Properly designed and assembled according to technology, the roof serves as a barrier preventing cold air and moisture from entering the house. From the outside, with the naked eye we see only a small part of the structure - the roofing. But the roof frame, which is the most an important component, performs the main supporting functions and takes on the effects of wind and snow loads.

To prevent it from deforming as a result of operation, it is necessary to correctly calculate the cross-sectional size of its elements and determine the distance between them, taking into account the weight of the roofing material, slope and climatic conditions. In this article we will tell you what the rafter system of a gable roof of a house is, what it consists of, how it is designed and assembled with your own hands.

A rafter system for a gable roof of a house is a system of interconnected supporting elements that together make up the frame of the structure.

It is made of wood or metal in accordance with the calculation of the loads that will affect them during operation. The roof rafter frame performs the following functions:

1. Gives the roof slopes the necessary slope. The traditional shape in the form of an equilateral rectangle of a gable roof is given by the rafter frame, which forms the slope between the base of the roof and its ridge. The angled surface allows snow and water to slide freely off the slope.
2. Distributes the load from weight roofing pie . The weight of the roofing pie, taking into account the snow load, can reach up to 500 kg/m2, so the gable roof is subject to intense load, especially in winter. The rafters of a gable roof evenly distribute the weight that rests on them, and then transfer the load to the load-bearing walls and foundation of the house.
3. Serves as a basis for attaching thermal insulation and roofing material. The rafter frame of the roof serves as a kind of skeleton of the structure around which its “body” is built. Thermal insulation should be installed between the rafter legs, and a roofing covering should be fixed to the sheathing, which protects against moisture penetration.

Please note that the design of a gable roof truss system is quite complex to design and assemble, especially if the craftsman lacks experience. After all, in order for it to be able to withstand intense loads, you need to correctly calculate the cross-section of the rafters and the pitch of the rafters, taking into account the slope and length of the slopes, the roofing material used, and also draw up a drawing according to which the assembly will be carried out.

Types of rafter systems

Rafter systems differ in many factors; their composition depends on the layout of a wooden or brick house, the total weight of the roofing pie, the material from which the frame is made, as well as the type of roofing.

An important design characteristic is their load bearing capacity, which determines how much weight they can support without deformation. By characteristic features The following types of rafter systems are distinguished:

Layered

A layered rafter frame is a frame whose rafters have 2 support points. The upper end of the leg rests on a ridge girder mounted on vertical posts fixed to the inner wall. And with the lower end it is installed on the Mauerlat.

Assembly of a layered rafter system on a gable roof is possible only if there are at least 1 load-bearing partition or capital column. This design is often called non-thrust, because the second support point of the rafters compensates for the thrusting load on the walls of the house, which is assumed by the hanging installation of the frame.

Rafter legs of the layered type experience load only in bending, which can be eliminated by various struts. The layered rafter system allows you to cover houses up to 14 meters wide.

Hanging

The hanging rafter system is distinguished by the fact that its rafters rest only with their lower end on a mauerlat beam installed on the external load-bearing walls. The upper end of the rafter legs of this design does not rest on anything, but seems to hang in the air, which is why 2 types of load arise: bending and expansion.

The thrust load of such a layout of elements on the external walls is so great that it has to be compensated with the help of numerous crossbars and ties, due to which the rafter pairs are tied together.

The structure of a gable roof with hanging rafters consists of triangular trusses, the rigid shape of which is not subject to loads. The complexity of the dangling circuit is believed to be much higher.

The rafter system of a gable roof can be easily installed with your own hands if you correctly calculate the pitch of the rafters, that is, the distance between the rafters and the size of their cross-section.

Combined

Combining the best of both systems, it is recognized as the most reliable. It is used in cases where columns, rather than walls, are used indoors as support inside the house. Then hanging and layered rafters can be alternated to strengthen the structure with additional elements without increasing consumption building materials.

Important! A sliding rafter roof is another type of frame, which differs in that rafter legs installed on the Mauerlat not using a rigid fastening, but using a movable support. The sliding fastening allows the roof to change dimensions within the range of movement during the shrinkage of the wooden house.

Design

The construction of a gable roof truss system of any of the listed types is a set of auxiliary and supporting elements. They distribute the weight of the roofing pie evenly, and also compensate for the bursting and bending loads that arise between them.

The cross-section, length and pitch of the rafters are determined using an engineering calculation that takes into account the weight of the roofing pie, climatic conditions in the construction region, as well as the slope of the structure. Part rafter frame A gable roof usually includes the following elements:

1. Mauerlat. Install the Mauerlat beam on the outer walls of the house, on which the roof slopes rest. It serves to soften the pressure on the supports and evenly distribute the load from the weight of the roofing pie. It is made of durable timber with a cross-section of 150x150 mm or 200x200 mm and is attached to the upper chord of the walls using anchor bolts or long metal studs.
2. Sill. This is an analogue of the Mauerlat, only it is installed on internal load-bearing walls, and vertical supports must be placed on it for mounting the ridge girder.
3. Rafter legs. This term refers to frame elements that are made from boards with a cross-section of 150-40 mm and are installed at an angle to the base of the roof, forming an angle of inclination of the slope. The distance between the rafters, their length and thickness are determined using calculations that take into account the total loads to which they are subjected during operation.
4. Puff. A tie is called a beam that is placed horizontally and connects the legs of one pair of rafters to reduce the bursting load on the outer walls of the structure. The crossbar is a tie installed under the very ridge of the structure.
5. Racks. A stand is a vertical beam placed flat to support the ridge girder. It is easy to determine what distance should be between the racks, because it follows the pitch of the rafters.
6. Struts. Diagonally located supports that support the rafter legs in the middle or at the bottom, preventing them from bending, are called struts.

Please note that determining how to correctly position the elements of the rafter system can only be done by calculating the temporary and permanent loads to which they will be subjected during operation. Calculating the total weight of the roofing pie helps determine the correct distance between the rafters, calculate their length and required thickness.

The calculation of the rafter system of a gable roof is based on the fact that in the frontal dimension it has the shape of an equilateral triangle, the sides of which can be easily calculated using simple trigonometric formulas.

These simple calculations help determine the optimal distance between the rafters, their thickness and length. The design calculations are performed in the following sequence:

• Determine the structure and slope of the roof. Exist various ways choice of type and inclination roofing structure. This parameter depends on climatic conditions and performance characteristics selected roofing material.
• Determine the total load on the structure. To do this, sum up permanent loads (the weight of the roofing, the weight of the frame, thermal insulation and ceilings) with temporary loads (snow load, wind load), multiply by correction factor, taking into account the slope of the slopes, and then add 10-15% to this figure so that the frame has some margin of safety.
• Calculate the length of the rafter legs. To do this, they use the Pythagorean theorem, because the truss is an equilateral triangle. It turns out that the square of the length of the rafter leg is equal to the sum of the squares of the height of the blood and half the length of the laying. Knowing how to calculate the length of the rafters, you can calculate the height of the ridge.
• Determine the cross section of elements. The optimal cross-section of elements is selected from tables in accordance with the length of the rafter legs and the distance between them. The higher these indicators are, the thicker the rafters should be.

Remember that before you calculate the rafters for the roof, you need to decide on the basic design parameters. In particular, it is necessary to know exactly the height of the ridge and the slope of the roof, as well as the dimensions of the room being covered. The result of the calculation of roof elements should be detailed diagram rafter system, reflecting their sizes and angles between them.

Calculating the angle of inclination

The angle of inclination of the slopes is selected not depending on aesthetic preferences, but based on weather conditions, taking into account the roofing material. Steeper slopes of 40-45 degrees are constructed in areas with a lot of snow cover, and flatter slopes of 10-20 degrees in places with strong gusty winds.

Keep in mind that the steeper the slope, the higher the consumption of materials, the higher the final cost of the roof. Be sure to take into account the requirements of the material:

1. Tiles and slate require a slope of at least 22 degrees, otherwise precipitation will seep through the joints between the elements.
2. Metal tiles are laid at an angle of at least 14 degrees, since they suffer greatly from gusts of wind, they can become deformed or even fly off.
3. The soft roof allows an inclination angle of up to 5-10 degrees, making it possible to cover slopes of any geometry.
4. Ondulin is considered one of the most reliable materials and can be used even for roofs with a slope of less than 6 degrees.
5. Corrugated sheets cannot be laid at an angle of less than 15 degrees, however, it is advisable to treat slopes even with an acceptable slope with sealant for better waterproofing.

Assembly technology

Before installing the roof frame, it is necessary to calculate the parameters of its elements, based on calculating the total load on the structure, and also create detailed drawing, reflecting its results.

Having a frame diagram in front of you, it is much easier to carry out high-quality installation of the rafter system of a gable roof. The technology for assembling the structure implies the following sequence:

1. First, a mauerlat is laid on the upper belt of the external walls, on which the slopes will rest, and a bench is mounted on the internal partitions, if the system is layered. These elements must be firmly fixed using anchor bolts or studs.
2. Then the rafters are fastened. They are fixed with nails to the Mauerlat, and are also connected to each other using a metal plate. It is worth remembering that the rafters are cut to fit the mauerlat timber, and not vice versa. First, the rafters located on the edge are installed in order to set the level along which the remaining pairs will be aligned.
3. After installing the rafters, auxiliary supporting elements, which I will support them - struts, tightening, contractions. To fix the crossbar more reliably, its end is made with a protrusion half the thickness of the beam and it is cut to the rafters, fixing it with nails in several places.
4. A sheathing is nailed over the rafter legs, onto which the roofing material is fixed. The material and pitch of the sheathing are selected in accordance with the characteristics of the roofing material and the slope of the roof.

Remember that a well-designed and high-quality rafter system is the key to the strength, reliability and durability of a gable roof. Therefore, do not neglect the help of professional roofers and designers when creating a roofing design for your home.

Video instruction

A gable roof or gable roof is a roof with two slopes, i.e. having 2 inclined surfaces (slopes) of a rectangular shape.

Due to its design features, the frame of a gable roof ideally combines simplicity of design and maintenance with reliability and durability. These and many other parameters make the construction of a gable roof practical and rational decision for private and commercial housing construction.

In this article, we will look at how to make a rafter system for a gable roof with your own hands. For effective perception of the material, it is presented in the form of step-by-step instructions from A to Z, from selection and calculations, to installation of the Mauerlat and sheathing under the roof. Each stage is accompanied by tables, diagrams, drawings, drawings and photos.

The popularity of the house roof is due to a number of advantages:

• design variability;
• simplicity in calculations;
• naturalness of water flow;
• integrity of the structure reduces the likelihood of leaks;
• efficiency;
• preservation usable area attic or the possibility of arranging an attic;
• high maintainability;
• strength and wear resistance.

Types of gable roof

The installation of a gable roof truss system depends, first of all, on its design.

There are several options for gable roofs (types, types):

The most common roof installation option due to its simplicity and reliability. Thanks to symmetry, a uniform distribution of loads on the load-bearing walls and mauerlat is achieved. The type and thickness of the insulation does not affect the choice of material.

The cross-section of the beam makes it possible to provide a reserve of bearing capacity. There is no possibility of rafters bending. Supports and struts can be placed almost anywhere.

An obvious drawback is the impossibility of arranging a full attic floor. Due to sharp corners, “dead” zones appear that are unsuitable for use.

The arrangement of one angle of more than 45° leads to a reduction in the amount of unused area. There is an opportunity to make living rooms under the roof. At the same time, the requirements for calculations increase, because the load on the walls and foundation will be distributed unevenly.

This roof design allows you to equip a full second floor under the roof.

Naturally, a simple gable rafter roof differs from a broken roof, not only visually. The main difficulty lies in the complexity of the calculations.

Design of a gable roof truss system

Building a roof of any complexity with your own hands requires knowledge of the purpose of the basic structural elements.

The locations of the elements are shown in the photo.

• Mauerlat. Designed to distribute the load from the rafter system onto the load-bearing walls of the building. To arrange the Mauerlat, a timber made of durable wood is selected. Preferably larch, pine, oak. The cross-section of the timber depends on its type - solid or glued, as well as on the expected age of the structure. The most popular sizes are 100x100, 150x150 mm.

  Advice. For a metal rafter system, the Mauerlat must also be metal. For example, a channel or an I-profile.

• Rafter leg. The main element of the system. To make rafter legs, a strong beam or log is used. The legs connected at the top form a truss.

Silhouette roof truss determines the appearance of the building. Examples of farms in the photo.

The parameters of the rafters are important. They will be discussed below.

• Puff- connects the rafter legs and gives them rigidity.

• Run:

• Ridge run, is mounted at the junction of one rafter to another. In the future, the roof ridge will be installed on it.

• Side purlins, they provide the truss with additional rigidity. Their number and size depend on the load on the system.

• Rafter stand- vertically located beam. It also takes on part of the load from the weight of the roof. In a simple gable roof it is usually located in the center. With a significant span width - in the center and on the sides. In an asymmetrical gable roof, the installation location depends on the length of the rafters. With a broken roof and arrangement of one room per attic attic- the racks are located on the sides, leaving free space for moving. If there are supposed to be two rooms, the racks are located in the center and on the sides.

The location of the rack depending on the length of the roof is shown in the figure.

• Strut. Serves as a support for the stand.

Advice. Installing the brace at an angle of 45° significantly reduces the risk of deformation from wind and snow loads.

In regions with significant wind and snow loads, not only longitudinal struts are installed (located in the same plane as the rafter pair), but also diagonal ones.

• Sill. Its purpose is to serve as a support for the rack and a place for attaching the strut.

• Lathing. Designed for movement during construction work and fixation of roofing material. Installed perpendicular to the rafter legs.

Advice. An important purpose of the sheathing is to redistribute the load from the roofing material to the rafter system.

Having a drawing and diagram indicating the location of all the listed structural elements will help in the work.

Advice. Be sure to add information about the passage structure to the gable roof rafter system diagram ventilation shaft and chimney.

The technology of their installation is determined by the type of roof.

Selection of material for rafters

When calculating the material for a gable roof, you need to choose high-quality wood without damage or wormholes. The presence of knots for beams, mauerlat and rafters is not allowed.

For sheathing boards, there should be a minimum of knots, and they should not fall out. The wood must be durable and treated with the necessary preparations that will increase its properties.

Advice. The length of the knot should not exceed 1/3 of the thickness of the timber.

Calculation of the rafter system of a gable roof

Calculation of material parameters important stage, so we present the calculation algorithm step by step.

It is important to know: the entire rafter system consists of many triangles, as the most rigid element. In turn, if the stingrays have different shape, i.e. are an irregular rectangle, then you need to divide it into separate components and calculate the load and amount of materials for each. After calculations, summarize the data.

1. Calculation of the load on the rafter system

The load on the rafters can be of three types:

• Constant loads. Their action will always be felt by the rafter system. Such loads include the weight of the roof, sheathing, insulation, films, additional roofing elements, finishing materials For . The weight of the roof is the sum of the weight of all its constituent elements; such a load is easier to take into account. On average, the constant load on the rafters is 40-45 kg/sq.m.

Advice. To make a safety margin for the rafter system, it is better to add 10% to the calculation.

For reference: The weight of some roofing materials per 1 sq.m. presented in the table

Advice. It is desirable that the weight of roofing material per 1 sq.m. roof area did not exceed 50 kg.

• Variable loads. They act at different times and with different strengths. Such loads include: wind load and its strength, snow load, precipitation intensity.

In essence, the roof slope is like a sail and, if you take into account the wind load, the entire roof structure can be destroyed.

The calculation is carried out according to the formula: wind load is equal to the regional indicator multiplied by the correction factor. These indicators are contained in SNiP “Loads and Impacts” and are determined not only by the region, but also by the location of the house. For example, on a private house surrounded by multi-story buildings, there is less load. Standing separately Vacation home or the cottage experiences increased wind loads.

2. Calculation of snow load on the roof

The roof calculation for snow load is carried out according to the formula:

The total snow load is equal to the weight of the snow multiplied by the correction factor. The coefficient takes into account wind pressure and aerodynamic influence.

The weight of snow that falls on 1 square meter. roof area (according to SNiP 2.01.07-85) is in the range of 80-320 kg/sq.m.

Coefficients showing the dependence on the slope angle are shown in the photo.

Nuance. When the slope angle is over 60 ° the snow load does not affect the calculation. Because the snow will quickly slide down and will not affect the strength of the beam.

• Special loads. Accounting for such loads is carried out in places with high seismic activity, tornadoes, and storm winds. For our latitudes, it is enough to make a safety margin.

Nuance. The simultaneous action of many factors causes a synergy effect. This is worth considering (see photo).

Assessment of the condition and load-bearing capacity of walls and foundations

It should be borne in mind that the roof has significant weight, which can cause damage to the rest of the building.

Determining the roof configuration:

• simple symmetrical;
• simple asymmetrical;
• broken line

How more complex form roof, the greater the number of trusses and sub-rafter elements needed to create the necessary safety margin.

The angle of inclination of a gable roof is determined primarily by the roofing material. After all, each of them puts forward their own demands.

• soft roof - 5-20°;
• metal tiles, slate, corrugated sheets, ondulin - 20-45°.

It should be noted that increasing the angle increases the area of ​​space under the roof, but also the amount of material. What affects the total cost of work.

Nuance. The minimum angle of inclination of a gable roof must be at least 5°.

5. Calculation of rafter pitch

The pitch of the gable roof rafters for residential buildings can range from 60 to 100 cm. The choice depends on the roofing material and the weight of the roof structure. Then the number of rafter legs is calculated by dividing the length of the slope by the distance between the rafter pairs plus 1. The resulting number determines the number of legs per slope. For the second, the number must be multiplied by 2.

The length of the rafters for the attic roof is calculated using the Pythagorean theorem.

Parameter "a"(roof height) is set independently. Its value determines the possibility of arranging a living space under the roof, the convenience of being in the attic, and the consumption of material for the construction of the roof.

Parameter "b" equal to half the width of the building.

Parameter "c" represents the hypotenuse of the triangle.

Advice. To the obtained value you need to add 60-70 cm for cutting and moving the rafter leg beyond the wall.

It is worth noting that the maximum length of the timber is 6 m.p. Therefore, if necessary, the timber for the rafters can be spliced ​​(extension, joining, joining).

The method of splicing rafters along the length is shown in the photo.

The width of the roof rafters depends on the distance between opposite load-bearing walls.

7. Calculation of the rafter cross-section

The cross-section of the rafters of a gable roof depends on several factors:

• loads, we have already written about it;

• type of material used. For example, a log can withstand one load, timber - another, laminated timber - a third;

• rafter leg lengths;

• the type of wood used in construction;

• distances between rafters (rafter pitch).

You can determine the cross-section of the beam for the rafters, knowing the distance between the rafters and the length of the rafters using the data below.

Rafter cross-section - table

Advice. The larger the installation pitch of the rafters, the greater the load on one rafter pair. This means that the cross-section of the rafters needs to be increased.

Dimensions of lumber (timbers and boards) for a gable rafter system:

• thickness (section) of the Mauerlat - 10x10 or 15x15 cm;

• the thickness of the rafter leg and tie is 10x15 or 10x20 cm. Sometimes a beam of 5x15 or 5x20 cm is used;

• run and strut - 5x15 or 5x20. Depending on the width of the foot;

• stand - 10x10 or 10x15;

• bench - 5x10 or 5x15 (depending on the width of the rack);

• thickness (section) of the roof sheathing - 2x10, 2.5x15 (depending on the roofing material).

Types of gable roof rafter system

For the roof structure under consideration, there are 2 options: layered and hanging rafters.

Let's consider each type in detail in order to make an informed choice.

Hanging rafters

They are used for roof widths of no more than 6 lm. Installation of hanging rafters is carried out by attaching the legs to the load-bearing wall and the ridge girder. The design of hanging rafters is special in that the rafter legs are under the influence of a bursting force. Hanging rafters with a tie installed between the legs reduce its impact. Puff in rafter system can be wooden or metal. Often the ties are placed at the bottom, then they play the role of load-bearing beams. It is important to ensure that the tie is securely attached to the rafter leg. Because a bursting force is also transmitted to it.

Advice.
The higher the tightening is located, the greater strength it should have.
If the tightening is not installed, the load-bearing walls may simply “move apart” from the pressure created by the rafter system.

Layered rafters

They are used for arranging roofs of any size. The design of layered rafters provides for the presence of a beam and a stand. The bench lying parallel to the Mauerlat takes on part of the load. Thus, the rafter legs are, as it were, inclined towards each other and supported by a stand. The rafter legs of the layered system work only in bending. And the ease of installation also tips the scales in their favor. The only drawback is the presence of a stand.

Combined

Due to the fact that modern roofs are distinguished by a wide variety of shapes and complexity of configurations, a combined type of rafter system is used.

After choosing the type of rafter system, you can accurately calculate the amount of materials. Write down the calculation results. At the same time, professionals recommend drawing up drawings for each roof element.

Installation of a gable roof rafter system

After the gable roof rafters have been calculated, installation can begin. We will divide the process into stages and give a description of each of them. It will turn out to be unique step-by-step instruction, containing additional information for each stage.

1. Attaching the Mauerlat to the wall

The beam is installed along the length of the wall on which the rafters will rest.

In log houses, the role of the mauerlat is played by the upper crown. In buildings built from porous material (aerated concrete, foam concrete) or brick, the Mauerlat is installed along the entire length of the load-bearing wall. In other cases, it can be installed between the rafter legs.

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Since the length of the Mauerlat exceeds standard sizes lumber, it has to be spliced.

The connection of the Mauerlat to each other is done as shown in the figure.

How to connect the Mauerlat?

The beams are cut only at an angle of 90°. Connections are made using bolts. Nails, wire, wooden dowels are not used.

How to attach the Mauerlat?

The Mauerlat is installed at the top of the wall. The installation technology provides several ways to attach the Mauerlat:

• strictly in the center of the load-bearing wall;
• with a shift to one side.

Advice.
The Mauerlat cannot be placed closer than 5 cm to the outer edge of the wall.

To protect the timber for the mauerlat from damage, it is laid on a layer waterproofing material, which most often is ordinary roofing felt.

Reliability of Mauerlat fastening important aspect construction. This is due to the fact that the roof slope is like a sail. That is, it experiences strong wind load. Therefore, the Mauerlat must be firmly fixed to the wall.

Methods for attaching the Mauerlat to the wall and rafters

Anchor bolts. Ideal for monolithic structures.

Wooden dowels. Used for log houses and beams. But, they are always used with additional fasteners.

Staples.

Stud or fittings. It is used if the cottage is built from porous materials (aerated concrete, foam concrete).

Sliding mount (hinge). Tying in this way allows for the displacement of the rafter legs when the house shrinks.

Annealed wire (knitting, steel). Used as additional fastening In most cases.

2. Manufacturing of trusses or pairs

Installation is carried out in two ways:

• installation of beams directly on the roof. It is not used often, since it is problematic to carry out all the work, measurements, and trimming at height. But it allows you to completely do the installation yourself;

• assembly on the ground. That is, individual elements (triangles or pairs) for the rafter system can be assembled below and then raised to the roof. The advantage of such a system is faster execution high-altitude work. The disadvantage is that the weight of the assembled truss structure can be significant. To lift it you will need special equipment.

Advice. Before assembling the rafter legs, you need to apply markings. It is very convenient to use templates for these purposes. The rafter pairs assembled according to the template will be absolutely identical. To make a template, you need to take two boards, the length of each of which is equal to the length of one rafter, and connect them together.

3. Installation of rafter legs

The assembled pairs rise to the top and are installed on the Mauerlat. To do this, you need to make a gash at the bottom of the rafter legs.

Advice. Since the slots on the Mauerlat will weaken it, you can only make cuts on the rafter leg. To ensure that the cut is uniform and fits tightly to the base, you need to use a template. It is cut out of plywood.

Methods of fastening the rafter leg are shown in the figure.

You need to start installing rafter pairs from opposite ends of the roof.

Advice. To correctly install the rafter legs, it is better to use temporary struts and spacers.

A string is stretched between the fixed pairs. It will simplify the installation of subsequent rafter pairs. It will also indicate the level of the ridge.

If the rafter system is mounted directly on the roof of the house, then after installing the two outer rafter legs, the ridge support is installed. Next, the halves of the rafter pair are attached to it.

It is worth noting that the opinions of professionals differ on this issue. Some advise using a staggered fastening pattern, which will allow the increasing load to be distributed more evenly on the walls and foundation. This order involves installing one rafter in a checkerboard pattern. After part of the rafter legs is installed, the missing parts of the pair are mounted. Others insist that it is necessary to mount each pair in a sequential manner. Depending on the size of the structure and the configuration of the truss, the rafter legs are reinforced with supports and racks.

Nuance. Connect additional elements structures using cutting. It is preferable to fix them with construction staples.

If necessary, you can lengthen the rafter leg.

Methods for splicing rafter legs are shown in the photo.

Advice. The method by which the mauerlat is lengthened (cut at 90°) cannot be used in this case. This will weaken the rafter.

4. Installing the ridge of a gable roof

The roof ridge unit is made by connecting the rafter legs at the top.

Roof ridge structure:

• Method without using a support beam (see figure).

• Method using rafter beams. Timber is needed for large roofs. In the future, it can become a support for the rack.

• Method of laying on timber.

• A more modern version of making a ridge knot can be considered the method shown in the photo.

• Cutting method.

After the rafter system is installed, we perform major fastening of all structural elements.

5. Installation of roof sheathing

The sheathing is installed in any case, and is designed for more convenient movement along the roof during work, as well as for fastening roofing material.

The sheathing pitch depends on the type of roofing material, for example:

• for metal tiles - 350 mm (the distance between the two lower boards of the sheathing should be 300 mm).
• for corrugated sheets and slate - 440 mm.
• We lay a continuous sheathing under the soft roof.

Rafter system of a gable roof with an attic - video:

Conclusion

As you can see, despite its apparent simplicity, the installation of a gable roof rafter system contains many pitfalls. But, based on the recommendations given, you can build without any problems reliable design with your own hands.

Among all the different types and designs of roofs, gable roof schemes are the most common in private housing construction. The gable roof has truly become the “people's choice” due to its simplicity of design, durability and reliability of the structure, and affordability. Today, a gable roof built by modern specialists can have such an unusual and original appearance that it is not always possible to recognize the basis of its structure.

Classic gable roof scheme

What is a gable roof? Until recently it was believed that this is a classical scheme formed by two inclined planes, which are connected to each other along the line of the ridge beam, at the top point of the roof, as in the photo. Today, this definition has lost its meaning due to the fact that many new species have appeared. gable structures, which are united by one feature - the roof of the house has two slopes of a flat surface.

Durability of the classic gable scheme determined design features supporting frame:

• Each of the two slopes is formed by a set of rafter beams, supported by a central ridge beam in the upper part and on the wall plate in the lower part of the frame. The creators of the gable roof laid its basis on the principle of mutual compensation of horizontal forces from the weight of the slopes and the ability to evenly redistribute the load from the weight of the frame, roofing “pie” and snow cover onto the walls of the building;
• Until the completion of the assembly of the rafter system and filling of the sheathing boards, each of the rafter legs participates in holding the entire frame in the calculated position, but at the same time “lives” as if “on its own.” This allows you to correctly align and fix the rafter in the desired position without weakening the strength of the entire structure and without affecting the “neighbors”;
• The use of the system allows the gable roof to “adapt” to the load in any conditions and at any temperature, without destruction or deformation load-bearing elements roofs.

Attention! The use of wood for the construction of a gable roof structure allows us to obtain the lightest and most durable frame that is immune to alternating loads and temperature fluctuations.

If you try to replace wooden beams with steel ones, the weight of the structure would increase significantly, and due to the high coefficient of thermal expansion and high thermal conductivity of the metal, the thickness of the thermal insulation would at least double.

In some cases, for example, if a small roof is required, rafters with floor beams and vertical posts can be assembled according to a pattern into one roof strength element. Knowing the pitch between the rafters and the size of the gable roof, you can put together required amount such preparations on earth. All that remains is to lift them onto the walls and install them, securing them with a ridge beam and sheathing boards.

Gable roof with terrace

This type of roofing has actually become business card country house or dachas. The method of arranging a holiday home implied the presence of a bedroom or guest room on the second floor of the building. Therefore, in such buildings, a terrace was necessarily installed on the pediment of the building. Structurally, the construction of this type of roof was practically no different from the arrangement of a conventional roofing scheme; part of the slope to the depth of the terrace was sewn up from the inside with clapboard, a fence and board flooring were installed on the front wall, which went into the floor of the upper floor.

The most interesting types of gable roofs

Development construction technologies made it possible to develop and construct several new types of roofing with two slopes. Today, gable options include all categories of roofing structures designed in the form of two inclined planes.

If a country house requires unusual design, choose one of the most popular schemes:

1. Asymmetrical gable roof;
2. A stylish multi-level system of two slopes, with a central or offset location of the ridge beam relative to the building frame;
3. Gable roof with bay window, mezzanine or dormer windows.

Important! The original appearance of a building, as a rule, requires very precise and painstaking work in calculating the load-bearing elements.

Unlike classical types gable roof, in this case it is not enough to know the features of the device; for the correct arrangement of the roof, a large amount of calculations will be required. Therefore, the most unusual types of gable roofs are developed using the specialized Archicad18 software package. In addition to high design productivity, in Archikad you can get complete detailing of a structure of the most complex type and design.

Fashion for asymmetrical gable roofs

Most often, the asymmetrical shape of a gable roof is associated with the specific layout of the building walls. If you look at a house with an asymmetrical gable roof from the front side, the reason becomes clear unusual design roofing covering of the house. One of the slopes of the house is relatively flat and long, with an inclination angle of up to 20 degrees. Under such conditions, the larger slope provides minimal resistance to air flow. If you reduce the slope of the slope to 11 degrees, the dynamic wind pressure will decrease by half. With a slope of 45 degrees, the most common when constructing gable roofs, the pressure air flow the area of ​​the slope will not decrease, but, on the contrary, will increase more than twice as compared to a 20-degree slope. Therefore, asymmetrical types of roofing structures not only have an impressive design, they are, first of all, designed and manufactured for areas with powerful but directionally stable air flow.

For example, if a country house or cottage is installed on a dividing strip between a wide field and a dense forest, it would be most rational to design and build an asymmetrical type of roof so that the wide and flat part of the roof is turned towards the field. This roof design effectively protects the building from winds blowing from open areas.

Multi-level gable roofs

Most often, this option is a modification of asymmetrical roofing schemes. Often a shorter roof slope is made below a larger roof slope. The rafters of the larger slope rest on a ridge board or mauerlat embedded on the top of the central load-bearing wall of the building, top part a short slope is usually attached to the floor beam of the upper floor. Thus, the small slope appears to be shifted in height relative to the larger one by one floor.

This type of coating can be considered a composition of two pitched roofs. This partially simplifies the construction of a gable roof, especially if you take into account that large slopes require the use of expensive long rafters and a large number of power elements, struts, racks, and crossbars.

The design option with multi-level slopes has not only an unusual and attractive appearance, but also a purely utilitarian purpose. This type of gable roof is used if there is a need to arrange a terrace, an extension or a canopy over the entrance to a two-story building. Thanks to the design features of the large ramp, it is possible to increase the size of the overhangs and place them on outriggers. Thus, the roof above the terrace is an organic continuation of the main roof covering.

In some cases, one of the slopes of a multi-level roof is made in the form of a broken structure. For example, this type of roofing is suitable if you need to install a roof for a nearby extension, for example, for a summer kitchen, garage or utility room.

The broken roof scheme, despite its close relationship to the gable version, has long existed as independent option arrangement two-story buildings. This look is ideal for organizing attic room increased comfort, the symmetrical design of the slopes allows you to perfectly balance the frame, and the variable angle of inclination makes it possible to make the most efficient use of the attic space.

Often the broken structure is complemented by a bay window or dormer windows.

Gable roof with bay window or mezzanine

The views of gable roofs with various kinds of additional superstructures look quite picturesque. For example, the view of a bay window protruding beyond façade wall and rising to the roof slope, gives the house and roof the appearance of an ancient building in the style of the 19th century. Often a guest room or dining room is equipped inside the bay window. The bay window cover most often fits into the gable roof of the building, but can also be made in the form of an independent turret. The appearance of a bay window always gave a two-story house the features of an aristocratic building.

A gable roof with a mezzanine or dormer windows looks more peaceful. If you need to arrange a full-fledged living space in the attic space or give the building the appearance of a two-story mansion, the best way there will be a mezzanine construction. Additional windows and balconies in the form of a superstructure for triangular roof They give the mediocre building a rather picturesque appearance.

Conclusion

The relative simplicity of arranging modern types of gable roofs has led to their wide distribution among individual developers. The absence of problematic nodes and transitions characteristic of other types of roofing allows the designer and planner to creatively use the possibilities of designing the interior space and decorative elements.

A gable roof is a roofing structure that is most often used in private housing construction. It is not only simple to construct, it is reliable and inexpensive if you correctly calculate the number of elements.. The article discusses what elements this type of roofing consists of, and how it can be assembled with your own hands. You will learn about the basics of calculations, rules and assembly stages, which will allow you to talk “on the same wavelength” with the contractors of the construction company.

Source oz90.ru

Online roofing calculator

To find out approximate cost gable roof, use the following calculator:

What elements does a double slope roof consist of?

From the name itself it becomes clear that such roofs have only two slopes, which can be the same or different in area. The former are called symmetrical, the latter asymmetrical

Not all gable roofs are made of the same elements. But among them there are basic ones that are present in all designs.

Mauerlat– beam 100x100 mm (minimum cross-section), on which the rafter system rests. The main purpose is to evenly distribute the load acting from the roof structure on the walls of the building. The Mauerlat is attached specifically to the walls (there are several options).

Rafters, otherwise they are called rafter legs. These are boards (rarely beams) with minimum thickness 50 mm, located with a slope towards the walls. They form the slopes. At the lower end they are attached to the mauerlat, at the upper end to the ridge beam or to each other.

Ridge beam It is not always used, but only when the roof is covered with layered rafters. More on this below. Its purpose is to support the rafter legs.

Rafters attached to the mauerlat Source krysha-expert.ru

Additional wooden elements, which are not used on all gable structures.

Supports for the ridge beam. They are installed only if one is present in the roofing structure.

Rafter supports. Used if the width of the building is more than 12 m. The longer the rafters, the lower their load-bearing capacity.

Run, aka timber, laid on racks across the rafter legs. The rafters rest on it, and not on the supports.

Sill– a beam located parallel to the girder, only in the lower part. Rafter racks are mounted on it.

Puffs. These are bars that pull paired racks together (between each other).

Types of rafter systems

There are two of them: hanging and layered. The first type, in which the upper ends of the rafters rest against each other, and are fastened together. To increase the strength of the connection and the reliability of the structure, a tightening is often installed between them.

The second type is legs resting on a skate. They can also be tightened if the goal is to increase the load-bearing capacity of the entire system.

Attention! The tightening functions for the hanging variety can be performed by the floor beam on which the legs rest.

Hanging and layered rafters Source kayabaparts.ru

On our website you can find contacts construction companies who offer roof calculation, installation and repair services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

Rules for assembling a gable roof

A gable roof is assembled in different ways. Dependency - type of rafter system. Let's look at each one separately.

Assembling hanging rafters

There is a strict sequence of operations:

Produce installation of Mauerlat on walls. It is attached to them using pins, which are installed in the poured reinforcing belt. The upper end of the stud is the threaded part onto which a nut with a wide washer is screwed. It is with them that the Mauerlat is pressed against the wall.

Produce installation of ridge beams. To do this, support posts made of timber or boards are installed along the roof structure right in the middle (if a symmetrical roof is being constructed). They are attached to the beam or to the floor beams with special metal corners on self-tapping screws. Additionally, supports and jibs are installed to maintain the verticality of the racks.

For the latest fits ridge beam , which is fixed to the racks with the same metal profiles(corners, plates, etc.). The main task of the workman is to align the ridge girder in a horizontal plane.

Rafters are installed in pairs, forming triangles of the roofing system.

Hanging rafters Source kayabaparts.ru

If there is a need, then under the rafter legs they are installed additional racks. They are either attached directly to each other, or laid on top of the posts with a run across the legs.

On top of the rafter system lathing is installed from wooden blocks or boards.

On top of the sheathing roofing material is stuffed.

Assembly of layered

Layered rafter system of a gable roof frame house, and not only frame, it is assembled not on the roof, but on the ground. The thing is that it is difficult to fit the elements together when they do not have support at one end. To do this, it will be necessary to build an additional supporting structure temporary type. This is a waste of time, effort and money that no one needs.

Therefore, paired rafters, which when assembled are called trusses, are assembled in the plane of the ground. Since the structure of the truss is a triangle, which is also isosceles in a symmetrical roof, it will not be difficult to assemble it. The main task of the work manufacturer is to comply with the dimensional parameters of the truss elements. Because it will be more difficult to adjust roof trusses if there are sufficiently large dimensional errors between them.

Raise the rafter assembly onto the roof crane or other device.

Installation of layered rafters Source pallazzo.su

At first install two extreme trusses along the gables of the house, align them with each other in height and secure them to the floor beams with supports and jibs (temporary).

Pull between top points two trusses thread, along which the remaining rafter triangles are mounted.

The rest is the same as in the case of hanging rafter legs: the sheathing and roofing material are stuffed.

Video description

The process of erecting a gable roof in the video:

Calculation of rafter legs

An important preparatory measure on which the load-bearing capacity of the system as a whole depends. It is impossible to carry out the calculation yourself if you do not understand it. Therefore, ordinary people use online calculators or tables. The calculation manipulations are based on the cross-section of the bars (in mm) or boards, depending on the length of the legs and the installation pitch.

The dependence is this: the longer the legs and the greater the distance between them, the larger the cross-section of the beams should be. Eg:

installation pitch 2.15 m, rafter length is 3 m, for this purpose a beam with a section of 100x150 mm is used;

step 1.4, length 3, section 75x125 mm;

step 2.15, length 5 m, section 100x250;

step 0.9, length 5.5, section 50x200 mm.

For each position there is a specific parameter for the bars used. The tables are freely available.

Distribution diagram of rafter legs Source: chaos-heart.ru

Slope slope

Determining the slope of a gable roof structure is not easy. Take into account the type of roofing. The dependency is:

if asbestos-cement slate is used, then the angle should be not less than 22°, reducing this parameter will lead to leaks at the junctions of adjacent sheets;

metal tiles – angle 14°;

corrugated sheet - 12°;

bitumen shingles- corner should not exceed 15°, otherwise there is a possibility of the coating sliding off the sheathing;

rolled material (roofing felt, roofing felt and others) – slope within 3-25°.

But there is one nuance here. The steeper the roof, the less stress there is on its slopes, because rainwater and snow quickly disappear from the surfaces. But at the same time the windage of the structure increases. That is, wind loads increase. At the same time, high roofs mean an increase in the cost of building materials, which increases the cost of construction.

Roof slope angle Source arhplan.ru

Sloped roofs

Gable roof with different slopes today it occurs quite often. This is not to say that they are better than symmetrical ones, but the originality of the design made them popular. Let us add that such roofs are more complex than traditional ones with identical slopes.

These roofs are divided into three types:

Asymmetrical. Their ridge girder is located in the middle of the house. The slopes are located to each other at the same angle of inclination. But one of them is always longer than the other.

Asymmetrical. The length of the slopes can be the same or different, but the angle of inclination of both is different.

Asymmetrical with offset. The same as the previous option, only the ridge girder is shifted relative to the middle of the house to one side.

Asymmetrical gable roof with offset ridge girder Source pinterest.ca

Rules for the construction of asymmetrical gable roofs

A gable roof with different slopes is a complex structure. The whole difficulty lies in the fact that the displacement of the ridge beam relative to the middle of the building creates completely different loads. They are no longer distributed along the ridge. Their main pressure (central) falls on the long, flatter slope. That is why at the design and calculation stage it is necessary to accurately determine the location of installation of additional racks. They are installed under the rafters of a long, gentle slope.

In this case, the entire rafter system is not installed by eye. Even the smallest deviation from the project can lead to irreparable consequences. Making changes to the design will be difficult, and sometimes simply impossible.

Asymmetrical roof truss Source builtec.info

And one moment. For an asymmetrical roof (gable) the construction of a very strong Mauerlat is required, with the help of which uneven loads will have to be redistributed. Special attention attaching the Mauerlat to the walls of the house.

As for the construction of a roof with different slopes, the technology itself is no different from the traditional one. The main thing is to strictly adhere to the requirements outlined above. Typically, such structures are assembled from layered rafter legs with the installation of a ridge beam. Therefore, the main task of the work contractor is to accurately align the ridge horizontally on the site strictly according to the design. The dimensions of the rafters must be precisely maintained, mainly regarding the length.

Multi-level roofs

Another type of roof with two slopes. To understand what we are talking about, look at the photo below.

Multi-level gable roofs Source moscow.sk-evrodom.ru

According to its configuration, the roof is gable and covers the entire house. But individually, each slope represents single-slope structure. Usually a load-bearing wall is erected between them, on which both slopes rest.

But at the same time, the larger slope rests on the upper end of the wall, where the ridge beam or Mauerlat beam is installed, and the smaller one on its vertical plane, where it is usually fixed load-bearing beam. The construction of such roofs is carried out using the technology of a single-pitched structure.

Gable roofs with broken slopes

These structures are mainly used in houses where the construction of an attic is planned. Organizing a room under traditional slopes is problematic. The reason is the presence of “dead” zones at the junction of the rafter system and the wall of the house. To remove these zones, it is necessary to make part of the slope steeper in terms of inclination relative to the vertical.

The cross-section of the roof will not be triangular, but pentagonal. Assembling it is not easy, there are too many elements located under different angles. But she has serious advantages before everyone else:

holds up well snow loads ;

excellent resistance wind pressure.

Minus one - high consumption building materials. But the gain is clear - additional living room for a small outlay.

Broken mansard roof Source nkkconsult.ru

Construction mansard roof- this is the installation of racks on which the beds are laid and the lower ends of the rafter system rest. At the top, the ends of the rafters are connected at the ridge. The steep lower rafter legs rest against the mauerlat from below, and on the beds from above. The result is a fairly stable and durable structure.

Video description

In this video about the construction of a mansard roof:

Generalization on the topic

The variety of roofs with two slopes makes it possible to choose the option that fits into the architecture of the house being built. The effectiveness of the structure is just the visible part. The design is based on an accurate calculation of the elements and the loads on them. But, as practice shows, most roofs in the private housing construction category are gable.

A gable roof is a roof formed by two inclined surfaces. They are directed counter to each other, and the intersection is connected by one skate in parallel long side Houses. A gable roof with different slopes is a type of structure. It is distinguished from the traditional symmetrical design primarily by geometric parameters, and only then by specific features.

Basics of geometry

To understand how such a roof is constructed, you need to consider these properties and compare photos of the two types of structures. Since we are talking about gable variety, in a profile section this shape always forms a triangle. The upper ceiling of the building is the base of the figure and serves as the supporting surface of the structure. The roof slopes are the sides of the triangle.

Looking at the symmetrical roof (first photo), you can see that the inclined surfaces are equal in length and are at the same angle to the base of the triangle. The ridge, hiding the intersection of the slopes, is located exactly in the center of the building and passes through the axis of symmetry. A multi-slope design is characterized by different lengths of slopes and different angles at the base(second photo). This concept is the result of a geometric transformation. There is a proportional relationship between the elements of the triangle. If you change one, all the others are changed.

Photo No. 1 - gable roof with identical slopes

Based on this dependence, the roof structure under consideration has two main parameters: the length of the slopes and the slope. Using this name, the latter value would be correctly calculated as a percentage. To do this, you need to calculate the tangent of the angle at the base of the roof, multiplied by 100%. However, for convenience and quick understanding, degrees are most often used as a unit of measurement. Thus, each slope of an asymmetrical roof is characterized by a separate length and slope.

Photo No. 2 - roof structure with different slopes

Why are different slopes needed?

This is a question that a novice builder will ask. The choice of design is based on two areas: design and performance properties.

The appearance of the roof is important from the very beginning for those who want to make the building beautiful and unique from an aesthetic point of view. Symmetry in everything often gets boring, and many modern tendencies in the field of design they rely on breaking stereotypes and moving away from regular geometric shapes.

That is why in this regard, a design with different slopes stands out. The ability to play with sizes and angles even in a classic triangle allows you to build roofs that are original and interesting in design. Variability gives a chance to distinguish a building from others and make it more noticeable. This is because the roof is the main element that forms the appearance of the building.

Influence of weather conditions on design calculations

Technological features come from the same geometric parameters. How the structure will withstand weather conditions depends on the slope of the slope. It is based on climatic data that the angle value that will ensure the reliability and durability of the roof is determined. A reasonable step when planning is to study the wind rose over the last 2-3 years in the local area.

From it you can judge the strength of the wind and its most frequent direction. On the side of the roof, where gusts come from in most cases, it is recommended to install a slope with a smaller angle of inclination. This will reduce the load on the supporting structure and also reduce the noise created by vibration of the roof.

Precipitation affects the calculation of slopes. In dry and warm areas, the angles may be the smallest and the lengths the largest. Areas with heavy precipitation require steeper slopes from the structure so that all moisture and solid precipitation leave the roof as quickly as possible, do not stagnate and do not create unnecessary loads. Roof angle ranges vary widely, from 11º to 70º.

Organization of space

Increasing the roof slope allows you to profitably use the space in the attic. With this approach, you can arrange a spacious storage room, a comfortable room or a spacious attic under the roof. Often alone roof surface overlaps two floor spans at once. This is exactly the case when the slopes obviously differ in length. Also, it becomes possible to arrange a terrace, the canopy of which will be a continuation of one of the slopes.

Common methods of increasing the area include the use of broken structures, when one of the slopes, not reaching the base, changes the angle of inclination. Of course, such sophistications incur costs for additional building materials and complex work.

Material of construction

The roof of the roof is supported by a rafter system. From time immemorial, wood has traditionally been used as a material for construction, but metal or reinforced concrete can also be used. The first is in the lead due to the possibility of precise processing, strength and optimal weight of the frame. For the construction of the structure, certain types of wood are chosen:

• Pine is universal. Coniferous durable, resinous, which reduces the risk of rotting. The tree trunk is straight and light. The low cost of pine timber is explained by its wide distribution.
• Larch is durable.
• Spruce is just as durable, but more susceptible to moisture.
• Powerful oak is suitable for critical elements, for example, mauerlat. It is easy to handle. The material is expensive compared to other breeds.
• Aspen is resilient, but often has a rotten core, which limits its scope of application
• Beech is durable and lasts for many years, but is difficult to process.

Using wood in construction gable roofs with different slopes, it is strongly recommended to use only coniferous or only hardwood for all frame elements.

Metal, like reinforced concrete, is the basis of creation load-bearing structure benefits only for large construction projects, where pitched roofs are rare. One solid span can reach 2-3 tens of meters. In other respects, it is much inferior to wood: expensive, difficult to process, allows cold to pass through, and accumulates condensation.

Frame structure and correct calculation

When calculating a pitched structure, climatic conditions, wind forces, and the weight of the roof are taken into account. The latter is important: the coating layer creates a constant load on the frame supports. Heavy weight, for example, has ceramic tiles, soft roofing is much lighter. In combination, all these factors form the general requirements for the roof truss system and determine parameters such as rafter pitch, number of elements, beam thickness and frame material.

Drawing gable construction allows you to understand what elements the supporting structure consists of:

• The rafters are attached to the building using a mauerlat - a strong frame laid to the side load-bearing walls made of bricks and blocks. On the outside of the building, it is recommended to cover this frame element with an additional brick row for reliable fixation.
• The ridge run is the second support of the slopes. It installs on top corners pediments.
• The side purlins are attached parallel to the roof ridge. Together with the central beam, they are brought out a little further than the pediment in order to reduce the load.
• Rafters are supports for the roof. They serve as a connection between the ridge and load-bearing walls. To strengthen the opposite rafters, they are connected with special ties made of wood or metal. The roof elements are assembled in two ways: hanging and layered. The first is characterized by the fact that the opposing rafters hold each other with a strong connection, the roof load is bursting. The layered structure includes additional central supports connecting the bed and the ridge beam. This device is used when there are internal load-bearing walls. The presence of different slopes implies the installation of additional ties between the rafters and other beams to regulate the load.

A gable roof with asymmetrical surfaces is a bold step by the builder own home. This is an opportunity to improve your home with a permanent roof with effective use space.