Hip roof - design features and rafter system. Hip roof in the photo Hip roof with gable floor
Arrangement of a hipped roof on one side has clear advantages in a reduced amount of materials and good operational characteristics, but at the same time, the installation of a hipped roof is a rather complicated process, which is almost impossible to cope with on your own. We will talk about the features of making a hipped roof further.
Features and benefits of a hipped roof
For self-made a hipped roof should have at least basic skills in calculating it.
Among the main components of the hipped roof, we highlight:
- corner rafter;
- short rafters;
- ridge-type bar;
- central rafters;
- rafters of intermediate type.
Among the main advantages of this type of roof, we note its excellent aerodynamic drag, thanks to which it easily withstands even the most strong winds... Therefore, if hurricanes are expected in the region, then the best option would be to equip a hipped roof.
The main disadvantage is the severity of calculations and construction overall design... In addition, the attic space is small and has a small usable volume. The classical understanding of a hipped roof is due to its similarity to a pyramid, which consists of four slopes and a base. The option of supporting the slopes on the house or their going beyond its limits is possible.
If we consider the scheme for arranging a hipped roof, then it is distinguished by a certain simplicity, and a variety of methods are used to calculate it. In order to correctly design a hipped roof, the Pythagorean table is most often used, with its help, calculations of trapezoids and triangular structures are carried out with maximum accuracy.
It also does not take much time to calculate the ramps and hip sections, but in order to accurately determine the dimensions of the rafters for an overhead or ordinary purpose, you need to work a lot.
A short construction scheme includes calculations, frame assembly, roof fixing.
1. The ridge system must be made of the same type of wood.
2. Since intermediate boards are installed with a huge slope, they must be strong enough, the optimal size of the material is 5x15 cm.
3. For fixing short elements ridge boards are not required, they are fixed in the corner sections.
4. Rafters of a central, intermediate character are installed on the ridge board.
To make the design work much easier, you should study exactly design features roof, and the main purpose of each of its elements:
- the ridge acts as a bearing axis, which is the central part of the structure;
- in the form of power elements, it is recommended to equip nipples, one part of which is fixed on the ridge, and the second goes beyond the roof;
- the fixation of the central rafters occurs on the end section of the ridge, and the output, outside the walls;
- intermediate types of rafters will be fixed on the ridge and slopes.
To make measurements and design as accurate as possible, we recommend using not a level, but a measuring rod. For its manufacture, a plywood strip or a narrow strip is suitable.
Please note that it is better to choose the material from coniferous woods, since it is this wood that is most resistant to external irritants. In addition, the wood must undergo quality processing and drying. The thickness of the ridge bar and all the rafters must be the same. All measurements are taken in relation to the lower rib part of the rafter.
Upon completion of the work, a crate is made on the roof, the size and configuration of which depends on the further type of coverage, and then such works are carried out as:
- installation of a vapor barrier - to fasten the film, use construction stapler, and to improve the docking, a tape with sealing properties is laid on the surface of the seams;
- the layer of insulation is laid close to the rafters, starting from the bottom, please note that the interval between the layer of waterproofing and insulation should be at least 20 mm, thus it will be possible to organize a ventilation space;
- further work is carried out on laying waterproofing;
- The control lathing is the place to which the outer covering is attached.
Creating a hipped roof project
The most important feature of a hipped roof type is strict symmetry. Therefore, when arranging it, very strict calculations should be carried out. The whole difficulty lies in the design of the rafter system.
The arrangement of a hipped roof is possible only if it is located on a building that forms the shape of a square or regular polygon... In the first case, the roof will consist of four isosceles triangular structures. To calculate such a roof, it is enough to carry out calculations to determine the area of the slope and multiply this value by four. To determine the area, the base divided by two is multiplied by the height of the triangular structure. Further, the obtained value is summed up with the area of the eaves sections, which have the shape of a trapezoid with equal lateral sides.
The next step involves calculating the roof area in relation to the outer wall. Please note that the hipped roof is equipped with an inclination of thirty or forty degrees, this value is taken into account when calculating the ridge zone.
The ridge height is calculated by multiplying half of the length of the main roof section by the tangent and sine of the roof slope. Use the internet to determine the last two values. When the ridge height is found, the height of the triangular part of the roof is determined, according to which its sides are calculated.
To calculate the parameters of eaves overhangs, one should proceed from the structural features, the minimum value of the overhang is thirty centimeters.
If this procedure is too complicated for you, then it is better to contact a specialist, since incorrect calculations will significantly affect the quality and performance of the roof.
Features and design of the hipped roof
There are two options for arranging truss systems at a hipped roof:
- hanging;
- layered.
The first option is suitable for roofs with large spans, in the absence of the possibility of providing supports. Thus, the rafters rest exclusively on the walls, while creating a horizontal bursting pressure. To reduce it, you should install wooden or steel ties. At the top, the rafters should be connected to each other, and at the bottom they rest on the walls. This type of system is highly complex and rarely used.
The second option is simpler and more popular, but for its arrangement it will be necessary to have an internal load-bearing wall, on which part of the load will fall. This roof has several points of support, in the form of rafter legs and a ridge, while the pressure on the walls is practically not felt.
There is an interval of 400-500 cm between the supporting parts. If this value is increased, then it is recommended to equip supporting mechanisms in the form of struts. This type rafter system requires less material, lighter weight and simpler design.
The rafter system for the manufacture of a hipped roof consists of:
- diagonal beams that have an angular arrangement;
- Mauerlats - beams designed to support the lower part of the rafter system;
- rafters of the legs - parts that are attached to the rafters;
- struts - supports for the previous part;
- girders, crossbars, laths, providing additional rigidity to the entire structure.
Hip roof photo and preparatory stage of work
The hipped roof in the house must be equipped before the ceiling appears in it. The preparatory stage of arranging a hipped roof includes laying a bar around the perimeter of the house structure. As a bar, steel or wooden beams which help to distribute the weight evenly throughout the structure.
To fix them, special kind of pins are used. Next, you should perform a number of actions:
- mark the axis along the perimeter of the entire harness;
- calculate half the thickness of the ridge beam, and mark the area where the first rafter element will be installed;
- install a rail for taking measurements with one end on the marked line and mark the place where the rafter will be located;
- to calculate the overhang of the rafters, install one part of the timber on the roof, and the second on outer corner walls;
- in order to clearly determine the location of each roof part, you should gradually move the rail on the wall surface, and mark the installation location of each of the elements;
- repeat all the above operations with other triangles.
Do-it-yourself hip roof: installation features
To independently build a hipped roof, you will need:
- electric saws;
- grinders or jigsaw;
- ax;
- electric planer;
- hammer with nails;
- dowels with self-tapping screws;
- beams and planks, preferably of the same wood species;
- metal staples, for the manufacture of which metal rods are used, at least 0.8 cm thick;
- roofing finishing material.
At the beginning of execution installation works the assembly of the main nodal elements of the roof is carried out. This will require the presence of logs, beams and boards of a certain section. The assembly procedure is carried out according to a previously prepared template.
The thickness of the material is influenced, first of all, by the length of the rafter, the pitch of the parts, the angle of inclination of the roof and the total load. The initial assembly of all elements is carried out on the ground.
If it is planned to equip a hipped roof in a wooden house, then it is installed on the upper crown of a bar.
It is necessary to start work with the arrangement of the main part of the roof. On the surface of the walls, Mauerlats and beds are laid. Please note that before carrying out this process, you should take care of preliminary waterproofing and install a material with increased moisture resistance on the walls, for example, plastic wrap.
Next, two rafters are raised at opposite angles from each other. Their connection is carried out in the ridge area. To avoid weakening the Mauerlat, do not make cuts and logs on its surface, it is preferable to use a board that has been previously cut under the beams.
Next, lift the two rafters at the other corners and also fix them in the ridge area. Fit the notches, fix the system with the ties. The construction of a hipped roof with your own hands implies the absence of a run, so the connection of the diagonal rafters is made directly on the ridge.
To provide additional rigidity to the structure, it is recommended to install a center post that will support the ridge.
The final stage involves the installation of racks, struts and handcuffs. To provide additional rigidity to the legs of the rafter system, parts in the form of strengels should be placed under their surface.
The main condition for the correct execution of all work is the installation of the rafters at right angles.
To ensure the protection of the walls of the building from high humidity, it is recommended to install the overhanging parts of the rafters between the wall with an interval of 450 mm. When installing non-protruding rafters, they need additional lengthening using pieces from the boards.
Rafters, without fail, are fixed on the walls. If the house is made of stone or brick materials, then it is enough to use a special five millimeter wire, which in the form of clamps is fixed in one part on the rafter, and the other on the wall, using a pin.
To fix the rafters to wooden walls, the use of metal brackets is sufficient. The next stage is the installation of the lathing, the provision of high-quality wind protection, steam and waterproofing work.
Please note that only with the correct calculation and observance of all technological aspects of the roof arrangement, it will serve its owner for a long time and efficiently, and will provide reliable protection of the entire building from negative environmental influences.
The procedure for strengthening the hipped roof and the technology of its implementation
To improve the rigidity and reliability of the entire structure of the hipped roof, its rafter system needs additional reinforcement, the technology for carrying out this process will be discussed further:
1. Installation of strengels will ensure the reliability of the reinforcement of the corner sections. This element is in the form of a bar, which is installed near the Mauerlat and contributes to the formation of an angle. We advise, in addition to the strengel, to install an element in the form of a truss.
2. To connect the floor and the timber, elements in the form of racks are used. They are responsible for the even distribution of the entire load.
3. If the length of the diagonal rafters is too long, it is recommended to install double beams instead of the usual timber.
4. To build the crate, use wooden planks or bars, with a cross section of 4x4 cm.
5. Before using any wood based materials, it is recommended to treat them with special formulations moisture-repellent and antiseptic purpose.
6. Do not use materials with high humidity, since as they dry out, they will lead to deformation of the roof.
7. Installation of the battens is carried out perpendicular to the rafter legs.
Sometimes gable roof looks boring and destroys harmony architectural style so designers have to invent something more original. One of these options with a "twist" is a hipped roof. The graceful symmetrical design on one side seems simple, but at the same time strikes with its exoticism, referring to the aesthetics of the East or northern yurts.
Roofing masters are advised to refuse self-erection hipped roof in the event that you are not sure about high level building skills and experience.
The easiest option is to trust design work and installation for professionals. However, nothing will prevent you from understanding how the hipped roof and its rafter system are arranged in order to assess the possibility of building on your own.
Design features
A hipped roof, the structure of which can consist of four or more slopes, in classic version considered as a kind of hip. The number of skates depends on geometric shape the base of the roof.
If the building is covered in the form of a square, then there will be four of them, and if it is round, then there may be five or six or even more, the main condition is that they are the same in shape and size.
The hipped roof structure consists of the following parts:
The hipped roof is designed based on the principle of symmetry. Therefore, maximum harmony can be achieved when a round or square structure is used as the basis for it. You can also build a hipped roof for a rectangular house, but this is much more difficult than building a hip roof.
Advantages
The hipped roof is quite difficult to design and laborious to install, but looking at the surrounding houses, you can see that it is very popular. Designers explain the use of hipped roof structures in projects by its advantages:
- Excellent aerodynamic properties that allow the hipped roof to withstand squally and even hurricane gusts of wind, without fear of falling off roofing material and the collapse of the attic.
- The design of the hipped roof with its steep slopes allows you to forget about such an unpleasant, routine event as cleaning the roof from snow.
- The hipped roof leaves the possibility of arranging a spacious, residential attic room... However, due to the lack of gables, it will be necessary to install expensive roof windows, which are mounted directly on the ramp.
- The original design makes the houses with the hipped roof stand out. hipped roof th from a series of similar projects with a gable triangular roof.
The device of the rafter system
The rafter system of the hipped roof is the frame on which it is held, its basis. Depending on, the hanging and layered varieties are distinguished.
Hanging rafters rest on two points - the mauerlat and the ridge knot, and the layered rafters have additional support on upright rack, which is installed on an internal load-bearing wall. The choice of the type of hip roof truss system depends on the layout and area of the house.
It consists of the following elements:
The rafter system can be made of metal or wood. Wood is a cheaper, easy-to-process material, but it needs pre-treatment with an antiseptic, fire retardant to protect it from decay and fire.
Nuances of design
The device of the hipped roof begins with the calculation and creation of a working project. Not only architects can help with this, but also special computer programs. They calculate the angle of inclination of the slopes, the height of the ridge knot, the section of the frame elements.
The hipped roof contributes to the rational distribution of heat in the house, protects from rain, prevents the formation of a snow cap, and is also suitable for an openwork gazebo, a monumental respectable cottage!
Video instruction
In ancient times, our ancestors built their dwellings in the form of tents. Used for this natural materials: wood, stone, animal skins, etc. The modern tent house is a more fundamental building. It has several varieties and is endowed with certain technical properties.
Finished project of a house with a hipped roof
They can be of two types:
- Full-fledged, built in the form of a tent;
- Incomplete, when they are erected as an ordinary structure, in which the roof structure is hipped.
The houses will differ in construction technologies and materials used in the process of work.
Characteristics of full-fledged tent houses
Such structures have. Quite often they can be found on summer cottages... Construction is economical and the assembly itself is fairly straightforward.
So, the tent house is based on a frame. The projects are quite varied. You can create them yourself or contact a professional architect for help.
Projects for tent houses are drawn up in a similar way to planning this type of roof structure.
Only not taken into account load-bearing walls houses, which will be used as slopes.
Variant of the project of a house with a hipped roof Their shape can be with one or two slopes, with four, as well as multi-slope.
That is, in fact, a tent house is a roof that is immediately installed on a prepared base.
The most interesting are the projects of houses with multi-sloped walls. The number of such rays can be any.
Only now it is worth considering that the functionality of such a house may decrease, since there will be a rather large amount of limited space due to the construction of additional supporting elements of the frame.
The most functional and practical are houses with one, two and four slopes. It is much easier to distribute space in them.
Note. It is worth considering that the height of such a house can be any. But it is necessary to make it in such a way that the ceilings inside the house reach at least 2.4-2.5 m. In this case, the walls will be inclined.
Although you can make them even and, accordingly, slightly reduce the usable area of the house.
Diagram of the device of the hipped roof There are several ways to operate a building. Firstly, you can use the tent house only in the summer. In this case, a large amount of money is not spent on its construction. Secondly, you can live in it all year round, which implies high-quality insulation and insulation work. Especially if houses with a hipped roof are built from the usual building materials.
How to build a tent house
First, you need to select building designs, which are subdivided into a foundation plan and structure walls. Secondly, you need to initially decide on the choice of building materials. The cost of the future home will depend on them.
So, as soon as there is an exact certainty with all this, you can proceed to work, which is divided into several stages:
All these stages have their own characteristics.
Selection and construction of the foundation
To build a high-quality tent house, you need to choose the right base for it. The following foundations are very popular:
Foundation projects are prepared in advance, after the selection of building materials. For example, if metal is preferred for the construction of the frame, then it is better to make a monolithic or pile foundation for such a house. They are considered the most durable.
The first type is characterized by manufacturing using concrete mortar and fittings. And the second is made using metal piles, which are also concreted in the ground at a certain depth.
Tape and slab bases are constructed in most cases under the wooden frame of a tent house, since the material itself does not have a large mass.
- Determine the composition of the soil at the site;
- Establish the level of occurrence of groundwater;
- Define specifications terrain.
The last requirement is characterized by the study of the terrain: are there any irregularities, slopes and other defects on the site. On such planes, preference is given only to the pile or pile-strip base.
Erection of a frame for a building
As mentioned above, a full-fledged tent house is based on a frame. It is constructed from two materials: metal and wood.
Detailed project two-story house Note. You can give preference to special profiles. But this is in the event that the structure is light, and the period of its operation is limited warm time of the year.
First, you need to draw up construction projects. They will allow you to correctly calculate the amount necessary materials for the construction of the frame.
The elements are as follows:
By its principle, the structure resembles the frame of a hipped roof. All elements are connected with special fasteners, and a litter of roofing material sheets is preliminarily constructed on the foundation.
Important. There should be pins and hooks on the surface of the base, which serve to secure the frame to it.
It is to them that they are welded or screwed load-bearing beams frame.
External and internal finishing of the frame
First, the tent house must be properly tiled. Secondly, do not forget about insulation and heat insulation works. They use modern sheet materials such as expanded polystyrene, polyurethane foam and polystyrene foam.
In rare cases, preference is given to mineral wool.
Important. This material is the least often used in the insulation of hipped-roof houses. This is due to the fact that over time it loses its properties and is able to absorb moisture.
Tent house cladding projects are quite varied. Today there are a lot of tools and materials to make the appearance of the structure unique.
Initially, sheets of OSB or dense plywood are mounted on the surface of the frame. Insulating or insulating material is already attached to them.
Cladding scheme frame house with hipped roof On top of it, a low crate is created, on which sheets of plywood or OSB are again mounted, prepared using primers. This will further make it possible to choose any Decoration Materials for cladding a building.
They are very popular now:
- Wood;
- Decorative cladding panels;
- Plaster;
- Plastic lining;
- Natural and artificial stone.
The latter material has a large mass and it is not recommended to mount it without surface reinforcement. It is best to use stone to decorate the bottom of houses.
Inside, the dwelling can look different. Let's say you can leave the walls of the building sloping or build profile frame which will align them. It is fixed on the slope of the structure and on the floor surface. From above, you can already mount OSB, drywall, plywood.
An example of the interior of a frame house The surface of these materials is treated with a primer and can be finished with any modern materials... You can also pre-insulate and insulate the house using similar means from the outside.
The tent house is a pretty simple design... It must be airtight, since there is no roof in such a structure.
In the process of building a house or a gazebo, the question inevitably arises of which roof structure to prefer. If the structure being erected has a quadrangular, and best of all, a square shape, designers and architects often opt for a hipped hipped roof. The complexity of this torus design pays off in the original appearance, excellent thermal insulation and aerodynamic properties. This article will tell you how a do-it-yourself hip roof is designed and installed.
Hip roof structure
In construction, it is customary to consider a hipped roof as a variation of a hip hip roof, in which the ridge connection was transformed into a ridge knot, that is, it changed from a line to a point. The hipped roof is a pyramid, the sides of which are formed by four slopes in the form of isosceles triangles. For installation will do any building with a quadrangle, however, the square shape allows for perfect symmetry, thus achieving the best result.
It includes the following main elements:
Construction stages
Project creation
A do-it-yourself hip roof is built only on the basis of a well-designed project that guarantees its reliability. Before making the drawings, you need to remember the school geometry course in order to make calculations of the angle of inclination of the slopes, the height of the ridge and the area of the slopes. There is a simple instruction to perform calculations:
Do not forget that for a hipped roof with a rectangular base, in contrast to the same construction with a square one, the slopes will have a different slope and different length of rafter legs. This must be taken into account in the calculations and installation!
The project is created manually or with the help of a computer program, which will not only perform calculations of the length of the elements of the rafter system for you, but also select their thickness. The result of the design stage is a diagram with the dimensions and relative position of the roof elements, which will become the support for the installation work.
The structure of the rafter system
The roof rafter system is made of softwood and consists of the following main and additional elements:
In the construction of a hipped roof, a hanging or layered rafter system is used, depending on the possibilities of planning the structure. However, experienced roofers do not advise using the layered type if the slope of the slopes exceeds 40 degrees.
Installation progress
When the project is approved and the materials are purchased, you can do the installation of the hipped roof with your own hands:
Some elements are longer than 6 meters, the standard size of lumber. Therefore, it is necessary to make type-setting rafters, made up of several parts, or glued.
Building a hipped roof with your own hands is hard, time-consuming work, but the result obtained, which distinguishes a house or a gazebo among neighbors of the same type, will reward you for your efforts and spent energy!
Video instruction
Some owners of suburban housing find it too commonplace and uninteresting, and they begin to search for more original options... These include tent structure, which looks extremely interesting outwardly, as if descended from illustrations for a history textbook or a book of children's fairy tales.
Despite the apparent simplicity, the rafter system of the hipped roof is one of the most difficult to construct. Taking on the construction of such a structure on your own, without having experience in such work, will be very risky. However, for those who wish to opt for just such a design, it will be useful to obtain information on the structure of the system, its main components, and to carry out basic calculations. It is in this context that this publication will be built. We hope that it will help to understand the nuances of the hipped roof rafter system, to really assess its complexity and the possibility of self-installation.
What is a tent rafter system?
In fact, the hipped roof is geometrically a "classic" pyramid, that is, a figure with a polygon at the base and edges, which are isosceles triangles converging at a single vertex.
In private construction, a pyramid with a base in the form of a quadrangle is most often used, although for outbuildings (turrets, bay windows, etc.) or light garden buildings (gazebos), the construction of more complex structures is practiced, in which a regular six- or octagon (sometimes even more).
In this publication, the emphasis will still be placed on the hipped roof. Variations are also possible here. A "classic" is a pyramidal structure resting on a square base with a top located on a perpendicular passing through the point of intersection of the base diagonals. In this case, all four slopes will be absolutely congruent triangles located at the same angle of inclination.
The diagram shows a pyramid with a square at the base - it is this that we will consider in the future. You will have to return to this drawing more than once in the course of the presentation.
It is quite possible to use a hipped roof scheme on a rectangular building, in which the length exceeds the width. However, in practice, this is rarely used - due to the unnecessary complication of both calculations and installation. With this option, the slopes resting on a shorter wall become longer and have a smaller angle of inclination to the horizon, that is, the external loads for them already have to be calculated individually. For rectangular bases, it is much more suitable - it is in many ways similar to a hipped roof, but it is better adapted to precisely such conditions.
The hipped roof provides many significant advantages:
- A house with such a roof stands out very advantageously against the background of standard gable roofs, possessing a kind of attractiveness.
- By its aerodynamic qualities, that is, by its ability to withstand wind load, especially with squally or even hurricane gusts, it is among pitched roofs, perhaps, has no equal. Moreover, the lifting component of the wind load is minimized - the effort trying to tear the roof up.
- The unique pyramidal shape contributes to the even distribution of all external and internal loads on the roof system and the building as a whole.
- At proper insulation roof slopes, such a roof is the optimal solution in terms of energy saving.
- At optimal choice the steepness of the roof slopes will not have any special problems with.
The disadvantage, in addition to a certain complexity of the design, can be called the fact that four identical slopes seriously "eat up" the volume of the attic, which complicates the organization of the "inhabited" area in it. To create residential attic, it is necessary to sharply increase the steepness of the roof and resort to "insertion" of additional windows and superstructures. It is clear that to undertake independently the calculation and construction of such complex design- it is simply pointless, as it requires highly professional architectural design and installation.
The main elements of the tent rafter system
Consider the basic structure of the hipped roof truss system. To do this, first we take a completely abstract house, the walls of which form a square, and try to try on such a roof for it.
In the context of this article, we are not particularly interested in roofing and walls. Let's hide them from sight in order to remain "one on one" already with, in fact, the very structure of the rafter system. Well, then let's take a look at it in detail.
The walls are hidden from view, but the Mauerlat is left (pos. 1). This is a powerful beam, which is fixed with a belt along the upper end of the walls - all the rafters will rest on it. Unlike, for example, gable roof, in our case, it must be a necessarily closed frame, rigidly connected - the strength and stability of the entire rafter structure directly depends on this.
From the corners of the Mauerlat up to the center, to the ridge knot (pos. 3), the ribs of the pyramid converge - their role is played by the slant rafters (pos. 2). These are the longest and most loaded of all the other rafter legs, and usually the most "powerful" lumber is used for their manufacture - this will be discussed below. On the pyramid drawing, they correspond to the segments [KA], [KV], [KS] and [KD]. The length of the layered rafter in the same diagram is designated Lн.
From the center of each side to the same ridge knot, there are central rafters (pos. 4). They determine the height of the isosceles triangle of each slope. In the drawing, this is, for example, a segment [KE] (rafter length - Lts). In geometry, there is a separate name for this element of the pyramid - apothem.
Finally, from each rafter leg shortened rafters or rafters (pos. 5), installed with a certain step, leave in both directions to the Mauerlat. Their number will depend on overall dimensions the entire system.
By the way, quite often, in order not to "overload" the ridge knot with connections, they refuse to install central rafters, and they only mount the rafters, placing them symmetrically to the apothem.
This diagram shows an option in which, without exception, the rafters, from the mast rafters to the shortest rafters, are made with a protrusion beyond the Mauerlat - to create the necessary cornice overhang. But in the future, all calculations will be carried out for the "pure" length - from the ridge bridle to the Mauerlat, and the elongation value will be calculated separately, depending on the planned width of the overhang and the angle of the slope.
rafter mount
Very often they do this - a powerful rafter beam ends on the Mauerlat, and the eaves light is provided by increasing the length due to special parts - filly from thinner boards. This allows for significant savings in lumber.
The diagram showed one of the most simple schemes when the slanting rafters are made in a hanging pattern, and are fully balanced. Let's be honest - this is very rare in reality. In practice, one has to resort to the installation of additional, reinforcing elements that ensure the strength and stability of the structure of the rafter system.
Firstly, the rafters can be installed on a layered system, that is, with support on the central post. The rack can rest on the capital inner wall(if there is such an opportunity), or on a bed laid in the center - a powerful bar resting on opposite external walls building.
1 - slant rafters;
2 - central rack (headstock);
3 - tightening (crossbars).
By the way, when erecting light structures, for example, gazebos, sometimes the central post is located along the entire height, from the foundation (floor) to the ridge knot, and serves as a kind of "interior" item.
Another option - the basis for the rack is horizontal ties (crossbars) connecting opposite rafters. These puffs can be located at the bottom, closer to, or approximately in the middle of the height of the "pyramid". Sometimes such crossbars serve as the basis for filing the roof of the attic.
The figure shows an example when the slant rafter legs (pos. 1) are diagonally tied with ties (pos. 5). At the intersection of the puffs, a central support is mounted (pos. 4). All rafters, including the central ones (pos. 2), are connected on a support (headstock), thereby forming a ridge knot (pos. 3).
Often, the B-pillar is not used at all. On small roofs, the rigidity of the structure is provided simply by reliable fastening of the central and oblique rafters on the Mauerlat and in the ridge assembly. In the ridge, the rafters are adjusted to each other with saws at a certain angle, and then this connection is reinforced with metal linings. Another option is to use a central insert element, to which the rafter legs are attached.
metal roofing
But with long lengths rafter legs sometimes - and wives, they still require reinforcement. For this can be applied additional elements systems.
This illustration shows one of the options. In the center of the square formed by the mauerlat (pos. 1), a bed is cut (pos. 2). As in the usual scheme - the slant (pos. 3) and central (pos. 4) rafters and rafters (pos. 5) are installed.
The cranial bars (pos. 6) are strengthened from the bottom of the rafter legs - they serve for more reliable support for established wives.
Both the central legs and the wristbands are connected to the opposite, symmetrically located parts with the help of ties (pos. 7). The screeds of the lower row, in order to exclude the deflection in the center, are supported on the bed, and at the same time they themselves serve as a support for the upper row, perpendicular to them.
From the screeds to each central rafter leg and to the rafters, there are vertical racks (pos. 8).
Instead of vertical struts (or together with them) struts can be used - support elements located at an angle to the horizon. This is convenient when the main load needs to be shifted to some one central point (for example, a bed or a capital lintel inside a building), and not to distribute it by tightening. The braces are usually located at an angle of 45 ÷ 60 °. They find application if the length of the rafter legs exceeds 4.5 meters. Such additional points of support allow to reduce the cross-section of the lumber used for the manufacture of rafters, that is, to both lighten and reduce the cost of the entire structure of the system.
The illustration shows two options. On the left - combined, in which both the stand (pos. 2) and struts (pos. 3) are fixed to the bed (pos. 1). In the right picture, they did without a stand, and only two struts rest against the bed, going up to the symmetrical rafter legs.
The diagram also shows connecting parts- metal pins (pos. 4) and steel brackets (pos. 5).
As already mentioned, the longest and most concentrated loads are the diagonal rafter legs. Not only are they usually thicker than others - they often have to be additionally propped up to prevent sagging or twisting. For this, the same struts extending from the central leg, or a special unit of the system, called a truss support, can be used.
This knot is a truss beam (pos. 9) that cuts into the Mauerlat at the corner, and from which the stand (pos. 10) extends vertically upward, supporting the slanting rafter leg. Sometimes, on large roofs, you have to install on a simple truss, and a truss truss, that is, to strengthen the vertical rack with struts.
There are other options for installing and strengthening the rafter system of the hipped roof - many craftsmen use their own, proven and proven methods over the years. But basic principle it still remains the same as shown above.
Now it is necessary to consider a block of issues related to the linear dimensions of the main structural parts, with the necessary section of sawn timber for their manufacture, with other geometric parameters of the system being created. In short, you need to dive into the calculations.
Basic calculations of the hipped roof truss system
Carrying out the proposed calculations will help the owners to determine in advance the main characteristics future roof and the required amount of materials. Calculations should be carried out in a certain sequence, since most of the parameters are closely interrelated, and, one might say, follow from one another.
The height of the "pyramid", the slope of the slopes and the planned roofing of the hipped roof
This group of parameters is highlighted in the first place. The listed characteristics are closely related to each other and will be decisive for the rest of the calculations.
Why is it necessary to know in advance the steepness of the slopes? Yes, if only because each owner sees in advance the roof of his future house, "dressed" in this or that roof covering, which is more to his liking. And when choosing coatings, whether you like it or not, you have to comply with certain requirements - each material has its own maximum permissible limits for the minimum slope.
The fact that the slope depends on the height of the top of the "tent" (and vice versa) is probably not necessary to explain - with the growth of one parameter, the second also increases. But the dependence here is not linear, but tangential. Let's refer to the diagram of the "pyramid" drawing.
The height of the ridge knot is indicated N Is a segment ... This vertex itself, in horizontal projection, lies exactly in the middle of either side of the square that forms the base. It turns out a right triangle KFE, leg which is known is half the width (length) of the building [AB]. Roof slope angle - α ... It is not difficult to determine the height:
H = 0.5 × [AB] ×tgα
This calculation will be easier with the built-in calculator:
