What does not surprise modern construction! It also houses houses with attic rooms, and other various designs. Large verandas and separate arbors. There is no end and edge to human ingenuity in the construction of houses, cottages and summer cottages. Despite the great diversity, most roofs have many common nodes, which should be mentioned as a base.
Roofing cake
Among the whole variety of modern structures in the installation of the rafter system, the main frame is typical of many projects. But the so-called roofing cake consists mainly of the same elements in all designs. It includes several layers. The roof device implies the upper part of the roofing system located above the flooring, which consists of two layers.
First of all, this is a layer of roofing material. The second component of the roofing cake is the waterproofing layer, which separates the layer of roofing material from the flooring and from the rafter frame. A layer of waterproofing material protects the flooring and the frame of the truss structure from external water and moisture, which is collected from the underside of the roofing material in the process of moisture condensation.
The sub-roofing part also consists of several layers. Depending on the design of the flooring, all subsequent layers of the building roofing cake are installed according to the rafter structure. The first layer under the floor is heat-insulating, it is protected from internal moisture coming from the attic with a layer of vapor barrier film. A layer of vapor barrier film in the roofing device is covered with a facing material, which completes the filling of the building roofing cake.
Preparing the roof frame
Each rafter frame has its own design. There are more than a dozen varieties of frame. But in most cases, only a few common structures of the rafter frame are used, which are used in private construction. This is a common roof railing system with attic rooms and flat roofs, which are used to create a rest corner on the top of the house.
The design of roofing systems differs among themselves by the ways of their fastening and configuration. But almost all types have the same construction principle, which depends not only on the structure, but on the roofing material. For materials with small sizes and flexible qualities, the rafter frame is covered with a continuous flooring without gaps. And for roofing sheets related to large and hard materials, flooring is made with gaps between the slats.
The indicated gaps of the flooring depend on the size of the roofing material and the degree of inclination. The steeper the slope, the wider the deck rails are installed and vice versa. Also, the ratio of the distance between the flooring rails depends on the size of the roofing sheet. Sheets of more than two meters have three points of contact on the formwork rail. The larger the size of the roofing sheets, the denser the slats or floorboards should be installed. Each sheet of roofing material should have a support point of no more than 50 cm. For flooring, boards with a cross-section of not more than 30 mm or thick waterproof plywood sheets are used.
Lathing for a polymer roof
For the crate for polymer tiles use high-quality wooden beams of pine wood. The device of gable roof roofs includes bars, and for the crate, the boards should have 100% drying in natural conditions. Despite the fact that polymer tiles belong to light roofing materials, the size of the bars for the battens does not differ from those sizes that are 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 crate proceeds from the size of the polymer tile, which is 320 mm with a roof slope of 65-75 degrees. With an increase in the degree of inclination, the crate pitch also increases to 345 mm. For the lathing of the cornice, you need to use bars wider than the usual bars of the lathing. Sometimes, for the lathing of the cornice part, a wide board of the same cross section is used as the bars for the lathing.
The lathing of the battens is carried out using a dimensional template cut from a wooden battens. The device of the rafter system of a gable roof has fastenings of rails with ordinary nails. The joining of the battens laths is carried out on the plane of the rafter log. In the case when the design has a remote cornice or a mansard broken roof, the crate is installed on the principle of sufficient overlap of the upper row on the lower row.
Roof frame construction
Each house has its own special roofing system. Of all the modern structures, the most popular in modern construction are gable, hip, half-hip, mansard, tent and spire. In the construction of each rafter system, there are many common nodes that need to be said as the foundation of all roof structures.
One of the first elements of all roofing structures is the Mauerlat - the base on which the rafter frame rests. It mainly consists of wooden beams that are installed on the strapping beam around the entire crown of the building. On the Mauerlat, the rafter frame is assembled from rafter logs, which are assembled in the truss in the form of triangles. There are two types of rafter frames - hanging and layered. The device of gable roof roofs begins with a design definition.
The roof device may be different. For example, a layered rafter 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 support rafter system has three points of support - two extreme and one in the middle. The rafters of the truss truss rely only on their lower ends on the Mauerlat. It seems that the rafters are in a hanging position between the span of the floor overlap.
Pitched roof
In most houses, the single-pitched roof has a complex structure, created according to the standard design for almost all types. But sometimes for small buildings or for buildings standing in places that are inconvenient for a gable roof, single-slope structures are created.
When creating a single-pitched roof frame, the rafter device has a slight slope of the slope to the rear of the room. Depending on the construction of the building, it can have an angle of inclination of 10 to 60 degrees. The greater the steepness, the more complicated its structure, since as the main support for a single-pitched frame, it is necessary to finish the front wall of the structure to create a slope. If the steepness is small, then the superstructure wall has a height of up to half a meter. If in the house with a single-pitched system an attic is provided, then the single-pitched design has a complex system. Instead of a solid supporting brick wall, a frame of the front wall of wooden beams is created, 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 overlap.
Thus, the skid structure, including the wooden roof device, consists of a front wall frame 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 front wall frame 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 single-slope system with a large slope does not block the front of the house from rain, a long visor above the front wall is provided for a single-slope system with a large slope.
Concrete building
The device of the rafter system of the gable roof of the house begins with the installation of the strapping beam for the frame. In most cases, it is used as a wooden beam with a cross section of at least 25-35 cm. To strengthen this board, bolt pins are mounted on the entire perimeter of the building, on 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 paws, at the joints, the strapping beam is strengthened by transverse fastening boards that connect the Mauerlat from stretching. A rafter frame consisting of triangular trusses is mounted on the Mauerlat. Rafter beams are joined in a triangular truss through 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. For additional connection of the rafter leg to the beam, brackets, slopes and metal corners are used.
The device of a pitched roof requires that the rafter frame has several points of attachment to each other. Rafter trusses are connected to the frame with the help of connecting running rails. Depending on the type and design, the rafter frame is divided into hanging rafters and layers. The hanging rafter frame differs from the layered one by the method of fastening and additional fixing beams. In any frame construction, including the installation of the roof truss system of large houses, additional fastening of the logs and legs creates a strength of resistance to the elements.
Rafter frame for polymer roof tiles
One of the most important factors in the design of the roof frame, including the attic roof, is that more reliable fastening of all nodes is required. High properties of polymer tiles are very convenient for roofing a house with existing attic rooms in the second attic space, when in the attic rooms the roof plays the role of walls.
Based on the fact that polymer tile refers to a light roofing material, accordingly, the device of the roof truss system will have light weight, which affects the load on the roof and on the base of the walls of the house. But at the same time, through lightness, its vulnerability to strong natural elements, wind, storm, hurricanes increases. Based on these indicators, it is necessary to take into account the reliability of fastening the roof frame for the polymer roof with additional fasteners, metal clamps and slopes. Duplicate the frame fasteners for the polymer roof, including the gable roof device, you need at all the main points of contact of the rafter frame to the base of the Mauerlat.
Roof system design
In the device of a wooden roof, lightweight wooden beam 50 x 150 mm can be used as rafters. The rafter pitch of the frame is calculated depending on the inclination. 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 fasten the rafter frame to the base of the upper strapping beam.
Mounting the roof frame to the Mauerlat
The first method of attaching to the base of the rafter leg involves creating a supporting heel on the rafter leg. The supporting heel is cut on the rafter beam no more than one third of the thickness of the rafters. A vertical cut of the supporting heel is made so that the rafter leg fits tightly on the Mauerlat beam. The rafter leg is attached to the Mauerlat with metal corners and screws. For additional fastening of the rafters to the beam in the rafter structure and in the device of the attic roof, slopes from wooden battens are used.
The second method of attaching the rafters to the base of the strapping beam or Mauerlat involves mounting without washing the supporting heel. The rafter leg in the roof device is fastened with galvanized corners. To fasten one rafter leg , at least three reinforced galvanized corners on one side of the rafter are required. To strengthen the fastening of the rafters without washing the supporting heel, supports from the boards are used, which are adjacent to the rafter on both sides.
Rafter system
The installation of the rafter frame has a standard sequence. Starts with installing Mauerlat. The rafter frame is mounted on the Mauerlat beam and the trusses are installed. Rafter legs are installed on the base and fixed in the beam with metal corners and screws. At the upper point, 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 roof device of a private house, in addition to attaching the rafters to the beam in the rafter leg, has a connection with longitudinal girders at the level of the overlap. As the runs at the level of the floor overlap, wooden beams with a section of at least 50 x 150 mm are used.
Runs that strengthen the rafter system for tearing are fixed with metal screws or nails to the rafters at the level of the rafter paws, with which the rafters abut against the Mauerlat. In addition to the longitudinal beams at the level of the interfloor overlap, the rafters are mounted just above the middle of the rafter leg with the same longitudinal beams, which at their ends are attached 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 the fastening, the attic roof device consists of rafters in the ridge part through the entire rafter system. The beam is laid, on which all the rafters rest with their skates. With its upper edge, the longitudinal beam abuts against the skates, and from the bottom it is supported by additional longitudinal rails, which are attached to the rafters with their ends. To fix the ridge beam and its retaining beam, the retaining board is jammed with a longitudinal run, which is fixed between the rafters and the retaining ridge beam. The reinforcing beams are attached to the frame with nails or screws.