What does not surprise modern construction! In it there are also houses with attic rooms, and other various structures. Large verandas and individual gazebos. There is no end to the ingenuity of man in the construction of houses, cottages and summer cottages. Despite the huge variety, most roofs have many common nodes that need to be said about the base.
Roofing cake
Among the variety of modern structures in the construction of the truss system, the main frame is typical for many projects. But the so-called roofing pie consists mainly of the same elements in all structures. It includes several layers. Roofing means the upper part of the roofing system, located above the deck, which consists of two layers.
First of all, it is a layer of roofing material. The second component of the roofing pie is the waterproofing layer, which separates the layer of roofing material from the decking and from the truss frame. Layerwaterproofing material is the protection of the deck and frame of the roof structure from external water and moisture, which collects from the underside of the roofing material during the process of moisture condensation.
The underlay part of the roof also consists of several layers. Depending on the design of the flooring, all subsequent layers of the construction roofing cake are installed along the truss structure. The first layer under the flooring is heat-insulating, it is protected from internal moisture coming from the attic space with a layer of vapor barrier film. The layer of vapor barrier film in the roofing device is covered with a facing material, which completes the filling of the construction roofing cake.
Preparation of the roof frame
Each truss frame has its own design. There are more than a dozen varieties of the frame. But in most cases, only a few common truss frame structures are used, which are used in private construction. This is a common roof rafter system with attic spaces and flat roofs that are used to create a sitting area on top of the house.
The design of roofing systems differs from each other in the ways of their fastening and configuration. But almost all types have the same construction principle, which depends not only on the design, but on the roofing material. For materials with small dimensions and flexible qualities, the truss frame is covered with a continuous flooring without gaps. And for roofing sheets related tooversized and rigid materials, decking is produced with gaps between the slats.
Specified decking intervals depend on the dimensions of the roofing material and the degree of inclination. The steeper the slope, the wider the deck slats are installed and vice versa. Similarly, the ratio of the distance between the slats of the flooring depends on the size of the roofing sheet. Sheets over two meters have three points of contact on the formwork rail. The larger the roofing sheets, the tighter the slats or deck boards must be installed. Each sheet of roofing material must have a fulcrum of no more than 50 cm. For flooring, boards with a section of no more than 30 mm or thick waterproof plywood sheets are used.
Crate for polymer roofing
For the lathing under polymer tiles, high-quality wooden beams made of pine wood are used. The device of gable roof trusses includes beams, and for the lathing, the boards must be 100% dry in natural conditions. Despite the fact that polymer tiles are lightweight roofing materials, the size of the battens for the crate does not differ from those used for all types of tile roofing materials.
The cross section of the lower beam, which serves as the basis for the lathing of the roof truss system, is 70 x 70 mm or 80 x 60 mm. The installation step of the lathing comes from the dimensions of the polymer tile, which is 320 mm with a roof slope of up to 65-75 degrees. As the degree of inclination increasesthe pitch of the crate also increases to 345 mm. For sheathing the eaves, you need to use bars wider than ordinary bars of the sheathing. Sometimes, for the crate of the eaves, a wide board of the same section is used as the bars for the crate.
Stuffing of battens is carried out using a dimensional template cut from a wooden batten. The device of the gable roof truss system has rail fastenings with ordinary nails. Docking of the laths of the crate is carried out on the plane of the rafter log. In the case when the structure has a remote cornice or a mansard sloping roof, the crate is installed according to the principle of sufficient overlap of the upper row on the lower row.
Construction of the roof frame
Each house has its own special roofing system. Of all modern structures, the most popular in modern construction are gable, hip, half-hip, attic, tent and spire. In the construction of each truss system, there are many common nodes that must be mentioned as the basis of all roof structures.
One of the first elements of all roof structures is Mauerlat - the base on which the truss frame rests. It mainly consists of wooden beams, which are installed on a tie beam along the entire crown of the building. On the Mauerlat, a truss frame is mounted from truss logs, which are assembled into truss trusses in the form of triangles. There are two types of truss frames - hanging and layered. The device of gable raftersroofs begins with defining the structure.
Roof device may be different. For example, a layered truss frame is installed on houses that have a supporting wall in the middle between the bearing walls, on which vertical beams rest, supporting the rafter frame in the ridge part. In other words, the supporting truss system has three points of support - two extreme and one in the middle. The rafters of the truss truss rest only with their lower ends on the Mauerlat. It looks like the rafters are hanging between the floor span.
Shed roof
Most houses have a shed roof device that has a complex design, created according to a standard project for almost all types. But sometimes for small buildings or for buildings that stand in places that are inconvenient for a gable roof, single-pitched structures are created.
When creating a shed roof frame, the truss roof device has a slight slope of the slope towards the back of the room. Depending on the design of the building, it can have an angle of inclination from 10 to 60 degrees. The greater the steepness, the more difficult its device, since as the main support for a shed frame, it is necessary to complete the front wall of the building to create a slope. If the steepness is small, then the superstructure wall has a height of up to half a meter. If an attic space is provided in a house with a shed system, then the shed structure also has a complex system. Instead of a solid supporting brick wall, a frame is createdfront wall of wooden beams, which is installed on the crown of the main attic beam. The latter, in turn, is placed and strengthened to the base of the floor slab.
Thus, the frame of a shed structure, including the device of a wooden roof, consists of a frame of the front wall and a rafter frame, which is fixed to the wooden frame of the front wall of the second floor. The rafters are fastened to the frame of the front wall in the usual way, using metal nails, clamps or bolts, slopes and other devices that are provided for attaching the rafter frame. Due to the fact that a steep slope system does not cover the front of the house from rain, a long canopy is provided for a steep slope system above the front wall.
Concrete building construction
The installation of a truss system for a gable roof of a house begins with the installation of a strapping beam for the frame. In most cases, a wooden beam with a cross section of at least 25-35 cm is used as it. To strengthen this board, bolted studs are embedded around the entire perimeter of the building, onto which the beam is mounted. In addition, the boards are attached to each other. Paws are cut out on each beam and fixed with large nails or self-tapping screws.
In addition to fastening in the paws, at the joints, the strapping beam is reinforced with transverse fastening boards that connect the Mauerlat from stretching. A truss frame consisting of triangular trusses is attached to the Mauerlat. truss beamsare joined into a triangular truss by means of several connections. The main docking of the truss truss is made at the installation point on the beam and in the ridge of the structure. The rafter leg is attached to the beam with nails or self-tapping screws. Staples, slopes and metal corners are used to additionally connect the rafter leg to the beam.
The pitched roof device requires the truss frame to have several attachment points between them. Rafter trusses are connected into a frame with the help of connecting running rails. Depending on the type and design, the truss frame is divided into hanging rafters and layered ones. The hanging truss frame differs from the layered ones by the method of fastenings and additional fastening beams. In any frame structure, including the roof truss system of large houses, additional fastening of the lag and legs creates a fortress of resistance to the elements.
Rafter frame for polymer tiles
One of the most important factors in the design of the roof frame, including the mansard roof device, is that more reliable fastening of all nodes is required. The high properties of polymer tiles are very convenient for roofing a house with existing attic rooms in the second attic space, when the role of walls in the attic rooms is played by the roof.
Based on the fact that the polymer tile is a lightweight roofing material, respectively, the roof truss system device will have a light weight, which affects the load of the roof and the base of the walls of the house. But at the same time, through ease risesits vulnerability to strong natural elements, wind, storms, hurricanes. Based on these indicators, it is necessary to take into account the reliability of fastening the truss frame for a polymer roof with additional fasteners, metal clamps and slopes. It is necessary to duplicate the frame fasteners for a polymer roof, including in a gable roof device, at all the main points of contact between the truss frame and the Mauerlat base.
Roof system design
In the device of a wooden roof, a lightweight wooden beam 50 x 150 mm can be used as rafters. The rafter step of the frame is calculated depending on the slope. The average distance between the rafters is within one meter. With an increase in the degree of inclination, the rafter step increases and becomes 1, 2-1, 4 m. With a decrease in the degree of inclination, the rafters are stacked denser - 0.8-0.6 m. All frame nodes must be connected by several types of fasteners. There are several ways to attach the truss frame to the base of the upper strapping beam.
Fastening the truss frame to the Mauerlat
The first method of attaching to the base of the rafter leg involves creating a support heel on the rafter leg. The support heel is cut on the rafter beam no more than one third of the thickness of the rafter. The vertical cut of the support heel is made in such a way that the rafter leg fits snugly on the Mauerlat beam. The rafter leg is attached to the Mauerlat with metal corners and screws. For additional fasteningrafters to the beam in the truss structure and in the device of the mansard roof, slopes made of wooden slats are used.
The second method of fastening the rafters to the base of the strapping beam or Mauerlat involves fastening without washing down the support heel. The rafter leg in the roof device is attached with galvanized corners. To attach one rafter leg, at least three reinforced galvanized corners are required on one side of the rafter. To strengthen the fastening of the rafters without washing down the supporting heel, supports from boards are used that are adjacent to the rafters on both sides.
Rafter system
Installation of the truss frame has a standard sequence. It starts with the installation of the Mauerlat. A truss frame and trusses are installed on the Mauerlat beam. Rafter legs are installed on the base and reinforced in the beam with metal corners and screws. At the top, the legs are fastened with a triangular metal or wooden plate. In addition, the truss legs of the farm are attached with additional lags for stretching. The device of the roof of a private house, in addition to attaching the rafters to the beam in the rafter leg, has a connection with longitudinal runs at the level of the ceiling. Wooden beams with a cross section of at least 50 x 150 mm are used as purlins at the floor level.
Runs, strengthening the truss system to break, are fixed with metal screws or nails to the rafters at the level of the rafter paw, with which the rafter rests against the Mauerlat. In addition to the longitudinal beams at the level of the interfloor overlapthe rafters are fastened a little higher from the middle of the rafter leg with the same longitudinal beams, which are strengthened with their ends to the rafters and are tie beams. In the ridge, the rafters are reinforced with mortise heels and additional metal plates, corners or clamps.
To improve fastening, the mansard roof device consists of rafter beams in the ridge part through the entire truss system. A beam is being laid, on which all the rafters rest with their skates. With its upper edge, the longitudinal beam rests against the skates, and from below it is supported by additional longitudinal slats, which are strengthened with their ends to the rafters. To fix the ridge beam and its retaining beam, the retaining board is pinched by a longitudinal run, which is strengthened between the rafters and the retaining ridge beam. Reinforcing beams are attached to the frame with nails or screws.
