Country plots are not large. Therefore, many build houses of small area and increase living space by creating additional living quarters in the attic. This is possible if the hip roof truss system is correctly installed.
Such a roof is made in the form of four slopes. Two of them are classic lateral ones in the form of a trapezoid, and two more are triangular at the ends of the roof. Unlike a hip roof, where all four slopes converge at one point, a hip roof has two peaks connected by a ridge.
Hip roof with four slopes
It is the side triangular gables, which are performed with a slope, and are called hips. The gable roof also has triangular end gables, but they are located strictly vertically, at the hip roof these slopes are inclined, which is a hallmark of this type of roof.
Double pitched roof
A hip roof is called if the end slopes, starting from the ridge, reach the outer wall, that is, to the eaves. But there are options when the ramp is interrupted and in one place goes into a vertical plane. Then such a roof is called half-hip or Dutch.
According to the method of installation and the use of various materials, such roofs can be classified as complex structures. In general, the design of the hip roof consists of a Mauerlat, a ridge beam, rafters - angular, short and intermediate.
Mauerlat is a wooden beam mounted around the entire perimeter of the house at the very top of the walls. It serves for the correct transfer and distribution of loads exerted by wind, snow cover, the weight of the roof and itself on the load-bearing walls of the building. This element is a connecting upper trim for walls made of piece materials - brick, concrete blocks.
Mauerlat hip roof
For walls made of logs or timber, the Mauerlat is not suitable. Its role is performed by the upper crowns of the log house.
The ridge beam is the main element of the truss system, which connects all the roof slopes into a single structure. It must be of the same section with the rafter legs. Otherwise, in the future, a distortion of the entire truss structure and the roof as a whole may occur.
Corner rafters, otherwise called slanted or diagonal rafters, are the basic power parts that connect the corners of the building box with the ridge beam. For their manufacture, you will need a board equal in thickness to a ridge beam. At one end it is attached to the ridge, the other rests on the Mauerlat. Depending on the roof project, a different number of such rafters is used, but not less than four.
Corner rafters hip roof
Short rafters can be of different lengths, but when assembling the roof structure, they are all displayed at the same angle and are parallel to the intermediate rafters. When the necessary calculation of their number is made, first of all, the area of \u200b\u200bthe entire roof is taken into account. At one end, the short rafter legs are connected to the corner rafter, and at the other they rest on the outer wall of the building.
The central rafters are installed with the upper end on the ridge beam, the lower end rests on the load-bearing walls of the house. As a rule, their calculation is as follows: three on one side of the roof and the same number on the other, but when designing truss systems for large houses, an increase in their number is allowed.
Intermediate rafters are elements that are mounted on a ridge on one side and rest on a Mauerlat on the other. They are usually not used on hip slopes, since the entire area is covered with short rafters. The calculation of the cross section and the number of intermediate elements is based on the bearing capacity of the truss structure and the type of roofing material.
If the building is large, it will be necessary to install additional reinforcing elements in the form of struts and vertical posts supporting the ridge beam, and trussed structures to prevent sagging of the diagonal rafters.
Rafter systems in these types of roofs are made in various versions. For example, if the hip slope does not reach the ridge, as a result of which a vertical small triangular pediment is formed at the top, then such a roof is called Dutch.
Dutch hip roof
Hip roofs also stand out. They have all four slopes of the same shape, and there are simply no side gables in such designs. Hips in this embodiment are triangular surfaces, the slope of which is made at the same angle with other slopes. As a rule, such systems are used for buildings that have a square-shaped area in the projection. In the group of hip roofs there are semi-hip mansard roofs, four-slope, gable, multi-gable and gable.
Hip roof
In addition, there are broken roofs, consisting of slopes of various sizes, the angle of inclination of which is different. Such structures are very complex in design, and it is also difficult to calculate them. Therefore, they are not common, but it should be noted that they have a very attractive appearance. You can evaluate the effectiveness of roofs with a broken structure of the truss system in the video, which also talks about the features of their construction.
The device of hip truss systems begins with the development of their project. A correct and competent project will allow you to assemble the roof in a short time. The optimal choice of the angle of inclination of the slopes is determined depending on the climatic conditions:
- In a region where windy weather prevails, the angle of inclination should be smaller, this will reduce the wind load on the roof.
- During snowier winters, the angle of inclination of the slopes, on the contrary, is increased so that ice and snow do not accumulate on the roof.
Hip truss system project
When choosing the angle of inclination of the rafters, accordingly, the calculation of the required amount of material is also carried out. And if for the lathing in almost all cases the calculation is based on the total area of \u200b\u200bthe roof, then the number and cross section of angular and short rafters are calculated separately, depending on the type of roof chosen.
In addition to the climatic features of the region, when choosing the angle of inclination, the type of roofing material is taken into account:
- If type-setting material is used, for example, slate or metal tiles, then in order not to increase the load on the rafters, it is better to make the angle at least 22 °.
- When using roll coatings, the number of layers is taken into account. The more of them, the less you can make the slope of the slopes.
- The device of a larger angle of inclination of the slopes allows the use of roofing material - corrugated board, but the height of the profile is taken into account. The angle of inclination in this case can vary in the range from 20 to 45 degrees.
The choice of the angle of inclination of the roof according to the material
The correct calculation of the angle of inclination of the roof begins with the determination of the end axis of the building on the upper trim. After that, it is necessary to mark the middle of the ridge beam, at this point the central rafter leg will be located. Then it is necessary to determine the location of the next intermediate rafter, for which the distance corresponding to the calculation of the distribution of intermediate rafter legs is measured. In most cases, it does not exceed 70–90 cm.
The length of the rafters is determined so that their lower end protrudes 40–50 cm above the outer wall, and the upper end rests on the ridge beam.
A similar calculation is carried out on all four sides of the roof to calculate the location of the intermediate rafter legs on the ridge beam. An example of their correct location is shown in the photo.
When designing hip roofs, two types of rafters can be used - hanging and layered. Hanging ones rest only on the walls of the building, transferring all spacer loads to the Mauerlat. If an attic device is planned, then additional installation of metal or wood screeds will be required, which are laid on the load-bearing walls of the building and subsequently serve as the basis for the floor device. The photo shows how mansard hip roofs with a hanging truss system are arranged.
Mansard hip roof with hanging truss system
Laminated rafters are used if they are supported in the form of columns or internal load-bearing walls. When designing the system, alternation of two types of rafters is allowed. Where the inner walls play the role of supports, they are attached to the walls, and in other places they are hanging.
The fastening of the rafters is mainly carried out by means of sawing (saddles). But their depth cannot exceed a quarter of the width of the rafter board. In order for the wash to be the same on all legs, you need to make a template. In addition, the elements of the truss system are attached using metal corners, self-tapping screws, nails. Fastening can also be done with brackets, bolts and studs.
Fastening the elements of the hip roof truss system
When installing the Mauerlat, do not forget to lay a layer of waterproofing along the top of the walls. If the walls are made of brick, then embedded parts are installed in the last rows of masonry for further fastening of the Mauerlat. Such fasteners can be made in the form of vertical studs or bolts, installed in increments of no more than one and a half meters.
Hip roofs are complex structures, but this does not in the least reduce their popularity. Despite the complexity of the construction, they make it possible to arrange additional living quarters in the attic space, and if you carry out high-quality work, you can also operate it in the winter.
The hip roof is perhaps the most popular type of hipped roof. It is suitable for covering private houses of large and small areas, baths, even gazebos. A recognizable geometry is given to it by a truss system, a set of supporting elements that work like a frame.
The complexity of this design lies in the large number of components and attachment points that require special skills and experience. This article will answer questions about what it consists of, what materials are used for construction, and how installation work is performed.
hip roof construction
The hip roof belongs to the four-pitched type, that is, it is formed from four slopes, planes that have one common side. Two slopes that replace the pediments are called hip or end, they have a triangular shape. And the other two, in the form of trapeziums, are designated by the term facade. The line in which all four slopes converge is the ridge, the highest part of the roof. The hip type design consists of:
- Hip slopes, which have the shape of a triangle, are located in a place belonging to the gables.
- Facade slopes of a trapezoidal shape.
- The ridge, the line that the upper connection of the rafter pairs, the tops form.
- An overhang that protrudes beyond the perimeter of the house of the part of the roof formed due to the length of the rafter legs or filly. It protects the surface of the walls from melt and rain water.
- The truss system of the hip roof, the frame supporting and distributing the weight of the roof structure.
- Roofing material, a coating that is laid on the rafters of a hip roof to protect against precipitation.
- Gutters, drainage systems for water accumulating on the roof. It consists of a gutter, a funnel and a downpipe and carries moisture from the surface of the blood to the storm sewer.
- Snow retainers, elements that prevent snow masses accumulated on the roof from collapsing and injuring people passing by.
Types of truss system
The hip roof truss system can be of three types, depending on how the rafters are located:
- Hanging. This means that the rafters are supported by two points: in the upper part on the ridge run, and in the lower part on the Mauerlat. The hanging truss system experiences deflection, compression and expansion loads. All these forces have a destabilizing effect on it, so additional compensating elements are needed - puffs, crossbars, grandmothers. They complicate the design and installation of a hip roof, so experienced roofers are advised to abandon the hanging rafters, if possible.
- Naslonny. With this type of hip roof truss system, the rafters are supported by three points: at the top on the ridge, in the middle on the rack, and at the bottom on the Mauerlat. Racks are installed on internal load-bearing walls. Additional vertical supports reduce the deflection of the rafter legs and eliminate the bursting force. Therefore, a layered system is considered more reliable and stable than a hanging one, and besides, it is easier to install.
- Combined. This term means that the rafter system consists of alternating layered and hanging elements. This is possible if not an internal load-bearing partition is used as a support for the rack, but a pole or column. The roof turns out to be of an open type, that is, all beams and racks are not hidden by the sheathing, but are visible.
Important! With the help of a hanging truss system, it is possible to cover a building no more than 6 meters wide. The use of layered rafters with one additional support increases this distance to 12 m, with two - up to 18 m.
Material used
The hip-type roof truss system consists of many components that reflect the drawing, they are made of the following materials:
Properly processed and prepared wood is an excellent material for the manufacture of a truss system. It is much easier to work with it, it does not require special tools. A good price will keep costs down. Moreover, only those who are confident in the margin of safety of the foundation can afford the metal frame of the roof.
System elements
Depending on the area and features of the layout of the house, the hip roof truss system takes on various types, but it is based on the following elements:
Note! Some elements of the hip roof truss system are of considerable length. And the standard size of sawn wood is limited to six meters. To get out of this problematic situation, roofers make glued or stacked rafters, made up of two or three parts.
Mauerlat installation
Mauerlat installation is the starting point for creating a truss system for a hip roof. Proper installation will provide a solid foundation for the rafters. During the construction of a house from a bar or log, the role of the Mauerlat is performed by the upper crowns. In structures made of bricks, gas silicate blocks, it is fixed as follows:
- On the upper section of the walls, the formwork is adjusted and a concrete belt reinforced with reinforcement is poured into which metal studs are embedded.
- Mauerlat timber is treated with a deep penetration antiseptic and holes are made in it for studs. Moreover, the location of the holes is calculated in such a way that they do not coincide with the attachment points of the rafter legs, but are located between them.
- After the concrete belt hardens, which occurs within 2-3 days, waterproofing is mounted on it. These functions are usually performed by a roofing material folded into two soybeans.
- Mauerlat is laid on waterproofing and attracted with metal studs.
Please note that a large number of holes reduce the strength of the Mauerlat, provoke the appearance of cracks, defects, reducing its support functions. Remember, in the Mauerlat they never cut under the rafters, it is impossible to violate its integrity!
Assembly steps
The result of the calculation, made manually or by the program, is fixed by creating a drawing that reflects the dimensions and relative position of the elements of the truss system, and then they begin to assemble it according to the following plan:
Competent calculation, detailed drawing and high-quality installation are the key to a long service life and reliability of the roof truss system.
Video instruction
A four-pitched roof is familiar to most developers. But its second name - hip can bewilder even an experienced builder. It's all about the triangular end slopes (hips), which replaced the vertical gables.
Why did the creators of such a roof need to complicate the construction of a gable roof, you ask?
There are several reasons for this:
- The aerodynamics of a hip roof is better than that of a gable roof. Therefore, it steadfastly resists strong winds.
- Triangular slopes make the roof rigid and reliable.
- The hip design makes it possible to install wide cornice overhangs along the perimeter of the building, protecting the facade of the building from rain.
- The aesthetic appearance of such a roof is better than a gable roof.
The device and varieties of hip roofs
In order to understand how a hip hipped roof is arranged, consider its main elements.
The design of the hip impassable roof
As can be seen from the diagram, the main elements of this roof are the same as those of a gable roof. There is a ridge run, rafters and mauerlat for attaching them to the wall, racks that support the ridge and struts that unload the middle part of the rafter legs.
The wind beam holds the rafters together during the installation of the roof, and the filly lengthens them, forming roof overhangs. Differences begin with diagonal rafters forming hip slopes. Short rafter legs adjacent to the diagonal rafters are called rafters. To reduce the deflection of long hip beams, sprengels are placed under them. This is the name of short T-shaped racks-stands, cut into the Mauerlat with their ends.
Depending on the width of the building and the presence of internal walls on hip roofs, two types of truss structures are used:
- hanging;
- layered.
The name of each speaks for itself. Hanging rafters rest only on the outer walls. In the upper and lower parts, they are connected by horizontal tie-beams, which ensure the rigidity of the structure. The rafters in the ridge joint rest on vertical posts, in the middle part - on struts, and the ends are placed on the outer walls.
Structural schemes of hanging and layered truss systems of hip roofs
In addition to the classic hip roof, there are several varieties of it, created for reasons of aesthetic appeal:
- half-hip 4-pitched (Danish);
- gable semi-hip (Dutch);
- tent (4 identical hip slopes);
- hip with a broken slope.
Calculation features
The process of calculating a hip roof can be divided into three stages:
- The choice of the angle of inclination of the slopes, depending on the type of roofing material.
- Determination of the lengths of the structural elements of the roof, based on the drawings of the cross-section of the building and the plan of the floor to be covered.
- Selection of the cross section and pitch of the rafters along their length, taking into account the type of wood used and the normative snow load of the construction region.
The angle of inclination of the slopes depends on the material of the roof. Therefore, when making a diagram of a truss structure, it is necessary to take into account its minimum value recommended by the standards (in degrees):
- for slate - 22;
- soft tiles - 11;
- metal tiles - 14;
- corrugated board - 12;
For a roof made of a waterproof membrane, the angle of inclination of the slopes can be any. Based on the minimum allowable slope value, its actual value is chosen depending on the purpose of the attic space.
If a living space is built under the hip roof, then its slopes should have an angle of inclination that allows comfortable movement within the "living area".
The actual length of the structural elements of the roof is easiest to determine by drawing the truss system in a scale convenient for measurements.
Knowing the length of the rafters, their pitch and cross section can be found in the table. Here the dependence of the geometric dimensions of the rafters on the type of wood and the magnitude of the snow load of the construction region is indicated.
Selection of the section of the rafters and their pitch depending on the length, type of wood and snow load
This table can also be successfully used in reverse order. By choosing the pitch and section of the rafters, the type of wood and the amount of snow load, you can easily find the maximum length of the rafters allowed by the standards.
The cross section of the Mauerlat beam must be no less than the cross section of the rafter leg. Most often it is 10x15 cm, 15x15 cm or 15x20 cm. The cross section of the ridge beam is usually equal to the cross section of the rafter legs.
For the lathing, a board 25 mm thick is used, stuffing it at the interval recommended for the selected roofing. For the installation of a solid flooring on the roof frame, an OSB plate with a thickness of 12-15 mm is used.
Mounting Features
Judgments circulate on the Internet that the installation of a hip roof is very difficult and time-consuming. There is some truth in this, but, in essence, the assembly of this structure is not much different from the construction of a conventional gable roof.
Hip roof for a gazebo - invaluable assembly experience
The process of installing a hip roof truss system includes several stages:
1. A mauerlat is laid along the perimeter of the walls. In this case, it is placed on steel threaded studs embedded in the masonry and tightened with nuts. At the docking sites (at the corners of the house and at the splicing points), landing planes are selected on the Mauerlat, cutting off half of the beam.
2. The further sequence of work depends on the width of the overlapped span (roof area). This point must be taken into account at the stage of drawing up a drawing or a roof diagram.
Racks supporting the ridge beam can be dispensed with if the width of the building (span) is less than 7.5 meters. With a house width of 6 to 7.5 meters, the hanging rafters in the upper part must be connected with a crossbar (a beam with a section of 50x100 mm).
If the width of the building is small (up to 6 meters), then lower puffs (floor beams) will be sufficient to ensure the rigidity of the truss system.
Having laid the Mauerlat, the central axis is marked on the end walls. Two extreme racks are set along it and fastened with temporary struts to the floor beams. If the building is covered with panels, then a central beam is laid along them (the cross section is the same as that of the Mauerlat). The lower ends of the extreme racks are fixed on it.
The initial stage of installation - the installation of vertical racks under the ridge
Intermediate racks are placed in increments of 1-2 meters. If the house is covered with beams, then the racks can be mounted on them, fixing them with brackets or self-tapping screws.
3. A ridge beam is laid on the racks, the places for installing the rafter legs are marked on the Mauerlat and they are mounted. To attach the rafters to the Mauerlat, a notch is used (a cutout is made on the rafter leg for tighter contact).
Cutting the rafter leg into the Mauerlat increases the reliability of the joint
4. Hip (sloping, diagonal) rafters are fixed with the lower end to the Mauerlat, and with the other end to the junction of the ridge beam and the extreme ordinary rafters.
After that, short rafter legs (spiders) are attached to them.
Anyone who wants to make a hip roof with their own hands must remember that the main attention here is paid to the quality of assembly of nodes. It is very responsible to approach the installation of the ridge beam, the joining of the diagonal rafters with the ridge and with the sprigs.
The joint of the sprig with the hip rafter
On large roofs, the standard length of the beam (6 meters) is not enough to make a solid diagonal rafter. Therefore, it is assembled from two parts, securely fixing them together.
The overhangs of the hip roof are made by stuffing on the rafter legs trimmings of a beam or a thick board (filly) that extend beyond the perimeter of the walls by 50-100 cm.
Having finished the installation of the truss system, the crate is nailed to it and the roofing material is laid.
The roof protects the building from the penetration of adverse atmospheric phenomena into the premises. To guarantee the reliability and strength of roof structures, it is necessary to choose the right type of roof and know all its structural elements. The load from the coating and snow cover is taken over by the truss system. Most often, a hip roof becomes the best option. But what is she like?
What is a hip
The design of the hip roof is a four-pitched system. In the center of which is a ridge or just a junction point of the slopes. Roof slope - sloping surface,
This type is best suited for covering buildings that are close to a square in terms of, that is, having a large width. During the construction, there are no gables, the walls around the entire perimeter are of the same height. The optimal value of the angle of inclination in degrees will be a value from 20 to 45.
Its main parts are:
Structural elements of a hip roof
The device of the hip roof truss system assumes the presence of the following elements:
hip roof elements - Rafter legs (rafters)- the main load-bearing structures (only available for rectangular hips) are inclined beams, resting at one end on the Mauerlat, and at the other on the ridge crossbar.
- Narozhniki- rafter legs, resting with the upper and lower ends on the sloping legs. Mauerlat often acts as a lower support. These elements are the main structural parts of a square hip roof. With a rectangular shape of the building in plan, they are used in conjunction with conventional rafters, the pitch and section are the same.
- Slanted legs- diagonal rafters forming end slopes. At the lowest point, they rest on the corner of the building. They usually have a larger cross section than ordinary rafter legs. They are relied upon by the guards.
- Ridge crossbar- a horizontal beam located in the central part of the building (absent with a square building). The design of the hip roof assumes the presence of racks along it (with a gable roof, the support occurs on the gables). It is the top support for inclined beams.
- Mauerlat- a beam installed along the edge of the wall from the inside. Provides lower support for the rafters, evenly distributes the vertical component of the load along the walls and perceives the horizontal (thrust). In a log or log house, the upper crown of the wall structure serves as the Mauerlat.
- Struts- inclined racks supporting rafters, slanted legs or crossbar. Intermediate supports allow you to reduce the cross section of the bearing elements. The hip roof truss system involves the installation of struts at an angle of 60 or 45 degrees relative to the horizontal plane.
- Racks- vertical intermediate supports.
- Sprengel- horizontal beams diagonally laid in the corner of the building. They provide support under the rack set to support the skew leg. This design transfers the load to perpendicular walls and is used when it is not possible to install the rack on the ceiling. For example, it is impossible to install a support post in the middle of a reinforced concrete slab, since the slab can withstand a certain load, in which the main component is the mass of furniture, equipment and people.
- fight- a horizontal element that tightens the rafters preventing them from moving apart, can be located at the Mauerlat level or higher.
- crate- boards or bars of small section, laid perpendicular to the rafters on top of them. They serve as the basis for roofing material. A do-it-yourself hip roof is often erected with the installation of a sparse crate (through one board), but you need to remember that in especially critical places (valleys, cornices) the crate is solid.
- Control grille- bars or boards of small section. In the construction of the roof are not always used. They are installed on top of the rafter legs, parallel to them under the crate. Needed to raise the crate above the insulation between the rafters, thereby providing the necessary ventilation gap.
- Filly- boards attached to the lower end of the rafters, providing the necessary overhang of the eaves.
Some of these elements are missing in the construction of a simple roof, the mandatory structures for the hip are:
- conjurers;
- sloping legs;
- Mauerlat;
- crate.
Preparatory work
Before you make a hip roof, you need to make several design decisions, namely:
Table for calculating the pitch of hip roof rafters - rafter step;
- section of rafters and sloping legs;
- roof slope.
The step of the rafters depends on the purpose of the roof space and the width of the building. The larger the span of the rafter leg, the less you have to take a step. If the space under the roof will be used as an attic floor or a heated attic, additional insulation will be required.
Warming is carried out using three types of materials, depending on which the step is selected:
- rigid mineral wool slabs - rafter pitch 58 or 118 cm;
- polystyrene foam (polystyrene or extruded) - rafter pitch - 60 cm;
- polyurethane foam (foam) - any step.
Installation diagram of rafters in accordance with roof windows These values are due to the convenience of workers. If we take a step of supporting structures of 58 cm when using mineral wool, then convenient installation of standard slabs with a width of 60 cm will be ensured.
The manufacturer recommends that the thermal insulation material be a few centimeters wider than the distance between the clean rafters, this will ensure the most snug fit and prevent the appearance of cracks and cold bridges. The appointment of a size of 118 cm provides for laying plates in two strips in width.
When using expanded polystyrene with a standard width of 60 cm, installation with a spacer is not required. The material is held between the supporting structures by glue, special nails and the bottom battens. The gaps between the wooden elements and the slabs of heat-insulating material are filled with mounting foam or sealant.
Polyurethane foam in the form of foam removes the requirements for rafter spacing. The material can take any form given to it, which provides freedom of action in this matter.
If skylights are installed, their dimensions must also be taken into account. The clear distance between the inclined beams is taken 4-6 cm more than the width of the window. If roof insulation is not provided, choose a convenient rafter pitch, usually 1 meter.
Supporting the rafter legs on the truss The cross section of the rafters is taken by calculation, but in the general case, you can specify the following values:
- 5x15 cm for spans up to 3 m;
- 5x20 cm for spans up to 4 m;
- 7.5x17.5 for spans up to 5 m;
- 7.5x200 for spans up to 6 m.
The values are given for a rafter pitch of 0.9. As the distance increases, the cross section must also increase. The cross section of the oblique legs is also taken a little more.
Mounting
Do-it-yourself hip roof is a feasible task, but you need to know the main knots for connecting structures.
The connection of the rafter legs at the top point depends on the type of rafter. They can be:
- layered;
- hanging.
The top ones rest on the crossbar. To do this, a notch is made in a horizontal beam. Fastening is done with nails.
Hanging rafter legs provide for the absence of a crossbar. They are most often used when it is necessary to organize a free layout and the absence of a central wall. In this case, there is no support under the junction. Inclined beams are fastened together with nails. Additionally, at the junction, wooden linings 22-25 cm thick are provided on both sides of the rafter legs. These linings are tightened with studs or bolts.
To fix the rafters at the lowest point, a notch is made in the Mauerlat. Inclined elements are installed and fixed with nails or metal corners. The spears are joined end-to-end to the slanting elements, at the same level.
To resist the wind loads of the roof, trying to rip it off, twists of wire are provided that connect the lower end of the rafters to the wall. In the wall, the twist is fixed on a ruff (fixing device).
When building walls from wooden materials, staples can be used instead of twists. Twists or staples are installed on each rafter leg or through one.
If you build the truss system correctly with a competent selection of the section and the pitch of the rafters, the roof will last a long time.
(four-pitched, hipped) roof is one of the design options when additional slopes are built in place of the gables.
Nonetheless, hip structures are widespread especially in areas with frequent changes in wind direction.
It turns out a roof that has inclined planes on all sides, which creates a lot of profitable positions:
- The absence of gables makes the load on the foundation less, in addition, it is distributed absolutely evenly.
- The wind load on the slope is much lower than on the vertical plane.
- The cost of finishing the gables is excluded from the total repair estimate.
- In decorative terms, the hip roof looks more solid, assembled.
The disadvantage of this design is:
- Increased complexity of the design of the truss system.
- Higher flow, which creates additional dangerous areas of possible leaks.
- The presence of bursting loads on load-bearing walls, necessitating ligaments of the lower bases of the slopes.
The main design feature of the tent-type truss system is the presence of diagonal edges, connecting the corner points of the roof with a ridge beam, which has a shorter length than the entire roof (the classic hipped roof does not have a ridge at all, the ribs converge at one point).
In the rafter system, these ribs are called angular, or diagonal. Their presence requires installation as full-fledged rafters going from to the base - Mauerlat, and shortened elements- sprigs connecting the base and diagonal rafters.
hipped roof scheme
Four-pitched roof: elements of the truss system
The elements of the hip-type truss system have a more numerous composition than with a gable design. The truss system consists of the following parts:
- Mauerlat. A bar laid along the perimeter of the load-bearing walls and which is the basis for the entire truss system.
- Sill. A horizontal beam of the same section as the Mauerlat, located along the longitudinal axis of the roof and serving as a support for the run posts. A layer is required between the overlap and the bed.
- Sprengel. An element that binds and reinforces the corner joints of the Mauerlat bars. It is made from the same beam as the Mauerlat and is installed diagonally to it.
- puff. Connecting elements connecting the parallel bars of the Mauerlat along the long side. Remove the bursting load from the load-bearing walls.
- Rack. A vertical element supported by a puff and supporting a ridge beam.
- Run. Skate beam.
- Diagonal (angular, oblique) rafter. Connects the corners of the Mauerlat with the ends of the run, forming ribs - the junction of the roof planes.
- rafters. Inclined elements based on the Mauerlat from below and on the run from above.
- Narozhniki. These are the elements that rest on top of the diagonal edges. Essentially, these are rafters cut to the length required at a given point.
- Struts. Reinforcing elements, spacers located perpendicular to the rafters and resting at an angle on the puffs.
The designs of all elements may have deviations from the generally accepted scheme due to the need caused by the peculiarities of the project of this building, but the scheme as a whole almost always consists of the named details and does not have any radical changes.
Hip roof truss system: diagram and photo below.
Scheme of the truss system
Photo of the truss system
Diagonal rafter legs
The elements of the rafter system, which form the ribs connecting the planes of the slopes, are called diagonal (sloping, angular) rafter legs.
Strictly speaking, diagonal and oblique - not quite identical elements, since the first are attached outside the corners of the Mauerlat, and the second - from the inside.
Otherwise, all properties are the same.
Corner elements have certain features:
- The length of the diagonal rafter legs is much longer than the length of the straight rafters.
- Diagonal rafter legs serve as a support for the sprigs on both sides of the connected planes.
The presence of such features creates an increased - about one and a half times - load on the rafters compared to conventional ones. Their length exceeds the usual length of the boards., from which the rafters are made, therefore, for the manufacture of sloping boards, they are rallied - they are connected along the face in two layers.
This solves several problems at once.:
- You can make beams of any desired length.
- Possibility to use one modular material size.
One or two supports must be installed under the diagonal rafter(depending on the length), and the point of location of the support is not in the middle, as it would seem at first glance, but at a distance of one third or a quarter of the entire length of the rafter, counting from the top point, since it is in this area that the place of greatest stresses is located.
Diagonal rafter legs
Supports for diagonal rafters
As a support for diagonal rafters, either struts or vertical posts made of timber or paired boards can be used. The rack can rest directly on the ceiling, through a layer of waterproofing and a wooden lining.
This requires sufficient rigidity and strength of the overlap. If there are no such conditions, then a strut is used, based on the bed and supporting the rafter at a given point.
The angle of inclination of the strut in this case does not play a role, the main thing is the connection point, i.e. place of load concentration. With a rafter length of up to 7.5 m, a brace from the upper point of maximum load is sufficient, and with a length of more than 9 m, an additional stand is required at the bottom.
This can be either a support on the ceiling, if it allows, or a support on a truss - the so-called. truss truss - a rack reinforced with struts on the sides.
Supports for diagonal rafters
The device of the conjurers
At the bottom of the sprigs are the same rafters, have a completely similar method of attachment to the Mauerlat, the same installation step. Mounted strictly at right angles to the base, the upper part - to the corner rafter leg.
Fastening is carried out with at least two nails or other elements. The upper part of the box is cut at the right angle to the horizontal and to the diagonal rafter, to provide a tighter fit and ensure load resistance.
The device of the conjurers
Hip roof over bay window
Bay window - a solid looking and decorating building structure, which is a small extension, a ledge in the wall, which performs mainly decorative functions. The section of the roof above the bay window can be any type of structure, but most often the option most suitable for the shape and section of the bay window is used.
The hip roof above the bay window may have an adjoining shape, i.e. be a half of a hip roof, a complex of three planes. Alternatively, there may be a dominant dome over the bay window, towering above the main roof.
Anyway, the construction of such a structure is a difficult task, and the complexity is not in the technical sense, but in the design and calculation work. The combination of several planes into one ensemble is a complex problem that requires precise and accurate thoughtful work.
ATTENTION!
Lack of experience, combined with haste, can lead to inconsistencies or miscalculations leading to violations of the tightness of the roof and a decrease in structural strength.
There are important points that play a significant role - for example, the angle of inclination of the bay window slopes must correspond to the angle of inclination of the main roof, the length of the fillies must also be in harmony with all roof overhangs.
The main feature is the combination of hip elements with valley elements, therefore the construction of the main truss system should be carried out in parallel or before the bay window to avoid unwanted discrepancies in system geometry.
Hip roof over bay window
Step-by-step instructions for installing a hip truss system
The description will begin from the moment the mauerlat is laid, all previous operations are considered completed, the floor is completely ready.
Also completed all the calculation and design work.
There is a prepared (dried) material - a beam and an edged board made of coniferous species, as the most suitable for the construction of a truss system in all respects.
For the correct installation of the elements of the truss system, it is necessary to stock up on connecting elements, allowing some movement of parts in relation to each other.
This is necessary to compensate for the shrinkage processes of the walls, foundation and the system itself. This is especially important for some load-bearing elements based on Mauerlat.
Movement of the base with fixed connections of the main components can lead to loosening of the connections and the formation of leaks.
Consider the stages of construction of the hip truss system:
- Mauerlat installation. The beam is laid on a waterproofed base, fixed with studs. If necessary, the segments are connected along the length of the "half-tree", with reinforcement of the joints with nails. Fasteners are installed immediately.
- Mauerlat corners are reinforced with sprengels and.
- Installation of the bed. One or two (depending on the project) beds are laid on a waterproofed base.
- Racks are installed on which the run is attached. Thus, the supporting skeleton of the truss system is created.
- Installation of diagonal rafter legs. Immediately, depending on the length, struts and (or) racks are mounted.
- Rafters are mounted according to design data. They are immediately adjusted in length / angle and sprigs are installed. All elements, if necessary, are reinforced with struts.
- The rafters at the points of attachment to the base and to the run are additionally reinforced with brackets, wooden bars and other fasteners.
Actually, the installation of the truss system at this stage is completed. Further work consists in creating a roofing pie, constructing a batten, roofing, etc.
It should be taken into account the impossibility of full and detailed coverage of all the nuances and trifles., on which the high-quality and reliable construction of the truss system depends, since there are many of them and all of them are worthy of separate consideration. However, the general sequence is reflected in sufficient detail.
The creation of a hip rafter system is not so much a complicated process as a responsible and dangerous one because mistakes made in the early stages become noticeable much later.
That's why it is very important to draw up a detailed work plan before starting work, to ensure full compliance with the project and to do everything as accurately as possible. Everything rests on the joints of wooden parts, so it is advisable to have experience and skills in working with wood.
Without the possession of this knowledge, it is better to seek the help of specialists, since the responsibility of the truss system for the preservation of the functional qualities of the entire building is too great.
Hip roof: drawing of the truss system below.
Drawing of the truss system
Useful video
In this video you will learn everything about the hip roof truss system:
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