Construction of a frame for a roof with four slopes is a complex process with characteristic technological features. During construction, our own structural components are used, the sequence of work is different. But the result will amaze with its spectacular shape and durability when repelling atmospheric attacks. And the home master will be able to be proud of his personal achievements in the field of roofing. However, before deciding on a device of such a design, it is worth familiarizing yourself with the algorithm according to which a rafter system of four pitched roof and with the specifics of its structure.
The class of hipped roofs combines two types of structures that resemble a square and rectangular envelope in plan. The first variety is called tent, the second - hip. Compared to their pitched counterparts, they are distinguished by the absence of pediments, called gables in the roofing industry. In the construction of both versions of hipped structures, layered and hanging rafters are used, the installation of which is carried out in accordance with standard technologies for the construction of pitched rafter systems.
Characteristic differences within the four-slope class:
Based on the configuration of the roofs in plan, it is clear that tent structures are usually erected over square buildings, and hip ones over rectangular houses. Both soft and hard roofing materials are suitable for covering. Characteristic square or rectangular shape repeat the drawings of the rafter system of a hipped roof with a clearly marked arrangement of elements in the plan and vertical projections of the slopes.
Often, hip and hip systems are used together in the construction of one building or effectively complement gable, lean-to, sloping and other roofs.
Structures with four slopes can rest directly on the upper crown of a wooden house or on the Mauerlat, which serves as the top frame of brick or concrete walls. If upper and lower supports can be found for each rafter, the roof frame is constructed using layered technology.
Installation of layered rafter legs easier and more accessible for an inexperienced home roofer, who needs to take into account that:
Issues of fastening the Mauerlat and the closely related method of installing rafter legs according to the rules are resolved at the stage of designing a house. If the building does not have an internal load-bearing wall or it is not possible to build reliable supports for the central part of the roof, nothing will work other than a hanging rafter system assembly scheme. True, in most cases the layered construction method is used, for the implementation of which it is necessary to provide in advance a load-bearing support inside the structure.
In the construction of rafter systems for hipped and hipped roofs, specific structural elements are used, these are:
Diagonal rafters and flanges are also used for the construction of valleys, only then concave corners of the roof are arranged, and not convex ones like hip ones.
The whole difficulty of constructing frames for roofs with four slopes lies in the installation of diagonal rafters, which determine the result of the formation of the structure. In addition, the slopes must withstand a load one and a half times greater than ordinary rafters of pitched roofs. Because they also work as a hobbyhorse, i.e. support for the upper heel of the runners.
If we briefly describe the procedure for constructing a layered frame for a hipped roof, then it can be done in several stages:
In the case of using a hanging frame scheme, the start of the construction of the tent frame will be the installation of a triangular truss in the center. The installation of a four-slope hip rafter system will begin with the installation of a number of roof trusses.
Construction of a hip rafter system
Let's look at one of the common examples of a hip roof with layered rafter legs. They will have to rely on floor beams laid on top of the mauerlat. Rigid fastening with a notch will be used only to fix the top of the rafter legs on the ridge girder, so there is no need to strengthen the Mauerlat fasteners. The dimensions of the box of the house shown in the example are 8.4 × 10.8 m. The actual dimensions of the roof in plan will increase on each side by the amount of the eaves overhang, by 40-50 cm.
Mauerlat is a purely individual element; the method of its installation depends on the material of the walls and the architectural features of the building. The method of laying the Mauerlat is planned according to the rules during the design period, because for reliable fixation of the Mauerlat it is recommended:
The mauerlat is made from timber measuring 150×150 or 100×150mm. If you intend to use the under-roof space, it is advisable to take thicker beams. The timber is connected into a single frame with oblique cuts. Then the connection areas are reinforced with self-tapping screws, ordinary nails or wood grouse, and the corners are reinforced with staples.
Floor beams are laid on top of the horizontally leveled mauerlat, constructed in the optimal way for a particular building. A beam with a cross section of 100×200mm is used. The first step is to lay a beam running exactly along the central axis of the building. In the example, the length of the timber is not enough to construct solid beams, so they are assembled from two beams. The docking point must be located above a reliable support. In the example, the support is an internal load-bearing wall.
The pitch between the floor beams is 60 cm. If the box being equipped does not have ideal parameters, as is the case in most situations, the distance between the beams can be changed slightly. Such an adjustment allows you to slightly “smooth out” the flaws in construction. Between the outer beams on both sides and the walls of the house there should be a gap of 90 cm wide, necessary for installing the outriggers.
Because the floor beams can independently form only two eaves overhangs; short half-beams of the floor - extensions - are attached to their ends. They are first installed only in the area of the main part of the hip roof, exactly where the rafter legs are to be mounted. The extension is nailed to the mauerlat, fastened to the beam with screws, large-caliber nails, dowels, and the fasteners are reinforced with corners.
The central part of the hip roof is an ordinary gable structure. The rafter system for it is arranged according to the rules dictated by the technology for constructing pitched roofs. In the example there are some deviations from the classical interpretation of the pitched principle: the bed on which supports for the ridge run are traditionally installed is not used. The work of the beam will have to be done by the central floor beam.
In order to build the ridge part of the hip roof rafter system you need to:
If the floor beams were laid across the frame, then the rafters of the main part of the roof would rest on the floor beams, which is much more reliable. However, in the example they rest on the stem, so it is necessary to arrange additional mini-supports for them. These supports should be positioned so that the load from them and the rafters located above is transferred to the walls.
Then three rows of outriggers are installed on each of the four sides. For the convenience of further actions, the roof contour is formed with a cornice board. It must be nailed to the floor beams and extensions strictly horizontally.
Installation of corner extensions
In the space limited by the eaves board, there were corner areas left unfilled with parts of the rafter system. Here you will need corner offsets, for installation of which is carried out as follows:
The remaining three corner extensions are manufactured and installed in the same way.
Installation of diagonal rafters
Diagonal, or also slanted, rafter legs are made from two boards sewn together with a cross-section equal to the size of ordinary rafters. In the example, one of the boards will be located slightly higher than the second due to the difference in the angles of inclination of the hips and trapezoidal slopes.
Sequence of work for the manufacture and installation of slopes:
Following the described algorithm, you need to install three more diagonal legs. Supports should be installed under each of them at the point where the corner extensions are connected to the beams. If the span is more than 7.5 m, another support is installed diagonally closer to the ridge.
Manufacturing and installation hip rafters
The lace between the top of the skate and the center of the slope is already stretched. It served as an axis for outlining cuts, and now you need to measure the angle γ using it and calculate the angle δ = 90º - γ. Without deviating from the proven path, we prepare templates for the upper and lower supports. We apply the top trim to the place intended for it and mark the cut lines on it for a tight fit between the diagonal rafters. Using the blanks, we make the central leg of the hip and fix it where it should be.
We install short extensions in the space between the corner extensions and the cornice board to add rigidity to the structure and to ensure strong fixation of the outermost, shortest extensions. Next, you should start making templates for the makers themselves:
In accordance with the actual length and “indications” of the templates, the splices are made, which are necessary for forming the planes of the hips and the parts of the main slopes that are not filled with ordinary rafter legs. They are installed so that the upper fastening points of the spigots to the diagonal rafters are spaced apart, i.e. top connecting nodes adjacent slopes should not converge in one place. The splices are attached to the slanted rafter leg with corners, to the floor beams and outriggers in the way that is more reasonable and convenient: with corners or metal toothed plates.
The technology for installing a hip roof is based on the already familiar hip principles. True, there is no ridge part of the rafter system in their design. The construction begins with the installation of a central support, to which the rafters are attached, and then the frames. If hanging technology is used in the construction of an envelope roof, then the finished truss is installed first.
We invite you to take advantage of our free online calculator for calculations of building materials when installing a hip roof - go here and follow the instructions.
The video will briefly introduce the sequence and rules for installing the rafter system of a hipped roof of the hip and hip categories:
Having become familiar with the specifics of the device and having mastered the intricacies of installing roofs with four slopes, you can safely begin to implement plans for its construction.
Rafter system- this is a combination of all the supporting elements that form the frame on which it rests roofing pie. The ability of the roof to withstand wind and snow loads and to protect interior spaces from water and cold. In order not to resort to expensive services of companies performing roofing professionally, we will tell you what the rafter system of a hipped roof consists of, what materials are required for its manufacture and how to assemble it.
The name “hippable” combines several types of roofs, consisting of four planes, slopes:
Despite the external differences, the rafter systems of a hipped roof are made up of the same elements, guided by the same rules.
The hip roof truss system takes different kind, depending on the initial conditions: the area of the house to be covered and internal layout. There are three types:
What type of rafter system is suitable for a particular house is determined during the design period, making calculations and drawing up drawings.
The design of the rafter system for a hipped roof begins with calculations that determine the geometry of the future structure:
The process of designing a rafter system for a hipped roof can be facilitated by special computer calculator programs that only require entering the initial data: the size of the house, the number of slopes.
The next stage of design is determining the composition of the elements of the rafter system and their cross-section. To do this, calculate the loads to which the hipped structure is subjected. They are divided into three types:
By summing up the values of all loads, the total load is determined, which, depending on the roofing material used, can reach 180-250 kg per square meter. Based on this figure, the number of elements of the rafter system and their cross-section are determined by checking the reference table. It is more convenient to calculate more complex systems in special programs, the result of which is a ready-made diagram of a hipped roof truss system.
The rafter system of a hipped roof consists of many components, mandatory and auxiliary:
Having a drawing of the rafter system in hand, you can begin assembly work. Since natural wood is mainly used as a material, it would not be superfluous to treat it with an antiseptic deep penetration to protect against moisture and bacteria. Roofers pay attention to a number of features that should be taken into account when installing a hip roof truss system:
A well-designed and well-assembled rafter system is the basis for the long-term operation of a hipped roof, which will become reliable protection from bad weather, regardless of whether it is a tent or a hip one!
Pitched roofs are quite popular in private suburban construction, and therefore many people are of great interest in the rafter system of a hipped roof, which has some design features.
This type of roof is the preferred option both for a country cottage and for a gazebo built on the adjacent territory.
It should be noted that the hipped roof gives the building a rather attractive appearance, and also allows for an additional large attic space.
The rafter system of a hipped roof has a complex structure and its installation should be carried out only according to a preliminary calculation, the result of which should be a diagram.
The calculation of such a roof, both for a house and for a gazebo, can be done with your own hands if you use a special program developed specifically for these purposes.
Its rafter system allows several various options. Hip roofs include half-hip roofs and hip roofs, and each of them has its own specific features and differences.
Some types of these types of rafter systems, the installation of which you can do yourself, are presented in the photo below.
The structure and design of the rafter system for a hipped roof type primarily depends on the configuration.
Currently, the most common are hip, hip, and half-hip rafter system structures, which can be used both for a private house and for a gazebo.
Each of them has both advantages and disadvantages.
In any case, the rafter system of a hipped roof requires a calculation that is made depending on the type chosen.
The hip type of rafter system is quite popular in private construction. Its design is quite resistant to various external influences and involves the construction and installation of trapezoidal type slopes.
As a rule, its installation is carried out using several separate rafters that extend from the two upper points. This type of rafter system can also be used to build a gazebo.
Hip roof options can be seen in the photo below.
Also quite common is a half-hip roof, the design of which vaguely resembles a gable roof.
The advantage of this type of rafter system is the ability to install a vertical window in the upper attic area.
Its design assumes the absence of a sharp protrusion, which allows it to withstand fairly strong wind loads.
In addition, in some cases, the half-hip rafter system makes it possible to equip full glazing of the upper space.
A hipped roof also belongs to the hipped roof, but for its arrangement it is necessary that the structure near the walls of the building be made in the shape of a square.
The construction of this type of roof implies, due to a certain design of the slopes, the formation of a triangle with equal sides. Very often, a hip roof is installed on gazebos.
Any type of this type of rafter system requires an exact calculation, on the basis of which the installation is carried out with your own hands.
A hip roof, regardless of its type, must have a frame, the design of which requires the presence of sufficient large quantity a variety of elements.
Each of them has a specific purpose and must meet its functional requirements.
In order for such a roof to withstand all possible loads during its operation, it is necessary to accurately calculate the capabilities of each of its constituent elements.
Such a calculation is quite complex calculations that cannot always be done by hand.
It is best to entrust the calculation of a hipped roof to qualified specialists who have professional training.
You can do the calculation yourself, but you will have to use a special program to do this.
It is easiest to make such a calculation for a gazebo, since its design has more simple form and involves using fewer elements.
When calculating the roof frame, it is important to avoid critical errors, as this can lead to serious consequences during its subsequent operation.
If mistakes are made, correcting them can lead to serious financial investments and an increase in the cost of the entire construction.
First of all, when calculating the roof frame, it is important to determine the angle of inclination of its slopes. Calculations show that the higher the angle of inclination, the more building materials will be required.
Also, when calculating the roof, you should definitely take into account the fact that the lower its angle of inclination, the more powerful the structure of the frame itself should be.
Correctly made calculations will make the rafter system better and more powerful.
A semi-hip, hip or hip roof of the hipped type is shown in the photo above.
The design of any type of hip roof frame can differ not only in the bay window, but also in the presence of certain components.
Thus, its installation involves the arrangement of a mauerlat, purlin, and also a support board. In addition, the roof frame must include tie rods, extensions, and the rafters themselves.
Installation of a hipped roof requires the installation of sheathing, as well as some other required elements.
The roof frame of the gazebo is a little simpler and this is due, first of all, to its design features. The installation of a hipped roof is shown in the video below.
In any case, in order to install the roof frame of a house or gazebo, it is necessary to develop a plan for the rafter system and this should be done as accurately as possible.
Both a half-hip roof and any other hipped roof consists directly of a frame and the rafter system itself, on which the roofing pie will subsequently rest.
An important point when arranging this type of roof with your own hands is the uniform distribution of the expected load over the entire surface of its structure and then onto the walls and directly onto the foundation of the building.
This can be achieved not only by the correct design of the roof frame, but also by its installation. For this purpose, rafter systems of the most different types.
Their choice mainly depends on the size of the house being built. In addition, the presence of load-bearing internal walls or additional supports is taken into account.
In any case, the installation of the roof can be carried out using hanging or layered rafters, which is described in detail in the video below.
Hanging type rafter systems are often used. This type of construction involves the arrangement of two independent supports, which do not imply any intermediate support.
Such rafter systems work in both bending and compression. Also, the hanging type of rafter system design creates a horizontal force, which is accordingly transmitted to all load-bearing walls.
This type of load can be reduced by using special puffs, which are jumpers made of wood or metal that connect all the wooden legs.
When constructing an attic or attic roof, such tie-downs are installed at the base of the legs. If such a tie is attached above the base of the rafters, then its main function is only securing.
It should be noted that the higher such a tightening is installed, the more durable all the constituent elements of the rafter structure should be.
In those buildings in which a load-bearing middle wall is provided, or special supports are additionally installed, as a rule, a rafter system is installed, which provides for the arrangement of layered rafters.
Such layered rafters with their lower parts rest directly on the mauerlat, which must be laid over the entire surface of the external walls of the house. In addition, in such a rafter system the middle part is additionally strengthened in the middle part of the house.
The design of the layered rafter system works in bending and has less weight than hanging rafters, which means that less building materials are used for its construction.
In addition, the rafter system, which is made using layered rafters, has higher strength and, accordingly, rigidity.
Any hipped roof, even if the device is designed for a gazebo, requires a complex structure, despite the fact that they can be equipped with a bay window of various shapes.
At the base of these types of roofs is a triangle, which determines their high rigidity and stability.
The main elements of such a roof, which bear the main load, are rafter legs, the design and installation of which should be given Special attention.
When installing such a roof with your own hands, it is recommended to maximum accuracy comply with construction rules and technology.
In addition, you should use only high-quality building materials that have the necessary strength and reliability.
When constructing a hipped roof, special attention should be paid to all its corner elements, which experience the maximum amount of loads.
If it is necessary to splice some frame elements, they should be additionally reinforced with appropriate racks and struts, which make it possible to reduce the overall load.
In general, a hipped roof is a structurally complex element of a house, which must be made in accordance with all requirements.
A roof made of four slopes - what is it good for? The numerous operational advantages of this type certainly outweigh the disadvantages. Is the rafter system of a hipped roof as simple as many construction beginners think? You will definitely find out soon! We will describe important nuances and features of the stages of erecting a hip roof in this article.
There are two options for hip roofs: hip and hip. The first type has the shape of a rectangular envelope, consisting of two main trapezoidal slopes and a ridge, and two pediment (side) slopes - triangles:
A hip roof is four identical isosceles triangles connected at one top point (reminiscent of a tent):
Both options provide for the installation of both layered and hanging rafters, which are installed using standard technologies.
In the absence of a central roof support, the choice is made in favor of a hanging rafter system. If you can find upper and lower supports for each rafter, then you should choose a layered structure. This option is simpler and more accessible for non-professional craftsmen. You just need to remember two main conditions: when rigidly fastening the bottom and top of the stops, a reinforced Mauerlat is needed, since the thrust is transferred to it; with a hinged fastening or a semi-rigid connection (for example, the top is hinged and the bottom is rigid or vice versa), the Mauerlat does not need to be reinforced:
The choice of one type of hip roof should be determined by the shape of the house itself. For square houses, hip rafters are erected, for rectangular ones - hip rafters. You can also find complex multi-pitched roofs combined type, which contain both hip and tent elements.
Both hip and hipped structures retain the basic functions of a gable roof (for example, the possibility of arranging an attic) and look very aesthetically pleasing:
“Why the extra headache and complexity?” you ask: “After all, you can build a simple gable roof much faster and cheaper.” Here the craftsmen emphasize some important points in favor of choosing exactly four slopes for the roof:
In addition to the listed “advantages”, a roof with four slopes perfectly conserves heat, can be covered with any roofing material and always has a neat appearance.
The hipped rafter structure consists of the following elements: Mauerlat, ridge beam, central and hip rafters, sloping legs, as well as beds, racks, crossbars, struts and other reinforcing parts. Let's look at the most basic elements.
Mauerlat is the most important detail structure, since the entire rafter system rests on it. It is a powerful wooden beam 100x200, 100x250, 100x100, 150x250, 200x200 cm. The mauerlat is made from solid high-quality wood, mainly coniferous. The rafter system of a hip roof, like any multi-pitched roof, requires thorough fastening of the base beam. The procedure for installing the Mauerlat in this case: the formation of a monolithic foundation at the end of the load-bearing walls with the installation of spiers; laying waterproofing; processing and installation of Mauerlat around the perimeter of the entire house; reinforced with anchors and other fastenings for maximum reliability of the base.
The Mauerlat can be laid on the edge of the wall, or in the pocket provided when laying bricks on the inside of the load-bearing walls.
Sloping legs are the four corner rafters that rest on the edges of the ridge and the corners of the mauerlat. They are the longest among all the rafter legs of the system, therefore they must have a cross-section of at least 100x150 mm for maximum rigidity.
Ridge run – horizontal beam, which connects all the rafters, the top of the rafter system. The beam must be strengthened with racks and struts. The ridge must be positioned strictly parallel to the plane attic floor and perpendicular to the posts.
Rafters for a hipped roof are divided into: central (attached to the mauerlat and ridge); main hip ones (attached to the ridge axis and Mauerlat); intermediate and shortened (installed on sloping legs and Mauerlat, connecting the corners of the slopes).
Additional reinforcing elements include ridge beam posts, crossbars or floor beams, rafter struts, wind beams, etc.
Let's consider step by step process construction of the truss structure. For clarity, we have chosen the most popular option - hip roofing. The hip roof rafter system, a diagram of which step by step, is presented to your attention below:
To depict your version of a hip roof in a drawing, you need to calculate the height, length, slopes of the slopes and roof area. This is necessary for clear and high-quality implementation of the project and selection required quantity Supplies:
Calculations should begin by choosing the angle of the roof slopes. Optimal slope The angle is considered to be 20-450. The magnitude of the slope must correspond to the climatic characteristics of the region. So, in particularly windy areas, the slope should be kept to a minimum, and for areas where there is frequent and heavy rainfall, the steepest slope angle is necessary. In addition to the weather environment, you also need to consider the roofing material you plan to use. For a soft roof the degree of inclination should be less, for a hard roof it should be greater.
And one more small but important nuance on this issue - it is better to make the slope angle the same for all four slopes. So the load will be distributed evenly, and the structure will be as stable as possible, and the aesthetic appeal will remain “at its best.”
Now, knowing the angle of inclination and the width of the house, we can use simple mathematics to calculate the height of the ridge, the length of the rafter legs, racks and other details of the rafter system. When calculating the length of the rafters, do not forget to take into account the eaves overhang (as a rule, its length is 40-50 cm).
The roof area for purchasing the required amount of roofing material is calculated as the sum of the areas of all slopes of the structure.
To erect a roof frame, you will need standard tools and equipment: drills, screwdrivers, jigsaws, hammers, chisels, etc. We already know the required amount of materials for the rafter system, so we can purchase them. The lumber for the frame must be solid, have no cracks, wormholes, have a light shade, without gray or yellow patina, and smell like fresh wood. Wet wood should not be laid on the roof immediately; it must be dried, treated with an antiseptic solution and dried again. Wood humidity should not exceed 20%.
Mauerlat is the basic part of the entire rafter system. It transfers thrust loads to the load-bearing walls of the house. Installing a Mauerlat for a hipped roof is no different from similar structures with two or one slope. This process is described in as much detail as possible in our previous articles.
The base beam, the parameters of which are described above, is placed on the armored belt and high-quality waterproofing. If it is necessary to connect the Mauerlat, then the bars are cut into half the section and overlapped using strong fasteners.
If there are load-bearing walls inside the house, then it is necessary to install beams on their ends - the basis for the support pillars of the roofing system. If there are no more load-bearing floors in the house, then the attic floor is covered with reinforced beams, on which roof supports are subsequently installed, and then the attic floor pie is laid.
Beams must have a cross-section of at least 100x200 mm. The step between them is 60 cm. You can slightly adjust this figure, depending on the characteristics of your home. The distance between the outer beams and the mauerlat should not be less than 90 cm. This distance is used for installing the half-beams of the eaves overhang (extension). The stems are attached to the two outer beams using strong anchors and reinforced metal corners.
Racks are an important part for supporting the structure; they redistribute the weight of the rafter system onto the beams or floor beams. The racks are installed strictly perpendicular to the plane of the bed. In hipped systems, the supports are installed under the ridge beam (hip roof) or under the corner rafters (hipped roof):
The racks must be securely attached to the base using metal plates and reinforced corners. The purlins are installed as additional support for the racks. In a hip roof, the purlins are rectangular in shape, while for the hips they are ordinary ridge purlins.
After we have made sure that the supports are installed correctly (using a meter and a level), we can attach the upper ridge beam. It is mounted on vertical posts and reinforced with reliable metal fasteners (plates, corners, anchors and screws). Now let's take on the corner extensions:
First, you need to install the side rafters, which rest on the ridge beam and the Mauerlat (or are secured with an offset). To do this, you need to make a template rafter with the appropriate cuts. We apply the rafter leg to the ridge, mark the place of the cut with a pencil, then mark the place of the cut of the rafters for joining with the Mauerlat and make cuts. Attach the rafter to the supports again to make sure that the connection is correct and to correct any imperfections. Now this sample can be used to make all the side rafters. Installation of the rafter legs of the main slopes is carried out according to the general rules described in the design of a gable rafter system (see article and video).
Diagonal (corner) rafters are installed next. Their upper edge is installed on the stand and joins the edge of the ridge beam. Before this, measurements are taken and the corresponding cuts of the rafter legs are made. The lower end of the diagonals is fixed in the corners of the Mauerlat:
Since diagonal rafters are longer than all other legs, they require additional support. This function is performed by trusses - support beams that are installed under each diagonal leg, in its lower quarter (this is where the greatest load occurs). Sprengel, like ridge posts, are installed on supporting corner beams located in the plane of the floor beams.
The space between the corner ribs is filled with auxiliary rafter legs - sprigs. Their lower part rests on the mauerlat, and the upper part rests on the diagonal rafter leg. The step between the frames should be equal to the step between the side rafters (50-150 cm).
All that remains is to complete The final stage formation of the roof skeleton - installation of sheathing. These are boards or bars 50x50 mm, which are attached to the rafters parallel to the ridge girder and the mauerlat. The pitch of the sheathing boards is 50-60 cm. This is quite enough for laying the roofing pie. When is it envisaged soft roof, the sheathing is laid in 2 layers (counter-lattice and sheathing).
So, we described the installation of the rafter system of a hipped roof, its basic principles, and even went a little deeper into some of the nuances. Hip and tent structures are, although not the simplest, but quite feasible options for every novice craftsman. Especially if he has good assistants. We wish you success in your work!
In private housing construction, in addition to the common gable roofs Stronger and more rigid hipped structures are often used. They are distinguished by the absence of pediments, which replace triangular slopes that cut off the ends of the ridge ridge. This configuration makes hipped roofs very attractive and economical, even though their construction increases the length of the eaves overhangs and the number of drainpipes and gutters. Therefore, they deserve the closest attention.
The design of the rafter system depends on the shape of the hipped roof. The most common configurations today are:
The hip hipped design is characterized by the fact that the slopes occupy the entire roof area - from the ridge to the eaves
The Dutch half-hip roof has truncated triangular slopes and part of the pediment into which a regular vertical window can be installed
The structure of the hip truss system depends on the selected roof configuration
Let us immediately note that the rafter system of a hipped roof will be more complex compared to traditional gable structures for two reasons.
Four-slope rafter systems are distinguished by the absence of full pediments, instead of which there are two triangular end slopes, as well as the presence of two lateral trapezoidal inclined planes, grooves and ribs
The support purlins in hipped structures have a closed contour, where diagonal rafter legs are located along the lines of the valleys and ribs
The main structural elements of the rafter system of a hipped roof are:
Thus, the number of elements of the rafter system of a hipped roof is much greater than, for example, that of a gable roof, and this, naturally, increases the cost of its construction. However, in general, as we noted above, the installation of a hipped roof will not cost much more due to the savings on laying the roofing pie, since waste insulating materials and the covering flooring when cutting into a multi-slope structure will be significantly less.
Despite the fact that the rafter system of a hipped structure is more complex and expensive, the construction of the entire roof is more profitable due to the savings on arranging the roofing pie
In addition, the hipped design:
The supporting structure of a hipped roof can be layered if the structure has capital interior walls, or hanging, when intermediate supports are not provided in the structure. With a hanging structure, the rafters rest on the walls of the house and exert a bursting force on them. To relieve the load on the walls in such cases, a tie is installed at the base of the rafter legs, connecting the rafters to each other.
The use of a layered structure makes the frame lighter and more economical due to the fact that less lumber is required for its arrangement. Because of this, the layered rafter system is used much more often in the construction of multi-pitched roofs. But regardless of the type of rafters used, only correct calculation of the supporting frame and accurate marking will increase the economic effect of constructing a hipped structure.
When calculating the rafter system, you must adhere to the following rules.
To determine the installation location of the rafters and find their length, you will need a template.
Using a template will make it much easier to measure and calculate the rafter frame of a hipped roof
The length of the rafter leg can be determined by its position (horizontal projection). There is a special table of coefficients for this, presented below. The length of the rafter is determined by the size of its projection, multiplied by a coefficient corresponding to the slope of the slope.
| Roof slope | Coefficient for calculating the length of intermediate rafters | Coefficient for calculating the length of corner rafters |
| 3:12 | 1,031 | 1,016 |
| 4:12 | 1,054 | 1,027 |
| 5:12 | 1,083 | 1,043 |
| 6:12 | 1,118 | 1,061 |
| 7:12 | 1,158 | 1,082 |
| 8:12 | 1,202 | 1,106 |
| 9:12 | 1,25 | 1,131 |
| 10:12 | 1,302 | 1,161 |
| 11:12 | 1,357 | 1,192 |
| 12:12 | 1,414 | 1,225 |
| Note: when constructing a roof frame for which there is no data in the table (for non-standard slopes), the parameters should be calculated using the Pythagorean theorem or using a mathematical proportion. | ||
Let's consider an example: a private house is being built in Yekaterinburg measuring 7.5x12 m with a planned height of a hip roof made of metal tiles of 2.7 m.
Before calculating the rafter system, it is necessary to make a sketch of the building and apply all the initial data to it
The tangent of the slope angle is determined by well-known formula calculating the sides of a right triangle as the ratio of the opposite side to the adjacent side
When arranging the rafter frame of a hipped roof, the position of the central rafter legs is initially determined using a template and a measuring rod
The length of the row and central intermediate rafters depends on the angle of the roof and the depth of their laying
Corner rafters differ from intermediate rafters in the arrangement of undercuts with a double bevel in the ridge area, deeper laying and longer undercuts for the supporting part
To calculate the length of the overhang, you need to multiply its position by the coefficient for the intermediate or corner rafters or to effective length rafters add the planned overhang length and at least 0.3 m to organize an external drainage system
Let's summarize - for the rafter frame of a hipped roof you will need:
There are only ten pairs of rafters, total length which will be approximately 100 linear meters. We add here 6 m for the ridge beam, as well as a ten percent margin, and we get that approximately 117 linear meters of lumber are needed to make a simple hip rafter frame with struts, spacers, crossbars, trusses and fillets. But if the design includes racks and a bench, then they will have to be calculated separately or a larger percentage of the margin should be added.
The measuring rod makes the work very easy and helps to avoid gross mistakes when taking measurements. It is most often made independently from plywood 50 mm wide.
A few words need to be said about short rafters. They are calculated in the same way as intermediate ones: the laying multiplied by the coefficient for intermediate rafters from the table. However, the task can be simplified and you don’t have to specifically calculate the length of the spigots, since a sufficient percentage of the margin is taken, and the trimmings of the boards will be needed for the manufacture of elements reinforcing the structure - struts, spacers, crossbars, etc.
The length of short rafters (springs) can not be calculated, since scraps of lumber will be useful for the manufacture of reinforcing structural elements
After marking the position of the components of the rafter frame, it is necessary to select suitable lumber, i.e., determine their permissible cross-section. For calculations, you will need a zoned map of snow and wind loads and thermal resistance, as well as auxiliary tables based on regulations- SNiP II-3–79, SP 64.13330.2011, SNiP 2.01.07–85 and SP 20.13330.2011.
The installation of a hipped roof includes the determination of the required cross-section of lumber, which is carried out based on an analysis of the loads on the truss structure during operation
The load from snow cover is determined by the formula S = S g µ, where S is the desired snow load (kg/m²); S g is the standard load for the real area, indicated on the map, µ is a correction factor depending on the slope of the roof. Since our tilt angle ranges from 30 to 60°, we calculate µ using the formula 0.033 · (60 – 36) = 0.792 (see note to the table below). Then S = 168 · 0.792 = 133 kg/m² (Ekaterinburg is located in the fourth climatic region, where S g = 168 kg/m2).
| Determining the angle of the roof | |
| Tangent value | Angle α° |
| 0,27 | 15 |
| 0,36 | 20 |
| 0,47 | 25 |
| 0,58 | 30 |
| 0,7 | 35 |
| 0,84 | 40 |
| 1 | 45 |
| 1,2 | 50 |
| 1,4 | 55 |
| 1,73 | 60 |
| 2,14 | 65 |
| Note: if the slope angle (α) ≤ 30°, then the coefficient µ is taken as 1; if angle α ≥ 60°, then µ = 0; if 30°< α < 60°, µ высчитывают по формуле µ = 0,033 · (60 - α). |
|
| Region No. | I | II | III | IV | V | VI | VII | VIII |
| S g, kg/m 2 | 56 | 84 | 126 | 168 | 224 | 280 | 336 | 393 |
We calculate the wind load using the formula W = W o k c, where W o is the standard indicator on the map, k is the tabular index, c is the aerodynamic drag coefficient, varying from -1.8 to +0.8 and depending on the slope of the slopes . If the angle of inclination is more than 30°, then according to SNiP 2.01.07–85 clause 6.6, the maximum positive value of the aerodynamic index, equal to 0.8, is taken into account.
Yekaterinburg belongs to the first zone in terms of wind load, the house is being built in one of the city districts, the height of the building including the roof is 8.7 m (zone “B” according to the table below), which means W o = 32 kg/m², k = 0 .65 and c = 0.8. Then W = 32 · 0.65 · 0.8 = 16.64 ≈ 17 kg/m². In other words, it is with this force that the wind at a height of 8.7 m presses on the roof.
| Building height Z, m | Coefficient k for terrain types | ||
| A | IN | WITH | |
| ≤ 5 | 0,75 | 0,5 | 0,4 |
| 10 | 1,0 | 0,65 | 0,4 |
| 20 | 1,25 | 0,85 | 0,55 |
| 40 | 1,5 | 1,1 | 0,8 |
| 60 | 1,7 | 1,3 | 1,0 |
| 80 | 1,85 | 1,45 | 1,15 |
| 100 | 2,0 | 1,6 | 1,25 |
| 150 | 2,25 | 1,9 | 1,55 |
| 200 | 2,45 | 2,1 | 1,8 |
| 250 | 2,65 | 2,3 | 2,0 |
| 300 | 2,75 | 2,5 | 2,2 |
| 350 | 2,75 | 2,75 | 2,35 |
| ≥480 | 2,75 | 2,75 | 2,75 |
| Note: “A” - open coasts of seas, lakes and reservoirs, as well as deserts, steppes, forest-steppes, tundra; “B” - urban areas, forests and other areas evenly covered with obstacles more than 10 m high; “C” - urban areas with buildings over 25 m high. |
|||
| Region No. | Ia | I | II | III | IV | V | VI | VII |
| W o , kg/m 2 | 24 | 32 | 42 | 53 | 67 | 84 | 100 | 120 |
Now let's calculate the load on the supporting frame from the weight of the roof. To do this, add up the weight of all the layers of the roofing pie laid on top of the rafters. We leave the rafters open to achieve a decorative effect, which means we lay all the layers on top of the rafters. The roof load on the elements of the rafter system will be equal to the sum of the weights of the metal tiles, sheathing and counter-lattens, insulating films, insulation, additional sheathing and ventilation slats, a solid plywood base and facing material under-roof room.
When determining the load on the supporting frame from the weight of the roof, the weights of all layers of the roofing cake laid on top of the rafters are summed up
The mass of each layer can be found in the manufacturer's instructions by selecting the highest density value. We calculate the thickness of the heat insulator using a thermal resistance map for a specific area. We find it using the formula T = R λ P, where:
So, T = 5.2 · 0.04 · 40 = 8.32 ≈ 9 kg/m². Thus, the total load of the roof will be equal to 5 (metal tiles) + 4 (solid flooring) + 23 (main, additional and counter lathing) + 0.3 2 ( insulating films) + 9 (insulation) + 3 (cladding) = 44.6 ≈ 45 kg/m².
Having received all the necessary intermediate values, we determine the total load on the supporting frame of the hipped roof: Q = 133 + 17 + 45 = 195 kg/m².
The permissible cross-section of lumber is calculated using the formulas:
The following notations are used here:
Substitute the numerical values into the formula → H ≥ 9.5 · 4.79 · √ = 9.5 · 4.79 · 0.55 = 25.03 cm ≈ 250 mm.
| Board thickness, mm | Width (H) of boards, mm | ||||||||
| 16 | 75 | 100 | 125 | 150 | - | - | - | - | - |
| 19 | 75 | 100 | 125 | 150 | 175 | - | - | - | - |
| 22 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | - | - |
| 25 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 32 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 40 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 44 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 50 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 60 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 75 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 100 | - | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 125 | - | - | 125 | 150 | 175 | 200 | 225 | 250 | - |
| 150 | - | - | - | 150 | 175 | 200 | 225 | 250 | - |
| 175 | - | - | - | - | 175 | 200 | 225 | 250 | - |
| 200 | - | - | - | - | - | 200 | 225 | 250 | - |
| 250 | - | - | - | - | - | - | - | 250 | - |
From the table, the thickness of the board with a width of 250 mm can vary from 25 to 250 mm. A table of the dependence of the cross-section on the pitch and length of the rafters will help you determine more specifically. The length of the intermediate rafters is 4.79 m, pitch 1.0 m - look at the table and select the appropriate section. It is equal to 75X250 mm.
| Rafter spacing, cm | Rafter length, m | ||||||
| 3,0 | 3,5 | 4,0 | 4,5 | 5,0 | 5,5 | 6,0 | |
| 215 | 100Х150 | 100Х175 | 100Х200 | 100Х200 | 100Х200 | 100Х250 | - |
| 175 | 75Х150 | 75Х200 | 75Х200 | 100Х200 | 100Х200 | 100Х200 | 100Х250 |
| 140 | 75Х125 | 75Х175 | 75Х200 | 75Х200 | 75Х200 | 100Х200 | 100Х200 |
| 110 | 75Х150 | 75Х150 | 75Х175 | 75Х175 | 75Х200 | 75Х200 | 100Х200 |
| 90 | 50Х150 | 50Х175 | 50Х200 | 75Х175 | 75Х175 | 75Х250 | 75Х200 |
| 60 | 40Х150 | 40Х175 | 50Х150 | 50Х150 | 50Х175 | 50Х200 | 50Х200 |
Let's give another table for those who will use hardwood lumber.
We check the correctness of the calculations by substituting the numerical parameters into the following inequality / ≤ 1. We get (3.125 · 195 x 4.79³) / (7.5 x 25³) = 0.57 - the cross section is selected accurately and with a good margin. Let's check less powerful beams with a section of 50x250 mm. We substitute the values again: (3.125 · 195 x 4.79³) / (5 x 25³) = 0.86. The inequality is satisfied again, so a beam measuring 50x250 mm is quite suitable for our roof.
After all the intermediate calculations, we summarize: to erect the roof we will need 117 linear meters edged boards section 50X250 mm. This is approximately 1.5 m³. Since it was initially agreed that for a four-slope hip structure it was desirable to use lumber of the same section, then for the Mauerlat you should purchase the same amount of timber, equal to the perimeter at home - 7.5 · 2 + 12 · 2 = 39 linear. m. Taking into account a 10% margin for cutting and scrap, we get 43 linear meters or approximately 0.54 m³. Thus, we will need approximately 2 m³ of lumber with a section of 50X250 mm.
The length of the rafters is the interval from the cut for the supporting part to the cut for the ridge beam.
The arrangement of a hipped structure has its own characteristics that must be taken into account:
Manufactured and assembled in compliance with all the rules, a layered rafter frame for a hipped roof will be a non-thrust structure. You can prevent the appearance of thrusts if the planes of the rafters are made horizontal in places where they support the Mauerlat.
In most cases, two schemes are used to support the rafter legs.
In hip hip structures, the length of the corner legs is often longer than the typical length of the lumber. Therefore, the beams and boards are spliced, trying to place the joints at a distance of 0.15 span lengths (L) from the center of the supports, which is approximately equivalent to the interval between the support points. The rafters are connected using the oblique cutting method, tightening the joints with bolts Ø12–14 mm. It is recommended to make the cut on the rafters, and not on the support beam, so that the cut does not weaken the support.
Since the standard length of most lumber does not exceed 6 m, diagonal rafters are increased in length using the oblique cutting method and connected with bolts when using timber or with nails and clamps if boards are spliced
| Span length, m | Types of supports | Location of supports |
| less than 7.5 | stand or strut | at the top of the rafters |
| less than 9.0 | stand or strut | at the top of the rafters |
| truss or stand | at the bottom of the rafters - 1/4L inc. | |
| over 9.0 | stand or strut | at the top of the rafters at the bottom of the rafters - 1/4L pr |
| truss or stand | in the center of the rafters | |
| rack | in the center of the rafters | |
| Note: Lpr is the length of the span, which is covered by rafters. | ||
To connect the frames to the rafters, the top of the half-rafters is ground off, keeping them in the same plane as the corner legs, and secured with nails. When placing sprigs on the rafters, make sure that they do not converge in one place. If you use 50X50 mm cranial bars, packed in the lower zone of the rafters on both sides, rather than a notch when installing the rafters, then the rigidity of the rafter legs will be higher, which means their load-bearing capacity will increase.
To increase the rigidity of the rafter frame, it is recommended to use cranial bars stuffed on both sides at the bottom of the rafter legs when installing the rafters.
The construction of the frame of a hipped roof is carried out in several stages.
The Mauerlat in hipped structures is laid around the entire perimeter and is well secured to the walls, especially in the corners, to create a strong unit for attaching diagonal rafters
Truss grating is used for steep roofs and relatively large spans in order to avoid deflection of diagonal rafters
When installing the rafter system of a hipped roof, you need to carefully consider the joining of the diagonal rafters, the central rafter at the end of the building, as well as the ridge beam
Self-construction of a hipped roof is, of course, not an easy process. But if you have measuring instruments, as well as the necessary tools, you will succeed. The main thing is the desire to assemble the structure with your own hands and the desire to adhere to general principles. And in order for the roof to last as long as possible and maintain its amazingly beautiful appearance, try not to skimp on the elements of the rafter frame and use modern reliable metal fasteners for wood to fix them.
A hip roof, provided it is constructed correctly, is distinguished not only by its presentable appearance, but also by increased strength, which allows it to effectively withstand precipitation and strong winds. In this article we will talk about the structure of the rafter system of a hipped roof, consider the types of such frames, and also describe detailed plan works on their construction.
The four-slope roof category includes 2 types frame systems, which schematically look like square (tent structure) and rectangular ( hip roof) envelopes. In our country, the envelope roof is quite popular. The main feature of hipped roofs is the absence of gables. To construct the rafter system of a hipped roof, in both cases hanging and layered rafters are used. Their assembly methods are standard for roofs with any number of slopes.
Distinctive features of hipped roofs of various designs:
Studying the plan of the rafter system of a hipped roof, we can conclude that the choice of the configuration of a hipped roof depends on the shape of the building. That is, square houses are covered with hipped structures, and rectangular houses are covered with hip roofs. In this case, you can use any roofing materials, both hard and soft.
When drawing up drawings of the rafter system of a hipped roof, you should clearly indicate the geometric shape, as well as indicate the position of individual elements and projections of the slopes with exact dimensions.
As a rule, hip and hip rafter systems are combined with traditional ones - single-pitch, gable and broken roofs within one object.
To support a hipped structure, you can use a mauerlat, which is the top frame on concrete or brick walls oh, and also the top crown of the log house. Layered technology is used in cases where it is possible to install upper and lower supports under each rafter leg.
Please note that the method of laying the Mauerlat and the entire rafter system should be provided for at the building design stage. In the absence of internal load-bearing walls and the impossibility of placing supporting elements for the central part of the roof, hanging rafter technology is used. However, most often they install an inclined type of stable frame, having provided for the presence of load-bearing structures in advance.
When constructing hip and hip frames, the following specific components of the rafter system of a hipped roof are used:
The same structural elements are used to create valleys, with the only difference being that the corners are made concave.
It is the installation of slanted rafters that poses the greatest difficulty. Moreover, these elements will bear an increased load, since they serve as a supporting element for fastening in the upper part of the ridges, that is, they act as a ridge. Therefore, before starting work, it is necessary to calculate the rafter system of a hipped roof.
In general, the process of erecting a roof with four slopes includes the following steps:
If a hanging type of rafter system is assumed, then the first stage of creating a tent structure will be the placement of a central truss in the shape of a triangle. When creating a hip-type structure, several trusses are attached at the starting stage.
Since private construction mainly uses hip roofs with layered rafters, let us consider in more detail the process of installing a hipped rafter system of this design. The support for the structures will be the floors placed on the Mauerlat.
Fixation using the cutting method will be performed only at the junction of the ridge with the rafters, so the Mauerlat can be installed on conventional fasteners. In the building under consideration, the box of the house has dimensions of 8.4 × 10.8 m. The roof on the plan will exceed the dimensions of the house by 40-50 cm on each side - this is the width of the eaves overhang.
Depending on the material used to construct the walls of the building, the mauerlat can be laid in various ways.
For the Mauerlat you will need a beam with a cross section of 100×150 or 150×150 mm. When planning the use of space under the roof, thicker beams should be used. The frame elements are joined with oblique notches, followed by reinforcement with nails, screws or screws, and in the corners with staples.
Next, you need to place the ceiling elements on the Mauerlat. They are made from bars with a cross section of 100×200 mm. The central beam is laid first. If the length of the lumber is not enough, it is made from two pieces of timber. Moreover, the connection point should be on a supporting element, for example, a load-bearing wall.
In this case, the beams are laid in 60 cm increments. As a rule, the box has non-ideal dimensions, so the spacing between the beams can be slightly adjusted to smooth out imperfections. The distance from the walls of the house to the outer beams located on both sides should be 90 cm. This is required for the installation of outriggers.
Extensions are attached to the end parts of the floor beams. For convenience, they are first placed only in those places where the rafters will be installed later. They are fastened to the surface of the outrigger mauerlat with nails, and to the beams with dowels, large-section nails, and self-tapping screws, after which the fastening is reinforced with corners.
The central section of the hip roof is nothing more than a traditional gable structure. Consequently, its assembly is carried out using technology for pitched roofs. Although such a design usually involves the presence of a beam on which supports for the ridge are placed, in this example the functions of such an element are assigned to the central floor beam.
The ridge section of the roof is done as follows:
Typically, floor beams are placed perpendicular to the frame so that the support of the rafter legs in the central part of the roof rests on them. Since in the example under consideration the rafters are connected to the extension, the installation of additional supports is necessary. They are placed in such a way as to redistribute the load from the rafters and supports to the walls.
In the end, you need to install three rows of stems on each side. After this, a cornice is attached strictly horizontally to the floor beams and extensions, facilitating further work on the roof.
It is necessary to install corner extensions in the corners behind the cornice board.
They are attached like this:
The same actions are performed with all remaining offsets.
The diameter of the diagonal rafters coincides with the dimensions of the ordinary elements. Since in our example the slope of the trapezoidal slopes and hips is different, one of the sloped legs is placed slightly higher than the other.
The process of creating and installing slopes is as follows:
The manufacture of the remaining 3 parts is carried out in the same way. Supports are installed under each of these rafters in the places where the beams meet the corner extensions. Additional supports near the ridge are required if the span exceeds 7.5 m.
Using a stretched cord from the ridge to the center of the slope, we measure the lower angle γ and calculate the opposite angle δ=90º-γ. Just as with diagonal parts, templates are made for cuts on the upper and lower heel of the element so that it fits tightly between the diagonal rafters. Having made the central hip rafter, it must be installed in the appropriate place.
Structural rigidity and reliable fastening of the shortest extensions are ensured by installing short extensions between the cornice and corner extensions.
At the next stage, they make templates for the makers:
The production of spigots is carried out taking into account the estimated length of the elements and according to the manufactured templates. They will fill the planes of the hips and main slopes. The installation of these parts is carried out so that the junction points of the slopes with the spouts on opposite sides do not converge in one place, that is, apart. The fastening elements for connecting the frames with the diagonal rafters are angles, and with the outriggers and floor beams - jagged plates or angles - whichever is more convenient.
The construction of a roof with a hip frame is carried out using the same technologies as with a hip frame. The only difference is the absence of a ridge in hip roofs. In this case, the installation of the hip roof rafter system begins with joining the diagonal rafters, and then the splices. If hanging rafters are used, the central truss is installed first.
Thus, a detailed study of the features of the construction of hipped roofs will allow you to begin creating frame structure with knowledge of affairs.
In private housing construction, in addition to the common gable roofs, stronger and more rigid hipped structures are often used. They are distinguished by the absence of pediments, which replace triangular slopes that cut off the ends of the ridge ridge. This configuration makes hipped roofs very attractive and economical, even though their construction increases the length of the eaves overhangs and the number of drainpipes and gutters. Therefore, they deserve the closest attention.
The design of the rafter system depends on the shape of the hipped roof. The most common configurations today are:
The hip hipped design is characterized by the fact that the slopes occupy the entire roof area - from the ridge to the eaves
The Dutch half-hip roof has truncated triangular slopes and part of the pediment into which a regular vertical window can be installed
The structure of the hip truss system depends on the selected roof configuration
Let us immediately note that the rafter system of a hipped roof will be more complex compared to traditional gable structures for two reasons.
Four-slope rafter systems are distinguished by the absence of full pediments, instead of which there are two triangular end slopes, as well as the presence of two lateral trapezoidal inclined planes, grooves and ribs
The support purlins in hipped structures have a closed contour, where diagonal rafter legs are located along the lines of the valleys and ribs
The main structural elements of the rafter system of a hipped roof are:
Thus, the number of elements of the rafter system of a hipped roof is much greater than, for example, that of a gable roof, and this, naturally, increases the cost of its construction. However, in general, as we noted above, the installation of a hipped roof will not cost much more due to savings on laying the roofing pie, since there will be significantly less waste of insulating materials and covering flooring when cutting into a multi-slope structure.
Despite the fact that the rafter system of a hipped structure is more complex and expensive, the construction of the entire roof is more profitable due to the savings on arranging the roofing pie
In addition, the hipped design:
The supporting structure of a hipped roof can be layered if the structure has permanent internal walls, or hanging when intermediate supports are not provided in the structure. With a hanging structure, the rafters rest on the walls of the house and exert a bursting force on them. To relieve the load on the walls in such cases, a tie is installed at the base of the rafter legs, connecting the rafters to each other.
The use of a layered structure makes the frame lighter and more economical due to the fact that less lumber is required for its arrangement. Because of this, the layered rafter system is used much more often in the construction of multi-pitched roofs. But regardless of the type of rafters used, only correct calculation of the supporting frame and accurate marking will increase the economic effect of constructing a hipped structure.
When calculating the rafter system, you must adhere to the following rules.
To determine the installation location of the rafters and find their length, you will need a template.
Using a template will make it much easier to measure and calculate the rafter frame of a hipped roof
The length of the rafter leg can be determined by its position (horizontal projection). There is a special table of coefficients for this, presented below. The length of the rafter is determined by the size of its projection, multiplied by a coefficient corresponding to the slope of the slope.
| Roof slope | Coefficient for calculating the length of intermediate rafters | Coefficient for calculating the length of corner rafters |
| 3:12 | 1,031 | 1,016 |
| 4:12 | 1,054 | 1,027 |
| 5:12 | 1,083 | 1,043 |
| 6:12 | 1,118 | 1,061 |
| 7:12 | 1,158 | 1,082 |
| 8:12 | 1,202 | 1,106 |
| 9:12 | 1,25 | 1,131 |
| 10:12 | 1,302 | 1,161 |
| 11:12 | 1,357 | 1,192 |
| 12:12 | 1,414 | 1,225 |
| Note: when constructing a roof frame for which there is no data in the table (for non-standard slopes), the parameters should be calculated using the Pythagorean theorem or using a mathematical proportion. | ||
Let's consider an example: a private house is being built in Yekaterinburg measuring 7.5x12 m with a planned height of a hip roof made of metal tiles of 2.7 m.
Before calculating the rafter system, it is necessary to make a sketch of the building and apply all the initial data to it
The tangent of the angle of inclination of the slopes is determined by the well-known formula for calculating the sides of a right triangle as the ratio of the opposite side to the adjacent one
When arranging the rafter frame of a hipped roof, the position of the central rafter legs is initially determined using a template and a measuring rod
The length of the row and central intermediate rafters depends on the angle of the roof and the depth of their laying
Corner rafters differ from intermediate rafters in the arrangement of undercuts with a double bevel in the ridge area, deeper laying and longer undercuts for the supporting part
To calculate the length of the overhang, you need to multiply its position by the coefficient for the intermediate or corner rafters or add the planned length of the overhang and at least 0.3 m to the estimated length of the rafters for organizing an external drainage system
Let's summarize - for the rafter frame of a hipped roof you will need:
There are only ten pairs of rafters, the total length of which will be approximately 100 linear meters. We add here 6 m for the ridge beam, as well as a ten percent margin, and we get that approximately 117 linear meters of lumber are needed to make a simple hip rafter frame with struts, spacers, crossbars, trusses and fillets. But if the design includes racks and a bench, then they will have to be calculated separately or a larger percentage of the margin should be added.
The measuring rod greatly facilitates the work and helps to avoid gross errors when taking measurements. It is most often made independently from plywood 50 mm wide.
A few words need to be said about short rafters. They are calculated in the same way as intermediate ones: the laying multiplied by the coefficient for intermediate rafters from the table. However, the task can be simplified and you don’t have to specifically calculate the length of the spigots, since a sufficient percentage of the margin is taken, and the trimmings of the boards will be needed for the manufacture of elements reinforcing the structure - struts, spacers, crossbars, etc.
The length of short rafters (springs) can not be calculated, since scraps of lumber will be useful for the manufacture of reinforcing structural elements
After marking the position of the components of the rafter frame, it is necessary to select suitable lumber, i.e., determine their permissible cross-section. For calculations, you will need a zoned map of snow and wind loads and thermal resistance, as well as auxiliary tables based on regulations - SNiP II-3–79, SP 64.13330.2011, SNiP 2.01.07–85 and SP 20.13330.2011.
The installation of a hipped roof includes the determination of the required cross-section of lumber, which is carried out based on an analysis of the loads on the truss structure during operation
The load from snow cover is determined by the formula S = S g µ, where S is the desired snow load (kg/m²); S g is the standard load for the real area, indicated on the map, µ is a correction factor depending on the slope of the roof. Since our tilt angle ranges from 30 to 60°, we calculate µ using the formula 0.033 · (60 – 36) = 0.792 (see note to the table below). Then S = 168 · 0.792 = 133 kg/m² (Ekaterinburg is located in the fourth climatic region, where S g = 168 kg/m2).
| Determining the angle of the roof | |
| Tangent value | Angle α° |
| 0,27 | 15 |
| 0,36 | 20 |
| 0,47 | 25 |
| 0,58 | 30 |
| 0,7 | 35 |
| 0,84 | 40 |
| 1 | 45 |
| 1,2 | 50 |
| 1,4 | 55 |
| 1,73 | 60 |
| 2,14 | 65 |
| Note: if the slope angle (α) ≤ 30°, then the coefficient µ is taken as 1; if angle α ≥ 60°, then µ = 0; if 30°< α < 60°, µ высчитывают по формуле µ = 0,033 · (60 - α). |
|
| Region No. | I | II | III | IV | V | VI | VII | VIII |
| S g, kg/m 2 | 56 | 84 | 126 | 168 | 224 | 280 | 336 | 393 |
We calculate the wind load using the formula W = W o k c, where W o is the standard indicator on the map, k is the tabular index, c is the aerodynamic drag coefficient, varying from -1.8 to +0.8 and depending on the slope of the slopes . If the angle of inclination is more than 30°, then according to SNiP 2.01.07–85 clause 6.6, the maximum positive value of the aerodynamic index, equal to 0.8, is taken into account.
Yekaterinburg belongs to the first zone in terms of wind load, the house is being built in one of the city districts, the height of the building including the roof is 8.7 m (zone “B” according to the table below), which means W o = 32 kg/m², k = 0 .65 and c = 0.8. Then W = 32 · 0.65 · 0.8 = 16.64 ≈ 17 kg/m². In other words, it is with this force that the wind at a height of 8.7 m presses on the roof.
| Building height Z, m | Coefficient k for terrain types | ||
| A | IN | WITH | |
| ≤ 5 | 0,75 | 0,5 | 0,4 |
| 10 | 1,0 | 0,65 | 0,4 |
| 20 | 1,25 | 0,85 | 0,55 |
| 40 | 1,5 | 1,1 | 0,8 |
| 60 | 1,7 | 1,3 | 1,0 |
| 80 | 1,85 | 1,45 | 1,15 |
| 100 | 2,0 | 1,6 | 1,25 |
| 150 | 2,25 | 1,9 | 1,55 |
| 200 | 2,45 | 2,1 | 1,8 |
| 250 | 2,65 | 2,3 | 2,0 |
| 300 | 2,75 | 2,5 | 2,2 |
| 350 | 2,75 | 2,75 | 2,35 |
| ≥480 | 2,75 | 2,75 | 2,75 |
| Note: “A” - open coasts of seas, lakes and reservoirs, as well as deserts, steppes, forest-steppes, tundra; “B” - urban areas, forests and other areas evenly covered with obstacles more than 10 m high; “C” - urban areas with buildings over 25 m high. |
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| Region No. | Ia | I | II | III | IV | V | VI | VII |
| W o , kg/m 2 | 24 | 32 | 42 | 53 | 67 | 84 | 100 | 120 |
Now let's calculate the load on the supporting frame from the weight of the roof. To do this, add up the weight of all the layers of the roofing pie laid on top of the rafters. We leave the rafters open to achieve a decorative effect, which means we lay all the layers on top of the rafters. The load of the roof on the elements of the rafter system will be equal to the sum of the weights of the metal tiles, sheathing and counter-lattens, insulating films, insulation, additional sheathing and ventilation slats, a solid plywood base and the facing material of the under-roof room.
When determining the load on the supporting frame from the weight of the roof, the weights of all layers of the roofing cake laid on top of the rafters are summed up
The mass of each layer can be found in the manufacturer's instructions by selecting the highest density value. We calculate the thickness of the heat insulator using a thermal resistance map for a specific area. We find it using the formula T = R λ P, where:
So, T = 5.2 · 0.04 · 40 = 8.32 ≈ 9 kg/m². Thus, the total load of the roof will be equal to 5 (metal tiles) + 4 (solid flooring) + 23 (main, additional and counter lathing) + 0.3 2 (insulating films) + 9 (insulation) + 3 (cladding) = 44 .6 ≈ 45 kg/m².
Having received all the necessary intermediate values, we determine the total load on the supporting frame of the hipped roof: Q = 133 + 17 + 45 = 195 kg/m².
The permissible cross-section of lumber is calculated using the formulas:
The following notations are used here:
Substitute the numerical values into the formula → H ≥ 9.5 · 4.79 · √ = 9.5 · 4.79 · 0.55 = 25.03 cm ≈ 250 mm.
| Board thickness, mm | Width (H) of boards, mm | ||||||||
| 16 | 75 | 100 | 125 | 150 | - | - | - | - | - |
| 19 | 75 | 100 | 125 | 150 | 175 | - | - | - | - |
| 22 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | - | - |
| 25 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 32 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 40 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 44 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 50 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 60 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 75 | 75 | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 100 | - | 100 | 125 | 150 | 175 | 200 | 225 | 250 | 275 |
| 125 | - | - | 125 | 150 | 175 | 200 | 225 | 250 | - |
| 150 | - | - | - | 150 | 175 | 200 | 225 | 250 | - |
| 175 | - | - | - | - | 175 | 200 | 225 | 250 | - |
| 200 | - | - | - | - | - | 200 | 225 | 250 | - |
| 250 | - | - | - | - | - | - | - | 250 | - |
From the table, the thickness of the board with a width of 250 mm can vary from 25 to 250 mm. A table of the dependence of the cross-section on the pitch and length of the rafters will help you determine more specifically. The length of the intermediate rafters is 4.79 m, pitch 1.0 m - look at the table and select the appropriate section. It is equal to 75X250 mm.
| Rafter spacing, cm | Rafter length, m | ||||||
| 3,0 | 3,5 | 4,0 | 4,5 | 5,0 | 5,5 | 6,0 | |
| 215 | 100Х150 | 100Х175 | 100Х200 | 100Х200 | 100Х200 | 100Х250 | - |
| 175 | 75Х150 | 75Х200 | 75Х200 | 100Х200 | 100Х200 | 100Х200 | 100Х250 |
| 140 | 75Х125 | 75Х175 | 75Х200 | 75Х200 | 75Х200 | 100Х200 | 100Х200 |
| 110 | 75Х150 | 75Х150 | 75Х175 | 75Х175 | 75Х200 | 75Х200 | 100Х200 |
| 90 | 50Х150 | 50Х175 | 50Х200 | 75Х175 | 75Х175 | 75Х250 | 75Х200 |
| 60 | 40Х150 | 40Х175 | 50Х150 | 50Х150 | 50Х175 | 50Х200 | 50Х200 |
Let's give another table for those who will use hardwood lumber.
We check the correctness of the calculations by substituting the numerical parameters into the following inequality / ≤ 1. We get (3.125 · 195 x 4.79³) / (7.5 x 25³) = 0.57 - the cross section is selected accurately and with a good margin. Let's check less powerful beams with a section of 50x250 mm. We substitute the values again: (3.125 · 195 x 4.79³) / (5 x 25³) = 0.86. The inequality is satisfied again, so a beam measuring 50x250 mm is quite suitable for our roof.
After all the intermediate calculations, we summarize: to erect the roof we will need 117 linear meters of edged boards with a section of 50X250 mm. This is approximately 1.5 m³. Since it was initially agreed that for a four-slope hip structure it was desirable to use lumber of the same section, then for the mauerlat the same timber should be purchased in an amount equal to the perimeter of the house - 7.5 2 + 12 2 = 39 linear meters. m. Taking into account a 10% margin for cutting and scrap, we get 43 linear meters or approximately 0.54 m³. Thus, we will need approximately 2 m³ of lumber with a section of 50X250 mm.
The length of the rafters is the interval from the cut for the supporting part to the cut for the ridge beam.
The arrangement of a hipped structure has its own characteristics that must be taken into account:
Manufactured and assembled in compliance with all the rules, a layered rafter frame for a hipped roof will be a non-thrust structure. You can prevent the appearance of thrusts if the planes of the rafters are made horizontal in places where they support the Mauerlat.
In most cases, two schemes are used to support the rafter legs.
In hip hip structures, the length of the corner legs is often longer than the typical length of the lumber. Therefore, the beams and boards are spliced, trying to place the joints at a distance of 0.15 span lengths (L) from the center of the supports, which is approximately equivalent to the interval between the support points. The rafters are connected using the oblique cutting method, tightening the joints with bolts Ø12–14 mm. It is recommended to make the cut on the rafters, and not on the support beam, so that the cut does not weaken the support.
Since the standard length of most lumber does not exceed 6 m, diagonal rafters are increased in length using the oblique cutting method and connected with bolts when using timber or with nails and clamps if boards are spliced
| Span length, m | Types of supports | Location of supports |
| less than 7.5 | stand or strut | at the top of the rafters |
| less than 9.0 | stand or strut | at the top of the rafters |
| truss or stand | at the bottom of the rafters - 1/4L inc. | |
| over 9.0 | stand or strut | at the top of the rafters at the bottom of the rafters - 1/4L pr |
| truss or stand | in the center of the rafters | |
| rack | in the center of the rafters | |
| Note: Lpr is the length of the span, which is covered by rafters. | ||
To connect the frames to the rafters, the top of the half-rafters is ground off, keeping them in the same plane as the corner legs, and secured with nails. When placing sprigs on the rafters, make sure that they do not converge in one place. If you use 50X50 mm cranial bars, packed in the lower zone of the rafters on both sides, rather than a notch when installing the rafters, then the rigidity of the rafter legs will be higher, which means their load-bearing capacity will increase.
To increase the rigidity of the rafter frame, it is recommended to use cranial bars stuffed on both sides at the bottom of the rafter legs when installing the rafters.
The construction of the frame of a hipped roof is carried out in several stages.
The Mauerlat in hipped structures is laid around the entire perimeter and is well secured to the walls, especially in the corners, to create a strong unit for attaching diagonal rafters
Truss grating is used for steep roofs and relatively large spans in order to avoid deflection of diagonal rafters
When installing the rafter system of a hipped roof, you need to carefully consider the joining of the diagonal rafters, the central rafter at the end of the building, as well as the ridge beam
Self-construction of a hipped roof is, of course, not an easy process. But if you have measuring instruments, as well as the necessary tools, you will succeed. The main thing is the desire to assemble the structure with your own hands and the desire to adhere to general principles. And in order for the roof to last as long as possible and maintain its amazingly beautiful appearance, try not to skimp on the elements of the rafter frame and use modern reliable metal fasteners for wood to fix them.
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” a more interesting look. 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.
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 the extreme points of the ridge beam.
Despite the fact that there are four slopes in any case, the design and calculation of these roofs are different. The assembly order is also different.
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.
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 the roof slopes, they are guided by aesthetic and practical considerations. With aesthetics, everything is more or less clear - the building should look proportional. And it looks better with enough high roofs- 0.5-0.8 heights 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).
If a hip roof is made, it is most often a 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 rely on external or internal corners buildings 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 of the outer wall. Serves as the extreme lower support for the rafters.
As already mentioned, slanted (corner) rafters carry an increased load: from the shortened rafters of the side slopes and from the hips. In addition, the length of the diagonal 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).
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.
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 residential premises are planned mansard type), the connection method depends on the material from which the rafters are made:
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.
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.
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 when complex device roofs (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.
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, a support board with a thickness of at least 5 cm is packed. 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:
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.
For square gazebo 4.5 * 4.5 meters made a hip roof covered with 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 do simple system(in the picture 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. A 90*140 mm beam 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 support pillars. 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 big houses- this stand 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 optimal way - reliable and not too complicated - is to 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.
