For roofs consisting of 4 slopes, the rafter system can be hanging and layered. It all depends on the method of fastening the rafters. As for the hanging system, its installation is very difficult, and its repair is quite complicated. A similar system is used in buildings where there are no walls inside. For her, the outer walls play the role of support.
The layered system is easier to install, and it is cheaper in terms of investments. A similar design is used when a supporting wall passes in the middle of the building, and there are also intermediate supporting reinforced concrete pillars. Such a support increases the length of the span covered by the layered rafters. Often, if the roof slope is less than 40 degrees, this particular system is used.
Types of hipped roofs
Roofs with a hipped design are different types. They are divided into:
- hip;
- tent;
- half hip.
hip roofs
The plane of 2 of the 4 slopes of such a roof is made in the form of a trapezoid, and the other 2 are in the form of a triangle. The latter are called "hips". This design is not equipped with gables. Windows in the attic or dormers are installed on slopes.
hipped roofs
In this design, the plane of 4 triangular slopes are joined at the top. Because of this, it turns out pyramid, consisting of 4 corners, at the base of which is a rectangle or square. There are also no pediments.
Half hip roofs
Here the hip plane will be a broken line, consisting of 2 parts: the upper one - triangular, and the bottom trapezoidal.
Features of the design of rafters for a hip-type roof
The rafters of such a roof have 4 legs diagonally. They are rested on the bottom in the corners of the house, and on top they converge in pairs in the skates of the supports. For rafters located diagonally, the support is:
- frame house- the top of the frame fasteners;
- wooden house- the top of the walls outside;
- brick house- Mauerlat.
The ridge run, which is the basis for the rafters at the top, is a beam of wood, the section of which coincides with the rafters diagonally. Instead of a brick pediment, the supports for such beams are wooden stand 100×100 mm, step 3-4 m.
In terms of length, the rafters are superior to others, and the load from the rafters is also transferred to them. So it turns out that in general, the diagonal load on the rafter is 1.5 times higher than on the rest.
Hip roof slopes are obtained thanks to intermediate rafters. They are fastened together with the help of a Mauerlat, as well as skate beams. The distance between them should be 100-120 cm. The cross section of these elements is calculated separately, depending on the loads that fall on them.
Rafters from corners differ more short length so they are often called half-footed". The end at the top of the corner rafters rests on the diagonal, and at the bottom - on the Mauerlat.
Features of the truss system for a hipped roof
The rafter system of a 4-pitched roof of a hipped type is distinguished by such features. The structure rests on 4 supporting walls. All of them should have Mauerlat, it transfers the load to the supporting walls. Mauerlat must be rigidly attached to the wall using metal structures that go deep into the walls.
Often, the outer walls keep the Mauerlat from horizontal shift. At the top of the wall, where the Mauerlat is held, an opening is left inside the masonry.
If the roof is not large, then there is no mandatory use of long Mauerlats, you can simply use a short beam that connects at the corner of the roof at an angle of 90 degrees. But keep in mind that then diagonal reinforcement will be required.
In a hipped roof 4 rafters. They are attached in the corner of the base of the roof, and they converge where the Mauerlat connects. At the top, the rafters converge at one point. Slant rafters are layered type (in the presence of load-bearing walls) or hanging. If a layered truss structure is used, then it will be lighter in weight, but can withstand high loads.
To increase rigidity, the Mauerlat is interconnected by jumpers diagonally. Often this reinforcement is required with a short Mauerlat.
By design, these systems can be divided into:
- hanging;
- layered.
The first are bars, with 2 reference points in the form of walls. In this case, there are 2 types of loads on the leg: bending and compression. The distribution of the load horizontally by hanging rafters is carried out on their reference points. To reduce this effect, they need to be connected with a puff made of metal or wood.
Laminated rafters are a bar with an intermediate support, which has supports on the walls inside the building or additional supporting elements. The main influence on the support is bending. To create a supporting roof structure, you can use layered ones, in the case of intermediate supports between them. no more than 6.5 meters.
If you decide to create a rafter system for 4 pitched roof with your own hands, it is important for you to know general rules , if you follow them, your work will be successful:
- Choose the type of rafter system that suits you.
- Do roof drawing.
- Determine the future angle of the roof.
- Choose the type of truss system. If the house small size, then a hanging system will do. In the case of a larger building, a layered one will be required.
- Calculate the required footage of material, the thickness of the board and bars.
- Buy all the tools.
- It is better to assemble the main part of the rafter structure on the ground, and then lift it up and continue to mount the rest.
- Securely fasten all elements to each other.
- Stick everyone safety regulations, because the work is carried out at height.
Presentable appearance, reliability, durability - all this is a hipped roof, the drawing, calculation and installation of which, of course, is quite difficult to do on your own, but you can always turn to qualified specialists for help.
A noticeable advantage of hipped roofs is that it is very convenient to equip attic floors in such buildings. The premises are very comfortable and spacious, ideal for living, unlike houses, for example, with gable roofs.
Currently, more and more buildings made according to such a plan began to appear. The advantage of a multi-pitched roof is the possibility of using it on completely different buildings, from a bathhouse to a large private cottage.
Houses with hipped roofs look really solid and expensive, and therefore, you should not spare time and money for its arrangement.
The main types of hipped roofs
There are no pediments (these are the triangular completions of the facades of a building, bounded on the sides by two roof slopes, and at the base by a cornice) on such a roof there are no, and attic windows are placed in the slopes.
This roof is much more economical than a gable roof in terms of the cost of wall building materials, but the inclined ribs at the junctions of the hips and front slopes require the installation of a very complex truss structure and additional measurement, adjustment roofing material.
Slopes are often made with different levels of inclination, due to which the silhouette is created. broken roof.
- Semi-hip (Danish) design. It differs from the previous one in the presence of a pediment, which has a small hip at the top. Protection from wind loads in such a roof is provided by a ridge (the upper horizontal edge of the roof, formed due to the intersection of two slopes). Most often, such a roofing device is found in regions with frequent strong winds.
- Tent construction. It looks like a pyramid: four triangular slopes, converging at the tops in one place. Such roofs do not have gables; they are erected on small buildings in the form of an equilateral polygon or square. Installation of a truss system on such a roof is very difficult.
Creating a pitched roof project
Before starting work on the arrangement of the roof, it is necessary to design it, carry out calculations for the structure, and also create its drawing.
The project of a hipped roof provides that the slope of the slopes of such a roof can be in the range from 5 to 60 degrees. It depends on atmospheric loads, the purpose of the attic and the type of roofing materials used.
In areas with frequent and heavy precipitation, the slope of the slopes should be significant (from 45 to 60 degrees). In regions with strong winds and rare rains, the slope of the slopes is usually made much less.
If the angle of inclination is approximately 5-18 degrees, it is recommended to use roll coating; 14-60 - asbestos-cement sheets, roofing metal; 30-60 - tiles.
The height of the roof ridge is calculated using a trigonometric expression for right triangles.
Calculation of rafters is the beginning of drawing up the entire project of the house. Their cross section is determined depending on the expected load (weight of truss structures, roof pie, external influences), and the degree of slope of the roof. With the help of calculations, the step between the rafters is also determined, they are checked load bearing capacity.
The plan of the rafters of a hipped roof provides for which rafters it is advisable to use - layered or hanging. It also turns out whether additional elements are needed: braces, puffs, etc.
If it happens that the standard lumber parameters are not suitable for the future roof, you can modify them. For example, you can lengthen the rafters or double the beams. You can also use glued or type-setting rafter legs (they are noticeably more powerful and longer than usual).
The impact of loads on the rafter system
Rafters are subjected to constant (mass of roofing, battens, rafters, etc.) and temporary (wind, precipitation) loads. The main design parameter of snow load, adopted in Russia for middle lane– 180 kg/m?. A snow bag can increase this figure to 400-450 kg/m².
If the roof slope is greater than 60 degrees, the snow load is not taken into account.
The standard design value of the wind load for central Russia is 35kg/m².
If the roof slope is less than 30 degrees, the wind correction is not taken into account in the drawing.
The load parameters are adjusted for local climate conditions through special coefficients. The total mass of the roof is calculated based on the amount of materials used and the total area of \u200b\u200bthe structure.
Payload indicators for the system are included in the calculations if ceilings are suspended from the trusses, water-heating tanks, ventilation chambers, etc. are installed.
It is obligatory to calculate the strength of the rafters and the degree of possible deformation during various conditions.
The most commonly used as rafters are: a rectangular beam with a section corresponding to the calculated loads, boards with parameters 5x15, 5x20 cm.
Most often, the choice is stopped on softwood lumber (spruce, pine) with a moisture content in the range of 18-22%, processed antiseptics and flame retardants.
To increase the rigidity and stability of the geometry of the truss system of a multi-pitched roof, sometimes they introduce steel elements.
Installation and installation of the truss system
Before proceeding with the installation, you need to select the necessary materials and tools. In addition, it would be nice to get a drawing of the entire structure on paper. Of the materials you will definitely need: thermal insulation ( mineral wool e.g.), waterproofing, vapor barrier, wooden beams, roofing material, wood for lathing. Required Tools: drill, screwdriver, hammer, nails, self-tapping screws, level, tape measure, measuring rod, etc.
The scheme of a hipped roof assumes the presence of rafters, support beams, braces, and other elements necessary to stiffen the entire structure.
Rafters having a cross section of 5 × 15 cm will add reliability to the structure. When you go shopping for lumber for rafters, don't go for wet, twisted, or severely flawed lumber.
Roofing is always done from the bottom up. First of all, support beams (Mauerlat) are laid, on which rafters are subsequently installed. So you get a lower frame, which should extend beyond the walls by 40-50 cm. It is not desirable that the rafters protrude from the edges of the walls exceed the limits specified above, otherwise the object will look inharmonious.
Do not forget to check the correct installation using the building level.
If the building wooden walls, support beams are not needed, since the upper crown of the log house will act as a Mauerlat.
After that, frame rafter legs are installed from each corner of the building, they are called oblique (diagonal). The upper parts of the rafter legs, if necessary, can be held by a system of braces and racks. Their main task is to unload the rafters by redistributing the load along interior walls or supporting pillars, as well as to give the entire structure sufficient rigidity.
Special care should be taken with the attachment points of the rafter legs to the Mauerlat. These are the main points that are responsible for the strength of the truss system as a whole. The overhang of a hipped roof is regulated by the length of the diagonal rafters.
A special table of coefficients will help in the work with the length ratios presented in it and the laying of the rafters for different slopes of the roof slope. In one of its columns, the coefficients for intermediate ones are indicated, in the other - for the corner rafter legs. In order to calculate the required length of the rafter, multiply the laying by the coefficient. You can easily find such a table on the Internet.
In those places where there are no load-bearing walls, the heels of the rafters can be placed on the longitudinal beams (side runs). In addition, a beam is mounted in the center, it is mounted on three supports: in the middle and at both ends.
If you have a large roof area, you can not do without the arrangement of truss trusses, which will take on part of the load from the rafters. Sprengel trusses need puffs on which they will rely. Sometimes they can be fixed on existing transverse or longitudinal beams.
The parameters associated with the height and degree of slope of the roof are determined precisely by the height of the rafters and the horizontal upper beam (ridge run).
After installing the guide rafters, proceed to the construction of the main frame. Attach the inclined (outdoor) rafters to the support beams, as well as to the ridge run.
They should be installed in increments of 40-50 cm, no more. If the gaps are too large, the rafter system may not withstand the loads from the snow that has fallen. The scheme of the truss roof system must take into account this fact.
Fasten the inclined rafters together at a distance of about a meter from the upper rafter beam. This can be done using boards with a cross section of at least 4 * 12 cm.
It is not necessary to select outdoor rafters strictly in length, because they will most likely have to be cut. The main thing is to make sure that they are not too short.
- in order to reduce the likelihood of errors to a minimum, use not a tape measure, but a special measuring rod when measuring;
- mark the center line along the top trim of the end wall. After that, measure half the thickness of the ridge beam, draw the placement line of the first of all the central intermediate rafters;
- align the end of the lath and the placement line of the rafter that you marked a little earlier. On the other end of the measuring rail, copy the line of the inner contour of the side wall (thus you will lay the intermediate rafter). Transfer the line of the outer contour of the wall and the overhang of the roof to the measuring rail;
- to determine the future location of the second of the central rafters, move the measuring rail to the side of the wall, transfer the desired location of the rafters from the inner corner to it top harness;
- repeat the entire algorithm of actions in each of the corners. Following this scheme, you will determine the location of the ends of the ridge beam, as well as all the central intermediate rafters.
After installing the truss system in accordance with the plan, they make a crate, vapor barrier, waterproofing, counter-lattice, as well as roof insulation.
The final stage of the construction of a hipped roof
After installing the entire structure, a hipped roof (like any other) provides for the creation of a crate. For this purpose, use wooden planks 50 or 40 mm thick. The main thing is that the material is of high quality and well dried.
Before installing the crate, it is necessary to lay a film that insulates the roof from steam and moisture. Such a film is attached with a stapler. In addition, in no case should you lose sight of the thermal insulation that should be equipped in the attic. Thermal insulation is necessary to maintain normal building conditions. temperature regime. And after that, the installation of a hipped roof is carried out.
And the last stage is laying the roofing. You are not limited in choice, be guided by your own taste, material capabilities and design features of your roof. The main thing is to attach the material firmly enough, carefully, so that rain cannot penetrate into the room through the joints, and the wind cannot tear off fragments of the roof.
The scheme of the hip roof truss system is very complex, as has been said more than once above, but do not be afraid of it. The most important thing is to make all the calculations and measurements correctly, and also not to make a mistake with the markup. Having thoroughly understood this once, you can easily repeat a similar construction. Of course, it will be quite difficult for one person to cope with the amount of work ahead, so a couple of assistants will not hurt.
Roofs of complex shape draw special attention to the architecture of the building. Four-pitched roofs are popular for construction country houses. Four slopes, located in different planes, give the dwelling a respectable look. Most often, slopes are performed different shapes: two of them are triangular and act as pediments, two have the shape of a trapezoid.
Design Benefits
Installing a four-pitched or hip roof, in addition to its aesthetic appearance, also has practical advantages:
- in the attic, surrounded by a roof on all sides, a comfortable temperature is maintained;
- the construction of the rafters is strong and durable;
- high resistance to winds and precipitation;
- the space under the roof can be used for the attic.
Types of pitched roofs
Having a common basis, subspecies of such coatings differ somewhat in execution:
- - a classic version with two triangular hips and two slopes in the shape of a trapezoid.
- Half hip - triangular slopes have a shortened shape, this design is performed for attic equipment.
- Tent - has the shape of a pyramid with triangular slopes. Suitable for square building.
Design
The angle of inclination for the slopes is selected based on the recommendations of the manufacturers of the roofing material and natural features. For soft roll roofing an angle of up to 18 degrees is enough, an angle of 15–60 degrees is suitable for slate, and under it is worth laying a slope of 30 to 60 degrees.
Of great importance is the amount of precipitation in winter, if a significant amount of snow falls, then it is better to choose steep slopes, on which precipitation lingers less.
When designing a truss system, a lot needs to be taken into account: the cross section of the beam, the length of the rafters, the size of the run, the installation step of the elements. All possible loads on the roof are clarified at the design stage, these include:
- the weight of the selected roofing;
- annual precipitation;
- mass of insulation and waterproofing;
- installation on the roof of various equipment (antennas, lights, windows, etc.);
In addition to the inherent loads, the roof of the house must have a margin of safety that guarantees the stability of the structure in an unforeseen situation. For the construction of the truss system, timber and boards are used. If there is a need to strengthen the elements, the boards are doubled.
Before starting work, all lumber is treated with an antiseptic.
Sequence of work
Installation of the roof begins with fixing the supporting base - Mauerlat. This is a bar with a section of 150 × 150 mm, which is laid along the perimeter of the walls. Its horizontal placement is controlled by the level. The beam should not be on the edge of the wall, you need to leave a distance of 5-7 cm. The Mauerlat is fastened to the studs immured in the masonry, which are tightened with nuts. This beam allows you to connect the truss system and the walls of the house into a common structure.
To install racks, beds or floor beams are required. These elements are made of bars measuring 100 × 200 mm or double boards. All supports are installed strictly vertically and attached to the bed metal corner or plate. For a hip roof, racks are installed in one line, a ridge run is attached to them. When erecting a tent-type roof, the supports are placed diagonally, equal distances are laid from the corner. As a result, they form a rectangle on which the runs fit. Fastening is carried out by corners.
The side rafters are installed after processing according to the template. A thin board is taken as a blank, applied to the run and washed down. The second end rests on the Mauerlat and a lower gash is outlined. The required number of rafters is prepared according to the template and installed with the selected fastening step, it can be from 60 cm to 1 meter. With the run and the base, the connection occurs with brackets or self-tapping screws.
Skew rafters with a ridge run form the angle of inclination of the slopes. These rafters are located diagonally and carry additional load, so double boards are used for them. The sawing of the rafters is carried out according to a template, their length takes into account an overhang of 50 cm. In the upper part, the rafters are connected by a crossbar to give strength. When constructing a hipped roof, the rafters are connected in the ridge knot with the help of puffs. The rafters are installed at an angle of 90 degrees and are necessarily connected to the walls with wire clamps.
Short rafters or rafters are attached to the diagonal rafters. They are made in different lengths, but must be parallel to each other. The rafters, together with ordinary rafters, form side slopes. For the tent model, the installation of sprigs and the fastening of racks, struts and trusses is also the final stage of construction.
To relieve the load from the diagonal rafters, sprengels are installed under them. These are vertical supports that rest on the beds. The side rafters are fixed with struts. One of the horses of the board rests on the bed, and the second is cut off at 45 degrees and attached to the rafter leg.
Sheathing and insulation
To complete the construction of the roof will allow its insulation with basalt wool or foamed polystyrene. The material is laid between the rafters. The waterproofing layer will protect the roof from moisture. The dimensions of the crate depend on the type of roofing; soft tiles look attractive on the hip type, it needs a continuous crate.
Watching a video explaining the nuances of installing rafters will help to conduct construction correctly.
Video
See how the truss system is installed:
Many are attracted by the spectacular and non-standard look of the hipped roof. Therefore, the question of how to properly build a hipped roof is constantly in the center of attention of those who are planning to build a roof or repair it. But we must admit that in order to build such a roof, you will have to make a little effort.
Everything in construction begins with the planning of the necessary actions, therefore, their outlines on how to make a hipped roof are first betrayed to paper.
Hip roof project: calculation of all parameters
Before creating a project for such a roof, you will need to determine its shape, take measurements and calculate all the necessary parameters. They start building directly, already having a design drawing in their hands future roof, on which all the required information will be noted in detail - the angle of inclination of the hipped roof, design, length, pitch, assembly order of the rafters, location and number of additional supporting parts, and more.
The key to the success of the construction of a hipped roof is in an accurate and detailed plan, so this stage can most likely be considered one of the most important.
The calculation of a hipped roof can be carried out using special programs posted on the Internet. But if you have not forgotten the basics of school geometry, you can do it differently - draw a prototype of your future roof on paper and use the simplest geometric shapes to calculate rafters, beams, the amount of material to cover and much more.
We start with the angle of inclination of the hipped roof
The theoretical first determine the angle of inclination of the hipped roof, taking into account the climate of the given zone, especially since the height of the hipped roof also depends on its value. According to the rules, for areas with heavy rainfall, the slope is increased (the consumption of all materials will increase accordingly).
Having determined the slope, the next step is to mathematically derive the height of the ridge by multiplying half the width of the span of the structure by the relative value (I take its value from special tables according to the angle of inclination). For example, for a 30° slope, the value of the relative value is 0.59, at 25° - 0.47.
The hipped roof rafter is a system consisting of two types of truss trusses: typical trusses with slopes connected in the ridge, and side triangular rafters resting on the ridge at the top. Thus, at the end points of the ridge, three rafters are joined: one central and two from the main slopes.
Quite simply, you can calculate the central location of the hipped roof ridge in the center: measure the length of the ridge, the length of the walls parallel to which it will be located, and calculate their difference. Dividing the difference in half, postpone the result obtained from the edges of parallel walls.
It is important that a right angle is provided between the ridge and the slats, which automatically ensures that the corner ridges are correctly installed.
location of the skate in the center
The calculation of these parameters of the hip roof can be made easier if you first mark the joints of the walls and rafters. The attachment points of the side rafter triangles can be determined by dividing the length of the transverse wall in half.
Mounting a pitched roof: precision and strength
The installation of the roof begins with the installation of rafters and trusses, according to preliminary calculations and marks. Farms are assembled according to a template. Various additional elements help to achieve the rigidity of each of them, as well as the entire structure as a whole: headstocks, struts, crossbars, trusses with a rack, racks.
How to make a pitched roof won't be too hard if you follow finished project and follow the correct order of work performed.
Work begins with the laying of a block or log Mauerlat structure (in the case of timber rafters) - a more common option in private construction. If it is supposed to use metal rafters, the Mauerlat is made of metal profile material. Mauerlat is securely attached to the walls using appropriate anchors.
It is important that high-quality waterproofing is provided between the base and the wall.
If necessary, a transverse beam is also installed, which will become a support for the uprights and, accordingly, the ridge run attached to them. When installing the ridge, it is necessary to strictly maintain its “horizon” and height, therefore, when installing it, it is imperative to use a plumb line and a rail. Racks under the skate are fixed with jibs.
By installing diagonal rafters, the planes of the slopes of the future roof are formed. The main requirement in this case is the exact same length of the rafters and the perfectly flat plane of each slope obtained. At the same time, the size of the overhang is also laid. Its average value is about half a meter.
In open areas where a strong gusty side wind is possible, it is advisable to increase the size of the overhang (up to 1 m).
Particular attention is required to insert elements in complex nodes. Let's say that three elements are joined at once with the end of the ridge: diagonal rafters (2 pcs.), Central rafters (2 pcs.) And central (ordinary) hip rafters (1 pc.). To perform this knot, a special undercut (double bevel) is made on the ridge beam.
At a further stage, strictly parallel to the ordinary rafters, corner (spiders) are mounted. At the same time, the sprigs of the neighboring, main and hip, slopes must be joined to the rafters in different places. For the joints of the "diagonals" with the sprigs, an ordinary cut or a support beam is used, which is sewn to the diagonal rafters on both sides.
The installation of a hipped roof also includes the installation of a batten under roofing. Whether it will be solid or sparse from boards, bars or poles depends on the chosen material for the roof.
Many people like houses with hipped roofs. Despite the fact that they require the most materials, and therefore the most money, they are popular. Firstly, because they give even a simple “box” more interesting view. Secondly, because they are strong and reliable. And although the truss roof system is one of the most complex, it can be developed and made by hand.
Types of hipped roofs
Four-pitched roofs are the most expensive and difficult to construct. But, despite this, they were and remain popular. And all because they look more attractive than all other types of roofs, have high mechanical strength, and resist wind and snow loads well. A house with a hipped roof or even a gazebo looks “more solid” than with any other.
Even a simple "box" under a 4-pitched roof looks impressive
There are two main types of 4-pitched roofs: hip and hip. Hipped is suitable for square buildings, hip - for rectangular. In a hipped roof, all four slopes look like triangles and they all converge at one point - in the center of the square.
The classic hip roof has two slopes in the form of trapeziums that converge on the ridge. These slopes are located along the long side of the rectangle. The other two slopes are triangles that adjoin extreme points ridge beam.
For all that, there are four slopes in any case, the arrangement and calculation of these roofs are different. The assembly order is also different.
Half hip
The hip roof is much more common - after all, there are much more rectangular buildings than square ones. There are several other varieties of it. For example, half-hips - Danish and Dutch.
Half hip roofs - Danish and Dutch
They are good because they make it possible to install full-fledged windows in the vertical part of the side slopes. This allows you to use the under-roof space as a living space. Of course, compared to a full-fledged second floor, there is less living space, but the construction costs are also not so high.
The slope of the slopes and the height of the roof
The angle of inclination of a hipped roof is determined based on the snow and wind loads in your area. The higher the snow load, the higher the skate should be raised - so that the slope is steeper and the snow does not linger in large volumes. At strong winds, on the contrary, the skate is lowered lower - to reduce the area of \u200b\u200bthe slopes and, consequently, the wind load.
Even when choosing the angle of inclination of the roof slopes, they are guided by aesthetic and practical considerations. With aesthetics, everything is more or less clear - the building should look proportional. And it looks better with enough high roofs- 0.5-0.8 height of the first (or only) floor.
Practical considerations can be of two kinds. First, if the under-roof space is planned to be used as residential, pay attention to the area that will be comfortable for use. It is more or less comfortable in a room with a ceiling height of 1.9 m. And even then, this is for people of average height. If your height is higher than 175 cm, the bar will have to be raised.
On the other hand than great height will have a roof, the more materials will be required for its manufacture. And this is the second practical aspect that needs to be taken into account.
There is one more point that should be taken into account: roofing materials have a minimum and maximum slope angle with which this coating can “work”. If you have certain preferences for the type of roofing material, consider this factor. It depends on what height the truss system of the hipped roof should be raised (relative to the walls).
Hip roof truss system
If they make a hipped roof, most often it is a hip roof. Let's talk about her first. The central part of the truss system repeats the system one to one. The system can also be with layered or hanging rafters. Hanging rafters are installed "in place" - on the roof, two people are enough for such work. Rafter trusses, in the form of triangles, can be assembled on the ground, and then, ready, lifted and installed. In this case, there is less work at height, but in order to raise and install finished trusses, either equipment (crane) or a team of four or more people is needed.
The main differences between the rafter system of the hip roof are in those places where the rafters are shortened (truss half-legs) and the hip is formed - triangular slopes. Diagonal rafters are installed here, which are also called slanting. They rely on external internal corners buildings are longer than conventional rafter legs. Special attention should be paid to the diagonal rafters, since they have one and a half loads (when compared with neighboring rafters). Therefore, the corner rafter legs are made reinforced - they are assembled from two boards, splicing them in width with nails. Also, to support the diagonal rafter legs, additional racks and slopes are installed, which are called a trussed block.
Another truss system of a hip-type four-pitched roof is different in that the Mauerlat is laid around the perimeter of the building, and not just along the long sides of the box. This is understandable - the rafters are located along the perimeter, and not just on two sides, as in a gable roof.
Mauerlat- an element of the roofing system of the building. It is a bar or log laid on top around the perimeter outer wall. Serves as an extreme lower support for the rafters.
Diagonal rafters
As already mentioned, slanted (corner) rafters carry an increased load: from the shortened rafters of the side slopes and from the hips. In addition, the length of the diagonal hip roof rafters usually exceeds the standard length of lumber - it is more than 6 meters, so they are made spliced and doubled (paired). This solves two problems at once: we obtain a beam of the required length, we increase its bearing capacity. Two paired boards can withstand greater loads than a solid beam of the same section. And one more thing: spliced beams for rafters are made of the same material as ordinary rafter legs. It's cheaper, and you don't need to look for special material.
If spliced beams are used, diagonal rafters are usually insured by installing struts and / or trusses (racks).
- If the length of the beam is up to 7.5 m, one strut is enough, which abuts against the upper part of the beam.
- With a length of 7.5 m to 9 m, an additional rack or sprengel is installed. These supports are placed at the bottom, 1/4 of the length of the rafter.
- With a length of an inclined rafter of more than 9 meters, a third, intermediate support is needed - a stand that supports the middle of the run.
Sprengel- a special system that consists of a beam supported by two adjoining external walls. A rack rests on this beam, supported on both sides by slopes (the slopes are set if necessary).
A truss truss is usually not considered, but is made from the same materials as the truss system. For the beam itself 150 * 100 mm, racks - 100 * 100 mm, for cuttings - 50 * 100 mm. This can be a beam of a suitable section or spliced beams.
Supporting the sloping rafter leg
Diagonal sling legs with their upper end rest on a ridge beam. The exact execution of this node depends on the type of system and the number of runs.
If there is only one run, the consoles are made 10-15 cm longer than the sub-rafter frame. If such an issue is too large, then it is cut. But you shouldn’t make it shorter - growing it is much more difficult and expensive. The oblique diagonal legs will rest at this point.
The rafters are cut at the right angle, joined on the console. Fasten with nails. You can strengthen the connection with metal patch plates.
If there are two ridge spans (they are done if an attic-type living space is planned), the connection method depends on the material from which the rafters are made:
- If spliced boards are used, a truss is needed, which relies on the extensions of the ridge runs. Diagonal rafters are cut and rest on a trussed post.
- If a beam is used, a surf is installed in the place of support - a piece of board with a thickness of at least 50 mm. The board is fastened with nails to two runs, and to this board there are already rafter legs that will form a hip.
The lower part of the rafter legs is cut horizontally and attached to the Mauerlat or strapping board. For greater reliability of the assembly, you can install an additional oblique beam and fix the corner beam to it (in the figure below).
Fastening - nails on both sides, if necessary, can be additionally fixed with wire twists or clamps.
How to attach sprigs and semi-legs
To the installed diagonal rafter legs, on the one hand, shortened rafters of the side slopes (also called semi-legs) are attached, on the other hand - rafters - rafters that form a hip. They must be arranged in such a way that the joints do not coincide. Sometimes for this you have to change the distance between the outdoor rafters (better - in the direction of decreasing the step).
Usually shortened rafters are cut and fastened with 2-3 nails on both sides. This attachment is sufficient in most cases. But, if you want to do it “correctly”, you need to make a “cut” for each rafter - a recess no more than half the thickness of the beam. The rafters are cut, set to the desired position, the desired contour is circled on the beam (an uneven trapezoid is obtained due to different connection angles). A notch is cut out along the resulting contour, into which the half-leg is inserted, after which it is fastened with nails on both sides. This is a complex knot, and it takes a long time to do it. But the bearing capacity of such a connection is much higher. There is another option, which is much simpler in execution, but differs little in reliability.
The best way to fasten sprigs and semi-legs to the slanted beam can be considered to be their fastening on nails with the additional installation of cranial bars (see the figure above). For this, a beam with a section of 50 * 50 mm is used, which is nailed along the lower edge of the beam between the fixed rafters. In this embodiment, the beam becomes an I-beam, which greatly increases its elasticity, and the bearing capacity increases.
How to fix the lower ends of the rafters
The method of attaching the lower ends of the rafters depends on what type of truss roof system is chosen - with hanging or layered rafters, which particular scheme is used. System with sliding rafters(usually used for buildings that are contraindicated for expansion loads - wooden, frame, lightweight concrete) is implemented using special metal fasteners. They consist of two parts. One is installed on the mortgage board, the second - on the rafters. Between themselves, they are connected movably - with the help of a long slot or plate.
With such a device, when the load changes, the roof "wins back" - the rafters move relative to the walls. There are no spacer loads, the entire mass of the roof and precipitation is transferred vertically down to the walls. This fastening allows you to compensate for uneven loads that occur with a complex roof structure (with adjunctions in the form of the letter G or T).
A rigid mount can be made in different ways - with a cutout for a power plate / strapping board or with a hemmed support bar. Fastening is usually with nails, it can be reinforced with metal plates and corners.
A connection with a cutout is made if a hipped roof with an outlet - overhangs. Usually the overhangs are quite large and, in order not to buy long beams, they grow them - add boards that are nailed through to the bottom of the beams. This allows you to make overhangs as long as you want without a lot of overspending on materials.
Danish half hip roof
truss system Danish-type four-pitched roof differs from the classic hip roof. The difference in the design of the hip - here, at some distance from the ridge, a supporting board with a thickness of at least 5 cm is stuffed. Diagonal double rafters are attached to this board. How low to lower the base board is your choice. But, the lower the board is lowered, the smaller the angle this slope will have, and the worse the precipitation will go. With a large area of \u200b\u200ba half-hip, you will have to consider the load and select the thickness of the rafters.
But the low-lying support board allows you to put horizontal window sufficient area. This is beneficial if a residential area is located under a hip hipped roof.
So that the surf (a board connecting two opposite rafter legs) does not bend from downward loads, a shorty is installed - a segment of the same board, which is nailed to the stand supporting the ridge beam. The same stops are made on the edges of the surf, having well fixed the short ones with nails (the installation step is in a checkerboard pattern in 5-10 cm).
With such a device, it is necessary to strengthen the attachment points of the layered rafters, since the load from them is transferred to the extreme pair of rafter legs. There are two amplification methods:
- The extreme rafters are made double.
- Install struts from double boards. The lower part of the strut rests against a bed or rack. They are fastened with nails, the joints are reinforced by installing scraps of boards.
If the house has rectangular shape and the hip is not too wide, you can either install struts or make extreme rafters from double beams. Otherwise, the truss system of the Danish-type four-pitched roof is assembled in exactly the same way as described above.
Device 4 pitched hipped roof on the example of a gazebo
For a square gazebo 4.5 * 4.5 meters, they made a hipped roof covered with soft tiles. The slope angle is chosen "floor material", taking into account snow and wind loads - 30 °. Since the building is small, it was decided to do simple system(pictured below). The distance between the rafter legs is 2.25 m. With a rafter length of up to 3.5 m, a board of 40 * 200 mm is needed. A bar 90 * 140 mm was used for the strapping.
They assembled the truss system on the ground, fixed it on the support pillars, then installed a solid flooring from, after -.
First, we assembled the harness, which will be attached to the supporting pillars. Next, they installed rafters that rest on the middle of the strapping. The procedure here is as follows: in the middle we put a rack, on top of which the rafter legs will join. In this version, this rack is temporary, we only need it for a while - until we connect the first four rafters in the center. In other cases - for large houses - this rack can remain.
We take a board of the desired section, lean it against the rack in the place where they will be connected (depending on the desired angle of inclination). We note how it should be cut (above, at the junction and where it joins the harness). We cut off everything superfluous, try it on again, adjust if necessary. Further on this blank we make three more of the same.
Now the hipped roof truss system can begin to be assembled. Most questions arise about the junction of the rafter legs in the center. The best way - reliable and not too complicated - is to take a piece of timber of a suitable section, make an octagon out of it - for joining eight rafter legs (four corner and four central).
The size of the faces - according to the cross section of the cut of the rafter legs
Having fixed all four central elements of the truss system with nails, we perform the same operations with the corner rafters: we take one, try it on, cut it out, make three copies according to the template made, mount it.
By the same principle, we make semi-legs (shortened rafters). If desired, all connections can be further strengthened with corners or metal plates, then the truss roof system will be more reliable and you will not be afraid even in the heaviest snowfalls.
We put the assembled system on the racks of the gazebo, fasten it with nails, corners, and fix it with mowing. After that, you can mount the crate (in this case, solid) and lay the roofing material.
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