Hip roofs have a lot of weighty advantages. Among them are aesthetic qualities and a significant reduction in wind load. Due to the rejection of the gable walls, the total cost of the structure is reduced. However, in terms of technology, hip structures are one of the most complex options that require careful selection of proportions and mandatory design.
It is imperative to make a calculation of the hipped roof, which is required for an impeccable construction result. How to do it right, we will analyze in this article.
Typical representatives of the class of four-slope roofs are hip and hipped varieties with an appropriate number of pitched planes. The main feature is the absence of end walls, which creates a kind of "streamlined" shape.
This configuration is very popular in regions characterized by high wind load, is actively in demand in areas with sparse vegetation and in mountainous areas.
The spectacular outlines of the hip roofs served as the basis for a tangible expansion of the scope of use. The aforementioned schemes are used not only to reduce the effect of gusty winds, but also for purely architectural and design reasons.
In addition, roofs with four slopes contribute to the removal of rainwater, and with proper selection of steepness, they also prevent the accumulation of snow deposits.
Roof elements with four slopes
Due to the inclined position of the end planes, the shape of the slopes of this type of structure is far from a rectangle. According to geometric indicators in hip roofs, they are divided into two symmetrical pairs of isosceles triangles and trapeziums. Triangles, called hips, just formed the basis of the technical term. Hipped roofs with a square base have only hips.
Let's analyze the device of the main hip version as the most striking representative of the class of hipped roofs. If we consider their central part without inclined end sections, it is difficult not to notice the resemblance to a standard gable roof.
They construct the central part by analogy with gable structures, using. Priorities are for the layered type, according to which the rafters rest on a running beam located at the top of the roof. It defines a ridge fracture or otherwise an edge. The run itself is installed on the running frame, consisting of racks and a horizontally laid bed. The rigidity of the frame provides multiple wind ties.
The running frame of the hip roof must be supported on a solid foundation. The optimal base is a load-bearing wall located in the center of the equipped box. Instead of one central run in multi-span hip truss systems, there can be two parallel counterparts based on two load-bearing walls.
In the absence of load-bearing walls suitable for installing a purlin frame on them, a strong ceiling must become the basis for the hip device. It must withstand the pressure of the rafter system along with the components of the roofing pie and with all kinds of atmospheric loads.
When used as a floor of concrete slabs, it is possible to construct a roof of any degree of complexity. The concrete base can easily withstand the installation of numerous structural parts, the weight of the material, powerful snow deposits in the grooves. There is no need to especially calculate the details of a hipped roof of a house with a similar top floor if it has been tested for a concentrated impact.
When constructing a beam wooden floor, the purlin frame is installed on a thick beam 100 × 200 mm or 150 × 200 mm, from which it is constructed. From a similar material, the run itself and the bed are made if it is used in the construction of the roof. Supports under the racks of the running frame are laid in a cross over the floor beams. They, wind ties and strut struts are made from a bar 100 × 150 mm.
All the complexity of the device of a four-slope design lies in the device of a support for the hips and the zones of the main slopes associated with them. To do this, the corners of the box are connected to the ridge run with diagonal rafters, otherwise called slanting rafter legs.
The plane of the slopes in the area where the hips are located is formed by sprigs - shortened rafter legs, installed with a step equal to the step of installing ordinary layered rafters. Diagonals in some way perform the function of a ridge run, because. the support of short rafter legs is made precisely on them. Therefore, they are most often made from a double board used for the installation of a truss system.
Stitching two boards for diagonal rafters allows you to solve several significant tasks at the same time:
- Increases the bearing capacity, thanks to which the pumping leg, without damage and displacement relative to the elements of the system, holds the weight of the roofing pie, rainfall and the maintenance worker in case of need for repairs.
- Allows you to form a conditionally uncut beam with the length required to span the span from the edge of the ridge run to the corner. The standard length of the board used in the construction of the truss system is usually not enough for this. Rallying with a mixture of the edges of the board allows you to increase the length and thickness.
- Provides the opportunity to use boards of the same height in the construction of the system, which eliminates the need for adjustment and additional calculations.
Simply put, it is much easier to work with a material of the same size, where it is necessary to simply pair it, and use it without doubling where it is not necessary.
When the rafter has to cover a large span, additional supports are installed to ensure its rigidity. They are made in the form of racks from a bar or a paired board, a strut or a truss truss.
Additional supports are used in the following order:
- If the length of the diagonal rafter does not exceed 7.5 m, the rigidity of the structure is provided by one brace. The bottom of it rests on the bed, the top on the rafter leg. The element is located closer to the ridge run, set at an angle of 45–53 ° relative to the horizon.
- If the length of the sloping rafter leg is up to 9 m, in addition to the strut, one more support is used. This is a rack or truss truss, installed at a distance of a quarter of the span from the corner of the box.
- If the length of the diagonal element is more than 9 m, in addition to the listed supports, one more rack is introduced in the center of the span. On the reinforced concrete floor, it is installed through the waterproofing directly on the base. On a wooden floor, a horizontal support beam is arranged under it.
The splicing of two boards of the sloping rafter is carried out so that the joining points do not fall on the support. Retreat should be a distance equal to 0.15 × L, where L is the full length of the span overlapped by the diagonal.
Given such a number of design nuances, before building a hip roof, everything must be thoroughly designed and calculated. In the process of creating a project, it will, of course, be adjusted and changed so that, in the end, the elements of the system can work interconnectedly.
Attic as a constructive component
All elements of a four-pitched roof structure can be combined into an integral system, i.e. don't have an attic. These types of roofs are called combined. They are built over attics or over outbuildings, in which it makes no sense to separate the roof structure from the premises with an upper ceiling. If they are separated by an attic, the roofs are called attic. This is the most common option in residential construction.
The attic space of four-pitched structures is rarely equipped for the purpose of operation. The fact is that the beveled position of all pitched planes significantly limits the usable area. A room with a clearance sufficient to straighten it to its full height turns out to be too small, which is especially noticeable if the country estate does not differ in impressive dimensions.
If there are no prerequisites for arranging an attic, insulation is carried out along the upper floor. If nevertheless it is planned to use the space, then the thermal insulation is laid between the rafters. In view of the above reasons, it is necessary at the stage of developing your own project to decide on the purpose of the attic, because. this decision will affect subsequent calculations.
Rafter leg installation step
The step between the rafters is usually a relative value, it can be slightly increased or decreased within the limits specified by the roofing manufacturer. For example, under stops can be installed at equal distances, the values of which are in the range of 0.6 - 0.9 m.
The spread is noticeable, but practically does not affect the bearing capacity of the truss system. Because with an increase in the step, some weakening of the structure is leveled by the crate, for which a larger bar is taken. In the same way, they act if corrugated board is to be laid. But under bituminous tiles, the step is allowed to reach values of 1.0 - 1.2 m, because the roof is laid on a continuous crate of plywood.
The traditional step selection algorithm for structures without insulation consists in dividing the wall into equal segments. When constructing an insulated roof, they are guided by the width of the thermal insulation plates so that they can completely fill the space between the rafters without cut pieces.
Selection of the angle of inclination of the slopes
Determining the correct slope of the pitched planes will eliminate problems in operation and greatly increase the service life of the roofing system. The specified angle sets the height of the ridge and the geometric proportions of the structure. Therefore, before you start calculating the dimensions of the rafters for a hipped roof, you should thoroughly understand this parameter.
The hip structure can be almost flat, gently sloping and rather steep. In choosing the angle of inclination of the slopes, there are a huge number of factors that require unconditional consideration, these are:
- roofing weight. The greater the specific gravity of the material distributed per meter of the roof in projection onto the base, the steeper the structure should be. In this way, the overall load on the truss system is reduced.
- The size of the coverage elements. The smaller the details of a piece of roofing, for example, ceramic tiles, the greater the likelihood of water seeping through its many joints. The fewer joints between large sheets, the lower the slope angle is allowed to be.
- Construction region. In areas with heavy snowfall in winter, it is customary to place roof slopes at an angle of 45º, which completely eliminates the retention of precipitation on the roof surface. In areas with an impressive wind load, the optimal roof slope is 4 - 7º.
- Chimney height. Taken into account for solid fuel stoves and fireplaces. The total height of the smoke channel must be at least five meters, taking into account the segment outside the roof. For a small one-story house with a sloping roof, this option will not work; you will have to choose a different chimney and type of heating unit.
- fire safety requirements. Must be observed for attic structures. The size of the attic must provide a through passage along the upper floor with a height of at least 1.6 m. The minimum width of the passage is 1.2 m.
For small attic compartments up to 2 m long, the dimensions of the passage in both directions can be reduced by 0.4 and 0.3 m, respectively.
All of the above circumstances must be taken into account when designing a roof. Without a competent project, it is impossible to start calculations. Do not be afraid of repeated alterations and adjustments to the real material and the specifics of the box at home. Corrections are inevitable, but it is better to make them on paper or a monitor than to correct them on the object.
In addition, at the design stage, you need to choose a method for forming cornice overhangs. They can be provided with the installation of rafter legs with a release for the Mauerlat and the wall. The second option is the complete support of the lower heel of the rafter leg sawn into the horizon on the Mauerlat without releasing it beyond the wall.
Load calculation algorithm
The calculation of the bearing capacity of structural elements is carried out according to the total load in the winter period, because It is at this time that the roof is loaded the most. Snow deposits, winds, the weight of the roofing cake and the inner lining are pressing on the rafter system. When wet, the mass of the insulation, for example, increases, therefore, it is customary to apply a safety factor in calculations.
To calculate the cross section of the rafter legs, the total pressure of snow, roofing cake and wind are added up in a banal way, and the result is multiplied by a safety factor of 1.1. The value obtained is expressed in kg / m 2, because. distributed per conventional square meter of area.
Note that for accurate calculations, the result obtained must be converted into a linear value, which should be expressed in kg/m. After all, the rafters are not installed all the way, but with a given step, and the total load acts on the roof as a whole. And we need to determine the pressure acting along the axis of the longitudinal element of the system.
To translate into the units we need, the total load should be multiplied by the installation step of the rafters. If the result does not suit you, the distance between the rafters can be slightly expanded or shortened. By adjusting the load collection area, a decrease or increase in its value is performed.
How to find the load from snow and wind
According to the rules, the calculation of the bearing capacity of the elements of the rafter system is carried out according to two limit states:
- To destruction. This refers to such a state of the truss system, when the limit of strength, endurance, stability is completely exhausted. In another way, it is called the design load, which indicates the maximum possible limit, the excess of which leads to the complete destruction of the structure.
- For deflection. This condition is characterized by the development of deformations, as a result of which connections are broken and nodes are revealed. It is called the standard load, the result of exceeding which are impressive deflections. As a result, the structure was not destroyed, but its operation is not possible without repair.
In construction organizations, bearing capacity calculations are carried out for both states in order to exclude the possibility of deflection or destruction of the designed roof. To make it easier for yourself, you can go the simplest way and learn from them the required values.
A private owner who intends to design, calculate and build a roof once does not have to delve into all the wisdom and formulas. It suffices to understand that in order to determine the limit state for destruction, a load from the mass of snow is needed.
Let's denote it as Q calc. is the calculated value. This is the calculated value, for the search for which, in the absence of other sources, one should refer to the zoning map of the territory of the Russian Federation, compiled according to the average snow load.
The simplest way to obtain the standard load, which we will denote as Q norm.sn. consists in multiplying the calculated value by a factor of 0.7.
Those. we act according to the following scheme:
- We found our settlement on the map and found out which zone it belongs to.
- The average statistical value of the calculated value of the load from precipitation was determined from the table according to the type of region.
- Multiply the calculated value by 0.7 to calculate the deflection limit state.
A pitched roof can be safely compared to a hill or rock rising above the rest of the terrain. It is clear that depending on the steepness and direction of the wind on such a hill, snow deposits will be distributed unevenly.
Therefore, for architecturally complex structures with several hip ribs and valleys, a correction factor µ is applied.
In these situations, both limit values are often affected by the slope angle and the direction of the prevailing winds. If there is increased wind activity and an abundance of precipitation in the construction area, then the coefficient should be included in the calculations.
Wind load is determined in a similar way. To calculate it, it is necessary to use the corresponding zoning map with the division of the Russian Federation into regions with equal wind pressure indicators. But on the map we will find not the calculated wind load W p, but the value that should be multiplied by k (z) - the coefficient of dependence of the wind force on the height z and c - the tabular aerodynamic coefficient.
We find the normative value of the wind according to the already familiar scheme by multiplying by 0.7.
Determining the weight of the roof
The total weight of the roof is the sum of the weight of the roofing, the approximate value of which can be taken from the table above, the weight of the batten and insulation, if used in the arrangement of the roof.
The mass of the crate will need to be calculated based on its type, installation method and weight of the material. For example, the weight of a cubic meter of a bar is 500 kg / m 3. If a sparse crate for metal tiles is arranged by installing 30 × 50 mm gratings every 0.3 m, then it will be necessary per square meter of roof.
Let's take an example. One roof square will have 3 elements of a sparse crate, each of which is calculated as follows: 1 m long × 0.03 m high × 0.05 m wide × 500 kg / m h. As a result, the weight of the lath will be 0.75 kg, the weight of the crate will be 2.25 kg.
And during construction, you will simply need the specific gravity of the material, for OSB or plywood board it is 650 kg / m 3, multiplied by its thickness. The specific gravity of thermal insulation is usually indicated by the manufacturer; its mass per square meter is easiest to find.
The obtained values for the weight of the roof, thermal insulation and lathing are summed up, converted into a linear value, the result of which should be verified with the requirements of SNiP 2.01.07-85. For reference, the value of the calculated load usually does not exceed 450 kg / m 2, the standard 315 kg / m 2.
The principle of design and calculations before the construction of a roof with four slopes:
The nuances of designing hipped roofs:
Familiarity with software tools that facilitate calculations:
instead of a conclusion. Many years of experience in the installation of hip roofs in our middle latitudes has shown that a 50 × 100 or 50 × 150 mm board is excellent for making rafters for a metal roof or shingles. For an insulated structure, it is recommended to prefer the second option so that there is no need to build up an additional counter-lattice and thereby unplannedly make the roof heavier.
For the supports, the run and the bed of the running frame, a material of 100 × 150 mm is required, for the installation of struts, wind ties, a wind board along the perimeter, a board of 25 × 100 or 25 × 150 mm is sufficient. Diagonal legs are sewn from two boards.
The most popular and most common roof construction of a house, without a doubt, is a gable. But recently, the hip roof has also become widespread. It differs in that it is four-pitched, two slopes of which (called hips - hence the name), replace the gables of the traditional gable roof. It has a number of undoubted advantages and has several varieties. In addition, the hip roof has a relatively complex design and manufacturing technology, which makes preliminary calculations of the main parameters of the roof and the need for materials an important stage in preparation for direct construction.
Types of hip roofs
Before performing the calculation, it is necessary to clearly understand what should be the result. There are the following types of roof structures under consideration.
Classic hip roof
The classic hip roof of the house has 4 slopes, two of which are trapezoidal, and the other two are triangular in shape. As mentioned above, triangular slopes, otherwise called hips, served as the reason for the origin of the name of the type of roof in question. The main advantages of this design are its high reliability, functionality, as well as an original and attractive appearance. The disadvantages include the relative design and technological complexity, as well as the high cost of construction.
Half hip roof
It differs from the classic variety in that the hips, that is, triangular slopes, have a truncated shape. The semi-hip roof is characterized by excellent performance and an attractive and very interesting appearance. However, this type of roofing is one of the most structurally and technologically complex, and expensive.
hipped roof
A fairly popular variety of the traditional hip roof, which differs from it in that all four or more slopes are triangular, converging at one point. The structure is crowned not by a horizontal ridge, but by a ridge knot located at the top of the pyramid, which is formed by slopes. As a rule, it is used in the case of a square building, or a structure in the form of an equilateral polygon.
broken roof
Another extremely attractive appearance of the roof of the house. It is characterized by the fact that all the slopes have different sizes and shapes. The disadvantage is similar to the half-hip design - the complexity of the design and manufacturing technology, as well as the high cost, even against the background of other expensive varieties of the type of roofs in question.
hip roof construction
Another important issue that needs to be clarified before starting to calculate the area and the need for materials is the design features of the roof, that is, the composition of the elements that will need to be calculated. Main structural elements:
- skate (ridge beam). It is located on top of the structure in the center of the roof. It is one of the main load-bearing elements on which most of the truss system is supported and adjacent to;
- corner (sloping) rafters. They are arranged in such a way that one end is attached to the edge of the building (or goes beyond it), and the second - to the ridge. They take most of the load of the roof, being, together with the ridge, the main type of load-bearing roof structures;
- central rafters. They form a truss system stretching along the entire length and height of the slopes from the ridge;
- hip (short) rafters. They form a rafter system of hips. Usually only one rafter leg rests on the ridge, the rest are attached to the corner rafters.
Basic rules for calculating the hip roof
As noted above, the design of the hip roof is quite complicated. Therefore, it is necessary to develop a project and involve specialists to perform the necessary calculations. Many years of experience of various builders has repeatedly proved that the desire to save insignificant funds for design and preliminary calculations leads, as a rule, to significantly greater losses at the construction stage.
But in the most extreme case, if savings are urgently needed, part of the drawings and elements can be made and calculated independently. In particular, with your own hands it is quite possible to calculate the place for the subsequent installation of the ridge and other elements of the roof truss system.
Determining the location of the ridge and rafters
To do this, you must perform the following operations:
- mark the line of the central axis from the ends of the house at the level of the top of the eaves. Thus, the location of the skate is determined;
- with the help of a measuring ruler, located at one end on the marked line of the ridge beam, and with the other - on the line of the side wall, the installation location of ordinary rafters is determined;
- then the length of the overhang is also determined with the help of a measuring ruler, only the ruler at one end extends beyond the boundary of the outer wall;
- a similar procedure is performed along the entire length of the wall in question, and then for the three remaining walls.
Thus, the places for the subsequent installation of the ridge and all rafters will be obtained.
A table of coefficients can significantly simplify the calculations of the length of the elements of the truss system, in which the ratios of the following indicators are indicated: roof slope / length of the intermediate rafter / length of the corner rafter.
Calculation of the hip roof area
After the location and dimensions of the truss system are determined, it is not particularly difficult to calculate the coverage area of the hip roof. To do this, it is divided into its constituent elements - slopes, for each of which its area is calculated taking into account overhangs. The formulas used in this are known from school and are quite simple.
Then the received data are summarized. The result of the addition will be the total area of the hip roof with one significant clarification. From the figure obtained, it is necessary to subtract the area of the chimney pipes and windows located on the roof.
Calculation of the angle of inclination of the hip roof
When calculating the angle of inclination of the hip roof, a fairly large number of indicators are taken into account, in particular, the amount of precipitation, the level of wind and snow load, the purpose of the attic, the roofing material, etc. Therefore, such calculations are best performed using specialized programs with the involvement of professional designers.
It should be noted that the angle ranges from 5 to 60 degrees.
All of the above applies to the simplest type of hip roof. The task of calculating the elements and material requirements is seriously complicated when additional architectural elements appear, for example, if there is a desire to decorate the house with a bay window. An example of calculating a roof with a bay window is shown in the video:
By analogy with the calculation of the roof with a bay window, calculations of other architectural elements are also performed. It must be remembered at the same time that the bay window example is one of the simplest.
The following needs to be added. To simplify the calculations, they often resort to the use of online calculators to help complete part of the calculations. For example, as in this case:
Conclusion
The hip roof has a rather complex structure. Therefore, the best calculation option is to invite professional designers in order to prepare a full-fledged project containing all the necessary dimensions, a specification of the need for materials, etc. If you want to save money, you can do some of the calculations yourself.
The hip roof has high performance and complex design, however, thanks to the online calculator, every homeowner will be able to calculate it. Our calculator will reliably calculate the construction of a hip hipped roof. Based on the results of the calculations, a 2D drawing of the roof is formed and 3D visualization is performed.
The hip roof has four slopes - end in the form of triangles and side in the form of a trapezoid. The slopes are located at the same angle to the base. Their sides are connected by hips (oblique ribs), and the tops are connected by a ridge. A mauelrat is laid along the perimeter of the house, on which the rafters rest. The hip hipped roof has a cornice overhang, depending on your preferences.
Advantages and disadvantages of a hip roof
Although the calculation of the hip roof is complicated, it is one of the most popular designs for a private house. It has a number of advantages:
- Streamlined roofing;
- Structural rigidity;
- Lack of gables
The hip roof also has a number of disadvantages:
- The complexity of calculations and installation of the roof;
- Large waste of material (especially MCH).
Thus, there are more advantages, and an online calculator with roof drawings in detail will help in its calculation.
The specifics of the hip roof calculator
Our calculator will make an instant calculation of the hip roof truss system - the length and number of rafters (including diagonal ones), the length of the ridge. The homeowner is required to enter only the initial parameters: the length and width of the house, the roof slope, and the height. I would like to note that the width of the board for the rafters must be chosen based on the loads, both from wind and snow, and from the mass of the roofing material itself. If you are making a warm roof, then the distance between the rafters should correspond to the width of the insulation in order to get rid of undercuts and not waste material.
crate
Lathing board is usually used with a thickness of 30 mm. The width can be different, for metal tiles with a step of 35 cm, in accordance with the length of the longitudinal axis of the Monterrey MCH module, the optimal board width is 100 mm, for other types of coatings, the step and width of the board may be different. Do not forget that OSB or plywood will be placed on top of the sheathing for soft roofing with a solid carpet.
When installing a warm roof, you need:
- Insulation with a thickness of 100 mm, but better than 150-200 mm.
- Waterproofing, vapor barrier;
- Counter-lattice with a thickness of at least 30 mm.
As you already understood, it is very easy to calculate a hip roof on an online calculator, even if you have very little knowledge in construction. The main design features of the hip roof are similar to the geometry of the school curriculum, so let's count together.
The complex design of the hip roof requires accurate calculations in the design process. Correct calculations will ensure the reliability, strength and long service life of the roof structure. You can quickly and correctly calculate the hip roof using a calculator. Such an online program will help to reliably draw up a complete roofing scheme, taking into account all the necessary parameters.
The hip roof is a hipped structure. Its lateral sides are made in the form of a trapezoid, and the end slopes have a triangular structure. All parts of the device are located at the same angle to the base.
To carry out the correct calculations of the design of the hip roof, all its main constituent elements should be taken into account:
- The top is a skate. The device is a beam, which is fixed at the highest point of the horizontal plane of the roof. It is somewhat smaller than the total length of the building and serves to connect the elements of the truss system.
- The rafters are central. Such load-bearing elements of the roof structure are placed along the height and length of the slopes, as well as the ridge.
- Corner rafters. Such bars are located at an angle. Their installation starts from the ridge and ends at the edge of the building.
- Hips. Such inclined elements are connected on one side to the ridge, and on the other side to the corner rafters.
- Mauerlat. This element allows you to connect the truss system with the walls of the building. Such binding is performed along the entire perimeter of the building.
- Overhangs. Usually this protective structure is an elongated part of the rafter legs. Hip roofs are characterized by cornice overhangs, which allow you to protect the walls of the house from moisture.
- Crate. Such a device is necessary for fixing the roofing material, as well as the waterproofing layer and insulation. The crate can be sparse and solid. Its type depends on the type of roofing.
When calculating the roof online, its coverage is taken into account. The material can be in the form of rolls, individual modules or sheets.
Hip roofs do not have gables. Their main advantage is the rigidity of the whole structure and good streamlining of the coating. But it is quite difficult to design this type of reliable roof without a large amount of material waste. Therefore, the best assistant in drawing up a roof construction plan is a calculator that, when entering all the data, will provide reliable calculations of the hip roof with a drawing.
online calculator
To perform the calculation using the provided calculator, you only need to reliably enter the parameters of the hip roof. The online program will quickly and accurately calculate the number of all necessary elements of the truss system, their length, as well as the dimensions of the ridge.
The main determining indicators of hip-type roof calculations are: the width and length of the building, its height and roof slope. The dimensions of the overhang are also taken into account. When choosing the width of the rafters, the loads of the roof lining material, as well as the pressure of wind and snow masses are taken into account.
crate
The correct choice of batten material affects the strength properties of the hip roof. The best option for a roof of this type is a board 3 centimeters thick and 10 centimeters wide. The parameters may vary upwards depending on the characteristics of the materials for coating the structure.
The step of the crate is carried out in the range from 20 to 70 centimeters. For metal tiles, the distance between the boards is 35 centimeters, slate requires a greater distance - from 50 to 70 centimeters. The lumber length is 6 meters.
When laying a soft roof, a continuous crate is used. Its construction consists of plywood or OSB sheets. Laying material in this design is carried out with a gap of no more than one centimeter.
More reliable parameters of the lathing can be clarified with the manufacturers of the material selected for roofing. Using a hip roof calculator, you can determine the required amount of wood for the entire truss system.
Material for a warm roof
An insulated roof is a fairly simple way to keep the heat in the house. This version of the roof structure allows you to use the attic as a living space. For laying the cake, various materials are used in this order:
- vapor barrier coating - metallized three-layer film;
- insulation - mineral wool made of basalt fiber with a thickness of at least 10 centimeters;
- waterproofing - a film material that protects the insulation from moisture;
- counter-lattice - a structure with a thickness of at least 3 centimeters made of wooden bars, providing a ventilation gap.
If polystyrene foam boards are used as thermal insulation, then the installation of a water vapor barrier can be omitted. Waterproofing material and insulation are laid on the roof only in a continuous layer. All joints must be hermetically glued with a special tape.
A hip roof is a type of four-pitched roof, in which two slopes are trapezoidal in shape, and the other two (end) are triangular (having the same name as “hips”). If the end slopes occupy the entire area from the ridge to the eaves - this is a hip roof, if they do not reach the cornice - a half-hip roof.
The roof of the house performs a dual function - on the one hand, it is entrusted with protecting the building from external influences, and on the other hand, it is designed to decorate the building and give it individuality.
Historically, in Russia they preferred simpler one-pitched roofs, while Europeans prefer a four-pitched or hip roof, which has advantages and disadvantages under certain conditions.
Hip roof - advantages and disadvantages
Pros:
- great structural rigidity. It is achieved due to the corner ribs connecting near the ridge support beam;
- the possibility of arranging more protruding overhangs, which provides additional protection for the walls of the house;
- aesthetic appeal.
Minuses:
- complexity of calculation and installation;
- higher cost of project implementation;
- reduction in the area of the attic (in particular, at the installation site of the diagonal supports);
- the impossibility of building an attic;
- natural light is possible only through the installation of windows in the roofing pie.
Since the shortcomings are not critical, the hip-type four-pitched roof is actively practiced in the modern construction of private houses.
Varieties (types and types) of a hip roof
When studying the device of the hip roof truss system, it should be noted that within this type, there are several types of structures. In turn, this makes adjustments to the overall process of erecting the frame of the truss system.
Classic hip roof
Differs in the support of the diagonal ribs on the support beam of the ridge and the location of the overhangs at the same height. The individual elements of the hip roof correspond to the triangle (gables) and the trapezium (slopes).
Hipped hip roof
Distinguished by the absence of a ridge support beam. This leads to the fact that all diagonal ribs converge at a single point, and ordinary short rafters already adjoin them. Such a roof is preferred in the presence of a square box at home. But the formation of a reliable ridge knot is quite complicated.
Half hip roof
It is distinguished by the presence of vertical gables in which windows can be installed. The picture shows the difference between two varieties of half-hip roofs (Dutch and Danish).
Broken hip roof or mansard hipped roof
The most difficult in terms of construction is the design of the hip roof truss system, since in this case, all the roof slopes have a different area and diverge at different angles. A broken (mansard) roof allows you to more rationally organize the internal under-roof space and, in addition to additional living space, give the house a spectacular appearance.
hip roof construction
Regardless of the type of roof, all types have the same elements of the hip roof truss system:
ridge support beam or ridge beam - used for a classic hip roof, it acts as a supporting element to which diagonal rafters are attached;
diagonal rafter (side, edge, slanting or corner rafter) - a longer rafter leg that is attached to the end of the ridge beam at an acute angle, forming one of the sides of the triangle;
central rafter - boards of the same length, which adjoin the ridge beam and form the edges of the trapezoidal roof slope. Between them are intermediate rafters;
intermediate or ordinary rafter - forms a plane of a trapezoidal slope, the distance between them determines the run of the truss system;
sprig or short rafter - a structural element that is attached to a diagonal rafter, forming a triangular overhang and the corner parts of the trapezoid.
hip roof calculation
The calculation of the hip roof truss system is carried out taking into account the following prerequisites:
- wind load in the region. The higher it is, the more gentle the slope should be, and the stronger the whole structure. To level out strong winds, the central and diagonal rafters are made thicker;
- the amount of precipitation. An inverse relationship is observed. The higher the amount of precipitation, the steeper the slope should be so that snow and rain do not create pressure on the rafter system;
- type of roofing material. Each type of roofing material puts forward its own requirements for the crate, and also has a certain weight. These factors must be taken into account at the design stage;
- the need for roof insulation. In this case, the installation step of the rafters is calculated taking into account the width of the heat-insulating material. In addition, the distance between the rafters depends on the type and section of wood.
The calculation of the roofing material is carried out according to the formulas, taking into account the angle of the roof. The optimal roof slope for roofing materials of various types is shown in the table:
The slope of the slope angle determines the laying of the rafters. In turn, the laying of the intermediate rafter is calculated as follows:
- first, an center line is applied to the upper trim of the end wall;
- then half the thickness of the ridge beam is calculated, and the placement line of the first of the central intermediate rafters is applied;
- then the end of the measuring rail and the placement line of the central intermediate rafter marked above are combined;
- a line of the inner contour of the side wall is applied to the opposite end of the measuring rail;
- the resulting point is the laying of the intermediate rafter.
The ratio between the length of the rafters and their laying is calculated using a correction factor, the value of which depends on the angle of inclination of the roof slope. The length of the rafter leg is determined by multiplying the laying by the coefficient.
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Formulas for calculating the hip roof
| Skate height |  |
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| Ridge bar length |
The length of the house minus its width |
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| The length of the central rafters (trapezoid) |
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Pythagorean theorem |
| Length of ordinary rafters | Calculated similarly to the length of the central rafters | |
| Rafter extension to form frame overhang |
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| Tilt angle ordinary rafters |
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| Diagonal length hip rafters |
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| Narozhniki (short rafters) |
 First short rafter |
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 Second short rafter |
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| Square hip roof |
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How to calculate the area of a hip roof?
To know how much to buy roofing material, you need to know the total area of \u200b\u200bthe roof.
To do this, you need to break the entire roof into constituent simple geometric shapes and make a calculation for each of them.
The calculation of the hip roof area allows you to determine in advance not only the cost of purchasing roofing materials and installation, but also determine the requirements for materials, as well as the need for arrangement and the exact configuration of the crate.
Drawing of the hip roof truss system
The result of the development of the project and calculations will be a diagram-drawing of the hip roof truss system. There are no similar drawings ready for use without taking into account the features of a particular structure and the place of its construction.
The development of a preliminary scheme can be done independently (a simple sketch will determine the direction of the project). But, it is better to entrust the drawing to specialists or use special programs for calculation. It should be remembered that the more complex the roof structure, the more accurately it is necessary to calculate the truss system: configuration and materials. This will also affect the cost and duration of installation work.
The hip roof drawing should include an indication of the purpose of the material, its installation location and method of attachment. The key nodes of the hip roof truss system, for example, the adjoining of diagonal supports to the ridge beam or the installation of rafter legs on the Mauerlat, it is advisable to put them in a separate drawing and describe them in more detail.
Drawing of a hip roof (layered rafters with an emphasis on two runs)
Drawing of a hip roof truss system with a bay window
The presence of a schematic drawing will be a good help in the manufacture of blanks and subsequent installation of the roof.
Tools for building a hip roof
The design of the roof and the methods of arranging the nodes determine the set of tools that should be prepared before starting work.
To work with wood, it is useful: a level, a hacksaw, a hammer, a tape measure, a marking cord, a stapler.
To work with metal structures, you will need an electric drill, a riveter, cutting shears.
The tool and consumables must be prepared in advance, because. complex installation of the hip roof truss system involves a large number of cuts and installation of nails.
To simplify measurements and be able to make all parts of the same size, the masters advise replacing the tape measure with a measuring rod. The measuring rail is made of plywood 50 mm wide, on which the main dimensions are applied.
hip roof material
The breed and type of wood have a direct impact on the durability and reliability of the roof structure. Masters are advised to give preference to lumber or pine lumber. All blanks require pre-treatment with flame retardants and antiseptics.
In addition to wood, you will need metal fasteners, nails, self-tapping screws, anchor bolts.
Note. When forming a hip rafter system on a wooden house that can shrink, craftsmen advise using floating fasteners to connect the rafters to the Mauerlat. This method compensates for the movement of the crowns during the natural shrinkage of a house made of timber or logs.
Hip roof truss system - installation technology
Do-it-yourself truss system devices step by step:
1. Preparation of blanks (rafters)
This is the most difficult and time-consuming part of the construction, because. associated with:
- the need to ensure a given angle of inclination of the rafter legs;
- different lengths of sprigs (short rafters);
- the presence of diagonal rafters (slanting), which are given special attention. Due to the length, the rafters carry a greater load than the main rafters, and therefore require the use of higher quality lumber with a large section. In addition, often the length of the diagonal rafters exceeds the standard length of the boards.
In order not to buy different lumber, in practice the method of splicing (pairing) edged boards is used to obtain a given length.
Advantages of rafter splicing technology:
- obtaining continuous beams of a given length;
- increasing the strength of the diagonal rafters of the hip roof due to the double section;
- simplification of the calculation and purchase of material (unification of dimensions: length and section);
- the possibility of using boards designed to form ordinary rafters.
2. Mauerlat mount
Mauerlat for a hip roof is a large-section wooden beam (100x100 or 100x150 mm) mounted around the perimeter of the walls. For Mauerlat, wood of the first grade is used.
The peculiarity of laying the mauerlat is that the beam is connected along the length only with an overlap, but not butt, using a variety of connection points with the base of the wall. The connecting nodes are additionally reinforced with metal brackets.
Since the purpose of the Mauerlat is to serve as a support for the rafter legs, it needs to be protected from moisture. For this purpose, a hydrobarrier is laid between the wall and the beam (for example, roofing material is used).
Note. Under the mauerlat in brick houses (or from aerated concrete, foam concrete, wood concrete), a reinforced concrete belt is poured with pre-installed studs for mounting the beam. The hairpin has a diameter of 10 mm or more and should protrude beyond the Mauerlat plane by 20-30 mm. The installation step of the studs is 1000-1200 mm.
3. Installation of the run
A run is a beam installed parallel to the sides of the Mauerlat. The run serves as the basis for the installation of additional supports under the rafter legs. The run device is not a mandatory stage of work and is performed only for hip roofs of a large area or with a configuration of increased complexity. The location of the run is shown in the diagram.
It should be noted that the point of maximum load will vary depending on the location - on the ridge of the hip or on the edge of the valley.
Note. The hip hip roof is mounted without support, and a complex knot is formed at the junction of the diagonal rafters.
4. Installation of support legs
Racks serve as a support when installing a ridge beam (orange in the picture).
5. Installation of the ridge beam
Installation of the hip roof ridge is accompanied by accurate measurements. Since the entire roof structure will rest on the ridge, the correctness of its installation is checked by height and level.
6. Fastening rafter legs
Regarding the sequence of work at this stage, the opinions of the masters differ. This makes it possible to single out two areas for work:
- the central rafters are mounted, and then the diagonal ones. This workflow is simpler;
- diagonal rafters are mounted, and then the rest.
During installation, the lower part of the rafter leg rests on the Mauerlat.
The support of the rafters on the hip roof is shown in the diagram. The first option (with a notch) is simpler, but the second (with a support bar) is preferable, because. in this case, the fastening does not weaken the rafter.
The formation of a node on a ridge beam is possible in different ways.
Top mounting options for diagonal rafters are shown in the diagram.
Advice. For rigidity, it is advisable to reinforce all nodes with metal elements (brackets, plates, corners).
Since the diagonal rafters have a significant load, they can be strengthened using such means as:
- rack installation. Mounted on the ceiling vertically;
- brace installation. Mounted at an angle. The angle of inclination is not critical. The ability of the strut to reinforce the diagonal rafter is important;
- sprengel. In fact, this is a T-shaped short beam, deployed 180o. It is used on long spans and is installed so that its base is oriented perpendicular to the diagonal rafter.
7. Installation of ordinary rafters
Privates are installed similarly to the installation of the central rafters, which form the edges of the trapezoid. Their lower part rests and is attached to the Mauerlat, and the upper part rests against the ridge beam. It is important to observe the same distance between ordinary rafters.
8. Installation of sprockets (short rafters)
Narozhniki are made only from solid lumber. At the junction of the sprig to the long rafter, cuts are made or support beams are installed. The installation site is additionally reinforced with metal elements.
Note. The installation of the hip roof splices is possible in a run-up to simplify installation.
In any case, sprigs are installed after the formation of the power frame of the roof. Their installation ends with the installation of the hip roof truss system.
Do-it-yourself hip roof step by step - video
The program shows the installation process of the truss system of a gable hip roof with a central bay window along a short wall.
After the rafter system is ready, you can proceed with the installation of the roofing, the specifics of the fastening of which determines the need for mounting the crate on the rafter legs.
Installation of a hip roof truss system is a lengthy process that requires attention to every stage of the work - from the calculation and selection of material, to the installation of parts and strengthening of attachment points. But, with the correct implementation of all stages, the result will be a beautiful and reliable roof for a private house.
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