall is carried out with bolts or brackets. To enhance the strength, you can fasten the power plate with annealed wire, which is embedded in the wall when laying bricks.
You will need:
Attic from hanging rafters.
After that, installation of rafter legs is carried out, which can either be ordered and assembled as a constructor, or be cut on the ground with your own hands according to the house design. To do this, use straight boards without knots, whose thickness is 40-50 mm and width 150 mm.
The truss construction provides a pitch of 100-120 cm, which is pre-marked on the main plate and the truss frame.First, fix the extreme rafters to the front. Then, to mark the level for the installation of the remaining rafters, the string is stretched. The top of the rafters must be aligned along the front edge line.
If the length of the mansard roof exceeds 7 m, it is necessary that the truss system is connected to the ridge beam. If the length is less, the ridge beam is not installed. In this case, the rafters are connected with the help of braces, which can later function as ceiling beams during the internal decoration of the attic. In winter, these stretch marks will take on some of the load from precipitation.
Types of roof truss systems.
After the truss system is fully mounted, the installation of the batten is performed. For greater strength and reliability, all nodes of the roof roof should be secured with staples and fired wire. Before proceeding to the finishing of the ceiling and walls of the attic, you need to install a hydro-barrier, lay a layer of steam and heat insulation.
If the roof construction involves the installation of windows, then during installation of the rafters, the window openings are tabbed. In the future, they will be mounted window frames. In the event that the truss system is installed in stages and carefully, an attic roof will last for many years and will decorate the house.
The installation of the roof truss system for the attic can be done in several ways. Firstly, it can be carried out using nylon and hanging trusses. The suspended rafters located on the lower slope are made in the form of a right triangle.
For greater resistance to various loads in the upper and lower parts of the rafters, fights are used. Hanging rafters mounted upper slopes of the roof. At the same time their tightening is applied to the ceiling suspension. In order to further avoid its bending, it is necessary to hang the tie on the headstock. To enhance the fixation of the rafters of the upper slopes, you can additionally secure with struts, headstocks, beams.
On the lower ramps, the rafters can be wound either with or without struts. Their pillars must be supported on the ceiling, and the lower part of the rafter legs must rest on the power plate. If the overlap is reinforced concrete, then it is necessary to lay the plank to support the pillars. On a flat floor surface, it lies directly on the waterproofing layer, in another case - on leveling pads. When wooden floors in the beam is required to perform a frame.
Secondly, the construction of the attic can be performed with the lower support of the rafter behind the external wall. In this case, the installation of roof systems is carried out using beams. In this method, you need to make a strut under the rafters, and the racks need to be embedded in the wooden beams of the ceiling. The depth of penetration must be less than 1/3 of the section of the beam itself.
Since the lower rafters are designed for compression, they must be additionally secured with wire twists and anchor joints. Next, at the intersections of the strut and truss legs, racks are mounted, the lower end of which rests against the beam of the ceilings above the outer wall.
To impart additional stability to the roof, lower rafters are connected by means of contractions at the lower slopes, and support bars in the lower part of the puff are mounted at the hanging rafters on the upper slopes. In these two versions, the truss system is performed as follows: first, racks are put on which the girders are subsequently laid, and then the hanging rafters are assembled for the upper skids.
Thirdly, the mansard roof can be installed from slit rafters. In this case, the rafters of the lower slopes are mounted in the same way as in the first two variants. In this case, the upper scraper, which acts as a support beam for the racks of naslon rafters of the upper slopes, should be made of wood of a large section.
On the lower slopes, if there is a side girder on racks or gables, the upper end of the rafters will support it. If it is missing, then the support will be placed directly on the racks. On the lower slopes, the support of the lower rafters is carried out on the floor beams. In this case, the construction of the roof truss system of the attic is mounted in a certain sequence: first of all, the U-shaped frame is assembled, on which the runs are then installed.
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