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Calculation of plywood for a hip roof. Calculation of the hip roof of a hip roof with a drawing. Mansard roof design

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Hip roofs belong to the category of complex structures. Like any architectural element, they have their own strengths and weak sides. In some regions of our country, such species are traditionally given preference; they are found most often.

It is impossible to make a correct calculation without understanding the subject itself. Each element plays very important role, any mistakes are extremely Negative influence on general indicators strength and stability of the system. Even small miscalculations can cause emergency situations. What parts does a hip roof consist of?

Table. Components hip roof

When choosing a hip roof, you need to know about its advantages and disadvantages.

Design advantages:

• during construction there is no need to take into account the direction of the prevailing winds, the roof has completely identical windage parameters on all sides;
• The roof is rigid and can withstand significant snow and wind loads. Usage special elements makes it possible to cover houses with a large area;
• has no pediments, which somewhat facilitates and reduces the volume of masonry work.

Flaws:

• requires a lot of lumber, this increases the estimated cost of the structure;
• technological complexity. The process of erecting a hip roof has many individual nuances; such work can only be performed by very qualified builders;
• a large amount of unproductive waste of roofing materials. This is especially true for metal roofs - pieces cut off at angles have to be thrown away.

General algorithm for the functioning of the calculator

There are many different calculators on the Internet, but they all work in the same way and use the same formulas. None of them can change the mathematical principles of calculations; the program includes generally accepted norms and formulas. At the output, users receive the parameters and number of rafters, including those located diagonally. Calculate the length of the ridge and the volume of lumber for. If desired, you can calculate the number of roofing materials depending on their type, the footage of waterproofing materials, etc. The user must enter the initial data one by one, and the recommended dimensions should be used.

What formulas does the calculator use? Let's list just a few of them.

A fairly popular type of roof is. This variety is classified as hipped structures.

For slate, an example calculation is as follows:

1. Typically, seven sheets of corrugated slate are used for covering, the useful area of ​​which is 1.335 m2.
2. If 8 sheets of such material are used, then the usable area is 1.56 m2.
3. Next, the value of the total roof area is divided by the value of the usable area of ​​the material. If the roof area is, for example, 26.7 m2, then the number of slate sheets required for roofing is 20 pieces.

Calculation example for metal tiles:

1. When choosing a similar material for coating, it is worth knowing that the smaller the size of the material, the larger the size of the joints must be used.
2. Initially, the value of the total area is multiplied by a correction factor equal to 1.1.
3. After this, the resulting area value is divided by usable area tiles, depending on its size and, accordingly, the size of the overlaps.

If the roof covering structure is combined and complex, then the cost overrun can reach 60%.

Roof calculator

Rafter pitch

The distance that forms between two rafters is called the pitch. Most of structures are made in such a way that the step is 1 m. Installed and minimal permissible value this parameter is equal to 60 cm.

The process of calculating the distance between the rafters is as follows:

1. Initially, you need to select the approximate expected pitch of the rafter system. You can build on the above values, i.e. the distance is 1 m.
2. The next value you will need is the length of the ridge.
3. After this, the length of the rafter is divided by the approximately selected pitch value. The resulting result is rounded up and then increased by 1.
4. The last thing in the calculation is dividing the total length of the slope by the value from the previous paragraph. This will be the required distance that must be maintained during the installation process.

Using an example, we can consider the design, the length of the slope is 12 m, and the approximately selected step distance is 0.8 m:

1. 12 / 0.8 = 15. If the number in the calculation is not an integer, then it should be rounded to the nearest integer value.
2. 15 + 1 = 16. Increase by one for more accurate calculations of the number of legs in the structure.
3. 12 / 16 = 0.75 m. This value will be optimal distance step for the rafter structure.

Rafter pitch

Selecting the roof slope angle and determining the height of the ridge

As in previous calculations, the process of determining the height of the ridge depends on the selected slope angle. Despite the fact that the hip roof structure allows you to build slopes with different angles, it is best to make a structure with the same angles.

This will allow the load to be distributed evenly and the roof to have an aesthetically pleasing appearance.

ATTENTION!

The angle of inclination relative to the hip version of the structure varies between 20 and 45 degrees.

A more specific definition of such a parameter is influenced by:

1. The factor of increased snow load suggests the construction of a structure with a steeper slope.
2. If the wind in the area where the house is located is strong and gusty, then it is recommended to make the slope no more than 30 degrees.
3. The intention is to use the attic space as a living space. In this case, the ease of movement around the attic and the ability to provide all communication structures in such a way that they can be easily accessed if necessary are taken into account.
4. The coating chosen for the roof also plays an important role. When choosing a specific material, you need to inquire about the minimum permitted characteristics regarding the angle of the slope.

Regarding the height of the ridge, it is very simple to determine it, knowing the value of the angle of the slope. In the design, it is necessary to conditionally select a right triangle, in which one of the sides will be the desired height.

Formula: h = b / 2 * tanA.

Roof angle

Conclusion

The stage of designing a house and all its structural elements is quite complex and painstaking. It is very important to carefully carry out all calculations and double-check them each time. This task can be made easier visual image on a smaller scale of the entire future structure.

In contact with

Planning the future appearance of the roof of a house almost always comes down to the problem of checking the designed rafter system for strength, rigidity and stability. Very beautiful and elegant on paper, hipped, hipped, broken, hip and half-hip structures in practice require the developer to have knowledge and understanding of how to calculate a hip roof in the most understandable and in an accessible way. The more complex and intricate the arrangement roof structure, the more difficult it is to calculate its characteristics and obtain reliable results.

What does it mean to correctly calculate a roof?

There are several basic methods that allow you to calculate the hip roof of a house with a relatively small error. All of them are widely used in everyday design and have been tested many times in practice. For a private non-professional developer, three methods can be used to calculate the parameters of the roof, having knowledge within the school mathematics course:

• The tabular calculation method is the most beloved and widely used in the design of hip and any other standard roofing schemes. It allows you to calculate the main parameters of the roof structure using tabular data compiled in reference books and manuals;
• Calculate parameters based on trigonometric formulas and the simplest model hip roof. By graphically constructing and drawing the future hip structure on an enlarged scale, you can obtain all the necessary information about the roof parameters by simple measurement;
• Use of ready-made programs and online calculators. It is almost impossible to do a similar amount of work manually, to calculate the strength and geometry of the roof without basic education and preparation in another way.

There are a great many specialized programs, and often choosing the right software package today is much more difficult than calculating the geometry of a hip roof using it.

For your information! Full-fledged software systems are highly customizable and allow you to calculate the most complex options, for example, to calculate a hip roof with a bay window.

As with any other program, when working with ASPSK you need to understand the essence of the calculations, and, if necessary, be able to perform a test calculation of the angle of a hip roof using school trigonometric formulas. Today, almost everything is more or less complex calculations are performed using only three basic techniques. Even experienced and self-confident design engineers and architects prefer to carry out calculations of a hipped hip roof with mandatory double-checking, as they say, “on paper.”

What is a hip roof and why do you need to calculate it?

The hip scheme is currently used in 90 cases out of 100 in the construction of new and renovation of old houses. A hipped or half-hipped roof has a number of advantages:

• The design turns out to be quite compact, with good resistance to horizontal wind loads, pressure from rainwater and snow layers;
• The hip roofing scheme makes it possible to minimize heat loss through the roofing covering and eliminate the flow of water through the gables, which often affects gable roofing schemes;
• Weight rafter frame And roofing material The hip roof is smaller than that of traditional gable structures, but the cost of assembly and arrangement work is much higher.

If you calculate the roof according to all the rules, the cost of arranging the roof will only slightly exceed traditional lean-to and gable structures. As a result, by spending some resources on calculating the optimal parameters of a hip roof, you can optimize costs as much as possible, and at the same time obtain the strongest, warmest and most durable roofing structure.

Features of the use of various methods for calculating a hip roof

In addition to the strength and stability of the structure, important information is the consumption of materials, especially expensive ones, long timber and logs, insulation and roofing. Before calculating the selected option for the stiffness and deflection of the rafter beams, a preliminary selection and calculation of the angle of the hip roof is performed. This parameter depends on:

• Selection of the height of the ridge and the nature of the roofing material planned for use in the hip roof structure;
• Based on the angle and roofing material, you can calculate the area of ​​the hip roof and the size of the load-bearing elements.

Knowing the parameters of the roof and rafter frame elements, it will not be difficult to calculate total weight hip design and cost of materials. You can calculate the cost of constructing a roof and the amount of pressure on the walls and foundation of the building.

The simplest calculation of hip roof geometry

For preliminary calculation For the hip roof frame, you can use the simplified model shown in the figure below.

As initial parameters we take the dimensions of the base of the roof or building frame. Before calculating the area of ​​the hip roof, it is necessary to resolve the issue of the angle of inclination. Usually the customer offers several options for roofing, each of them has its own optimal angle tilt The second factor that you need to know in order to correctly calculate the load-bearing capacity of the roof is the maximum thickness and weight of the snow cover. For higher latitudes, the angle of the hip roof is chosen to be at least 30° and even 45°, which makes it possible not to take into account the pressure of the snow mass on the rafters.

Important! A simplified hip roof model can be used to calculate any hip structure. For example, to calculate the area of ​​a classic roof with two short hips and two elongated hip slopes, it is enough to add to the area hip roof the size of the surface of the rectangles of the slopes formed by the ridge beam and the long ordinary rafter leg.

After choosing the angle, you need to calculate the ridge of the hip roof; this is not difficult to do, using the sine or tangent formula right triangle. Using trigonometric formulas, you can calculate the length of ordinary and corner rafters, but in practice, most often the dimensions of individual elements of the rafter frame are simply recalculated using coefficients from tables. Knowing the angle of inclination and the length of the ordinary rafters, you can calculate the angular and intermediate values.

After they became known preliminary values sizes of the ridge, layered and ordinary rafters, it is necessary to draw up exact drawing hip roof, on which you can graphically calculate and more accurately measure the resulting details of additional power elements. This method was used to calculate the wooden skeletons of ships, bridges, and complex structures of buildings made of stone and wood for several centuries, until modern mathematical methods appeared.

If you use a small enough scale, about 1:7 or 1:10, you can graphical method calculate absolutely all the details of the hip roof on the finished drawing. Oddly enough, the accuracy of such a calculation is only slightly higher than the standard value accepted for ordinary engineering calculations. Moreover, when drawing up details and calculating the dimensions of workpieces for specific parts, for example, for rafter beams or struts, the length and cross-section are selected with the required allowance for cutting or grinding the surface of the beam.

Only after drawing a draft design drawing can you begin to carry out the most important stage - carrying out calculations for strength and rigidity, or most often - the maximum deflection of rafters, ridge beams, overhangs and other structural elements. The easiest way to calculate roof parameters is to use a ready-made program.

Method for calculating a hip roof using programs

In the simplest case, you can check and calculate preliminary information and characteristics of a hip roof using online calculator. Companies providing online software packages use ready-made modules that contain the basic requirements building codes and the rules “Loads and Impacts”, as well as the defining provisions of TKP 45-5.05-146-2009. True, only the simplest version of a hip roof can calculate such a calculator.

For the calculation, you will need to enter only a limited set of basic information about the roof structure:

• Dimensions of the base or roof plate;
• The angle of inclination of the slopes;
• Length of end and side overhangs;
• Materials for the manufacture of load-bearing elements and roofing;
• Step of rafter legs and sheathing;
• Wind and snow load data for a specific region.

At the output of the calculator, the program produces a fairly large amount of information. First of all, the compliance of the specified angle of inclination of the rafters with the selected material for the roofing is checked. The second point the program will try to calculate the roof area taking into account overhangs and the total load on rafter system at specified angles of inclination of the hip and side slopes, separately for clean roofing material and separately under the maximum layer of snow.

At the second stage, the parameters of the rafter system are given:

• Length of hip, corner and row rafters;
• The number of rafter legs on each part of the hip roof;
• The total weight of the rafter frame and the recommended cross-section for each rafter.

As a result of the program, you can additionally find out the volume of lumber and the area of ​​the roofing. The data obtained allows you to calculate the costs and cost of materials for the manufacture of the roof. Some calculators provide several calculation options, but most often you have to calculate the cheapest and most durable option yourself. On average, to obtain the most optimal slope pattern and rafter sizes, you have to work at least 30-35 various options. 10-12% is usually added to the cost for costs associated with preparation for construction and delivery to the construction site.

Conclusion

A significant drawback of such calculators is the simplified scheme by which the parameters of a hip roof have to be calculated. Simple online program does not answer the main question - how stable and rigid the frame will be, and what will be the maximum deflection of the rafters and sheathing under the most unfavorable loading conditions. Therefore, complex options for roofing structures are best calculated using specialized software systems ASPSK.

Hip-slope roofing structures not only have a spectacular and attractive appearance, but also have many other advantages. However, the calculation of hipped roofs and their elements, as well as their installation, is a technically complex matter and cannot be carried out without careful familiarization with the features of this process.

Types of hipped roofs

Roofs with four roof slopes have quite a few varieties, the most common of which are the following:

• hip;
• tent;
• half-hip;
• broken

There are other options for hipped roofs, but they are much less common.

Hip roofs have two triangular end and two trapezoidal slopes. The end slopes are called hips and extend from the ridge at the top to the cornice at the bottom. Similar design makes a roof like this the best option for rapid removal of precipitation from it. At the same time, due to technological features buildings, calculation of a hipped hip roof and installation work according to its installation are the most difficult to perform.

The slopes of hip roofs are four triangles with equal sides. The bases of these triangular slopes form a square. Area calculation hipped roof This type is also technically quite complex, although somewhat simpler compared to the previous version. Such roofs are often made on gazebos. Before you make a hipped roof for a gazebo, you need to make careful calculations.

Another type of hip roof is also quite widespread - half-hip roofs. They are a cross between hip and regular gable roof. You need to know how to calculate a half-hip roof correctly. A design feature of such roofs is the absence sharp corners, and their pediment is made in the shape of a trapezoid. Knowing how to calculate the area of ​​the pediment, you can immediately order material for cladding the pediment. The functional advantage of half-hip roofs is their high stability to strong wind loads. Design and installation work here may have some peculiarities, and if we talk about how to correctly calculate a hipped roof of this type, then the weather conditions of the area should be taken into account. Where there is frequent snowfall, steeper slopes and small canopies are installed, and in less snowy regions, the opposite is true.

Broken hipped roofs are also quite common. Their peculiarity is that geometrically their end sections represent a broken line, which is where the name comes from. The advantage of sloping hipped roofs is that they have an attractive appearance and make it possible to make the most efficient use of living space. Of no small importance is the fact that such roofs have a relatively simple rafter system. At the same time, the question of how to calculate the area of ​​a broken-type hipped roof is quite complex, and is usually done by construction professionals.

In general, the calculation of hipped roofs of any type, and accordingly their installation, is not an easy task, requiring a certain skill and experience in the field of construction work.

Design Features

Due to the inclined position of the pitched surfaces, the design of a hipped roof differs significantly in shape from a rectangular one. It is the non-standard shape that primarily determines the main difficulties in calculations and during the installation process, in particular in how to calculate the area of ​​a hipped roof of a house, calculate the required number of certain elements, how to connect the structural parts of the roof together, how to calculate the volume of a hipped roof roofs, etc.

Roofs with four slopes, depending on the type, may have a different structure and constituent elements. However general principles their devices are largely identical, and they can be considered using the example of hip roofs - as the most typical version of hipped roofs.

When considering the structure of the central part of the hip roof, you can notice the similarity with the usual gable roof. The process of arranging the central part of such roofs also has much in common. Most often, layered rafter systems are used here; hanging rafter structures are used somewhat less frequently. When arranging the layered variety of rafters, they are supported on a ridge purlin located at the top of the roof, which, in turn, is installed on a purlin frame. The frame for installing the ridge girder consists of racks and a horizontally located bed. Very important point is its support on a solid foundation, which can serve as a load-bearing wall in the center of the structure being built. Sometimes in rafter systems of complex hip roofs there is not one central purlin, but two parallel beams.

If location load-bearing walls does not allow them to be used as a support for the purlin frame, then for this purpose a powerful ceiling is installed, for example from concrete slabs. The strength of the floor must be sufficient to withstand the weight of the rafter system, all components of the roof covering and the resulting external loads.

The reliability of concrete slabs is usually large enough to withstand the load from a roofing system of any type and weight. Therefore, the question of how to calculate a hipped roof in terms of weight indicators in this case does not have of great importance. It is only important to correctly make all other measurements, and then carry out the installation process in accordance with them.

Sometimes instead of concrete slabs for arrangement supporting structures an overlap of wooden beams. Naturally, this method is noticeably inferior in strength to the previous option. The purlin frame is installed on a thick beam measuring 100-150 by 200 millimeters. The ridge purlin itself is made from a similar material, as well as the bench, if there is a need to use it. The stands are laid under the racks of the purlin frame crosswise with the floor beams. Stands, struts and wind braces are made of timber measuring 100 by 150 millimeters.

The complexity of the design of a hipped roof makes it difficult to arrange supports for pitched surfaces. To this end corner areas connected to the ridge girder by means of diagonal rafter beams (sloping rafter legs). These beams are longer than usual and should have greater strength, since the shortened rafters of pitched structures rest against them.

Installation work becomes even more complicated if a hip roof with additional extensions. In this case, the question of how to calculate the quadrature of a hipped roof and its other parameters is a difficult task, for the solution of which complex design The roof is conventionally divided into several simple sections, and then for each of them calculations are made separately.

The main stages of installation of a hip roof rafter system

The process of constructing a rafter system for a hip roof consists of the following sequential steps:

1. Installation of the frame for the ridge girder.
2. Installation of first the layered and then the central parts of the rafter structure.
3. Marking with a cord or rope the directions for installing diagonal beams.
4. Installation of diagonal rafter legs in accordance with the markings made.
5. Installation of shortened rafter legs - spigots - resting on the diagonal rafters.
6. Sheathing with wind boards around the perimeter of the roof.

Shortened rafter legs, called sprigs, form a plane for the location of the hip roof slopes. The diagonal rafters, against which the frames rest, are most often made of double sewn boards, which helps to increase their load-bearing capacity. This is important because the load on them exceeds the load on conventional rafters by approximately one and a half times. If diagonal rafter beams cover a large area, then to give them additional strength, additional supports are installed: struts, trusses or racks made of timber.

As you can see, the process of arranging the hip roof rafter system has big number nuances that must be carefully taken into account when carrying out calculations and installation work.

Attic arrangement

A four-slope roof covering can be installed over a finished attic room either above outbuilding, over which there is no point in equipping a separate attic. If such a roof is installed over a residential building without an attic, then there is usually a need for an attic. Attic hipped roofs are widespread in residential construction.

At the same time, it should be noted that the attic spaces of hipped roofs are usually not intended for active and frequent use, since the slope various surfaces roofing leads to significant inconvenience in this regard. In order for the attic to be suitable for use as a separate utility room, its height and dimensions will have to be significantly increased. In this case, the consumption of materials will also be significantly greater. All these nuances should be taken into account before calculating the height of the hipped roof, so that attic space met the requirements and requests of the home owners.

A few words should also be said about how to calculate the height of the ridge of a hipped roof. The ridge structure, as a rule, is the central and most elevated part of the roof structure. The question of what height to install it generally also depends on the intended use of the under-roof space, as well as on the personal preferences of the owners of the house. A higher roof will provide more efficient use attic or attic. At the same time, a low-height roof is the best option in terms of efficiency, minimum flow materials and labor costs.

Parameters that should be calculated when arranging a hipped roof

If we talk about the necessary calculations before carrying out installation work, first of all we should mention how to calculate the roof area of ​​a hipped roof. The correct option here is to count for each of the roof slopes separately, followed by adding up the results. In this case, standard mathematical formulas are used to calculate the area of ​​certain geometric shapes.

So, for example, if the slope has triangular shape, then from its top, using a rope or cord, a perpendicular line is drawn to the base, called the height. Next, this same height of the triangular slope is multiplied by the length of the base, and the resulting amount is divided in half. The result will be the area of ​​the triangular roof slope.

For trapezoidal slopes, the formula is slightly different: first, the length of the upper and lower bases of the trapezoid is added up, then their sum is divided in half and multiplied by the height of the slope.

Another important point when calculating a hip roof is determining the required distance between the rafters. The size of the gaps depends mainly on the roofing material. So, for example, for metal tiles and corrugated sheets it is 60-90 centimeters, and for bitumen shingles– 100-120 centimeters, since in the latter case the roof is laid on continuous sheathing from sheet plywood.

Calculation - what and how to calculate

It is also important right choice the angle of inclination of the roof slopes, where a number of factors must be taken into account:

• The weight of the roofing - the greater it is, the steeper the roof should be.
• Dimensions of coating elements. If they are small and there are many joint areas between them, then the likelihood of water penetrating between them increases, and therefore the slopes should be located at a higher angle.
• Climate of the area. In areas where frequent snowfalls occur, roof slopes should be positioned steeper, which ensures rapid convergence of precipitation.
• Rules fire safety For attic roofs. In accordance with them, when large sizes the attic must have a through passage through it 160 centimeters high and 120 centimeters wide. If the attic is small (up to 2 meters in length), then minimum dimensions passages should be 120 and 90 centimeters, respectively.
• Chimney height for fireplace and stove structures. Overall height together with the outer part extending beyond the roof, must be at least 5 meters. Of course, this heating option is not suitable for small buildings with flat roofs.

The cross-sectional size of the rafter beams can also be different and depends on the total load falling on the rafter system. The total load is determined by the weight of the roofing pie and pressure external factors such as wind and snow. Accordingly, the roofing material and the climate of the area also matter here. It is clear that the greater the load on truss structure, the larger the cross-section the rafter beams should have.

In addition to the above nuances, there are some other features that should be taken into account when choosing a hip roof for a house:

• The design of the hipped roof allows for large overhangs on all four sides, ensuring protection of the facade and walls from precipitation.
• Although, in general, a hipped roof structure is more expensive than a gable roof structure, however, due to the lack of need for arranging gables, this difference is not so great.
• If the hipped roof is intended for attic building, then visually it will look lower, which should be taken into account when designing.
• Installation of any type of hipped roof should begin with a ridge structure. The Mauerlat must be securely fixed and connected at the corner areas, and the racks of the purlin frame must have a solid base.
• For fixing various roofing elements It is recommended to use modern metal fasteners.
• Upon completion of all work, before considering the hipped roof of the house completely ready for use, you should once again inspect all structures, elements and butt joints.
• Since erecting a hipped roof is not an easy task, you can only undertake it if you have sufficient self-confidence. Otherwise, most the right decision will entrust installation work to specialists.

• During the construction of a house, questions arise, such as calculating the material for the roof, which are directly related to its architectural form - the number of slopes, the presence of an attic, etc. When drawing up a design for a structure, all its parameters must be carefully verified to ensure its reliability and safety.

  A hipped roof is characterized by two triangular slopes (hips) on the end sides. It is classified mainly as hip or tent. The hip consists of two triangles and two trapezoids (the side slopes are isosceles triangles, and the front slopes are regular trapezoids). If its slopes do not reach the eaves at the lowest point, then it is called half-hip. The building box in this case has the shape of a rectangle. If it is presented in the form of a square, a hip roof is made, the four triangular slopes of which converge at a single peak.

  How to calculate a hipped roof: dimensions of the base, slope

  Knowing the linear dimensions of the base and the angle of inclination of its slopes, you can calculate a hipped roof. As a rule, it is carried out according to the following principle: the slopes are divided into several elements, each of which is calculated separately, after which the results are summed up. In this way, you can calculate the total area of ​​the hipped roof.
  The supporting structure of the hipped roof has a complex frame. The central rafters included in it create unnecessary load. In addition, the rafters must withstand the load of the roof covering, as well as snow and wind. Therefore, it is necessary to additionally calculate the parameters of the hipped structure, for example, the weight of roofing and finishing materials, climatic features of the region.

  Obviously, any inaccuracy in the calculations can have serious consequences, so they are carried out with great care and taking into account all possible options.

  The following indicators should also be taken into account:

  Competent calculation of a hipped roof requires taking into account data from meteorological services of the area of ​​residence. For precise definition required roof height and inclination angles of all four slopes, the following data is required: indicators

  • wind strength and speed in the area of ​​the house under construction;
  • precipitation intensity;
  • roofing material used.

  Design and calculations: we make a project using a drawing

  Before starting work on arranging the roof, it is necessary to design, calculate and draw a drawing of the future hipped structure.

  The slope of the slopes, depending on the purpose of the attic, atmospheric loads and the type of roofing material, ranges from 5º–60º.

  In regions with frequent strong winds or low precipitation, the slope of the slopes is small, and in areas with significant snow loads and frequent rains, it is significantly greater, 48–60º.

  In turn, based on the angle of inclination, the roofing material is selected:

  • 5º–18º – roll covering,
  • 14º–60º – roofing metal, asbestos cement sheets;
  • 30º–60º – tiled.

  The height of the ridge of a hipped roof for a given slope of the slopes is calculated using trigonometric formulas for right triangles.

  The design of a house with a hipped roof begins with the calculation of the rafters. Their cross-section depends on the angle of inclination of the slopes and the total value of the expected total loads: the weight of the rafter structure, roofing pie, snow and wind loads. The minimum safety margin of the rafters should be 1.4.

  Using calculations, we also determine:

  • step of the rafters and their load bearing capacity,
  • which rafters to use - layered or hanging,
  • necessity additional elements: braces that help reduce the load on the rafters, or ties that protect the structure from loosening,
  • the need to increase the length of the rafters or double the beams to strengthen them, etc.

  When designing, the rafter system is calculated:

  • for strength - the rafters should not break;
  • on the degree of deformation under certain parameters, for example, rafter deflection for mansard roofs should not exceed 0.4% of their length.

  Features of calculating the load on the rafter system

  The rafter system is under the influence of permanent and temporary loads.
  The first includes the mass of the roof, sheathing and counter-lattens, purlins and the rafters themselves, and the second includes wind, snow and useful loads - this is the load from ceilings, water heating tanks, ventilation chambers and other things suspended from trusses.

  The standard parameter for calculating snow loads for the middle latitudes of the country is 180 kg/m² per horizontal projection of the roof. Having accumulated snow bag can increase this value to 400–450 kg/m². For the same regions, the design parameter for wind loads is 35 kg/m².

  When the slopes are inclined more than 60°, it is not taken into account snow load, and when the slope is less than 30°, the wind is not taken into account. The parameters of these loads can be adjusted using existing correction factors that take into account local climatic conditions. The total mass of the roof is calculated based on the area of ​​the structure and the materials used.