If you need to create a durable and reliable roofing system for a private house, you can create a hipped roof with your own hands. It is important to carefully consider the development of the rafter system project and strictly follow the technology for installing structures.
Design of a hipped roof
A hip or hipped hipped roof differs from a gable roof in the absence of gables - instead of them, additional triangular slopes are mounted at the ends. This design is more labor-intensive to construct, but is characterized by increased strength and reliability. At the design stage, it is necessary to correctly calculate the parameters and location of the elements, and during the installation process, they need to be precisely adjusted to the installation locations.
It should be noted that building a roof with your own hands may require the use of non-standard solutions if the builders do not have suitable building materials at their disposal.
Project of four pitched roof is developed taking into account all types of loads that it will experience. At the first stage, the angle of inclination of the roof slopes should be determined. This parameter primarily depends on factors such as:
- purpose attic space;
- choice of roofing material;
- the nature of atmospheric loads in the construction area.
Typically, the angle of inclination of the roof slopes is 5 – 60 degrees. If the region is characterized by low rainfall and strong winds, you can build a roof with a slight angle of inclination. In areas with heavy snowfall and frequent rain, it is recommended to build roofs with a slope angle of 45 to 60 degrees.
When choosing a roofing material, you should take into account the features of its installation:
- Flat or wavy slate can be mounted on slopes with an inclination angle of less than 18 degrees, roll materials;
- if the angle of inclination is less than 30 degrees, it can be used different kinds tiles;
- if the slopes are located at an angle from 14 to 60 degrees, the number suitable materials included roofing metal.
The roofing structure diagram must contain detailed information about the locations and sizes of the system elements. After determining the optimal angle of inclination of the slopes, it is necessary to calculate the height of the roof ridge (based on the formula right triangle).
Rafter system
The installation of a hipped roof includes determining the required cross-section of the elements of the rafter system. It is performed based on an analysis of the loads that the rafter system will experience during operation. It is necessary to take into account the wind load, the maximum mass of snow in winter period, angle of inclination of the slopes.
It is recommended to select a rafter safety factor of at least 1.4, as well as evaluate their load-bearing capacity and take it into account when calculating the rafter spacing. The type of rafter system is selected based on the parameters of the building: if there is an internal load-bearing wall or columnar supports, it is more convenient to use a system with layered rafters; if it is not possible to create a supporting structure, installation of hanging rafters is provided. In some cases, both types of rafters can be used.
During the design process, it is important not only to determine the type of rafter system, but also to determine the need for additional fastening elements, such as braces and tie-downs. They provide rigidity to the entire structure, prevent it from loosening over time, and reduce the load on the rafters.
Load calculation
Considering in detail how to make a hipped roof, it is worth paying special attention to the principles of calculating loads. There are two types of loads:
- permanent (weight of sheathing, insulation, insulating materials, roofing);
- temporary (weight of snow accumulated on the roof, exposure to wind, etc.);
- additional (any structures attached to the rafters).
According to SNiP, when designing a roof, one should proceed from average size snow load, which is 180 kg/m2, but in the event of a snow bag, in such an area the load increases to 400 kg/m2. In this case, the snow load is not taken into account if the angle of inclination of the roof slopes exceeds 60 degrees. It is also necessary to take into account wind loads, but their value is noticeably less - up to 35 kg/m2. If the angle of inclination of the slopes is less than 30 degrees, the wind correction can be neglected.
It is recommended to correct the above averaged load parameters using correction factors corresponding to the climate characteristics in the construction area.
An additional load comes from any suspended objects attached to the roof rafters. These could be vents, a water tank, or other devices installed in the attic. The possibility of their installation should be taken into account at the design stage of a hipped roof.
When designing a rafter system, it is necessary to perform two calculations. The first calculation is aimed at assessing the strength parameters of the structure - it is necessary to make sure that the system will not break under load. The second calculation makes it possible to assess the degree of deformation of structural elements. For example, rafter deflection mansard roof should not exceed 1/250 of its length.
Special computer calculator programs can significantly simplify the calculations of the design of a hipped roof and avoid possible errors.
After performing the necessary calculations, a drawing of the rafter structure of the hipped roof is drawn up. The detailed diagram contains information about the dimensions of each element and the method of their fastening.
Materials for the manufacture of the rafter system
A do-it-yourself hipped roof is usually made using lumber from wood coniferous species– larch or pine. You should carefully consider the type of wood - the lumber should not have defects that affect its strength and durability.
Wood moisture content should be no more than 18-22%. Otherwise, the boards and timber should be dried before use to avoid deformation of the roofing structure during operation.
To create a rafter system, it is optimal to use a rectangular beam, the cross-section of which is determined by design calculations. As an alternative solution, a board with a cross section of 50×100 or 50×200 mm can be used. If necessary, double boards are installed.
The strength of a multi-pitched roof structure can be increased by steel elements that hold the rafters and keep their relative positions unchanged. Supports for the most loaded ridge girders can also be made of metal. Combined structures are characterized by increased strength.
Features of the construction of a hip roof
The support for a roof with four slopes is the Mauerlat, the installation of which is described in detail in the instructions for constructing a gable roof. A special feature of the hip roof is that the mauerlat must be laid on all four external walls of the building. When figuring out how to make a hipped roof, it should be noted that the key feature of the design is the presence of diagonal rafters connecting the ridge and corners of the building. It is these rafters that take on the maximum load.
It is extremely important to correctly mark the diagonal rafters, ridge girder and supports for it. This makes it possible to ensure absolute symmetry of the structure, which is the key to uniform distribution of loads on the roof of the structure and prevents its deformation.
After installing the Mauerlat, supports are installed for the ridge girder, which must be fixed strictly horizontally at the height provided for by the project. Diagonal rafters made of timber or double boards are attached to the ridge girder.
To ensure the required length of the diagonal rafters, in some cases it is necessary to install them in two parts. To relieve the load on the joint, it is recommended to install a support under it. The greatest rigidity of the structure can be achieved if the joint with the support is located at a distance equal to a quarter of the length of the rafter from its upper part, fixed to the ridge. In general, for the installation of diagonal rafters it is most convenient to use prefabricated (glued) rafters rafter legs, which are highly durable and ideal for the construction complex structures.
After installing the main structure, consisting of a ridge girder and diagonal rafters, rafters are installed for installing the sheathing. The peculiarities of the hip roof include the use of not only full-size rafter legs, which are attached with the upper part to the ridge (central rafters), but also flanges - corner rafters, resting with the upper end against the diagonal rafters. The length of the sprigs decreases as they approach the corner of the triangular or trapezoidal slope. The spacing of the rafter legs is determined at the design stage, and at least three central rafters must be mounted on each slope, regardless of its length.
To ensure the rigidity of the entire structure, supports, tie-downs and braces are installed in the right places. Installation of the sheathing completes the creation of the rafter system. Waterproofing and roofing material are being installed. Insulation and vapor barrier are fixed from the inside. If the space under the roof is intended to be used as a living space, special attention should be paid to thermal insulation and ventilation of the roof. In addition, it is necessary to design and then correctly install roof windows.
Details on how to build a hipped roof on your own can be found in the thematic video.
Many people like houses with hipped roofs. Even though they require the most materials, and therefore the most money, they are popular. Firstly, because they give even a simple “box” more interesting view. Secondly, because they are durable and reliable. And even though the rafter system of a hipped roof is one of the most complex, it can be developed and made with your own hands.
Types of hipped roofs
Hip roofs are the most expensive and difficult to install. But despite this, they were and remain popular. And all because they look more attractive than all other types of roofing, have high mechanical strength, and resist wind and snow loads well. A house with a hipped roof or even a gazebo looks “more solid” than any other.
Even a simple “box” under a 4-pitch roof looks impressive
There are two main types of 4-pitch roofs: hip and hip. The hip roof is suitable for square buildings, the hip one - for rectangular ones. In a hip roof, all four slopes look like triangles and they all converge at one point - in the center of the square.
The classic hip roof has two slopes in the form of trapezoids that converge at the ridge. These slopes are located along the long side of the rectangle. The other two slopes are triangles that are adjacent to extreme points ridge beam.
Despite the fact that there are four slopes in any case, the design and calculation of these roofs are different. The order of assembly also differs.
Half-hip
Hip roofing is much more common - after all, there are much more rectangular buildings than square ones. There are several more varieties of it. For example, half-hip ones - Danish and Dutch.
Half-hip roofs - Danish and Dutch
They are good because they make it possible to install full-fledged windows in the vertical part of the side slopes. This allows you to use the under-roof space as a living space. Of course, compared to a full second floor, there is less living space, but construction costs are also not so high.
Slope angle and roof height
The angle of inclination of a hipped roof is determined based on snow and wind loads in your region. The higher the snow load, the higher the ridge must be raised so that the slope is steeper and the snow does not linger in large volumes. In strong winds, on the contrary, the ridge is lowered lower to reduce the area of the slopes and, consequently, the wind load.
Even when choosing the angle of inclination of roof slopes, they are guided by aesthetic and practical considerations. With aesthetics, everything is more or less clear - the building should look proportional. And it looks better with fairly high roofs - 0.5-0.8 of the height of the first (or only) floor.
Practical considerations come in two directions. First, if the under-roof space is planned to be used as a living space, pay attention to the area that will be comfortable for use. It is more or less comfortable to be in a room with a ceiling height of 1.9 m. And even then, this is for people of average height. If your height is higher than 175 cm, you will have to raise the bar.
On the other hand, the greater the height of the roof, the more materials will be required for its manufacture. And this is the second practical aspect that needs to be taken into account.
There is one more point that should be taken into account: roofing materials have a minimum and maximum slope angle with which this coating can “work”. If you have certain preferences for the type of roofing material, take this factor into account. This determines the height to which the rafter system of a hipped roof should be raised (relative to the walls).
Hip type hip roof rafter system
If they make a hipped roof, most often it is hip roof. Let's talk about it first. The central part of the rafter system repeats the system one to one. The system can also be with layered or hanging rafters. Hanging rafters are installed “in place” - on the roof; two people are enough for such work. Layered roof trusses, in the form of triangles, can be assembled on the ground, and then, ready, lifted and installed. In this case, there is less work at height, but to lift and install ready-made trusses, you need either equipment (a crane) or a team of four or more people.
The main differences between the rafter system of a hip roof are in those places where the rafters are shortened (rafter half-legs) and a hip is formed - triangular slopes. Here diagonal rafters are installed, which are also called rafters. They rest on the outer or inner corners of the building and are longer than ordinary rafter legs. Particular attention should be paid to diagonal rafters, since they carry one and a half loads (when compared with neighboring rafters). Therefore, the corner rafter legs are made reinforced - they are assembled from two boards, joining them in width using nails. Also, to support the diagonal rafter legs, additional racks and slopes are installed, which are called a truss block.
Another rafter system for a hip-type hipped roof is distinguished by the fact that the Mauerlat is laid around the perimeter of the building, and not just along the long sides of the box. This is understandable - the rafters are located along the perimeter, and not just on two sides, as in a gable roof.
Mauerlat- element of the roofing system of a building. It is a beam or log laid on top along the perimeter outer wall. Serves as the extreme lower support for the rafters.
Diagonal rafters
As already mentioned, slanted (corner) rafters carry increased load: from the shortened rafters of the side slopes and from the hips. In addition, the length of the diagonal rafters of a hip roof usually exceeds the standard length of lumber - it is more than 6 meters, so they are made spliced and doubled (paired). This solves two problems at once: we obtain a beam of the required length and increase its load-bearing capacity. Two paired boards can withstand greater loads than a solid beam of the same section. And one more point: spliced beams for slanted rafters are made of the same material as ordinary rafter legs. It's cheaper, and you don't need to look for special material.
If spliced beams are used, diagonal rafters are usually secured by installing struts and/or trusses (racks).
- If the length of the beam is up to 7.5 m, one strut is sufficient, which rests on top part beams.
- For lengths from 7.5 m to 9 m, an additional stand or truss is installed. These supports are placed at the bottom, 1/4 of the length of the rafters.
- When the length of the inclined rafter is more than 9 meters, a third, intermediate support is needed - a stand that supports the middle of the purlin.
Sprengel- a special system that consists of a beam resting on two adjacent external walls. A stand rests on this beam, supported on both sides by slopes (the slopes are installed if necessary).
A truss truss is usually not considered, but is made from the same materials as the truss system. For the beam itself 150*100 mm, for the racks - 100*100 mm, for the slopes - 50*100 mm. This can be a beam of a suitable cross-section or spliced beams.
Supporting the rafter leg
The upper end of the diagonal rafter legs rests on the ridge beam. The exact execution of this assembly depends on the type of system and the number of runs.
If there is only one purlin, the consoles are made 10-15 cm longer than the rafter frame. If such an outlet is too large, it is then trimmed. But it’s not worth making it shorter - growing it is much more difficult and expensive. The slanted diagonal legs will rest at this point.
The rafters are cut at the desired angle and joined on the console. Fastened with nails. The connection can be strengthened using metal overlay plates.
If there are two ridge spans (done if an attic-type living space is planned), the method of connection depends on the material from which the rafters are made:
- If spliced boards are used, a truss is required, which rests on the outriggers of the ridge girders. Diagonal rafters are trimmed and supported on a truss post.
- If timber is used, a crimp is installed at the point of support - a piece of board at least 50 mm thick. The board is attached with nails to two purlins, and to this board there are already rafter legs that will form a hip.
The lower part of the slanted rafter legs is trimmed horizontally and attached to the mauerlat or trim board. For greater reliability of the unit, you can install an additional oblique beam and fix the corner beam to it (in the figure below).
Fastening - with nails on both sides; if necessary, it can be additionally secured with wire twists or clamps.
How to attach sprigs and half-legs
Shortened rafters of the side slopes (also called half-legs) are attached to the installed diagonal rafter legs on one side, and on the other side - rafters that form a hip. They must be placed in such a way that the joints do not coincide. Sometimes for this you have to change the distance between the external rafters (preferably in the direction of decreasing the pitch).
Typically, shortened rafters are trimmed and secured with 2-3 nails on both sides. This type of fastening is sufficient in most cases. But, if you want to do it “correctly”, under each rafter you need to make a “notch” - a notch no more than half the thickness of the beam. The rafters are trimmed, installed in the desired position, and the desired contour is drawn on the beam (an uneven trapezoid is obtained due to different connection angles). A recess is cut out along the resulting contour, into which the half-leg is inserted, after which it is secured with nails on both sides. This is a complex knot, and it takes a long time to do. But the load-bearing capacity of such a connection is much higher. There is another option, which is much simpler in execution, but differs little in reliability.
The optimal way to attach the spigots and half-legs to the mowing beam can be considered as fastening them to nails with additional installation cranial bars (see picture above). For this, a beam with a cross section of 50*50 mm is used, which is nailed along the lower edge of the beam between the fixed rafters. In this version, the beam becomes an I-beam, which greatly increases its elasticity and increases its load-bearing capacity.
How to fasten the lower ends of the rafters
The method of fastening the lower ends of the rafters depends on what type of rafter system of the hipped roof is chosen - with hanging or layered rafters, and what kind of scheme is used. A system with sliding rafters (usually used for buildings for which thrust loads are contraindicated - wooden, frame, lightweight concrete) is implemented using special metal fasteners. They consist of two parts. One is installed on the embedded board, the second - on the rafters. They are connected to each other movably - using a long slot or plate.
With this device, when the load changes, the roof “plays back” - the rafters move relative to the walls. There are no thrust loads; the entire mass of the roof and precipitation is transferred vertically downwards to the walls. This fastening allows you to compensate for uneven loads that arise with a complex roof structure (with junctions in the form of the letter G or T).
Rigid fastening can be done in different ways - with a cutout for the Mauerlat/tying board or with a hemmed support bar. Fastening is usually done with nails; it can be reinforced with metal plates and corners.
The connection with the cutout is made if the roof has a hipped roof with an outlet - overhangs. Usually the overhangs are quite large and, in order not to buy long beams, they are extended by adding boards that are nailed right through to the bottom of the beams. This allows you to make the overhangs as long as you want without overspending on materials.
Danish half hip roof
The rafter system of a Danish-type hipped roof differs from the classic hip roof. The difference is in the design of the hip - here, at some distance from the ridge, it is stuffed support board at least 5 cm thick. Diagonal double rafters are attached to this board. How low to lower the support board is your choice. But the lower the board is lowered, the smaller the angle this slope will have, and the worse the precipitation will be. If the half-hip area is large, you will have to calculate the load and select the thickness of the rafters.
But the low-slung support board allows you to install a horizontal window of sufficient area. This is beneficial if there is a living space under a hipped hip roof.
To prevent the crimp (a board connecting two opposite rafter legs) from bending from downward loads, a short piece is installed - a piece of the same board that is nailed to the post supporting the ridge beam. The same stops are made on the edges of the grooves, securing the short ones well with nails (installation step is staggered every 5-10 cm).
With such a device, it is necessary to strengthen the attachment points of the layered rafters, since the load from them is transferred to the outer pair of rafter legs. Two methods of amplification are used:
- The outer rafters are made double.
- Install struts from double boards. The lower part of the strut rests on the bench or stand. They are fastened with nails, and the joints are reinforced by installing cuttings of boards.
If the house is rectangular in shape and the hips are not too wide, you can either install braces or make the outer rafters from double beams. Otherwise, the rafter system of a half-hip Danish type hip roof is assembled in exactly the same way as described above.
Construction of a 4 pitched hipped roof using the example of a gazebo
For a square gazebo 4.5*4.5 meters, we made a hip roof covered soft tiles. The slope angle chosen was “floor material”, taking into account snow and wind loads - 30°. Since the structure is small, it was decided to make a simple system (in the figure below). The distance between the rafter legs is 2.25 m. For rafter lengths up to 3.5 m, a board of 40 * 200 mm is needed. 90*140 mm timber was used for the strapping.
We assembled the rafter system on the ground, secured it to support posts, then installed a continuous flooring made of, then -.
First, we assembled the harness that will be attached to the support posts. Next, we installed rafters that rest on the middle of the frame. The procedure here is as follows: in the middle we place a stand, on top of which the rafter legs will be joined. In this version, this rack is temporary, we only need it for a while - until we connect the first four rafters in the center. In other cases - for larger houses - this rack can remain.
We take a board of the required section and lean it against the stand in the place where they will connect (depending on the desired angle of inclination). We mark how it should be cut (at the top, at the joint and where it joins the harness). We cut off everything unnecessary, try it on again, and adjust if necessary. Next, using this blank, we make three more of the same kind.
Now you can begin to assemble the rafter system of the hipped hipped roof. The most questions arise about the junction of the rafter legs in the center. The best way- reliable and not too complicated - take a piece of timber of a suitable cross-section, make an octagon out of it - for joining eight rafter legs (four corner and four central).
The size of the edges is according to the cross-section of the rafter legs
Having fixed all four central elements of the rafter system with nails, we perform the same operations with the corner rafters: we take one, try it on, cut it out, make three copies using the template we made, and mount it.
Using the same principle, we make half-legs (shortened rafters). If desired, all connections can be further strengthened with corners or metal plates, then the rafter system of the hipped roof will be more reliable and you will not be afraid even in the heaviest snowfalls.
We install the assembled system on the gazebo posts, fasten it with nails, corners, and secure it with slopes. After this, you can install the sheathing (in this case, solid) and lay the roofing material.
The roof is no less important element houses than the foundation and walls. Its design sets the mood for the entire architectural ensemble, making the building neat and attractive. The hipped roof has gained wide popularity not only because of its high reliability and external attractiveness, but also due to the opportunity to equip additional structures - attic and dormer windows, bay windows, etc. Despite the fact that the installation of such a roof is a little more expensive and more complicated than a gable structure, it is still easy to build it with your own hands.
Advantages of hip roofs over gable structures
One of the main tasks that appears even at the stage of designing your own home is choosing the type of roof. The presence of many options among gable and hipped structures requires an answer to the question of which roof to give preference to. And although the aesthetics of the structure plays an important role, the criteria of reliability and practicality still come to the fore.
A gable roof is a classic structure that is formed by two opposite slopes and a pair of vertical end parts called gables. The spacious under-roof space allows you to equip an attic, living space or use the attic for domestic purposes.
The classic gable roof is easily recognized by a pair of rectangular slopes that adjoin each other along the central axis of the building, and two triangular gables at its ends
Structures of this type due to their simplicity and practicality long time remained the most popular in individual construction. At the same time, the dependence of the roof geometry on the size of the building, as well as the complication and rise in cost of the structure when arranging the attic, forced the search for other, more practical and functional options. And they were found in the form of various hipped roofs, which are based on a pair of triangular and two trapezoidal slopes. The latter are often called hips, and the roof itself is called a hip roof. When erecting a structure of this type, there is no need for gables and it becomes possible to make the building more modern and original.
The slopes of the simplest hip roof define surfaces in the form of two trapezoids and a pair of triangles There are several advantages of hip roofs over traditional gable structures:
- the possibility of installing attic windows directly on the slopes;
- increased strength, reliability and stability of the rafter system;
- increased resistance to weather factors;
- the possibility of increasing the area of the attic by simply reducing the width of the base of the hip;
- more uniform distribution roof weight;
- improved temperature regime when arranging an attic room.
Don’t be fooled by the numerous advantages of a more stylish hipped roof - it also has disadvantages. These include a more complex design, a slight reduction in the size of the attic space and wasteful use of roofing material. As for expenses, the budget required for the construction of one and the other roof differs slightly.
The hipped roof is not a know-how in architecture - its design has been known since ancient times Classification of hip roofs
Differences in the shape of buildings, as well as the requirements for functionality and practicality of the traditional hip roof, have led to many variations. If we do not consider the most exotic of them, then we can distinguish several main types of hipped roofs.
- Traditional hip roof, the side slopes of which reach the eaves level. To construct its main surfaces, straight rafters are used, and the ribs of the hips form beams extending from the ends of the ridge. The elaborate design and distribution of the weight of the roof over a larger area allows not only to position the overhangs on the same line, but also to increase their reach. Thanks to this, the façade of the building is reliably protected from rain even in strong gusts of wind.
Glazing elements are often built into the slopes of a classic hip roof. - A hip roof can be installed on a house that has a square shape in plan. A special feature of this design is the slopes of the same configuration. Their ribs converge at one point, and their hips have the shape of isosceles triangles.
Hip roofs are widely used in modern individual construction - Half-hip roofs got their name because of the shortened hips. Unlike traditional roofing, their length is reduced by 1.5–3 times compared to the size of the main slopes.
The side slopes of half-hip roofs have a shortened length, so they do not reach the eaves line - The Danish half-hip roof has a small gable under the ridge and a short hip on the eaves side. This design allows you to install ventilation and lighting elements directly into the vertical end of the roof, thereby eliminating the need for installation skylights.
The Danish project is good because it allows you to easily equip attic spaces - A half-hip Dutch roof has a vertical gable that divides the hip into two short slopes. Although the Dutch rafter system has increased complexity, it allows you to make the attic space more spacious and practical. In addition, this design is excellent for installing vertical glazing in the attic.
A roof built according to a Dutch design is still rare in our area. - A sloping hip roof has several slopes different sizes on one slope. Thanks to their different slopes, it is possible to increase the volume of the under-roof space. Although a broken structure cannot be called simple, houses with such a roof are very common. The reason for its popularity is the ability to arrange additional living rooms on the top tier. For this reason, a roof with broken slopes is often called an attic roof.
broken roof somewhat burdens the architecture of the building, but it allows you to arrange several living spaces in the attic space
There are also more complex structures from many hips, as well as those in which a hipped roof is combined with other types of roofing systems. The design and installation of such a roof requires many years of experience and knowledge, so it is better to entrust the construction of a sophisticated roof to specialists.
Design of hip roofs
When developing a hip roof, all types of loads that will affect it are taken into account. To do this, you must first resolve several important issues:
- purpose of the attic space;
- roofing material;
- degree of atmospheric influence in the construction region.
Based on these factors, the degree of slope of the slopes and the roof area are determined, the loads are calculated and a decision is made on the design and parameters of the rafter system.
Geometric parameters of slopes
The angle of inclination of the slopes depends on the snow and wind load, therefore it varies greatly within wide limits- from 5 to 60 degrees. In areas with rainy weather and high snow cover, roofs with a slope of 45 to 60 degrees are erected. If the region is characterized by strong winds and minimal precipitation, then the slope can be reduced to the very minimum.
When determining the angular parameters of the roof, it is necessary to take into account what material it will be covered with:
- slate sheets, ondulin, roofing metal and rolled materials are laid on slopes with a slope of 14 to 60 degrees;
- the tiles are mounted on a surface with a degree of slope from 30 to 60 degrees;
- Roll coating is used on sloping slopes - from 5 to 18 degrees.
Having decided on the angle of the roof, it is not at all difficult to calculate at what height the ridge will be. To do this, use simple trigonometric formulas for a right triangle.
Roof area
Even the most complex hip roof consists of individual slopes that follow the contours of the simplest geometric shapes, so most often for calculations it is enough to know the linear dimensions of the base and the angles of inclination of the hips.
To determine the square footage of the roof, it is necessary to add up the areas of the slopes of which it consists The total roof area is calculated by summing the square footage of the individual hips. Slopes of complex configuration are divided into several simple surfaces, after which separate calculations are carried out for each of them.
The principles for calculating the geometric parameters of hip roofs are based on calculations for simple surfaces Load calculation
Loads acting on a hipped roof are divided into two types:
- permanent,
- periodic.
The first includes the weight of roofing materials, rafters, sheathing and other frame parts. The second is the forces exerted by precipitation and wind force. In addition, when calculating, one should take into account the payload in the form of various engineering systems and communications attached to the elements of the rafter system.
Based on SNiP, when designing a roof it is necessary to assume a snow load of 180 kg/sq.m. m. If there is a danger of snow accumulation on the roof, this parameter increases to 400–450 kg/sq. m. If the roof has a slope angle of more than 60 degrees, then the snow load can be ignored - precipitation does not linger on surfaces with such steep slopes.
The force of wind loads is much less - up to 35 kg/sq. m. If the roof slope is from 5 to 30 degrees, then the effect of the wind can be neglected.
The above parameters atmospheric influences are average values accepted for the middle band. When performing calculations, correction factors should be used depending on the region of construction.
Calculation of the rafter system
When calculating the rafter system, the pitch of the rafters and the maximum load they can carry are determined. Based on these data, a decision is made to install braces, which help redistribute the load, and tie-downs, which protect the frame from loosening.
The main load of the hip roof falls on the diagonal rafters The presence of hips on hipped roofs, in addition to the usual rafters, requires the installation of diagonal rafters (in other words, slanted ones) - those that are attached to the ridge and directed to the corners of the building. Their length is greater than the transverse node elements of the roof. In addition, shortened elements - sprigs - are attached to the diagonal ribs. Compared to conventional rafters, slanted legs experience a load increased by 1.5–2 times, so their cross-section is doubled, and to ensure multi-span they are supported by one or two racks.
Often, hip roofs have a complicated rafter system, which, in contrast to a simple hipped structure, places additional load where vertical supports are installed. This feature must be taken into account when calculating the strength wooden frame roofs.
The laying distance of the rafters is called the pitch and is determined based on the length of the rafter leg and the cross-section of the lumber used. It is most convenient to determine this parameter using special tables, one of which is given below.
Table: dependence of the cross-section and pitch of rafters on their length
Manual calculations are quite labor-intensive. To reduce design time, you can use one of the online calculators to determine the parameters of hip roofs. With its help, you can determine not only geometric parameters, but also a lot of other equally important factors:
- amount of moisture and heat insulation, taking into account overlaps;
- amount of roofing material, including waste generated during cutting;
- the volume of lumber required for arranging the rafter system;
- length of overhangs, etc.
Video: using a construction calculator to calculate a roof
What materials will be needed to assemble the rafter system?
For the construction of a hip roof, timber and boards made of larch, pine and other coniferous wood are best suited. When choosing material for construction, it is necessary to carefully reject defective boards. Fungal damage, knots and cracks reduce the strength of the boards and affect the durability of the roof. When the wood moisture content is more than 22%, lumber is stacked on outdoors and dry. It should be understood that under-dried boards may warp, and this, in turn, will lead to a violation of the geometry of the roof with possible damage to the finishing coating.
To assemble a wooden frame, a rectangular beam with a cross-section from 80x80 mm to 150x150 mm is used - the exact parameters are determined by calculation or using the table above. As an alternative, you can use a board with a section of 50x100 mm or 50x200 mm. If there is a need to strengthen the rafter leg, then paired boards are used.
For reliable fastening, as well as increasing the rigidity of the wooden frame, steel staples and other metal elements. Often, steel supports, rather than wooden ones, are installed under particularly loaded ridge girders. Combined frames have increased strength and reliability.
Features of the rafter system
In order to correctly design and install a hip roof, it is necessary to understand in detail its design, as well as the design features of the most common types of hip roofs.
The structure of the rafter system in detail
The frame of a hip roof consists of most of the same parts as a gable roof, but a more complex rafter system requires installation additional elements. Upon closer examination, the following components can be found:
All these elements can be found in any type of hip roof. The only exception is the hip roof, which does not have side rafters or ridge beams.
In wooden and frame houses The rafter system is mounted without a Mauerlat. In the first case, its functions are taken over by the outer crowns, and in the second - by the upper trim.
Types of rafter systems for hip roofs
Since the basis of the hip roof rafter system is made up of slanted rafters, when installing the roof frame, you must adhere to the following rules:
- In structures where the slanted legs experience increased load, timber of double thickness is used for their manufacture.
- The splicing of individual parts of diagonal rafters is carried out in places with maximum load (most often in their upper part) and strengthened with the help of struts and vertical posts installed at an angle of 90° to the rafter legs.
- When making slanted rafters, allowance should be made for local trimming, so the estimated length of the beam is increased by 5–10%.
- Critical connection points of slanted rafter legs must be reinforced with metal fasteners - staples, twists or perforated construction strips.
When choosing a rafter system, it is necessary to take into account the size of the building and the presence of internal supports or permanent walls. Based on specific conditions, a scheme with hanging or layered rafters is chosen.
Hanging rafter system
The roof structure with hanging rafters has no supports midline, so the main weight falls on the outer perimeter walls. This feature manifests itself in the redistribution of internal forces - the rafter system is subjected to compressive and bending loads. As for the walls, significant pushing forces are transmitted to them. To eliminate this factor, each pair of rafters is connected to each other by so-called puffs - jumpers made of wooden beam or rolled metal.
The tie can be located either at the base of the rafter legs or above. In the first case, the lintel will also act as a transverse beam, which is a good option when constructing an attic roof. If the tightening is installed in the area of the midline or above, then it will only serve as a securing link. It should be noted that the cost of the rafter system depends on such a seemingly insignificant moment as the installation height of the tie rods. The higher the cross-lintels are located, the larger the cross-section of all components of the wooden frame should be.
Hip roofs with layered and hanging rafters have differences between the supporting elements of the structure Construction with layered rafters
A hip roof with layered rafters is suitable only for those houses inner space which are divided into two equal parts by a main wall or support pillars installed to support the ceiling. In this case, the lower edge of the rafter legs rests on the mauerlat, and the middle part rests on the load-bearing partition. The presence of additional support points allows you to relieve the elements of the rafter system by removing alternating horizontal forces from them, as well as from the walls of the building. Like roof beams, rafters begin to work only in bending. A frame with layered rafters becomes more rigid and durable compared to a structure that uses unsupported rafters. And this despite the fact that in the first case you can use timber of a smaller cross-section. And this helps reduce the weight of the wooden structure and reduces the cost of purchasing lumber.
Installation of a hip roof
The assembly of the rafter system must be carried out in a strictly defined order. This is necessary in order to correctly install and secure all structural elements of the roof.
- To redistribute the load exerted on the walls by the roofing structure, wind and precipitation, a Mauerlat is laid on the external walls. In individual construction, timber with a cross-section of at least 100x150 mm is used for these purposes. Anchor pins are used to secure the longitudinal beams of the structure. They must be laid in the upper rows of the masonry at the stage of wall construction. Waterproofing of the Mauerlat is carried out using two layers of roofing material, which is laid on top of the load-bearing walls.
The Mauerlat is attached to the load-bearing wall using bolts or anchors - If it is necessary to install vertical supports, beds are laid on the load-bearing walls. Wooden pads are used to horizontally level the elements of the rafter system. In the future, this will greatly simplify the installation of racks and purlins. If capital partitions are not provided for in the building plan, then vertical supports are mounted on floor beams. To do this, they are strengthened by joining two 50x200 mm boards or using one 100x200 mm beam.
Support of vertical posts on beams is allowed only if the structure rests on a permanent pier - Exhibit support posts. To level them, use a plumb line or laser level, after which temporary supports are installed. For attaching a vertical support to a bench or horizontal beam use metal corners and plates.
- Purlins are laid on top of the racks. A traditional hip roof requires the installation of one purlin, which, in fact, forms the ridge. Tent structures require the installation of four purlins. As with the installation of racks, fastening is carried out using metal corners and self-tapping screws.
The ridge purlin can be attached either directly to the rafter leg or by means of wooden overlays - Preparing the rafters. The side rafters of simple hipped roofs are mounted in exactly the same way as the rafters on a gable roof. First you need to make a template. To do this, from the side of the outer support, apply a board of the same width as the rafters to the ridge. Its thickness should not exceed 25 mm - the template should be light. On this board, mark the notch necessary for reliable support and precise fit of the rafter leg to the ridge beam, as well as a cutout corresponding to the junction with the Mauerlat. The marked areas are cut out and then used for quick preparation of the rafter legs.
Making a template can reduce the time it takes to prepare rafters for installation - By applying the manufactured sample to the purlin, it is necessary to check whether precise adjustment of the rafters is necessary. If there are gaps, cuts in the rafters are made taking into account the amendments. After all the supporting legs are ready, they are set in increments of 50–150 cm and attached to the Mauerlat and the ridge. For installation, staples are best suited, but strong metal corners can also be used.
- As already mentioned, diagonal rafters are made from spliced boards or timber of increased cross-section. To install them, you will also need a template, which is prepared in full accordance with the method described above. Since the slanted rafters are adjacent to the corner of the mauerlat on one side, and rest on the racks on the other, the cut is made at an angle of 45° to the plane.
The layout of rafters and soffits on a hip roof is carried out according to a template - In the gaps between the sloped rafters, sprigs are attached. Their step corresponds to the distance between the rafters, and the diagonal legs and the mauerlat act as support points. The load experienced by the rafters cannot be compared with the weight that falls on the rafters, so the former can be constructed from boards 30–50 mm thick. To speed up installation, you will need a template with notches on the side of the diagonal rafters and the mauerlat, but the cutouts on half of the frames must be made in a mirror image.
Use of metal fastening elements makes the rafter system more rigid and stable - If there is a need, fillies are attached to the rafters and frames. The ends of the rafter elements are cut along the cord.
Attaching the rafters to the Mauerlat can be done in several ways - Strengthen the slopes and side rafters. In the first case, vertical trusses are used, and in the second, struts installed at an angle of 45° are used. They are supported on beds or beams.
- After the rafter system is assembled, a roofing pie is installed on top of it.
The rafter system is prepared for installation of roofing materials
Lathing and insulation
Before proceeding with the installation of the sheathing, a vapor barrier and, if necessary, rolled thermal insulation are laid on top of the rafters. The insulation layer is covered with a waterproofing film on top, which is mounted with an overlap of 10–20 mm wide and attached to the beam construction stapler. After this, counter battens are nailed to the rafters. If the roofing pie is installed without insulation, then a vapor barrier is not required - a layer of moisture-resistant material will be sufficient.
Of course, additional slats will not be needed in this case, since the boards supporting the roof will be attached directly to the frames and rafter legs.
- Depending on the type of roofing material, one of two types of sheathing is used on hip roofs:
- continuous;
sparse. The first one is most often equipped for soft roof and only in some cases - for arranging the attic space. This type of lathing is made from boards with a width of 100 to 200 mm and a thickness of at least 20–25 mm. Installation is carried out without gaps. In addition, the use of plywood sheets and OSB boards . Their advantage is an extremely flat surface, which allows you to lay roofing material with minimal costs
time and effort. Under the soft roof, a continuous sheathing of OSB, plywood or boards packed without a gap is installed
For sparse sheathing, the same boards are used as in the first case, but they are mounted with a gap. Since this type of base is used for laying slate, corrugated sheets, metal tiles and roofing iron, the distance between individual boards must take into account the characteristics of the roofing material.
The sheathing is fastened with nails, the length of which is equal to triple the thickness of the boards. If self-tapping screws are used for fixation, then you can use a shorter threaded fastener with a length corresponding to double the thickness of the lumber. For fastening slate, ondulin and others sheet materials use sparse lathing The roofing pie is mounted from the bottom up, with the first board of each slope being aligned parallel to the Mauerlat. First, the sheathing is stuffed on the hips, after which the protruding edges are cut off with a hacksaw flush with the diagonal ribs. Next, they begin to fasten the lumber on the main slopes, releasing the edges of the boards beyond the sloped rafters. After this, the ends of the boards are sawed down similarly to the first case.
Video: building a hip roof with your own hands
Typical hip roof design
When building a simple hip roof, you can use a standard project developed by specialists. Project documentation includes:
- technological map;
- roof plan;
- rafter system diagrams;
- drawings of sections and corner connections;
- statement and specification with full list materials used.
As an example, below is the documentation for standard project hip roof for a house with an area of 155 sq. m.
Gallery: drawings and diagrams of a hipped roof
The drawing indicates the exact dimensions of all roof elements. Triangles lie at the base of the truss. Rafters of trapezoidal slopes rest on long load-bearing walls buildings Tie-rods are installed at the base of the rafters and act as floor beams. When creating a project, it is necessary to take into account the length of the rafters, their pitch, the recommended cross-section of timber or boards. To fasten the rafters, wooden and hardware Fastenings allow you to transfer the load from one element of the system to another
Despite the apparent complexity of a hipped roof, building it with your own hands is not much more difficult than a gable structure. It is only important to carefully understand the purpose of the individual elements and the principles of constructing the rafter system. Otherwise, the reliability and durability of the roof will still depend on adherence to technology and careful installation. As for the additional difficulties and costs, they will be repaid with complete satisfaction from the work, which will make the building brighter and more attractive.
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A hip roof is considered one of the most complex structures. Like any other, it has its advantages and disadvantages. To make an informed decision, you need to familiarize yourself with the actual performance characteristics of a hipped roof.
Flaws
As you can see, the advantages of a hipped roof are questionable, but the disadvantages are significant.
Practical advice. Professional builders recommend choosing hip roofs only in exceptional cases when other options are unacceptable for various reasons.
Types of hipped roofs
Each country has its own building traditions and style preferences. What types of hip roofs are used by architects?
Table. Types of hipped roofs.
| Hip roof view | Short description |
|---|---|
| The simplest roof has two hip slopes of a regular triangular shape and two inclined ones in the shape of a trapezoid. The lower the angle of inclination of the slopes, the greater the overhang can be made to protect the facade and the surrounding area. |
| All slopes converge at one point, the roof ridge is missing. It is used as a covering for buildings of regular square shape. |
| A successful attempt to improve the classic hip roofs. The hip slopes are slightly lowered, which allows the installation of small windows. It has a significant drawback - due to the installation of windows, the already difficult installation of the rafter system becomes even more complicated. There are more complex versions of such a roof - another small hip slope is made above the window. |
| It has low pediments and small hips above them. The peculiarity of this design is that all rafter legs rest on parallel load-bearing walls. Due to this, the design is slightly simplified and the attic space is increased. |
There are no universal recommendations for choosing the type of hipped roof; each developer must make a decision independently or after consultation with architects. But you should always remember that there are other, cheaper and more successful options for rafter systems.
Step-by-step instructions for building a hipped roof
As an example, let’s look at the simplest of the listed types of hip roofs – the classic one. But even such a simple hip roof design is much more complex than any gable roof.
Important. You can start building a hip roof only after the professionals have made all the calculations. The best option– order a house project from the relevant organizations. This will cost much less than restoring the structure after its destruction.
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At the final stage of building construction, it is necessary to equip the roof. There are a large number of its structural solutions, but among the variety, owners of private cottages often prefer the construction of a hipped roof. This type of roofing is characterized by its complexity installation work, but the result exceeds all expectations, since the design has excellent appearance, thanks to many variations, as you can see by looking at the photo. In addition, the hipped roof has a long service life.
Variety of hip roofs
When deciding how to make a hipped roof for a house, you need to consider possible options. Its main varieties are: tent, hip, half-hip.
Hip roof . Its design consists of four triangles, the vertices of which converge at a single point. The base of such a roof can be a square or a rectangle, and the slopes, respectively, can be equal in size or paired (more details: " ").
Hip roof . Building a hip roof of this type with your own hands seems difficult, but if you have the skills to create a conventional roof, this task is quite doable. When the base of the house has the shape of a rectangle, a hip structure is usually used. Two triangular planes are arranged at its ends, and two facade slopes are made in the form of a trapezoid. These two triangular shaped surfaces are called hips.
Design calculations for a hipped roof
Installation of a roof of this form cannot be implemented if there is no project for its construction.
The procedure for calculating a hip roof correctly is known only to employees of specialized design organizations. The technical documentation prepared by specialists contains drawings of the truss structure, its main connection points, a diagram of the roofing “pie” and other elements for arranging the roof.
When calculating strength indicators, it is taken into account that the rafter system is subject to constant (including the weight of the roof itself) and temporary loads. The latter factors include precipitation, strong winds, and the weight of people inspecting or repairing the roof. The weight of the roof is determined by multiplying specific gravity each material used per surface area of the slopes. To do this you need to know.
The rafters, which are the most important part of the rafter system, are made from rectangular timber with a cross-section from 50 to 150 millimeters. Thanks to this element, the necessary rigidity is ensured, so the lumber for it must be made from quality wood, without defects.
The technology for how to build a hipped roof involves the sequence of installation of the truss structure. First, you need to install the mauerlat (the lower frame of the house roof), which is a support made of timber and logs. To check the correct installation of rafter system elements, use a building level (read also: " "). During installation, the Mauerlat is positioned so that the lower frame extends beyond the outer walls of the building by at least 40 centimeters along the perimeter of the building. To prevent the walls from getting wet, two layers of roofing material are laid between them and the Mauerlat. IN wooden log houses lower frame truss structures the upper crown protrudes.
When the Mauerlat is laid, they begin to install frame rafter legs, which are called diagonal or slanted. To give additional strength, they are secured with racks or struts, and thus the structure has greater rigidity and the load is distributed evenly. If there is a need for this, side girders are built to support the rafters. They are also installed on three supports of the central beam - on both sides and in the center. Then the main frame is assembled, for this purpose the inclined rafters are secured to the support beams and at the same time to the ridge girder. The installation step does not exceed 50 centimeters, otherwise the structure will be fragile and will not be able to withstand external loads.
Rafter system of a hipped roof, detailed video instructions:
To avoid excessive vibration in windy weather and to increase strength characteristics roofing system, you can fasten external rafters together at a distance of one meter from the ridge girder, for which boards with a cross-section of at least 40x120 millimeters are suitable.
Before making a hipped roof, you need to make sure that the material for the inclined rafters does not have a shorter length than the calculated value. True, absolutely precise selection regarding size is not required, since the rafter legs will be trimmed. When building a hipped roof, experts recommend using a lot of fasteners such as nails to ensure maximum reliability of the structure.
When the frame assembly is completed, they begin laying the roofing pie: vapor barrier, insulation, waterproofing and covering material. The choice of the latter depends on the angle of inclination of the slopes, and it must be selected first. Roll coating – perfect option For flat designs(5-18 degrees), and at 30-60 degrees use asbestos cement slate, corrugated sheet or metal tiles.
The amount of roofing material that needs to be purchased is determined based on the area of the roof. Before calculating the area of a hipped roof, the area of each slope is calculated and the resulting result is summed up.
When creating a hipped roof, a decent result can only be obtained if you have a project and drawings.