Designing any residential building, architects special attention give to the roof, as it performs not one but several functions at once, depending on its design features. It should be noted that not all future homeowners are satisfied with the usual gable roof, although it can be called the most reliable, since it has only two pitched planes and one junction between them. Many are attracted by more complex constructions, which add to the structure a special appeal and originality. Other, more practical homeowners, prefer mansard structures, which are simultaneously able to perform the role of the roof and the second floor.
The basis of any roof is an individual rafter system, which has its own design features. Make the choice of the desired skeleton of the roof will be much easier if you first figure out which ones types and schemes of rafter systems are used in construction practice. After receiving such information, it becomes more clear how complicated such constructions are in the installation. Especially it is important to know if the skeleton for the roof is supposed to be erected independently.
With the arrangement of pitched roof structures, the rafter system is a frame for covering and for retaining the materials of the "roofing pie". With a competent installation of the frame structure, the necessary conditions will be created for the proper "work" of insulated and unheated roof types, which protect the walls and interior of the house from various atmospheric influences.
Roof construction is also always the final architectural element of the exterior design of the building, maintaining its stylistic direction in its own way. Nevertheless, the structural features of truss systems first of all must meet the requirements of strength and reliability, which must correspond to the roof, and only then - already aesthetic criteria.
The frame of the rafter system forms the configuration and angle of the roof. These parameters largely depend on natural factors specific to a particular region, as well as on the wishes and opportunities of the homeowner:
- Amount of precipitation in different periods of the year.
- Direction and average wind speed in the area where the construction will be erected.
- Plans for the use of space under the roof - the arrangement of residential or non-residential premises in it, or its use only as an air layer for the thermal insulation of the lower rooms.
- A variety of planned roofing material.
- Financial possibilities of the homeowner.
Atmospheric precipitation and the strength of wind currents give a very sensitive load on the structure of the roof. For example, in regions with heavy snowfalls do not choose the truss system with a small angle of inclination of ramps, as snow mass will stay on the surface, which can lead to deformation of the carcass or roofing or leak.
If the area where the construction is being built is famous for its winds, it is better to choose a structure with a slight slope of the ramp so that the sudden gusts do not tear apart the individual elements of the roof and roof.
The main elements of the roof construction
Details and components of rafter systems
Depending on the type of rafter system chosen, the structural elements used can vary considerably, however, there are parts that are present in both simple and complex roof systems.
The main elements of the roof rafter system are:
- Rafting legs forming the roof slopes.
- Mauerlat - a wooden beam, fixed on the walls of the house and serving to fix the lower part of the rafters on it.
- The horse is the junction of the skeletons of two skates. It is usually the highest horizontal line of the roof and serves as a support on which the rafters are fastened. The ridge can be formed by rafters, fixed together at a certain angle or fixed on a ridge board (run).
- The lining is racks or beams, mounted on rafters with a certain pitch and serving as the basis for the flooring of the selected roofing material.
- Supporting elements, where you can carry the lodges, girders, racks, struts, screeds and other details, serve to increase the rigidity of the rafter legs, support the ridge, the binding of individual parts in the overall design.
In addition to the above structural details, it can include other elements, whose functions are aimed at strengthening the system and the optimal distribution of roof loads on the walls of the building.
Roofing system It is subdivided into several categories depending on different features of its design.
Attic space
Before proceeding to the consideration of different types of roofs, it is worthwhile to understand what an attic space can be, since many owners use it successfully as economic and full-fledged living quarters.
The structure of pitched roofs can be divided into uncrossed and attic. The first option is called precisely because the space under the roof has a small height and is used only as a warming room on top of the building of the air layer. Such systems usually include a single-pitched roof or having several skates, but located at a very small angle.
The attic structure, which has a sufficiently large height of the ridge, can be used in various ways, to be insulated and insulated. To such variants it is possible to carry a mansard or two-slope variant. If you choose a roof with high ridge, then it is mandatory to take into account the wind loads in the region where the house is built.
Slope of skates
To determine the optimal inclination of the roof slopes of the future residential structure, first of all you need to look at the already built low-rise neighbor's houses. If they stand for more than a year and stand up to the wind load, their design can be safely taken as a basis. In the same case, when the owners set a goal to create an exclusive original project, unlike the nearby buildings, it is necessary to familiarize yourself with the structural and operational features of various rafters and make the appropriate calculations.
It should be borne in mind that, as far as the slope of the roof slopes is large, the tangential and normal values of the wind force vary - the steeper the angle of inclination, the greater the importance of normal forces and less tangents. If the roof is sloping, then the design is more affected by the tangential load of the wind, since the lift increases on the leeward side and decreases from the windward.
Winter snow load should also be taken into account when designing the roof. Usually this factor is considered in combination with wind load, since on the windward side the snow load will be much lower than from the leeward slope. In addition, there are places on the skates where snow will necessarily be collected, giving a big load to this area, so it should be strengthened with additional rafters.
The slope of the roof slopes can vary from 10 to 60 degrees, and it should be chosen not only taking into account the consolidated external load, but also depending on the roofing to be used. This factor is taken into account because the roofing materials differ in their weight for their fixing requires a different number of elements of roof system, which means it will vary the load on the walls of the house, and how it will be great, too, it depends on the angle of slope of the roof. Of particular importance are the characteristics of each coating for resistance to moisture penetration - many roofing materials in any case, one or another slope is needed to ensure free flow of storm water or melting snow. In addition, when choosing the slope of the roof, you need to think in advance how the cleaning and repair work on the roof will be carried out.
When planning a particular angle of the roof slopes, you need to know, the fewer joints between the cover sheets, and the more tightly, the less the slope of the ramp can be made, of course, if it is not supposed to arrange a residential or utility space in the attic space.
If, however, a material is used to cover the roof, consisting of small elements, for example, ceramic tiles, then the slope of the stingrays must be made steep enough so that the water never lingers on the surface.
Given the weight of the roofing material, you need to know - the heavier the coating, the greater the angle of the skates, since in this case the load is correctly distributed to the rafter system and bearing walls.
The following materials can be used for roof coverings: metal tiles or profiled sheet, galvanized steel, corrugated asbestobetonnye bitumen and fibrous sheets, cement and ceramic tiles, roofing felt, soft roofing and other roofing materials. The following illustrations show the permissible angles of steepness of skates for different types of roofing.
Basic constructions of rafter systems
First of all, it is necessary to consider the basic types of rafter systems relative to the location of the walls of the house, which are used in all roof structures. The basic options are divided into a layered, hanging, and combined, that is, including in its design elements of both the first and second type of systems.
Layer system
In buildings where internal supporting walls are provided, a stacked rafter system is usually installed. Mounting it is much simpler than hanging, since the inner load-bearing walls provide a reliable support for its elements, and in addition, this design will require fewer materials.
For rafters in this system, the ridge is the defining reference point on which they are fixed. The irresponsible form of the on-board system can be arranged in three versions:
- In the first variant, the upper side of the rafters is fixed on a ridge support, called sliding, and their lower side is fixed by cutting to the mauerlat. In addition, the rafters at the bottom are fixed to the wall using wire or staples.
- In the second case, the rafters in the upper part are cut at a certain angle and joined together by means of special metal plates.
The lower edge of the rafter's feet is fastened to the Mauerlat with movable fasteners.
- In the third version, the rafters are rigidly fastened in the upper part by brusks or treated boards placed horizontally parallel to each other on both sides of the rafters connected at an angle, and between them a ridge run is jammed.
In the lower part, for fastening the rafters, in the same way as in the previous case, sliding fasteners are used.
It is necessary to explain why it is sliding mounts that are often used to fix the rafters on the Mauerlat. The fact that they are able to rid the load-bearing walls from excessive stress, since the rafters are not fixed rigidly, and when shrinking the structure they are able to move without deforming the general construction of the roofing system.
This type of fastening is used only in the on-board systems, which also distinguishes them from the hanging variant.
However, in some cases a spacer system is used for layered rafters, in which the lower end of the rafters is rigidly fixed to the Mauerlat, and in order to remove the load from the walls, tightenings and struts are built into the structure. This option is also called complex, since it includes elements of a nasal and hanging system.
For the construction of private homes is most often used is a collapsible system, so a few words should be said about the installation work.
- Waterproofing material is laid on the bearing walls of the house, which is often a roofing material.
- The waterproofing is fixed with the help of Mauerlat anchorages - this can be a large cross-section beam (for example, 120 × 150 or 150 × 150 mm).
- On the Mauerlate the rafters are fastened to sliding or rigid fasteners. Rarely often the rafters are additionally fixed on the inner side of the wall with the help of wire twisting. To do this, a crutch is screwed into the wall 250 to 300 mm from the surface of the Mauerlat, to which the wire is screwed, and then fixed to the rafter. Such fasteners will keep the roof unscathed during a strong wind.
In the diagram, the numbers indicate:
1 - rafters;
2 - Mauerlat;
3 - brick wall;
4 - a counter-rail;
5 - wire twisting;
6 - fastening element.
- In the upper part, the rafters can be connected by one of the methods described above.
- To form the overhang beams overlapping puffs or the rafter feet themselves are pulled out beyond the edges of the outer bearing walls. This design will protect the walls during the rain. The width of the overhang should be 500 ÷ 600 mm.
- Then the rafter system is strengthened by struts, struts and purlins.
Before the beginning of the installation operations for the installation of the rafter system, it is recommended that the floor beams, at least temporarily, be laid on the joists. This simple adaptation will secure the work and make them more comfortable.
Hanging system
Hanging rafter system is installed in buildings where there are no capital partitions inside the building, and the distance between the side bearing walls varies from 6 to 11 m and more. In this case, the roof construction is completely supported by the bearing walls and gives them a high spacer load. Therefore, that a little to weaken the tension, additional fastening horizontal elements are used, with which the rafter pairs are pulled together - these structural details are called bolts or puffs.
The crossbars can be fixed anywhere in the height of the rafters. They are often used as beams of attic flooring, laying on the Mauerlat.
For this type of construction, the rafters are made from a board with a cross section of approximately 50 × 200 mm, but for each specific structure, individual calculations must be carried out, which is best entrusted to specialists.
- The first step in this construction is to mount the Mauerlat on the lateral load-bearing walls.
- Further, the rafters at the bottom cut into the Mauerlat, and the upper can be joined in one of the three ways described above. Usually, first one rafter is built, which is mounted on the ground, then it is raised to the height and adjusted in place. After that, this pair is used as a template for making the remaining pairs.
- After all the pairs have been mounted, they are taken up by turns and installed on the Mauerlate, at a distance of the calculated step.
- The next step is to prepare a ridge run, which will be associated with individual rafter pairs in the upper part. When installing the run, it is very important to keep the distance between the rafter legs.
- Further, on each of the rafter pairs are fastened the tie boards. They are fixed for rigidity on both sides of the rafters and additionally fixed to the Mauerlat with special metal perforated corners.
- The nimbus of the connecting elements of the rafter system is usually carried out by nails, but after assembling and aligning the elements, they are rigidly fixed with bolts through metal plates and corners. Only such fastening will make the construction reliable and durable.
- If the distance between the walls reaches 10 ÷ 11 m, then the system should be further strengthened by stands and slopes.
Both suspended and stratified systems are used in the installation of various roof structures, which will be discussed below.
Roofs and their rafter systems
Roofs can have one or more skates connected in different ways. Each of the structures is formed by an individual frame system, the main elements in which are rafters. The names of the roofs directly depend on their designs:
So, depending on the specific conditions, on the type and architectural features of the building, the following roof structures are used:
- Shed roof.
- Flat.
- Gable construction.
- Hinged, four-sided.
- The half-wolf.
- Multi-clasp.
- Shatrovaya.
- Broken or mansard roof.
Now, knowing how each type of roof looks, it is worthwhile to figure out what they are, and what construction the rafters have.
Shed roof
As you can already understand from the title, this roof has one ramp, located under the slope. If the structure is small in size and completely erected from brick or concrete, the rafters of the structure are laid on the facade carrier high and on the back low wall. If between the building facade and the rear wall the distance is six or more meters, then between the front and rear wall are mounted retaining racks.
In addition, such structures can be formed entirely from a wooden beam or logs, this option is resorted to if the rafter system is installed on load-bearing brick walls having one height.
A single-pitch wooden truss construction designed for a building with a wall-to-wall distance of six meters or more consists of the following elements:
1 - Podkos supporting the rafters.
2 - Supporting stand, serving as a support for the rafter feet.
3 - Rafting leg.
4 - Ridge run, on which the upper sides of the rafter legs are fixed.
5 - Left, serves to fix the front pillar and the strut.
6 - Mauerlat, on which the lower side of the rafters is fixed by the method of cutting.
The complexity of the gable roof system directly depends on the distance between the bearing walls, that is - the length of the rafters themselves. Examples are shown in the illustration below:
1 - Simple layered rafters in the construction of a single-pitched roof, with a distance from the front to the rear wall from 3 to 4.5 m.
2 - If the distance between the bearing walls is from 5 to 6 m, the rafters are supported by struts attached to the Mauerlat.
3 - The construction with the distance between the walls from 6 to 7.5 and more meters is supported by stands (pasterns) supported by struts.
Such complex options The systems can be mounted between brick or concrete bearing walls.
One-pitched roofs can rarely be found over residential buildings. More often they are mounted over verandas, outbuildings, utility objects and garages.
This design can be called the easiest to install, especially in those cases when all calculations are correctly made. Another positive quality of a saddle roof is a small consumption of building materials.
The biggest disadvantage of a single-deck construction is a small overburden, so it can be called cold, since a small air gap will not keep heat in the premises of the house.
It is very important to correctly calculate the slope of a saddle roof, which will primarily depend on the roofing material to be used for the coating. There are recommended minimum gradients for all roofing. To determine this parameter, you can use the table below:
| Roofing material | Minimum angle of slope, degree |
|---|---|
| Profiled sheeting | 20 |
| Ruberoid | 3 ÷ 4 |
| Metal tile | 25 |
| Asbestos cement slate | 20 ÷ 35 |
| Ceramic, concrete tiles | 25 |
| Evroshifer (ondulin) | 6 |
| Bituminous soft shingles | 11 |
If a specific roofing is selected, the minimum angle of the slope can be determined from the table or following the installation instructions.
The simplest calculations of the parameters of the rafter system
If you have decided with the angle of the ramp, you can immediately determine the elevation of the pedimental part of the roof, using the formula given below:
The formula for calculating the elevation of the front of the roof is as follows:
Lbc = Ldd × tgA;
Ldd- the distance between the front and rear wall;
tgA- the slope of the roof slope.
After this, it will be easy to calculate the length of the rafters, which are suitable for the calculated structure (without taking into account the eaves).
Lc = Lbc / sinA
Lc = √ (Lcd² + Lbc²)
The values of trigonometric functions can be easily found in the corresponding tables.
By the way, it is these formulas that are quite suitable for calculating any roofing structure - you just need to be able to split the rafter system into triangles. For example, for gable roof Lbc simply becomes the height of the ridge over the overlap.
In order not to force the reader to look for reference data for self-calculation, two calculators are given below, which allow us to quickly calculate the basic parameters of the "roof triangle".
Calculator for calculating the height of the "truss triangle"
The calculator allows you to determine the height of the "truss triangle". Depending on the type of roof, this can be an excess, as in the case with sill, or the height of the ridge (fracture) for other structures.
Similarly, the length of the horizontal projection of the rafter should be differentiated. If for a single-pitched roof this is just the distance between the stacks, then in other cases there may be other "layouts". For example, for a symmetrical gable roof this will be half the length of the span.
The gable roof system is considered to be a fairly inexpensive option for a roofing device. It is often chosen by the owners of private residential buildings. This is a simple and practical rafter system. Its design is reliable and provides the necessary protection against bad weather. Further we shall consider more in detail possible options her device.
General information
The gable roof system is a combination of rectangular planes at an angle. From the sides, there are openings of a triangular shape. In them are inserted pediments. The roof structure (rafter system) includes various supporting and retaining elements. They provide reliability and durability. Next, consider what the roof structure consists of (a rafter system).
Mauerlat
The element is represented by a bar having a square section. It is made of coniferous species. Mauerlat is designed for uniform transfer of load from the rafter to the bearing walls. as a rule, is 10-15 cm. It is laid along the supporting walls. As the fastening element protruded rods on the thread or anchors.
"Leg"
It is a bar whose size is 15 X 5 (or 10) in the section. With this element, the triangular contour of the roof is assembled. It, in turn, carries all the load from atmospheric phenomena: snow, hail, rain or wind. To ensure greater reliability rafter legs are located at a distance of 0.6-1.2 meters. The distance is less than the depth of the roof. In addition, the step size in some cases will also be affected by design features 
Sill
This bar has the same cross-section as for the Mauerlat: 10 x 10 cm. It is laid horizontally on the bearing walls. This ensures a uniform load from the racks.
Tightening and braces
The first element completes the triangle of the "legs". The tightening prevents it from spreading. The struts fulfill the task of the link between the rafter legs and the supporting elements. When these parts are combined with the tightening, a farm is produced. This element is very strong. Even in the case of a large span, the farm will be able to withstand all loads.
Racks
For these elements, the same bar is used, as for the tightening. The racks are placed vertically. They take on the load from the ridge and transmit it to the bearing inner wall. 
Rims
Elements of the frame are laid perpendicular to the rafter legs. As a part of the crate, boards or bars can be used. This design transfers the weight of the roof to the legs of the rafters and provides their additional fastening. It is better to take trimmed elements for the crate. However, if there is no such possibility, you can use either the bar with the bark removed. If a soft roof covering is used, for example, tile based on bitumen, the crate is made solid. In this case, plywood sheets (moisture resistant) act as its elements.
The horse and overhang
The first element is the upper portion of the roof. Here, the roof slopes are connected. The horse is formed due to the connection of the legs. It is located horizontally. At a distance of about 40 cm from the walls is overhang. This element protects against rainwater.
"Worms"
These elements form a overhang. "Mares" are necessary only when the feet of the rafters are too short. For these elements smaller boards are used. 
Roof truss system: types
There are only two of them: a layered and hanging type. The latter are used when the walls external walls The buildings are located at a distance of up to ten meters from each other. Another condition, which uses a suspended roof rafter system (shown in the article) is the absence of a load-bearing partition between the opposite elements of the building. If it is, then the nylon type is used. In the event that the separation within the structure is carried out with the help of columns, and not the bearing wall, both rafters are used. The drawing will consist of the elements located under an inclination, and the hanging parts located between them. Next, consider the structure in more detail.
Hanging type
A feature of this scheme of the device system is the location of the rafters with support on the side walls. A disadvantage in this case is the formation of a bursting load, due to which the walls may eventually undergo destruction. To prevent this phenomenon, a tightening is used to join the rafter legs. As a result, a rigid triangle is formed, which does not undergo deformation under load. Instead of tightening, they are often used. They are especially relevant if an attic space is planned. Such a rafter system gable roof with their own hands settles quite simply. The advantage of this structure is the lack of the need to fasten the Mauerlat. Together with this, the elements of the structure are easily attached, where the rafter legs rest on the walls. The board, laid through the insulation layer, will make the farm even and stable. This is made possible by providing a larger footprint. There are several types of suspended rafters. They are all three-hinged. 
Simple triangular construction
This rafter system gable roofs with their own hands is the easiest. The structure is a closed triangle. Its two upper sides are subject to bending stress. The tightening used in this design does not work solely on stretching and does not apply to the carrier element. In this regard, it can be replaced by a steel cable. There are several options for organizing the device of the cornice unit. For this, plate or board mounts can be used, as well as frontal orthogonal cuttings.
Three-hinged triangular arch using raised elbow
Such a gable roof system with its own hands settles in the event that the equipment of the attic room is supposed. In this case, the tightening is not set at the bottom, but at the top. In this case, the tensile load is increased. The rafters themselves are kept on the beams of the Mauerlat. At the same time, the load becomes uniform, because of which the whole truss system of the structure will be more stable, should be carried out taking into account that the edges of the elements should protrude beyond the outer walls of the building. To prevent sagging, it must be balanced by a suspension. This is especially important when it is planned to build a suspended ceiling or laying an insulating layer. In case the tightening is short, it is fixed to the ridge and the crossbar. For this, two boards are nailed. If the tightening is long, then several suspensions are made. 
Layer type
If such a rafter system of a gable roof is arranged by one's own hands, then it is necessary to arrange a vertical beam exactly in the middle. The weight of the roof will pass through it from the ridge to the inner bearing wall located at the same distance from the edges of the building.
Uncontested built-up structure
It is possible to mount such a rafter gable roof system with your own hands in three ways. The first option involves the presence of Mauerlate as a support. Or the rafters are hemmed with a special beam. As a fastener, a tooth is used. To ensure the reliability of the structure is insured with a wire or clamps. In the upper part of the elements are necessarily fixed holes. According to the second variant, the roof rafter system is equipped with the help of a mobile joint of the slider type. You can also mount with a piece of bar. In order to ensure a strong hold on the leg, a nail is driven from above or a flexible steel plate is fixed. The rafters lying on the ridge run are fastened in pairs to the holes or to the run. As for the latest installation, there is a rigid connection here. In parallel, the ridge element is packed on either side of the bar or plank. In this case, a strong bending load is applied to the beam. However, the truss legs are much less bent. This type of installation is somewhat more difficult to perform than the first one. In this regard, it is applied less often. 
Spacer back-up elements
Such a roofing device is almost similar to the above options. However, there is a nuance: the movable attachment of the legs must be replaced by a fixed (rigid) one. In this case, the expanding load of the rafters will be transferred to the bearing walls. In general, such spacer elements act as an intermediate link from the inclined to the suspension system. However, you can do without a run. To equip the spacer system, a very strong fixation of the Mauerlatt to the wall of the house is necessary. At the same time, the building elements themselves must be strong and thick. 
Rafters with struts
In this case, the additional elements are installed at an angle of 45 degrees. The hinge, in fact, acts as the third leg of the rafters, which works on compression. Thus, it becomes possible to block spans that are up to 14 m in length. Beams with a small cross section can be used. Calculation of the attachment of the strut is unnecessary, since it is sufficient to substitute it under the rafters and nail it from the sides. In this case, the element will not move. However, the main thing is the exact cut of the angle of the strut. At the same time, the slope of the rafter should be taken into account. To determine the section of the bar, you need to determine the compression load.
Sub-truss constructions
They are used in buildings with two bearing walls. Podstropilnye structures include beams, laid along the long side of the roof. Under them are installed racks, which are laid beams. As the support is also the inner walls of the building and the log. The rafters in the upper parts are connected one to the other. They are bandaged with wooden or steel plates. Ridge run is absent, in connection with which there appears a spacer. The tightening is placed below the through runs. In this way, the spacer is eliminated. For the stability of the pillars at the bottom, fights are fixed. They take the load on the compression, acting as a deadbolt. The fastening of the stitches is carried out criss-crosswise.
The construction of any house ends with the erection of the roof. Its main element is the rafter system, which includes inclined rafter legs, struts and vertical racks. Of great importance is the design of the rafter system: before you begin to create a roof, you need to carefully think over the arrangement of the elements of the system. Roof erection is a responsible and time-consuming task, therefore haste is unacceptable.
Creation of rafters
The rafter system can be metal, wooden or combined. Most often, wood is used, so first consider the scheme of rafters of wood.
Such a design can be made independently, or it can be ordered at a specialized enterprise. Finished rafter systems are manufactured using special equipment. In the structures manufactured at the factory, metal plates are placed at the junction points. On the industrial enterprise it is possible to order the manufacture of a rafter system of any complexity. At the construction site will only be to collect it. If you want, you can immediately set up the farm previously assembled by the manufacturer upstairs, but this will require special equipment.
If the system is manufactured independently, the following can be used for fastening:
- clamps;
- groove-spikes;
- bolts, staples and nails.
Most often, nails or staples are used to join the rafters. But if the material during the assembly was wet, as it shrinks, the fasteners lose their strength. This can be avoided by resorting to the bolted joint, but because of the holes drilled under it, the rafter system of logs, beams or boards is weakened. Elements of rafters are also fixed with shaped steel details.
In the case of a metal structure, you can also go to a specialized plant. Now, such rafters are made of galvanized steel. If to compare with black hire, then the zinc-coated weighs less, thanks to which the design is easier to lift up the building and install.
If the metal system is manufactured independently, then you will have to buy corners and channel sections of the required cross-section. Also you can not do without welding works. Manufacturing - a laborious occupation, in addition, there are also difficulties with their fitting on the roof (for more details: ""). It is for this reason that many people use not wood, but wood: a rafter system of glued beams or boards is much easier to manufacture and install.
Connection of rafter elements
If for the production of rafters was chosen softwood, then you can use the following fastening methods:
- double or single tooth;
- application of struts and puffs with staples;
- use of clamps or bolts;
- connection of rafter legs with a tightening;
- leveling the rafters with a "mare";
- installation of rafters to the Mauerlat, with the adjoining to him of rafter legs.
To the rafter's feet do not slip by puff, these elements are connected with a tooth or a thorn.
Installation of rafters
Before you begin, you must create a drawing. This will help to avoid mistakes in its construction.
When installing the system, make sure to release the rafter feet behind the walls of the building. The size of the overhang for wooden buildings should be at least 55 centimeters. also bond with the walls. If this is not done, the design may be damaged in strong winds.
In the case of a wooden frame, the base of the truss is attached to the crown of the log. If the walls are brick, they put a yoke on the rafters, attached to the peg in the wall. To give the structure more rigidity, the rafters are connected by crosspieces.
In the case of creating a voluminous roof, additional supports will be required to protect the rafters from deflection. For roofing, the crate is made - perpendicular to the rafter legs.
The plan for rafters of a gable roof is difficult to compose on its own - such designs require compliance with even the slightest nuances. Minor errors can lead to the rapid destruction of the roof, so it's better not to take risks. But such a roof looks very beautiful and is very reliable, so if the appearance of the house is of great importance to its owner, it is worth considering this option.
The roof performs a number of important functions to create decent living conditions together with providing external appeal. It is quite reasonable to consider it a significant constructive component of the building. For the formation of the roof structure meets the rafter frame. He is duty-bound to keep the load, determine the configuration and combine with the exterior of the house. With the solution of the tasks set, only the correctly selected roof base can cope. Making the right choice is much easier if the owner of the country estate knows all possible types and schemes of rafter systems, they understand the specificity of their construction and scope of application.
The list of duties of the roof is not limited only to protection against atmospheric influences. Although the confrontation with weather phenomena in a specific locality, no doubt, leads an impressive list of tasks.
The roof as a finishing architectural touch complements the appearance of the building, gives it a stylistic orientation or completely deprives it. The roofing system as the basis of the roofing structure is obliged to meet the whole range of technical and aesthetic requirements, presented directly to the roof.
The factors in the choice of the "core" of the roof
The rafter system is an undeniable accessory of pitched roofs, which:
- specifies the configuration and the steepness;
- retains the finish coat and the components of the roofing cake;
- creates conditions for the perfect operation of the elements of the roofing system.
The choice of the roof eventually reduces to determining the ideal version of the rafter system, which, in addition to the personal preferences of the house owner, is influenced by such weighty factors as:
- The number of winter and summer precipitation, typical for the area in which construction is planned.
- Strength and direction with the speed of winds prevailing in the region.
- The owner's desire to use the space under the roof for the organization of economic or residential premises.
- Type of finishing roofing.
- Financial opportunities of the owner.
Climate data in no small measure affect the choice of roof and the construction of the rafter system. In regions with abundant snowfall it is not advisable to build structures with an insignificant steepness conducive to the formation of snow deposits. In areas with gusty winds, on the contrary, streamlined and low-slope forms are preferred, which will be difficult to tear down and carry away to a powerful weather phenomenon.
It is clear that the sloping structure is not adapted to the device in it of useful premises. For those wishing to equip the space under the roof there are rafter systems designed for construction in regions with varying degrees of wind loads.
If there is no need to use the attic, a roof of a complex or simple configuration can be built without it. There are lots of options, including a variety of combinations of basic versions, familiarization with which will give an idea of the essence of construction of a rafter system of any type.
In order not to suffer in guesses about the most rational form and the angle of slope of a pitched roof, it is enough to look at the surrounding low-rise buildings.
A proven configuration can be safely taken as a base option to adjust and refine it in accordance with the requirements of the future owner and the technical characteristics of the roofing. If there is no desire to copy neighbors, it is worth familiarizing with the constructive and operational specifics of various rafter systems.
Basic versions of rafter systems
The pitched roof can be simplified to be represented as a set of skates - planes on which atmospheric water "rolls". Rays are formed by ribs of rafter legs - the main elements of the rafter system. The classification of pitched roofs and their corresponding roofing systems is made depending on the number and configuration of the rajids. According to the indicated signs in their ranks are listed:
- One-run. Roofs with one slope suit mainly over household objects, outbuildings, verandas. They are supported on two walls or two rows of racks. One of the walls or one row of supports must be higher than the other, so that along the rafters formed by the plane could drain water without obstacles.
- Gable. Roofs with two rectangular slopes are most often found on domestic spaces. The rafters of the gable systems rely on two walls of a rectangular box of the house. In the classical version, the area of both skates is equal, as is the height of the support walls. True, design solutions with surface slopes differing in area and different in height support walls were not uncommon.
- Valve. Otherwise, they are called slides, based on the number of sloping planes. The rafter legs of the hip system form a pair of trapezoidal and a pair of triangular skates. The rafters of the trapezoidal components rest on the long walls of the box, and the triangular counterparts on the short end walls. In terms of a hip roof is similar to a postal envelope. It looks great, it is used everywhere. The four-slope category includes roofs with truncated triangular ramps, strongly recommended for construction in areas with high wind load.
- Shatrovye . The roof, which consists of triangles that converge in one vertex. The minimum number of skates is 4, the upper limit is not limited. The rafters of the tent system are supported by equal walls or supports of equal height. Tent structures prefer to be erected over verandas and gazebos. Variations with the steepness of the hipped roof allow them to be arranged in regions with any wind load.
- Broken. They are also called mansard, because it is the broken technology that allows creating the most spacious premises under the roof. The rafter legs of broken structures are installed by analogy with gable systems, but they are built in two tiers. The lower rafters are supported by the walls of the fitted box, the upper ones on the supports of the lower tier of the rafter frame.
These types of roofs and trusses have numerous variations on the pitched theme. For example, a gable roof can have a conventional gable-shaped gable on one end and a hip on the opposite side or be supplemented with a single-girder construction above the porch in the middle of the main ramp.
When the two gable systems are cross-shaped, a composite roof is formed with four wooden tongs or stone gables. In the arrangement of boxes of a T-shaped or L-shaped configuration, several types of rafter systems are often involved simultaneously. The upper tier of the broken roof can be built using hip technology.
The rafter structure of any complexity can be represented as a collection of simple forms. To make it easier to understand the construction intricacies, the object is better conditionally divided into separate blocks. They and will prompt how to erect each of the parts and connect to each other the above basic types of rafter frames.
Overview of sloping rafter structures
In order to understand the abundant variety of structures and in the possibilities of their arrangement, let us consider the main types of rafter systems and the corresponding schemes.
View # 1 - single-pitched rafter frame
Most saddle roofs refers to the category bescherdachnyh, because regardless of the steepness, the space created by them under the roof is not enough in volume. However, if you want to build a strictly horizontal ceiling, the ceiling, which separates the attic from the main premises, is still being built.
The scheme depends on the size of the span, which is to be covered by a single ramp:
- If the distance between the upper and lower support of the rafter is less than or equal to 4.5 m, additional struts and racks are not used.
- If the span is in the range from 4.5 m to 6 m, a high-end wall is placed near the high wall. It is supported by a hinge - a rear leg, providing rigidity of the rafters closer to the top of the span.
- If it is necessary to cover the span from 6m to 9m, the slopes are stacked on both sides and both legs are supported by the strops.
If necessary, cover a larger span, it is divided into sectors with the above distances. At the border of adjacent sectors, racks for runs are set up, and within the sector, set up levies and struts according to the rules described. For construction in regions with high wind activity, single-pitch roofing structures from the inside are supplemented by diagonal wind connections.
In terms of the scheme of a single-pitch rafter frame resembles a series of parallel laid beams. The roof with one slope is not too beautiful, but very economical. The optimal angle of inclination from 4º to 12º, is not prohibited and a greater slope.
Constructions with low ramps are desirable to be equipped with a continuous crate and waterproofing, which is not necessary for steep roofs. As a finish coat it is better to use for low constructions, profiled sheet or roofing metal for arrangement of structures in a steeper way.
View # 2 - rafter systems of gable roofs
Gable roof trusses are built on reinforced concrete floors and wooden beams, mainly with lofts. The most common type of roofs is a huge number of low and high, warm and cold modifications.
Depending on the architectural and technical conditions of the object, the rafter legs used in the device of gable roofs are divided into:
- Layered. These are the rafters, which have a strong support under the upper and lower heel. They are made and installed like the rafters' feet of single-pitched roofs. They build a layered roofing system above the boxes that have an internal bearing wall. It is needed as a support structure for ridge run. The role of the wall can play a number of pillars or columns. In the simplest nylon scheme with a span of up to 5 m, the tops of the rafters are supported by a run that rests on the leg through the support posts. Stiffness is provided by struts. Schemes for more solid spans are equipped with fights, pasterns and additional runs.
- Hanging. The rafters of the hanging type have only a lower support, they rest against each other at the top. The elements of the suspended roof truss are immediately made in the form of a triangle, so you can abandon the Mauerlat. The function of the Mauerlat in such cases is entrusted to the base of the triangle - the tightening, used to compensate for the spread of the roof from the weight of the snow, the roof and the system itself. Hanging technology is used in the arrangement of small boxes that do not have an internal support for the ridge run. If it is necessary to overlap the large-span structures, the suspension scheme is equipped with pendants, suspension struts, screeds,
Depending on the technical specifications roof crate is arranged solid or sparse. Low slopes up to 12º are completely covered with a waterproof carpet, high ones only in places of possible leaks: along cornices, ridge, hills, around pipes and other roofing passages.
View # 3 - hip and half-hail system
Hip, they are the same roof "envelope" from gable structures are characterized by the fact that the place of vertical gable-pediments in their constructions is occupied by inclined triangular slopes - hips. The central part of the roof is a standard double-sloped rafter system, to which the same hips are adjacent at an angle.
Variety in the family of hip structures is achieved by variations with proportions. Changing the ratio of the length of the ridge to the length of the base and the height of the ramp, you can get a design that meets any taste and architectural requirements.
In the construction of rafters for:
- Layered or suspended roof trusses with the corresponding structural elements: lezhnyami, ridge runs, puffs, etc.
- Diagonal rafters connecting the tops of the outer rafter trusses to the corners of the box.
- Nakosnye shortened stropilins, forming sloping hips and hips adjacent to the hips of the main stingrays.
Hanging structures are attic and bescherdachnymi. I must admit, they are not too suitable for the organization of premises under the roof. Four sloping ramps severely restrict space. However, for fans of attic houses there is a Danish variety with a shortened hip. Adherents of non-standard architecture will surely like the Dutch type, belonging to the category under the name "" on a par with the Danish option.
Rafter systems for roofs of hip and varieties are erected with an angle of inclination from 10-12º to 60º. In unconditional priority, the classical proportions are steep 25-30º.
In addition to penetrations, skates and cornice overhangs, all convex and concave corners of the hip construction require reinforced waterproofing. The difficult configuration of skates dictates the use of piece materials in the finishing finish. When cutting metal and profiled sheets, there will be too much waste.
View # 4 - hipped roof
A simple four-tented hipped structure is a hip roof, devoid of ridge parts. Its scheme in terms of a square resembles a diagonal passing from corner to corner. Triangular ramps are connected in one vertex, which makes the roof similar to the tent. Build on boxes of a clear rectangular or polygonal shape.
In the construction of tent roof systems, standard layer and hanging principles are used:
- A box with a central support or a supporting wall raises the rafter construction of the layered variety.
- Above the object without inner wall or supports erect a frame by a hanging principle.
The steepness and number of skates depend on the personal preferences of the future owner. The ideal roofing covering for finishing triangular stingrays will be piece material, solely because when cutting large sheets there remains an impressive amount of waste. Regardless of the steepness of the tent structures prefer to equip with a continuous crate and waterproofing carpet.
View # 5 - broken roofing system
Rails for broken lines, i.e. specifically focused on increasing the attic space with the goal of creating in it household or residential premises.
Broken technology is mainly used in the construction of attic roofs, which can be cold in suburban buildings and insulated in houses of permanent residence.
Each slope of the classic broken roof can be conditionally divided into two rectangular parts, creating an outer corner between them. The required shape is obtained by resizing the parts of the skates, the angles between them, and the angle in the ridge zone.
Rafting system of the mansard type is one of the most complex types of rafter systems: sketches and sketches of a broken frame introduce a complex structure structure. It consists of two tiers stacked on top of each other:
- The lower tier of the rafter legs is supported by the Mauerlat on the beams wood flooring, reinforced concrete slabs or a ceiling beam wooden house. To support the top of the rafters, runways are installed, which also serve as a support for the bottom of the rafters of the upper tier. The rafters of the lower part of the broken roof are allowed to be only stratified.
- The upper tier of the rafters with lower heels rests on the runs of the underline located under it. Runs are the basis for laying the ceiling beams of the attic. In the construction of the upper part, both the shoulder and hanging techniques can be used. The task of the top consists only in the formation of the ridge part, because the responsibilities for distributing the roofing cake are laid on the lower part of the roof skylight.
The owner chooses the angle of slope of the lower and upper parts of the skates according to his own preferences. An ideal form is considered if five corners intersect an imaginary circle. Solid or rarefied lathing is arranged depending on the type of roofing, and there are no restrictions at all on its choice.
On a more sloping upper part it is better to mount a continuous crate and waterproofing. On the steep lower part of the skates precipitation does not linger, but it is threatened by heavy winds.
To exclude the breakage of the broken roof in areas with frequent strong winds, each rafter is attached with a wire bundle to the wall, and not through one, as is customary for fixing conventional pitched roofs.
Video review of types and forms of roofs
Expert tips:
Photo-compilation (slideshow):
The presented schemes of different types of truss systems are suitable for the arrangement of a wooden house, a brick and foam concrete box. The only difference is in the fastening of the Mauerlat on wooden and stone walls. Information about the basic types of rafters will help you to decide correctly the type and configuration of the roof for suburban property.
Correctly constructed and assembled according to the technology, the roof serves as a barrier preventing the penetration of cold air and moisture inside the house. Outside, with the naked eye, we see only a small part of the structure - the roofing. But the roof frame, which is the most important component, performs the basic support functions and takes on the influence of wind and snow loads.
In order not to deform it into the result of exploitation, it is necessary to correctly calculate the cross section of its elements and determine the distance between them taking into account the weight of the roofing material, slope and climatic conditions. In this article we will describe what the rafter system of a gable roof of a house is, what it consists of, how it is designed and assembled with its own hands.
The rafter system for the gable roof of the house is a system of interconnected supporting elements, which together constitute the frame of the structure. It is made of wood or metal in accordance with the calculation of the loads that will affect them during operation. Roof rafters perform the following functions:
- It gives the roof slopes the necessary slope. The traditional form in the form of an equilateral rectangle gable roof is attached to the rafter frame, which forms a slope between the base of the roof and its ridge. An angled surface allows snow and water to slip freely from the ramp.
- Distributes the load from the weight of the roofing pie. The weight of the roofing cake, taking into account the snow load, can reach up to 500 kg / m2, so the gable roof is subjected to intensive loading especially during the winter. The rafters of the gable roof evenly distribute the weight that they lay on, and then transfer the load to the bearing walls and foundation of the house.
- It serves as the basis for fixing the thermal insulation and roofing material. The rafter frame of the roof serves as a kind of skeleton of the structure, around which its "body" is built. Between the rafter legs should be installed thermal insulation, and the crate is fixed roof covering, which protects against penetration of moisture.
Note that the design of the gable roof system is quite complex for design and assembly, especially if the master lacks experience. After all, in order to be able to withstand heavy loads, it is necessary to correctly calculate the cross-section of the rafters and the step of the rafters, taking into account the slope and length of the skates, the roofing material used, and also draw a drawing for the assembly.
Kinds
Rafting systems differ in many factors, their composition depends on the layout of the wooden or brick house, the cumulative weight of the roofing cake, the material from which the frame is made, and also the type of roofing. An important characteristic of a structure is their load-bearing capacity, which determines how much weight they can withstand without deformation. By the characteristic features distinguish the following types of rafter systems:
Important! The sliding roof truss is another type of carcass, which differs in that the rafter legs are mounted on the Mauerlat not with the help of a rigid fastening, but using a mobile support. Sliding fastening allows the roof to change within the limits of power reserve dimensions during the shrinkage of the wooden house.
Composition
The construction of a gable roof system of any of the listed types is a combination of auxiliary and supporting elements. They distribute evenly the weight of the roofing cake, and also compensate for the expanding and bending loads that arise between them. The cross-section, length and pitch of the rafters are determined by engineering calculation, taking into account the weight of the roofing pie, the climatic conditions in the construction region, and the slope of the structure. The structure of the gable roof gable usually consists of the following elements:
- Mauerlatt. Mauerlatny bar to install on the outer walls of the house, on which the roof rails rest. It serves to soften the pressure on the supports and evenly distribute the load from the weight of the roofing pie. It is made of a strong bar with a cross-section of 150x150 mm or 200x200 mm and is attached to the upper belt of the walls with the help of anchor bolts or long metal pins.
- Sill. This is an analog of the Mauerlat, only it is installed on the inner load-bearing walls, and it is necessary to put on it a vertical resistant for the installation of the ridge run.
- Rafting legs. This term designate the frame elements, which are made of boards with a cross-section of 150-40 mm and are installed at an angle to the base of the roof, forming a slope angle of the ramp. How to make the distance between the rafters, their length and thickness are determined by calculation, taking into account the aggregate loads to which they are subjected in the process of operation.
- Tightening. Tight is called a beam, which is placed horizontally and connects the legs of one rafter pair together to reduce the bursting load on the outer walls of the structure. Rigel is a tightening, installed under the very edge of the structure.
- Racks. A stand is called a vertical bar, which is exposed to the left to support a ridge run. Determine what distance should be between the racks simply, because it repeats the rafters step.
- The braces. Diagonally located supports supporting the rafter legs in the middle or in the lower part, preventing their deflection, are called struts.
Please note that it is only the calculation of the temporary and permanent loads that they will be subjected to during the operation to determine how to correctly arrange the elements of the rafter system. Calculating the total weight of the roofing pie helps to determine the correct distance between the rafters, calculate their length and the required thickness.
Calculation
Calculation of the roof gable roof system is based on the fact that in the front dimension it has the shape of an equilateral triangle, whose sides can easily be calculated using simple trigonometric formulas. These simple calculations help determine the optimal distance between rafters, their thickness and length. The design is calculated in the following sequence:
- Determine the design and slope of the roof. There are different ways to choose the type and bias of the roofing structure. This parameter depends on the climatic conditions and performance characteristics of the selected roofing material.
- Determine the total load on the structure. To do this, the permanent loads (the weight of the roofing covering, its weight of the frame, thermal insulation and overlapping) are summed up with temporary loads (snow load, wind load), multiply by a correction factor that takes into account the skates slope, and then add to this figure 10-15%, so that the frame had some margin of safety.
- Calculate the length of the rafter feet. To do this, use the theorem of Pythagoras, because the truss is an equilateral triangle. It turns out that the square of the length of the rafter's leg is equal to the sum of the squares of the height of the blood and half the length of the foundation. Knowing how to calculate the length of the rafters, you can calculate the height of the ridge.
- Determine the cross-section of the elements. The optimal cross-section of the elements is selected according to the tables in accordance with the length of the rafter legs and the distance between them. The more indicators this is, the thicker the rafters should be.
Remember that before calculating the rafters on the roof, you need to determine the main parameters of the structure. In particular, it is necessary to know exactly the height of the ridge and the slope of the roof, as well as the size of the room to be closed. As a result of the calculation of the elements of the roof, detailed scheme rafter system, reflecting their size and the angles between them.
Assembly technology
Before you mount the roof frame, you need to calculate the parameters of its elements, based on the calculation of the total load on the structure, as well as create a detailed drawing that reflects its results. Having a skeleton diagram before itself, it is much easier to install a rafter system of a gable roof in a qualitative way. The technology of assembly of the construction implies the following order:
- First, on the upper belt of the outer walls, on which the skates will be laid, the Mauerlat is laid, and on the internal partitions, if the system is collapsible, mount the lever. These elements must be firmly fixed using anchor bolts or studs.
- Then fasten the rafters. They are fixed with the help of nails to the Mauerlat, and also are connected together by means of a metal overlay. It is worth recalling that the rafters are made to drink under the Mauerlat bar, and not vice versa. First, the installation of rafters, located at the edge, is performed to set the level at which the remaining pairs will be aligned.
- After the installation of the rafters, it is necessary to put auxiliary support elements, which I will support them - struts, puffs, fights. To reliably fix the bolt, its end is made with a projection of half the thickness of the beam and cut it to the rafters, fixing nails in several places.
- Over the rafters, a crate is fastened on which the roofing material is fixed. The material and the step of the battens are selected in accordance with the characteristics of the roofing material and the roof slope.
Remember that a properly constructed and qualitatively assembled rafter system is the guarantee of the strength, reliability and durability of the gable roof. Therefore, do not neglect the help of professional roofers and designers when creating a roofing design for your home.
