Drawings of a hipped roof. Rafter system of a hipped roof: overview of hip and hip structures

Roofs with four slopes have higher reliability and resistance to loads. This design is much more complex than a conventional gable one, and installation takes longer. And yet, a do-it-yourself hipped roof is a completely doable task if you prepare properly and study in detail the intricacies of its construction.

The hip roof has many variations. The simplest design consists of 2 trapezoidal slopes connecting in the center of the roof, and 2 triangular slopes on the side of the gables. Sometimes all four slopes are made triangular, then the ribs of the roof converge at a central point. More complex designs involve the presence of broken lines, a combination of short slopes with pediments, built-in straight and inclined windows, as well as multi-level slopes.

Without appropriate experience, it is impossible to build a rafter system of such a configuration, so it is better to pay attention to a standard hip roof.

The slope of the slopes can have an angle from 5 to 60 degrees. To calculate the optimal slope value, the following factors must be taken into account:


Gentle slopes are not suitable for arranging an attic, since they take up too much free space. Therefore, if an attic is planned in the house design, the roof slope should be 45 degrees or higher. You can select the angle of inclination depending on the type of roofing using the table.

Atmospheric loads are also of great importance. Where there is a lot of snow, you cannot make a slope of less than 30 degrees, otherwise the rafter system will not withstand the loads. If the angle of inclination is more than 60 degrees, the snow load can be ignored. In addition to these factors, you should consider the location of objects such as water tanks or ventilation chambers. They are usually suspended from the rafters and place additional stress on them. After preliminary calculations, you can begin drawing up a drawing of the rafter system.

Materials for roof installation

Like a gable roof, a hip roof consists of a mauerlat, tie rods, rafters, support posts, ridge beams and sheathing. The difference between the second design is the location of the rafters and their length. For hipped roof It is recommended to use lumber from pine or larch, good quality, without defects, with a maximum humidity of 22%.

The rafters are made from boards with a section of 50x100 mm; if the roof area is very large, it is better to take 50x200 mm boards. For Mauerlat you need solid timber with a cross section of at least 150x150 mm. Additionally, you will need metal threaded studs for fastening the Mauerlat, boards for sheathing and overhead metal plates, which are used to connect wooden elements.

Before assembling the roof, lumber must be impregnated with an antiseptic agent.

During the work you will need the following tools:

  • hacksaw;
  • building level;
  • plumb line and tape measure;
  • hammer;
  • drill;
  • screwdriver;
  • chisel;
  • Circular Saw.

Rafter system installation technology

Step 1. Laying the Mauerlat

In houses made of timber, the functions of the mauerlat are performed by the last crown of the log house, in which special grooves are cut for the rafters. In brick houses, the Mauerlat is laid on the walls around the perimeter of the box, having previously secured metal studs with threads between the bricks of the last rows. To more accurately mark the holes for fasteners, the timber is lifted and laid on top of the tips of the studs, and then hit with a hammer. After this, clear marks remain on the tree, along which holes are drilled.

Having removed the timber for drilling, the surface of the walls is covered with one or two layers of waterproofing material, usually roofing felt. It is placed directly on the studs and pressed downwards. Next, lay the Mauerlat, aligning the holes with the studs, align them horizontally and screw the nuts tightly onto the threads. At the corners, the beams are connected with metal plates or brackets. After fastening, the beam should not move even a millimeter, because the reliability of the entire rafter system depends on this.

Step 2. Installation of racks

If the house does not have a central load-bearing wall, it is necessary to lay the support beam perpendicularly load-bearing beams ceilings Connect two boards with a cross section of 50x200 mm, leaving a gap of 50 mm between them. To do this, short bars 50 mm thick are inserted between the boards and nailed down. The distance between the bars is about 1.5 m; the beams are not fastened at the ends. Having measured the middle of the attic, lay the support beam so that its ends extend beyond the boundaries of the Mauerlat by 10-15 cm.

Now take 3 boards 50x150 mm, cut them to the height of the roof, and install them on the support beam using a plumb line. Each post should rest against the beam where the boards are connected by a block. The racks are temporarily reinforced with beams made from beams. The top of the racks is connected by a ridge beam, for which a 50x200 mm board is used.

Step 3. Attaching the central rafters

They take a rafter board and attach it with one end to the ridge beam and the other to the mauerlat on the front side of the building. Immediately adjust the length of the eaves overhang and cut off the excess. Mark the lines of the cuts with a pencil, after which they cut off the upper end of the board and make a groove in the mauerlat 1/3 of the width of the rafter. The board is nailed to the ridge, the lower edge is inserted into the groove on the Mauerlat and secured with metal plates.

The rest of the rafters are made in the same way and installed in 60 cm increments from the facade of the house. The outer boards should be positioned perpendicular to the ridge beam and attached to its ends. On the opposite side of the building, everything is done in the same way. On the hips there is only one rafter on each side: the board is placed on its edge and attached with the upper end to the ridge beam, and the lower end is inserted between the boards of the support beam and secured with nails.

Step 4. Attaching the corner rafters

To make corner rafters, two boards with a section of 50x150 mm are usually connected. In one of upper corners boxes, at the point of connection of the Mauerlat beams, drive a nail and tie a thin cord on it. At the point of connection between the ridge and the central rafter, a nail is also driven in from the hip side, a cord is pulled to it and secured. This is how the line of diagonal, or corner, rafters is designated. Their length must be the same, otherwise the roof will be uneven. The prepared rafter is lifted up, placed along the markings and connected to the ridge beam and mauerlat. The overhang of the rafters is approximately 50-70 cm.

Step 5. Installation of spigots

To secure the diagonal rafters, they use spigots - shortened rafters, the lower end of which rests on the mauerlat and located at right angles to the ridge beam. They are attached in increments of 60 cm, starting from the outermost ordinary rafter. As they approach the diagonal, the narozhniki make everything shorter. Now it is necessary to strengthen the structure with ties and braces, as well as install additional vertical supports.

If the span under the diagonal rafter is more than 7 m, you need to install another support at a distance of a quarter of the span from the corner of the attic. The lower end of the rack should rest on the floor beam. In the case when the beam is located further than the designated place or is completely absent, instead of a vertical post, a sprengel is attached - a horizontal jumper made of timber, the ends of which are nailed to the sprocket.

Step 5. Installation of the sheathing

When all the supports are installed, you can fill the sheathing. For a hipped roof, the sheathing is done in the same way as for a gable roof. First, a waterproofing membrane is attached to each slope separately. The joints are carefully taped, and then thin slats are placed on top of the membrane to ensure air gap. The boards are laid in increments of up to 40 cm, depending on the type of roof, and always perpendicular to the rafters.

At this point, the assembly of the rafter system is considered complete. All that remains is to insulate the structure, lay the roofing, install wind strips and sheathe the overhangs. To make a hipped roof look more stylish, it is recommended to install inclined or straight windows on the slopes.

Video - DIY hipped roof

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 consists of, what materials are required for its manufacture and how to assemble it.

Types of hipped roofs

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.

Types of rafter systems

The hip roof truss system takes different kind, depending on the initial conditions: the area of ​​the house to be covered and the internal layout. There are three types:


What type of rafter system is suitable for specific house, are determined during the design period by making calculations and drawing up drawings.

Calculation of the slope of the slopes and the height of the ridge

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.

Load calculation

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 the values ​​of all loads, the total load is determined, which, depending on the type used roofing material 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. More complex systems are more convenient to calculate in special programs, the result of which is ready-made diagram hip roof truss system.

Essential elements

The rafter system of a hipped roof consists of many components, mandatory and auxiliary:

  1. Mauerlat. A beam with a cross section of 100x100 mm or 150x150 mm, which evenly distributes the load along the perimeter of the load-bearing walls. The difference between a hipped roof is that its installation requires four Mauerlats, and not two, as for a gable roof.
  2. Sill. A beam that serves as a support for racks, which is used in a layered rafter system. It, like the Mauerlat, distributes the weight of the roof, but is located on the internal load-bearing wall.
  3. Rafter legs. Elements made of boards with a section of 50x150 mm or 100x150 mm, which carry the roofing cake and set the geometry of the slopes. In the construction of four pitched roofs use ordinary, layered and external rafters. The rows are arranged in pairs along the ridge run, forming trapezoidal slopes. The slopes, diverging from the ridge to the two corners of the house, form triangular end slopes. And the outer rafters rest top part on layers and have different lengths.
  4. Ridge run. Beam resting on vertical racks, to which the rafters are attached. This is the highest point of the roof.
  5. Racks. Vertical supports that are installed on a bench. They support ridge run or the middle of the rafter leg.
  6. Struts. Bars that are installed at an angle to the rafter legs to prevent them from bending.
  7. Tightening and bolt. Horizontal lintels made of wood or metal connecting pairs of rafter legs, reducing the bursting load on the walls. The crossbar is installed at the top of the rafters, tightened at the bottom, often used as floor beams.
  8. Sprengel farms. Sprengel is a vertical riser for sloped rafters. If there is nothing to rest it on, install a tie between two adjacent sides of the house and attach the truss using metal corners.
  9. Lathing. Base for laying roofing material. If the boards are nailed without gaps, the sheathing structure is called continuous. And if the boards are alternated with a small gap - lattice. The sheathing pattern depends on the type of roofing material.
  10. Eaves. The part of the rafters that protrudes 40-50 cm beyond the perimeter of the house, protecting it from moisture.

Assembling the rafter system

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!

Video instruction

The hipped (hip) roof is considered one of the most complex structures. Like any other, it has its advantages and disadvantages. To make an informed decision, you need to familiarize yourself with the real performance characteristics hipped roof.


Flaws


As you can see, the advantages of a hipped roof are questionable, but the disadvantages are significant.

Practical advice. Professional builders recommend choosing hip roofs only in exceptional cases when other options are unacceptable for various reasons.

Types of hipped roofs

Every country has its own building traditions and style preferences. What types of hip roofs are used by architects?

Table. Types of hipped roofs.

Hip roof viewShort description

The most simple roof, has two hip slopes of a regular triangular shape and two inclined ones in the shape of trapezoids. The lower the angle of inclination of the slopes, the greater the overhang can be made to protect the facade and the surrounding area.

All slopes converge at one point, the roof ridge is missing. It is used as a covering for buildings of regular square shape.

A successful attempt to improve the classic hip roofs. The hip slopes are slightly lowered, which allows the installation of small windows. It has significant drawback– due to the installation of windows it becomes even more complicated and so difficult installation rafter system. There are more complex versions of such a roof - another small hip slope is made above the window.

It has low pediments and small hips above them. The peculiarity of this design is that all rafter legs rest on parallel load-bearing walls. Due to this, the design is slightly simplified and the attic space is increased.

There are no universal recommendations for choosing the type of hipped roof; each developer must make a decision independently or after consultation with architects. But you should always remember that there are other, cheaper and good options rafter systems.

Step-by-step instructions for building a hipped roof

As an example, let’s look at the simplest of the listed types of hip roofs – the classic one. But even such a simple hip roof design is much more complex than any gable roof.

Important. You can start building a hip roof only after the professionals have made all the calculations. The best option– order a house project from the relevant organizations. This will cost much less than restoring the structure after its destruction.

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.

Types of rafter systems for hipped roofs

The design of the rafter system depends on the shape of the hipped roof. The most common configurations today are:

  1. Hip structure. All four slopes occupy the area from the ridge to the eaves overhang, with two side slopes having a trapezoidal shape, and two end ones (hips) having a triangular shape. A special feature of the hip rafter frame is the presence of two pairs of diagonally layered rafters, which extend from the edge of the ridge and serve as supports for the trusses and trusses.

    The hip hipped design is characterized by the fact that the slopes occupy the entire roof area - from the ridge to the eaves

  2. Dutch half hip. A device with truncated end slopes that do not reach the cornice. As a rule, they are 2–3 times smaller than trapezoidal ones. The advantage of this hipped roof structure is the possibility of installing a regular window at the ends of the house, as well as the absence of a typical gable roofs sharp protrusion, which greatly increases the wind resistance of the structure.

    The Dutch half-hip roof has truncated triangular slopes and part of the pediment into which a regular vertical window can be installed

  3. Danish half hip. It is characterized by the presence of a pediment at the ridge in the triangular slopes, which allows for full natural lighting of the under-roof space without installing roof windows.
  4. Tent structure. Installed on houses with a square frame. All four slopes of the hipped roof are identical isosceles triangles connected at one point. When constructing such a roof important aspect is to maintain symmetry.

    The structure of the hip truss system depends on the selected roof configuration

Features of the supporting frame of a hipped roof

Let us immediately note that the rafter system of a hipped roof will be more complex compared to traditional gable structures for two reasons.

  1. Due to the increase in the number of inclined planes and their joining to each other. At its core, the connection of slopes is intersection lines running at a certain angle to the horizon. The joints that form an angle protruding above the surface of the slopes are called roof ribs. From them, water flows down the slopes and accumulates in grooves (valleys) - lines of intersection with the internal corner. If all planes have the same slope, then the ribs and valleys divide the angle of the base at the junction of adjacent slopes in two and create a slope to the perimeter of the building of 45°.

    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

  2. Due to the fact that the purlins in a hipped structure form a closed contour, where the hip (diagonal) rafter legs are located along the lines of the ribs and valleys. They are longer than ordinary beams, which are installed longitudinally on the slopes at a distance between the intersections of the hip rafters in the upper frame. But between the lower parts of the diagonal legs, short rafters, called sprigs, are mounted. Distinctive feature The frame of a hipped roof is the presence of trusses - wooden struts under the hip rafters.

    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 the 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:


Video: gable or hip roof - what to choose

How to calculate the rafter system of a hipped roof

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.

Marking and calculation of the supporting frame of a hipped roof

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.

Table: relationship between the length and laying of the rafters

Roof slopeCoefficient for calculating the length of intermediate raftersCoefficient 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 look at an example: under construction a private house in Yekaterinburg measuring 7.5x12 m with a planned height of the hip roof made of metal tiles of 2.7 m.

  1. First of all, we draw a drawing or sketch of the roof.

    Before calculating the rafter system, it is necessary to make a sketch of the building and apply all the initial data to it

  2. We find the angle of inclination of the slopes using the formula: the tangent of the angle of inclination is equal to the ratio of the height of the roof to half the length of the span, in our case - to half the end side L = 7.5 / 2 = 3.75. Thus, tan α = 2.7 / 3.75 = 0.72. Using reference tables, we determine: α = 36°, which corresponds to the standards requiring a roof slope for metal tiles of at least 14°, and the climatic conditions of Yekaterinburg.

    The tangent of the angle of inclination of the slopes is determined by the well-known formula for calculating the sides right triangle as the ratio of the opposite side to the adjacent

  3. We determine the position and edge of the ridge ridge, for which we apply a template at an angle of 36° in the middle of the upper trim of the end (the installation location of the first central intermediate rafter) to a height of 2.7 m and project the outline onto the sketch.
  4. We retreat ½ the thickness of the ridge beam from the center (key) line and install the end of the measuring rod at this point. At the other end of the rail we make marks for the outer and internal contour side wall, as well as overhang. Turn the rack to the side and away from internal corner of the external trim, we mark the location of the intermediate rafter along the mark of the internal contour, thus determining the installation location of the second intermediate central rafter.

    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

  5. We carry out similar actions at all corners, determining the edges of the ridge ridge and the location of all central rafter legs.
  6. After planning the intermediate rafters, we determine their length from the table. In our example, the tilt angle is 36°, its tangent is 0.72, which corresponds to a ratio of 8.64:12. There is no such value in the table, so let’s calculate the coefficient relative to the line with the parameter 8:12 - 8.64/ 8 = 1.08. This means that the required coefficient is 1.202 · 1.08 = 1.298.
  7. By multiplying the depth of the intermediate rafters by the calculated coefficient, we find their length. Let us take into account the laying depth of 3 m, then L str = 3 · 1.298 = 3.89 m.

    The length of the row and central intermediate rafters depends on the angle of the roof and the depth of their laying

  8. Similarly, we determine the length of the diagonal rafters, having previously calculated the laying equal to the distance from the corner of the connection of the side and end slopes to the first intermediate central rafter. According to the initial data, the position of the corner rafters is 7.5 / 2 = 3.75 m. Then the estimated length of the corner rafters will be equal to 3.75 1.298 = 4.87 m.

    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

  9. We calculate the overhang using the Pythagorean theorem according to the markings made or simply add the desired size to the length of the rafters, for example, 0.6 m plus at least 0.3 m for arranging an external drain.

    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

  10. Having marked all the elements of the rafter frame, we determine the length of the ridge ridge, which is equal to the difference between the length of the side and the doubled value of the intermediate rafters: 12 – 2 3 = 6 m. It is at this distance that the ordinary rafters will be installed. If we take a step of 1 m, then we will need 5 row rafters, equal in length to the central ones. In addition, in the area where the intermediate central rafters are laid, which is 3 m long, two short rafters will be installed on one and the other side edge.
  11. Since the short rafters (spreaders) are attached to the diagonal ones, this means that two spandrels will also be installed on the end sides between the corner and central intermediate rafters on the left and right.

Let's summarize - for the rafter frame of a hipped roof you will need:

  • two pairs of hip (corner) rafters with a length of 4.87 + 0.6 + 0.3 = 5.77 m;
  • three pairs of intermediate central rafters with a length of 3.89 + 0.6 + 0.3 = 4.79 m;
  • five pairs of ordinary rafters 4.79 m long.

There are only ten pairs of rafters, the total length of which will be approximately 100 linear meters. We add here 6 m per ridge beam, as well as a ten percent reserve, and we find that approximately 117 linear meters of lumber are needed to manufacture 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.

Video: hip roof rafter system, installation technology

https://youtube.com/watch?v=n_Yr2QB3diM

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

Video: rafter frame of a hip roof, marking of elements and assembly

Calculation of lumber cross-section

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 in the fourth climatic region, where S g =168 kg/m 2).

Table: determination of the µ indicator depending on the roof slope

Determining the angle of the roof
Tangent valueAngle 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).

Table: standard snow loads by region

Region No.IIIIIIIVVVIVIIVIII
S g, kg/m 256 84 126 168 224 280 336 393

We calculate the wind load using the formula W = W o k c, where W o - standard indicator according to the map, k is a 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.

Table: k index value for different types of terrain

Building height Z, mCoefficient k for terrain types
AINWITH
≤ 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.

Table: standard wind load by region

Region No.IaIIIIIIIVVVIVII
W o , kg/m 224 32 42 53 67 84 100 120

Now let's calculate the load on load-bearing 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 reach 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 highest value density. 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:

  • T is the thickness of the heat insulator;
  • R is the thermal resistance standard for a specific area, according to the map included in SNiP II-3–79, in our case 5.2 m 2 °C/W;
  • λ is the thermal conductivity coefficient of the insulation, which for low-rise construction is taken equal to 0.04;
  • P is the highest value of the density of the thermal insulation material. We will use Rocklight basalt insulation, for which P = 40 kg/m².

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:

  • H ≥ 9.5 · L max · √, if angle α > 30°;
  • H ≥ 8.6 L max √, if α< 30°.

The following notations are used here:

  • H - board width (cm);
  • L max - maximum working length of rafters (m). Since the layered rafter legs are connected in the ridge area, the entire length is considered working and L max = 4.79 m;
  • R bend is an indicator of the bending resistance of wood (kg/cm). According to the set of rules 64.13330.2011 for wood of grade II R bend = 130 kg/cm;
  • B is the thickness of the board, taken arbitrarily. Let's assume B = 5 cm;
  • Q r - load per linear meter of one rafter leg (kg/m). Qr = A · Q, where A is the pitch of the rafters, which in our case is 1 m. Therefore, Q r = 195 kg/m.

Substitute the numerical values ​​into the formula → H ≥ 9.5 · 4.79 · √ = 9.5 · 4.79 · 0.55 = 25.03 cm ≈ 250 mm.

Table: nominal sizes of softwood edged boards

Board thickness, mmWidth (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.

Table: cross-section of lumber depending on the length and pitch of the rafters

Rafter spacing, cmRafter length, m
3,0 3,5 4,0 4,5 5,0 5,5 6,0
215 100Х150100Х175100Х200100Х200100Х200100Х250-
175 75Х15075Х20075Х200100Х200100Х200100Х200100Х250
140 75Х12575Х17575Х20075Х20075Х200100Х200100Х200
110 75Х15075Х15075Х17575Х17575Х20075Х200100Х200
90 50Х15050Х17550Х20075Х17575Х17575Х25075Х200
60 40Х15040Х17550Х15050Х15050Х17550Х20050Х200

Let's give another table for those who will use hardwood lumber.

Table: maximum deviations from the nominal dimensions of the boards

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.

Video: calculation of the hip roof rafter system

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 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% reserve 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.

Video: example of roof calculation using an online calculator

Rafter system installation technology

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.

Because the standard length 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

Table: position of supports for corner rafters

Span length, mTypes of supportsLocation of supports
less than 7.5stand or strutat the top of the rafters
less than 9.0stand or strutat the top of the rafters
truss or standat the bottom of the rafters - 1/4L inc.
over 9.0stand or strutat the top of the rafters at the bottom of the rafters - 1/4L pr
truss or standin the center of the rafters
rackin 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.

Do-it-yourself installation of a truss structure

The construction of the frame of a hipped roof is carried out in several stages.

  1. The materials are marked and calculated, after which roofing felt is laid as waterproofing along the entire perimeter of the building. A support for the racks and a Mauerlat are placed on top of it, securing it to the walls, fixing it especially well in the corners.

    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

  2. Install the frame for the ridge girder and lay the girder itself, strictly maintaining the height and spatial arrangement of the ridge, since the strength and reliability of the entire structure directly depends on this truss structure.
  3. Place the support posts using a water level for leveling and secure them under the ridge with inclined supports. The placement of racks is done based on the configuration of the roof - in a hip structure, the racks are installed in one row with an interval of no more than two meters, and in a hip roof - diagonally at the same interval from the corner.
  4. The central intermediate rafters are mounted, and then the ordinary ones, filling the middle of the side slopes.
  5. According to the markings, corner rafters are installed, preferably made with reinforcement, resting their lower part on the corner of the Mauerlat, and their upper fragment on the stand. The installation of the eaves overhang and drainage is also done here.
  6. Next, half-rafters (springs) are placed, strengthening the lower part of the diagonal legs with trusses, which will partially relieve the corner rafters, and they are sheathed along the perimeter of the roof with a wind board.

    Truss grating is used for steep roofs and relatively large spans in order to avoid deflection of diagonal rafters

  7. After installation of the rafter system, the roofing pie is laid, the eaves overhangs and drainage system are installed.

    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

Video: hipped roof on nails and stool

Self-construction a hipped roof is, of course, not an easy process. But if you have measuring instruments, as well as 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.

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 House master will be able to be proud of his personal achievements as a roofer.

However, before deciding to install such a design, it is worth familiarizing yourself with the algorithm according to which the rafter system of a hipped roof is constructed and with the specifics of its design.

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, 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:

  • In a hip roof, all four slopes have the shape of isosceles triangles, the vertices of which converge at one highest point. There is no ridge as such in a tent structure; its function is performed by the central support in layered systems or the top of a hanging truss.
  • For a hip roof, a pair of main slopes has a trapezoidal configuration, and the second pair has a triangular configuration. The hip structure differs from its tent-type counterpart in the obligatory presence of a ridge, to which the trapezoids are adjacent at the upper bases. Triangular slopes, also known as hips, are adjacent to the ridge at the top, and their sides are connected to the inclined sides of the trapezoids.

Based on the configuration of the roofs in plan, it is clear that hipped structures are usually erected over square buildings, and hip structures over rectangular houses. Both soft and . The characteristic square or rectangular shape is repeated in 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 wooden house or on a mauerlat, which serves as the top frame of brick or concrete walls. If you can find upper and lower supports under each rafter, roof frame It is constructed using layered technology.

Installation of layered rafter legs is simpler and more accessible for an inexperienced home roofer, who needs to take into account that:

  • With rigid fastening of the upper and lower heels of the rafters metal corners or using a supporting wooden plate, reinforced fastening of the Mauerlat will be required, because the thrust will be transferred to it.
  • If the upper heel is rigidly fixed and the bottom of the rafter is hinged, there is no need to strengthen the fastening of the Mauerlate, because if the load on the roof is exceeded, a hinged fastening, for example on sliders, will allow the rafter to move slightly without creating pressure on the mauerlat.
  • When the top of the rafters is hinged and the bottom is rigidly fixed, expansion and pressure on the Mauerlat are also eliminated.

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 under central part roof, nothing will work except for a hanging rafter system assembly diagram. 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, This:

  • Diagonal rafter legs forming the spinal connections of the slopes. In hip structures, diagonals, also known as slanted rafters, connect the ridge girder consoles to the corners of the roof. IN tent systems slanted legs connect the top to the corners.
  • Spreaders, or rafter half-legs, installed perpendicular to the eaves. They rest on diagonal rafters and are located parallel to each other, therefore they differ in different lengths. Narozhniki form the planes of tent and hip slopes.

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:

  • Installation of a mauerlat on brick or concrete walls. The process of installing a mauerlat on walls made of logs or timber can be eliminated, because it can be successfully replaced by the upper crown.
  • Installation of the central support for the hip structure or the supporting frame of the main part of the hip roof.
  • Installation of conventional layered rafters: a pair for a hip roof and a row determined by the design solution for a hip structure.
  • Installation of diagonal rafter legs connecting the corners of the systems with the top of the support or the extreme points of the ridge.
  • Manufacturing to size and fastening of spigots.

In the case of using a hanging frame scheme, the start of the construction of a tent frame will be the installation of a triangular roof 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 40-50cm.


Installation of the base according to the Mauerlat

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:

  • Lightweight foam concrete, gas silicate and similar walls should be equipped with a reinforced reinforced concrete belt, poured around the perimeter, with anchors installed during the pouring period to secure the Mauerlat.
  • Edge the brick walls with a side of one or two bricks along the outer edge so that a ledge is formed along the inner edge for laying wooden frame. During laying, wooden plugs are placed between the bricks to secure the Mauerlat with staples to the wall.

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 connection point should be located above 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 is no different 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 installed. The extension is nailed to the mauerlat, fastened to the beam with screws, large-caliber nails, dowels, and the fasteners are reinforced with corners.

Construction of the ridge part

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. 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:

  • Build a support frame for the rafter legs, the top of which will rest on the ridge girder. The purlin will rest on three supports, the central one of which is installed directly on the central floor beam. To install the two outer supports, first two cross beams are laid, covering at least five floor beams. Stability is increased with the help of two struts. For the manufacture of horizontal and vertical parts For the supporting frame, a block with a cross-section of 100×150mm was used, the struts were made of boards 50×150mm.
  • Make rafter legs, for which you first need to make a template. A board of suitable size is applied to the installation site, and lines for future cuts are drawn on it. This will be the template for the continuous production of rafters.
  • Install the rafter legs, resting them with the notch on the ridge girder, and with the lower heel on the stem located opposite.

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 ease of implementation further actions the contour of the roof is formed by 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:

  • To indicate the direction of installation, pull the string. We stretch from the point of conditional intersection of the outer support of the frame with the floor beam to the corner.
  • On top of the lace we place the block in its place. Holding the block, we outline the cut lines from below where the block intersects the floor beam and corner connection cornice boards.
  • We attach the finished stem with sawn off excess to the mauerlat and to the floor beam with corners.

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:

  • From the highest point of the skate, we stretch the lace to the corners and to the central point of the slope. These are auxiliary lines along which we will mark upcoming cuts.
  • Using a carpenter's goniometer, we measure the angle between the lace and top side corner offset. This is how the angle of the bottom cut is determined. Let's assume it is equal to α. The angle of the upper cut is calculated using the formula β = 90º – α.
  • At an angle β we cut off one edge of a random piece of board. We apply it to the place of the upper fastening, aligning the edge of this workpiece with the lace. We outline the excesses that interfere with a tight installation. You need to cut again along the marked lines.
  • At an angle α we saw off the lower heel on another piece of board.
  • We make the first half of the diagonal rafter using templates for the upper and lower support. If a solid board is not long enough, you can join two pieces together. They can be spliced ​​using a meter-long piece of inch mounted on self-tapping screws; it should be placed on the outside of the bevel leg being constructed. We install the finished first part.
  • We make the second part of the sloped rafter in the same way, but keep in mind that it should be slightly lower than its first half. The area where the boards are joined into one element should not coincide with the area where the boards are joined in the first half of the slope.
  • We sew two boards with nails at intervals of 40-50 cm.
  • Along the cord stretched to the center of the slope, we draw a line along which it will be necessary to adjust the cut to connect it with the adjacent rafter.

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 of 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 the 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:

  • We cut the piece of board at an angle δ and attach it to the place of attachment to the diagonal rafter.
  • We outline the excess that needs to be cut down again. The resulting template is used in the manufacture of all flaps, for example the right side of the hip. For the left part, the upper template will be filed from the opposite side.
  • As a template for the lower heel of the splices, we use a piece of board sawn off at an angle γ. If all previous steps were performed correctly, then this template is used to make the lower attachment points for all other springs.

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. the upper connecting nodes of 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 - and follow the instructions.

Useful video 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.