The last stage The construction of the building frame is the construction of the roof. IN square houses Most often, a hip roof is installed. This is currently a fairly popular design. The “tent” erected at the top of the building has its advantages and disadvantages. One of the positive aspects is that you can build a hip roof yourself, without the help of specialists.
Features of a hip roof
The design of a hip roof is a combination of several slopes of a triangular (less often trapezoidal) shape. Their number may vary depending on architectural features buildings. The most common are hipped hipped roofs, but building owners can build a roof with more slopes.
The architecture of the building determines the shape of the roof with six slopes
Historians claim that the hipped version of the roof appeared in ancient times. Hut buildings primitive man look like a tent. Roofs in the form of tents are found in archeology in Mesopotamia, where the ancient Sumerians lived. Such designs of the upper part of buildings were used in temples and other religious buildings in later historical periods.
The classic version of a hip roof is a pyramid with a square base. The support of the roof slopes goes mainly to the walls of the building, sometimes going beyond their boundaries. Overhangs can protrude beyond the building by 400–500 mm, thereby protecting the architectural structure from adverse effects weather.
Most often in individual construction they use the classic version of a hipped hipped roof Differences between hip and hip roofs
Another name hip roof- the roof is an envelope. This type is a type of hip roof. Envelope with rectangular base- the basis of the hip type of roof, and the square is more often used in the hip version.
The hip design is a combination of two slopes in the form of a trapezoid and two slopes in a triangular shape. Triangular slopes are connected in the tent roof.
Typical option hip roof consists of two triangular and two trapezoidal slopes If in hip roof If there is a ridge, then the hip roof is installed without this element. The tops of all slopes of the tent structure are connected at a single point. This occurs in the form of layering them on top of each other or attaching them to a separate support. There is no skate as such in this case.
Pros and cons of tent construction
- The main advantage of a tent roofing structure- its confident resistance to gusty winds. The aerodynamic “abilities” of the roof are manifested in the fact that air flows practically do not enter the attic part, they go down the triangular slopes.
- Another big advantage of a hip roof is the absence of gables. This is an excellent reason to save money, because much less construction and finishing materials will be needed for the roof.
- Many users of buildings with a hip roof note the rapid heating of the premises precisely thanks to this roof design. Rain and wastewater do not linger on the envelope of triangular slopes, but flow down. This extends the trouble-free service life of the roof.
But there are also negative aspects to the hip roof:
- Complex frame design.
- Small attic dimensions.
- Large amount of waste building materials because of design features roofs.
Hip roof design diagram
When calculating and constructing a hip roof, it is imperative to have basic information about its constituent elements.
To properly design a hip roof, you need to know all the basic elements of its design. The supporting part of the roof is the Mauerlat, placed around the perimeter of the building. It is attached to the walls of the building with outside. IN brick houses Mauerlat can be mounted with inside. Material for this element roofing system a beam with a large cross-section serves. Sloping rafters are designed to form a roof angle, and it is thanks to them that the pyramidal shape of the roof is obtained. The most difficult part of a hip roof design is the ridge assembly. In the ridge unit, together with the slanted rafters, the central rafters are connected, which regulate the height of each slope. Parallel to the central rafters, sprouts are installed. They are always shorter than the central rafters and are laid at a certain distance from each other.
Photo gallery: options for installing a hip roof
Combination different options hipped roofs give the house features medieval castle An external attic balcony can be incorporated into the design of a hipped roof. Hip roofs are often erected over permanent gazebos. The structure of a hipped roof can be supported by external pillars, forming a large canopy over the entrance. Complex broken roofs hip design require virtuoso performances and filigree performance techniques Garage square shape worth decorating with an elegant hip roof
Preparing for work
Before starting the construction of a hip roof, you should carefully study all available information about the construction of such a roof, prepare all materials and tools, having previously made calculations.
Calculation of materials
To make calculations, you need to acquire a special measuring rod. It can be built from plywood five centimeters wide. We will need the following parameters:
- length and width of the building;
- height of the ridge part.
The calculations themselves are not as complicated as they might seem at first glance:
All the necessary parameters of a hip roof can be calculated by referring to one of the online calculators that are easy to find on the Internet.
Required tools and materials
To install a hip roof, you should prepare the following tools:
- Bulgarian.
- Hand saw and gasoline saw.
- Jigsaw.
- Hammer.
- Plane.
- Electric drill.
For the construction of a hip roof, it is recommended to use only one type of wood. To fasten roofing elements, nails, dowels, steel brackets and self-tapping screws are required. You should also take care of the roofing material, the choice of which depends on the preferences of the developer and his financial capabilities.
We make our own hip roof
Despite the complexity of the hip roof design, it is quite possible to make this type of roof yourself.
The procedure for constructing a hip roof includes several sequential actions:
- Creating a hip roof project and carrying out all necessary calculations.
- Purchasing the required materials and preparing tools.
- Fastening the Mauerlat along the entire perimeter of the base of the building.
- Installation of a support beam for rafters parallel to the Mauerlat ( permissible distance 450 cm between them).
- Fastening diagonal elements, braces, struts to the base of the rafters.
- Roof insulation.
- Installation of the final roof and additional elements for drainage, ventilation, etc.
Carpentry professionals share tips that must be taken into account when building a hip roof:
- do not use wood of different species;
- do not assemble load-bearing roof elements from slats measuring less than 150 by 50 mm;
- do not attach short parts to the support post of the ridge part, they are fixed in the corners;
- Be sure to use intermediate rafter legs (in the center of the roof).
Step-by-step instructions for erecting a hip roof
Let's consider the construction of a hipped eight-slope roof on specific example. The roof will be designed for a building measuring 10 by 10 meters with a partition in the middle ( Basic structure).
- We install power plates. To do this, we use timber with a cross-section of 100*150 or 150*150 mm) and fastening with studs (thread more than M12).
The Mauerlat is laid around the perimeter of the building and attached to studs - We lay the floor and extension beams, moving from the center to the edges and maintaining the same distance between them (at least one meter or eighty centimeters).
- Using timber 150 by 150 mm, we mount the central support post in the ridge part of the roof. At the same time, be sure to check the verticality using a plumb line and a rod. We fix the rack using temporary jibs, which are dismantled after installing the central rafters.
Fastening devices for installing central and diagonal rafters are placed on the central support - Attach the four central rafters. These elements are “stitched together” metal corners or using nails.
- We install diagonal rafters, observing the required slope. If these elements are joined in two parts, then additional support is provided at the junction of the parts. To reduce the load on the beams, it is advisable to move the fasteners of such racks to the load-bearing walls.
- We lay and fasten ordinary rafters, the support is on the mauerlats and the support beam of the ridge part. The distance between the rafters is about 600 mm.
- We attach the flanges, trying to maintain parallelism between them and the rafters. If the roof is mounted with extensions, then we make supports under the extensions in this part of the roof.
Additional racks are used to secure and strengthen the structure in the places where the rigs are attached. - We make the sheathing using bars (50 by 50 mm) or boards 20–25 cm thick. Hemming of eaves overhangs is carried out at the final stage of construction of a hip roof
Video: we build a hip roof ourselves
After weighing all the positive and negative aspects of using a hip roof, you can decide to build it yourself. The main thing is to calculate everything and follow the clear instructions given by construction professionals.
Hip roofs are used both for low-rise residential buildings and for various outbuildings. Most often, they are built over buildings that have equilateral load-bearing walls and a square foundation plan. You can find such architectural elements above round structures, in this case the number of slopes is more than four.
The main difference between a hip roof is the complete absence of a ridge. This is very important detail rafter systems, it takes on the effort rafter legs. The function of this element is assigned to the central support, at the top of which the rafters converge. In this regard, great attention should be paid to its strength. There are options for rafter systems without a central support; the upper heels of the rafter legs rest against each other. Such options are most often used on small-sized buildings. All rays tent system have the shape of equilateral triangles.
A hip roof has many design options, but all must have the following elements.
Types of rafter systems, advantages and disadvantages of a hip roof
Table. The main types of hip rafter system.
Advantages of a hip rafter system
The disadvantages include the difficulty in manufacturing the rafter system. The hip roof has a large number of various nodes and elements, each of which can have Negative influence on sustainability indicators. Another drawback is the difficulty in converting attic spaces into residential ones; such variants of rafter systems are extremely rarely used for attics. Sometimes the increased consumption of roofing materials is considered a disadvantage, but this depends not so much on the features of the rafter system, but on the professionalism of the roofers.
Prices for timber
General tips for constructing hip roof rafter systems
Specific decisions are made by the master, taking into account the size and design features of the hip roof. But for all cases there are general recommendations, the implementation of which guarantees the stability of the structure.
Additional supports for sloped rafters
Top of the tent system
It is very complex from a technological point of view and the most critical from an architectural point of view. It has two solutions: the rafter legs rest on one support installed in the center of the building, or against each other. The first option provides maximum stability of the structure, but its installation requires a rigid support. The best option- in the middle of the building there is bearing wall. An acceptable option is during construction ceiling provided reinforced beams or lie down. When calculating the parameters, the maximum possible roof loads must be taken into account and a safety factor must be applied.
The use of connections only in the upper heels of slanted rafters without vertical support is used only on small structures. At the same time, a set of special construction measures is used to increase the rigidity of the structure.
Narozhniki
They can be fixed using special lower stops directly to the rafters or mixed way. Modern technologies allow you to fix the spigots without cutting, which not only strengthens the rafter system, but also significantly simplifies the work.
Structural solutions for a hip roof, especially without a central support, significantly increase the thrust loads on the mauerlat. This situation requires its strengthening; all nodes must be built according to accurate calculations and with unconditional compliance building codes.
And finally general recommendation– unless you have a serious practical experience construction of ordinary pitched rafter systems, then it is absolutely not worth taking on a hip roof. This is one of the most complex rafter systems; all its elements are so interconnected and interdependent that a violation of the stability of one becomes the reason for the complete destruction of the roof. Tent truss structure does not have completely identical elements; everyone must be approached individually.
Prices for construction boards
Construction boards
Calculation of a tent structure
First, let's look at the algorithm for calculating the basic values of the system. We take into account that the roof has four slopes, each of which is an equilateral triangle. The angle of inclination of the slopes is selected depending on the coverage area and the climatic zone of the object’s location. Taking into account the climatic zone, the minimum permissible angle of inclination of the slopes is selected in the tables of building codes and regulations.
The length of the central rafter depends on the angle of inclination and is determined by the well-known formula of a right triangle. First you need to find the length of the diagonal; this is done by calculation or ordinary measurement. The second method is simpler; use a tape measure to find this value.
We have the angle of inclination of the slopes, find the tangent on the Internet, multiply it by the length of half the leg and the result will be the height of the vertical support of the hip roof. Next, you should calculate the length of the sloped rafters. It is calculated using several formulas, the simplest of which is the Pythagorean theorem: c 2 =a 2 +b 2, Where:
c – rafter length;
a – half of the side of the structure;
b – height of the vertical support.
Hence, the length of the rafters is equal to square root the sum of squares of the indicated quantities. That's all, if it's difficult to do it yourself, then there are a large number of online calculators on the Internet. After entering the data, not only the dimensions of the system elements are displayed, but their number is also calculated.
In ancient times, our ancestors built their homes in the form of tents. Used for this natural materials: wood, stone, animal skins, etc. The modern tent house is a more fundamental structure. It has several varieties and is endowed with certain technical properties.
Ready-made house project with a hip roof
They can be of two types:
- Full-fledged, built in the form of a tent;
- Incomplete, when they are erected as an ordinary building, the roof structure of which is hipped.
The houses will differ in construction technologies and materials used in the work process.
Characteristics of full-fledged tent houses
Such buildings have. Quite often they can be found on summer cottages. Construction is economical, and the assembly of the structure itself is quite simple.
So, a tent house is based on a frame. The projects are quite varied. You can create them yourself or seek help from a professional architect.
Projects for tent houses are drawn up in a similar way to planning a roof structure of this type.
Only the load-bearing walls of the house, for which slopes will be used, are not taken into account.
Option for a house project with a hip roof Their shape can be with one or two slopes, with four, or 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-slope walls. The number of such slopes can be any.
But it’s worth considering that the functionality of such a house may decrease, since there will be a fairly large amount of limited space due to the construction of additional supporting frame elements.
The most functional and practical are houses with one, two and four slopes. Distributing space in them is much easier.
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 reduce them a little accordingly usable area Houses.
Hip roof design diagram There are several ways to operate a building. Firstly, you can use a tent house only in summer time. In this case, a large amount of money is not spent on its construction. Secondly, you can live in it all year round, which requires high-quality insulation and insulation works. Especially if houses with a hip roof are built from familiar building materials.
How to build a tent house
First, you need to select building designs, which are divided into foundation plans 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 begin 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 foundation for it. The following foundations are very popular:
Foundation designs are drawn up 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 production using concrete mortar and fittings. And the second is made using metal piles, which are also concreted in the ground at a certain depth.
Strip and tile foundations are constructed in most cases under wooden frame tent house, since the material itself does not have large mass.
- Determine the composition of the soil on the site;
- Establish the groundwater level;
- Define specifications terrain.
The last requirement is characterized by studying the terrain: are there any unevenness, slopes and other defects on the site. On such planes, only a pile or pile-strip foundation is preferred.
Construction 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 the case if the structure is light, and its period of operation is limited to the warm season.
First you need to draw up design plans. They will allow you to correctly calculate the amount necessary materials for the construction of the frame.
The elements are as follows:
- Bearing (support);
- Additional (supporting);
- Auxiliary (partitions between small cells).
In its principle, the design resembles the frame of a hip roof. All elements are connected with special fasteners, and a bedding made of roofing felt sheets is first constructed on the foundation.
Important. There should be pins and hooks on the surface of the base that 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
Firstly, the tent house must be properly lined. Secondly, do not forget about insulating and insulation works. When they are carried out, modern sheet materials such as polystyrene foam, polyurethane foam and polystyrene foam are used.
In rare cases, preference is given to mineral wool.
Important. This material is least often used in home insulation tent-type. This is due to the fact that over time it loses its properties and is able to absorb moisture.
Projects for cladding tent houses are quite varied. Today there are a lot of tools and materials to give appearance uniqueness of the structure.
Initially, they are mounted on the surface of the frame OSB sheets or thick plywood. Insulating or insulating material is already attached to them.
Cladding scheme frame house with hip roof A low sheathing is created on top of it, on which sheets of plywood or OSB are again mounted, prepared using primers. This will give you the opportunity to choose any Decoration Materials for cladding a building.
The following 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 install it without surface reinforcement. It is best to use stone to finish the lower part of houses.
The inside of a home may look different. For example, you can leave the walls of the building inclined or build profile frame, which will align them. It is fixed on the slope of the structure and on floor surface. You can already install OSB, plasterboard, and plywood on top.
Example of a frame house interior The surface of these materials is treated with a primer and finished with any modern materials. You can also pre-insulate and insulate the house using similar means from the outside.
The tent house is quite simple design. It must be airtight, since there is no roof in such a structure.
Construction of your house on personal plot or in the countryside makes us wonder about the shape of the roof. The hip roof (or hip roof in other words) is becoming increasingly popular. Its tent-like design has both advantages and disadvantages. In order to install such a roof, it is not necessary to call professionals. You can assemble the frame with your own hands. To do this, you need to be able to make calculations and have at least some idea of the design. The roof is attached in the same way as on other structures. To be sure, you can call a friend or neighbor.
1-Corner rafter. 2-Short rafters.3-Riding beam.
4-Central intermediate rafters. 5-Intermediate rafters.
The main advantage of the roof is its aerodynamics, which resists strong winds. Air currents go down the slopes without causing harm, without even entering attic space. Main disadvantage such - this is a complex frame, its installation and the fact that attic rooms small. The area is equal to the area of the ceiling, but the useful volume is very small. Hip roof design (in classic version) is a pyramid with a square (4 triangular slopes) or rectangular (2 triangular, 2 trapezoidal slopes) base. Both triangular slopes (hips) and trapezoidal ones either rest on the walls of the house or extend beyond them.
About inversion roofing.
Roof construction: basic rules
Subject to the following rules:
- When constructing the ridge system and rafters, the same type of wood is used.
- Intermediate boards have a steeper angle of inclination, and therefore their size must be at least 50x150 mm.
- The short members are attached to the rafter components located at the corners, rather than to the ridge board.
- The design uses intermediate (central) rafters, which must be secured to the ridge board.
- They must rest against the upper end of the harness and the ridge board. In order to do the installation yourself, you need to imagine the house and make a drawing.
- ridge (central part of the structure), which is the load-bearing axis;
- the power components of the rafter system are slanted rafters, one end of which protrudes beyond the building, and the other is fixed to the ridge;
- the central rafters are fixed at the ends of the ridge and extend to all the walls;
- intermediate rafters extend from the ridge and run along the slopes;
Hip roof: start of work
The installation of the hip roof should be done before installing the ceiling.
At the very beginning of work around the perimeter of the house (on top of the walls), we lay timber (wooden or metal beam) to distribute weight over the entire surface.
At the very beginning of work, we lay a beam (wooden or metal beam) around the perimeter of the house (on top of the walls) to distribute the weight over the entire surface. It's called Mauerlat. We attach it to the wall of the house with special studs. Then we proceed as follows:
- first we mark the axis (from the end of the house along the top frame);
- calculate 1/2 thickness ridge beam and mark the installation location of the first element of the rafter system;
- after this, the measuring rod (one end) is applied to the marked line and the place of the intermediate rafter is marked;
- in order to calculate the overhang of the rafters, we place one end of the beam on and the other on external corner walls;
- the location of other elements of the central rafters is calculated by moving the slats along the side wall and marking the dislocation of each rafter;
- at the other three corners the actions are repeated.
Calculation of roof elements
To calculate, you will need a measuring rod. It is made of simple plywood and is 5 cm wide. There is also a special table of relationships between and their length. Based on the data given in the table, the leg length of each rafter is the product of the coefficient (intermediate or angular) of its projection.
To increase the accuracy and reliability of calculations, be sure to make calculations using this table.
To increase the accuracy and reliability of calculations, be sure to perform calculations using this table.
Calculation example
Using a batten we measure the projection (horizontal) of the intermediate rafter. Using this table, we find the angle of inclination that suits our case and multiply the data.
The calculation of the overhang length of the rafters is carried out in the same way. We multiply the projection (horizontal) by a coefficient. You can also calculate these data using the Pythagorean theorem for a right triangle: a2+b2=c2. In this case, a and b are horizontal and vertical projections.
Corner (oblique) elements. On one side, all rafters have an oblique cut, which is needed for attachment to the ridge beam. The ridge itself has an undercut with a double bevel (for reliable fixation of parts in the corners of the house). The rafter (corner) calculation is carried out as follows:
- measure the full from the corner;
- its projection is the product of the squares of the lengths of the projections of the rafters (central).
We multiply this number by a coefficient (according to the table) and find out the length of the corner rafter.
Then we begin to calculate the area of the triangular slopes (hips). It is calculated using the Pythagorean theorem. To make calculations easier, we represent the slope in the form of two right triangles. After this, we calculate the area of the trapezoid of the side surface of the roof using the formula. In the end . The data of all areas is summed up, and the minimum area (or footage) of the roof is displayed.
Frame: DIY installation
Strengthening the roof directly depends on the dimensions of the building. An additional truss (beam between adjacent sides) is installed.
First, we install the verticals for the ridge beam (for pyramidal roof one rack in the middle is enough). Then we begin the installation of diagonal rafters (equal in length). After this, they begin to install sloped, and then ordinary (in increments of 60 cm) rafters, which are attached using a notch to the ridge and the mauerlat. The cutting can be done either with your own hands or with a power tool. Next, we attach the splices to the diagonal guides to connect the Mauerlat and mowing beams (at an angle of 90 degrees relative to the ridge).
Remember! Ordinary beams should not touch the mounting points of the Mauerlat.
Strengthening the roof directly depends on the dimensions of the building. An additional truss (beam between adjacent sides) is installed. A stand or truss truss is mounted on it. If the building area is very large, then double beams are used for the diagonals.
Tools and materials
You will need the following tools and materials:
- saw or chainsaw;
- grinder or jigsaw;
- hammer, nails, dowels;
- plane or jointer;
- axe;
- drill, electric drill;
- beams and boards (preferably from the same type of wood);
- roofing material;
- special steel brackets. You can make them yourself from a rod (8-10 mm), bending the ends and sharpening them.
In this way, you can build hip roofs in the form of a regular pyramid, elongated to one side, or a truncated pyramid.
A hip roof can be one- or two-level, have four or more slopes. For the right choice sections of its elements, it is necessary to perform a sketch and a correct calculation, which comes down to several formulas. In the article we will talk about the design of a hip roof and the method for calculating its rafter system.
A hip roof is one of the most common options when building a house or gazebo that has a circular, square or rectangular plan with a slight difference in the lengths of the sides. This design is good decision for houses relatively Not large area or two-story cottages with a small base. The roof got its name because of the pyramidal shape of the traditional eastern tent, formed by one peak and triangular slopes.
Hip roof options
The name “hipped roof” combines several roofing options that have structural differences.
A single-level hip roof is geometrically a tetrahedral pyramid. A two-level roof is more complex design: the upper part is a pyramid, the middle part is a cube or parallelogram, the lower part is truncated pyramid. It was as if the top of the roof had been cut off from the base and lifted up. The middle part is sometimes made in the form of a glass lantern or finished in the color of the walls.
A hip roof can have not only four slopes, but also six or eight slopes. This shape is more reminiscent of a cone than a pyramid, and is most common when building gazebos with a round base. The most difficult thing in implementing such a design is connecting the rafters in the center.
The rafter systems differ not so much aesthetically as structurally:
- hanging;
- layered.
A hanging rafter system rests solely on the walls of the house, while a suspended rafter system has a support located in the center of the building and rests on a load-bearing wall or on a pillar specially erected inside the house.
a - design of hanging rafters; b - design of layered rafters; 1 - rafter; 2 - crossbar; 3 - tightening; 4 - stand; 5 - strut; 6 - run; 7 - lying down
The choice of design depends on the size of the span (8 m is suitable hanging system, 12 m - layered is required) and maximum length timber for construction (when connecting a rafter leg in length, installation of a vertical support is required).
In practice, a layered system is often used as it is more reliable and maintainable. If the house does not have a suitable load-bearing wall or pillar for support, the base can be created from timber by bandaging at the level of the mauerlat.
Basic diagrams and elements of the rafter system
As we wrote, a hipped roof is geometrically a pyramid, so all calculations are carried out based on the rules that apply to the pyramids and triangles that make it up.
Essential elements
In order not to be confused in the future with terms, we will name the main elements of the rafter system of a hipped roof, schematically shown in the figure below, and tie them to the geometric image of a hipped roof in the form of a pyramid.
Design with hanging rafters
- Mauerlat. The foundation and support of a roof, especially in a structure with hanging rafters. It is located along the perimeter of the building (ABCD), rests on the walls or is attached to their outside. To construct the Mauerlat, large cross-section timber is used.
- Sloping rafters. Roof angles that converge at a central point and form a pyramid. On the pyramid diagram (without taking into account overhangs): AK = DK = CK = BK = Lн. The longest rafter legs in the structure.
- Ridge knot (K). Most complex knot in a design for a carpenter. If the base of the house is not square, and the ridge forms an edge, the hip roof is transformed into its “sister” - a ridge roof. In a structure with layered rafters, section KF (H) is the central support.
- Central rafters. They converge at the ridge unit with slanted rafters. They are the height of each slope, which is an isosceles triangle. On the diagram of the pyramid (without taking into account the overhangs) there is a segment KE, length Lt.
- Narozhniki. These are shortened rafters running parallel to the central one in both directions.
Now consider structures with layered rafters.
Transomless design with layered rafters
Along with the already designated elements: slanted (1) and central (2) rafters, as well as the ridge (3), new elements appear. The central support (stand) or headstock (4), which rests on the ties (5) connecting the mauerlat diagonally. This is an option for making a rack that rests not on the masonry, but on an element of the rafter system.
In the absence of central rafters and to strengthen the ridge assembly with the headstock (2), it is supplemented by crossbars (3), connecting oppositely placed sloping rafters (1) in pairs (see figure above).
Reinforcement elements
For greater strength and rigidity of the structure, especially in a climate prone to strong winds, or with a large building area, and therefore a large length of rafter legs, the main structural elements are supplemented with reinforcement elements.
Option to strengthen the truss structure
Along the axis of the building, a additional beam- lying down (2). The basis of the structure, as before, is made up of central (4), shortened (springs) (5) and slanted (3) rafters. The slanted rafters are reinforced by cranial bars (6), fixed at the bottom. This is a reinforcement for both the mowed legs and the riggers leaning on them. The ties (7) fasten the oppositely located rafters and serve as a base for installing the racks (8). They are fixed on top of the Mauerlat and on top of the bench and rest on them.
For particularly long rafter legs, struts are used - supports that are not located vertically, but at an angle of 45-60°. In practice, struts are installed when the length of the wall is more than 9 m (for a gable or four-pitch wall).
The system of strengthening the main elements also helps to save lumber. The cross-section of the main elements in such a design can be taken to be reduced. Another way to save is the formation of overhangs by adding rafters ending on the mauerlat with fillets - bars or boards of a smaller cross-section.
Calculation of the rafter system of a hip roof
The calculation is based on the following initial data:
- length of the house;
- width of the house
- ridge height.
Let's consider the procedure and formulas for calculations using a conditional example, using the geometric image of a hip roof (see above):
- house length: AB = DC = 9 m;
- house width: AD = BC = 8 m;
- height of the ridge located in the geometric center of the roof: KF = 2 m.
Calculation of the lengths of rafter elements
1. Length of beams Mauerlat.
- AB + DC + AD + BC = 9 + 8 + 9 + 8 = 34 m
2. Central rafters(excluding overhangs). They are the hypotenuse of a right triangle, in which one leg is the height of the ridge, and the second is half the width (8/2 = 4 m) or length (9/2 = 4.5 m) of the house.
Let's remember the Pythagorean theorem:
3. Sloping rafters(excluding overhangs). They are the hypotenuse of a right triangle, in which one leg is half the width or length of the house, and the second is the corresponding central rafter. For a roof with a ridge in the geometric center of the roof, the lengths of the slanted rafters are the same.
4. Narozhniki. The shortened rafters are located parallel to the central one, with a pitch depending on the length of the rafters. Let's consider a table compiled taking into account weather loads for the Moscow region.
Table 1. Data correspond to atmospheric loads in the Moscow region
| Rafter spacing, cm | Rafter length, m | ||||||
| 3,0 | 3,5 | 4,0 | 4,5 | 5,0 | 5,5 | 6,0 | |
| 215 | 100x150 | 100x175 | 100x200 | 100x200 | 100x250 | 100x250 | — |
| 175 | 75x150 | 75x200 | 75x200 | 100x200 | 100x200 | 100x200 | 100x250 |
| 140 | 75x125 | 75x125 | 75x200 | 75x200 | 75x200 | 100x200 | 100x200 |
| 110 | 75x150 | 75x150 | 75x175 | 75x175 | 75x200 | 75x200 | 100x200 |
| 90 | 50x150 | 50x175 | 50x200 | 75x175 | 75x175 | 75x200 | 75x200 |
| 60 | 40x150 | 40x175 | 50x150 | 50x150 | 50x175 | 50x200 | 50x200 |
Our center rafters are 4.472 m long and 4.924 m long. The rafters will be shorter, so you can look at the column - 3.5 m.
To calculate the lengths of narozhniks, let’s remember school and use the properties of similar triangles.
If in the figure AB is the central rafter, then MN is the frame, AC is half the length of the wall (4.0 and 4.5 m, respectively), AM is the step depending on the number of frames. MC for each narozhnik is calculated separately.
- MN = (AB · MC) / AC
We will calculate the options for choosing the most economical arrangement of shortened rafters, the results of which will be summarized in a table.
Table 2. Calculation of lumber for frames
| Pride step, cm | Beam cross-section, mm | Long side bars: AC = 4.5 m, AB = 4.472 m | Short side spigots: AC = 4.0 m, AB = 4.9242 m | ||||||
| quantity per half slope | AM, m | length in half slope, m | quantity per half slope | AM, m | length in half slope, m | volume of lumber for two slopes, m3 | |||
| 215 | 100x175 | 1 | 2,25 | 2,356 | 0,165 | 1 | 2,0 | 2,461 | 0,172 |
| 175 | 75x200 | 2 | 1,5 | 2,981 + 1,491 | 0,268 | 1 | 2,0 | 2,461 | 0,148 |
| 140 | 75x175 | 2 | 1,5 | 2,981 + 1,491 | 0,235 | 2 | 1,333 | 3,282 + 1,641 | 0,258 |
| 110 | 75x150 | 3 | 1,125 | 3,354 + 2,236 + 1,118 | 0,302 | 3 | 1,0 | 3,693 + 2,462 + 1,231 | 0,332 |
| 90 | 50x175 | 4 | 0,9 | 3,578 + 2,683 + 1,789 + 0,894 | 0,313 | 3 | 1,0 | 3,693 + 2,462 + 1,231 | 0,259 |
| 60 | 40x175 | 6 | 0,643 | 3,834 + 3,195 + 2,556 + 1,917 + 1,278 + 0,639 | 0,376 | 6 | 0,571 | 4,218 + 3,515 + 2,812 + 2,109 + 1,406 + 0,703 | 0,413 |
Obviously, for our example, options with with long steps. However, fastening requirements should also be taken into account roofing material and sheathing costs. From this point of view, the answer will not be so obvious.
Calculation of roof area taking into account overhangs
Since the previous calculation was made without taking into account the eaves overhang, which in our example is performed using fillies, we will consider this part of the roof again as a simple geometric figure.
Let us take the length of the overhang (DC) to be 0.5 m. To determine the area of the slope, we again use knowledge about the properties of similar triangles:
- EF / BC = AG / AD
BC - 8 and 9 m for short and long walls respectively.
AD - 4.924 and 4.472 m for short and long walls, respectively.
AG - 4.924 + 0.5 = 5.424 m and 4.472 + 0.5 = 4.972 m for the short and long walls, respectively.
- EF = (AG ∙ BC) / AD
- EF = (5.424 ∙ 8) / 4.924 = 8.812 m - for the short side
- EF = (4.972 ∙ 9) / 4.472 = 10.006 m - for the long side
The area of the slope is calculated using the formula:
- S = (EF ∙ AG) / 2
- S = (8.812 ∙ 5.424) / 2 = 23.9 m 2 - for the short side
- S = (10.006 ∙ 4.972) / 2 = 24.88 m 2 - for the long side
Total area of roofing material:
- 2 (23.9 + 24.88) = 97.56 m2.
Advice! When calculating the material, take into account the cutting, especially if it is sheet material, like slate or corrugated board.
Attention! The article discusses the calculation of only the main elements of the rafter system, which can help in drawing up a preliminary construction budget.