Rigid rafter system. Strong roof: roof truss system and its types

Arranging a gable roof is considered very practical and the right decision during the construction of a residential or commercial building. This option combines relative simplicity of execution and reliability, ease of maintenance and long service life. IN this material we will tell you how to install the rafter system gable roof with your own hands, what are its varieties, and how to calculate the sizes of its individual elements. Our step-by-step instruction will allow you to deal with any complications that may arise during the work process.

A roof with two slopes has a whole list of advantages:

• ease of calculations;
• various options execution;
• saving materials;
• possibility of natural outflow of water;
• low probability of water leakage due to the integrity of the structure;
• the possibility of arranging an attic or attic;
• reliability and long service life;
• convenience of preventive repairs.

Types of gable roofs

Let's consider the main types of roofs with two slopes, the rafter system in which will differ slightly in design.

Symmetrical gable roof

This is the simplest gable roof, however, is the most reliable and in demand. Symmetrical slopes allow you to distribute the load on the mauerlat and load-bearing walls evenly. In this case, the type and thickness of the insulating layer do not affect the choice roofing material. Thick rafter beams have a sufficient margin of safety, so they will not bend. In addition, spacers can be installed at your discretion.

Among the disadvantages of this option, one can only note that sharp corner slopes, which makes it difficult to use the attic floor and creates “dead” areas that have no use.

Roof with two asymmetric slopes

If the angle of inclination of the slopes is made more than 45º, you can use some unused areas of space. It will even be possible to arrange a living space in the attic. However, some additional calculations, since the load on the walls will become uneven.

Broken roof with external or internal fracture

This configuration makes it possible to place a spacious attic or attic under the roof. However, in this case, more complex engineering calculations will be required.

The design of rafters for arranging a roof with two slopes

The design of the gable roof truss system assumes the presence of the following components:

• Mauerlat. It is a durable beam made of oak, pine, larch or other strong wood, which is laid along the perimeter on the load-bearing walls of the building. The purpose of the Mauerlat is to evenly distribute the load. The cross-section of the bars is chosen based on their structure - solid or glued, as well as on the age of the building. The most commonly used beams are 100×100 or 150×150 mm.
• Rafters. The entire structure is created from such elements (read also: " "). Connecting at the top point, two rafters form a truss. They are made from logs or strong bars.
• Puff. This item serves to connect the rafters and ensure their rigidity.
• Runs. In those places where they join rafter legs, attach the ridge purlin, on which the ridge will subsequently be mounted. And with the help of side girders, the rafter frame is given additional strength. The expected load determines the size and number of such elements.
• Rafter stand. This is a vertical beam that partially takes on the weight of the roof. If the design of a gable roof is simple, then one such beam is placed in the center. A long span may require three bars - one in the center and two on the sides. If an asymmetrical roof is being erected, then the location of such a beam is determined by the length of the rafter legs. Under the rafters for sloping roof racks are placed on the sides to free up space for movement. Beams are placed in the center and sides if there are two rooms.
• Struts. These are the supports for the rack. If significant winds and precipitation are expected in winter period, install longitudinal as well as diagonal racks.
• Sill. The rafter stand rests on it, and the struts are also attached.

• Lathing. The selected roofing material is attached to it, and you can also move on it during work. Fix the sheathing perpendicular to the rafters. Please note that the lathing allows you to evenly distribute the mass of roofing material throughout the rafter system.

The installation diagram of the gable roof rafter system will greatly facilitate everything. construction works. How such a roof scheme will look depends on the type of roof.

Please note that the material for the rafter system must be of the highest quality, treated with fire retardants and antiseptics. There should be no knots or cracks on the beams for rafters, mauerlat and racks. Only a small number of knots firmly seated in the wood are allowed on the sheathing.

Calculation of frame elements for a gable roof

Laying Mauerlat on walls

This element is mounted on the load-bearing wall along its entire length. If we're talking about O log house, then the upper crown can serve as the Mauerlat. For buildings made of aerated concrete or brick, you will need a Mauerlat equal to the length of the wall. Sometimes this part can be laid between the rafters.

If there is insufficient length of material for the Mauerlat, several pieces can be spliced ​​together. In this case, the edges are filed at 90º and joined using bolts - wire, dowels or nails are not suitable.

There are two ways to lay the Mauerlat on top load-bearing wall:

• symmetrical in the center;
• with a shift in the desired direction.

Installation of the Mauerlat is carried out on a pre-laid waterproofing layer from roofing felt. This will protect the wood from rotting.

It is worth taking a responsible approach to the process of attaching the Mauerlat, since when strong wind it must withstand particularly heavy loads.

The following consumables can be used as fastenings for the Mauerlat:

• Anchors that are indispensable for monolithic materials.
• Wooden dowels. These parts are used in houses made of timber and logs, although they require additional fastenings.
• Staples.
• Reinforcement or special studs. This option is preferable for buildings made of foam or aerated concrete.
• Knitting or steel wire is an auxiliary fastening element that is almost always used.

Assembling trusses or rafter pairs

Trusses can be assembled using one of the following methods:

• The beams for the rafters are assembled and attached directly to the roof of the building. This process is quite labor-intensive, since all measurements, trimming and coupling of beams will have to be done at height. However, you can do it on your own, without the involvement of technology.
• Trusses or rafter pairs can be fixed to the ground, and then the finished elements can be raised to the roof of the building. On the one hand, this simplifies the process of installing the rafters, and on the other, due to the large weight of the structure, lifting it to the top will require special equipment.

Please note that you should start assembling rafter pairs only after marking has been applied. And if you make a template in advance, for which you take two boards, equal to length rafters, and connect them together, then all pairs will turn out exactly the same.

Installation of rafters

After assembly and lifting to a height, the gable roof rafters are installed wooden house. To fix them on the Mauerlat, cuts are made at the bottom of the rafters. The first to install are two trusses at opposite ends of the roof.

After this, a rope is pulled between the starting pairs, along which all other trusses will be aligned and the ridge will be installed.

Now you can mount the remaining pairs, observing the calculated step between them. In cases where the pairs are assembled directly on the roof, a ridge girder is attached between the two end trusses. The rafters are subsequently installed on it.

The procedure for installing rafter halves may differ according to the opinions of professionals. Some people prefer to lay the beams in a checkerboard pattern so as not to overload the foundation and walls during work. Others are inclined to install pairs of rafters in series. Be that as it may, rafter legs may need supports and posts - it all depends on the size of the roof and the shape of the trusses.

Skate attachment

A ridge is an element that is formed by attaching rafters at the highest point. As soon as all the parts of the rafter system for a gable roof have been installed, all structural elements should be thoroughly secured.

Installation of sheathing

The presence of sheathing is mandatory when constructing any roof. It not only supports the roofing material and allows it to be securely fastened, but also makes it possible to move along the roof while working.

The distance between individual boards is selected based on the type of roofing material:

• soft roofing is laid on a continuous sheathing without gaps;
• for metal tiles you need lathing in increments of 35 cm (between the two bottom rows - 30 cm);
• slate and corrugated sheeting can be laid on the sheathing in increments of 44 cm.

Results

Thus, in order to assemble a rafter system for a roof with two slopes, you should take into account many nuances and provide for any possible complications. We hope that our tips will help you cope with this difficult task and create a high-quality and durable roof for your home.

For the manufacture of rafters in individual construction, they usually use wooden materials: boards, beams, logs. Despite their relative cheapness, wooden roof rafters are strong enough to withstand all roofing loads and serve faithfully long years.

Other possible materials for rafter systems - metal and reinforced concrete - are not practical for private construction due to their heavy weight, complex installation and high cost.

Rafter system must be strong, but not heavy. Of course, for the load-bearing foundation of the roof of large industrial buildings and high-rise buildings, you have to use metal or reinforced concrete. But for ordinary private houses this is an unnecessary excess. In this case, the rafters are made of wood - from boards, timber (regular or glued), logs.

Logs are rarely used, exclusively for log houses. This material is too heavy, requiring high professionalism from the carpenter and the ability to make complex cuts in the fastening areas.

Timber is the most the best option, from which you can mount strong and durable rafters. The only drawback of the timber is the high price.

Cheaper boards with a minimum thickness of 40-60 mm are often used as a replacement for timber. The list of their advantages can also include light weight, ease of installation and high safety margin.

The following requirements apply to the selected lumber:

• The minimum acceptable types of wood are 1-3. The presence of knots is allowed in small quantities (it is better to do without them at all!), no more than three knots, up to 3 cm high, per 3 m.p. Cracks are also acceptable, but they should not penetrate right through the wood, and their length cannot exceed half the length of the material.
• It is allowed to use dried wood with a moisture content of up to 18-22%. If these indicators are higher, the rafters, as they dry, may crack or bend and lose their shape.
• The load-bearing parts of the rafter system are made of material with a thickness of 5 cm and a width of 10-15 cm.
• Length of elements from coniferous species- up to 6.5 m, and from hard deciduous trees - up to 4.5 m.
• All wooden parts of the rafters, before use, must be treated with protective compounds to prevent them from rotting, fire and damage by wood-boring insects.

Main parts of a wooden rafter system

The main component unit of a wooden rafter system is a truss - a flat triangular structure. The sides of the “triangle” form rafter legs connected at the top at an angle. To connect the rafters horizontally, tie-rods, crossbars, and clamps are used.

The rafter system is made up of several trusses placed on the mauerlat and fastened together by purlins.

To better understand the specifics of the farm, let’s define its elements. Their composition and quantity in one structure depends on the type of roof, its dimensions and the type of rafters used.

So, the components could be like this:

• Rafter leg- These are the rafters themselves, onto which the sheathing is stuffed and the roofing material is laid. The truss consists of two rafters (beams) connected at the top at the ridge in the form of a triangle. Their angle of inclination equal to angle slope of roof slopes.
• Puff- a crossbar that fastens the rafter legs horizontally and prevents them from moving apart when loaded different sides. Used in the system hanging rafters.
• Rigel- a beam similar to a puff, but working on a different principle. In the system it is compressed, not stretched. Fastens the rafter beams in their upper part.
• Fight– also a horizontal crossbar that connects the rafter beams and increases the stability of the truss. Used in a layered rafter system.
• Rack– a horizontal beam that serves as an additional support for fixing the rafter legs.
• Strut- an element mounted at an angle to the horizontal, giving the rafters additional stability.
• fillies– used to lengthen rafter legs when it is necessary to create overhangs.

Also, the rafter system can include parts that are not directly related to the trusses, but are used for their installation and assembly. They are:

• Run- a beam running along the slopes, connecting the rafter legs of the trusses. A special case is a ridge purlin, which is installed along the roof slopes at its highest point (ridge).
• Lathing- consists of beams or boards placed on the rafters from above along the roof slopes. Roofing material is mounted on the sheathing.
• Mauerlat– timber or boards laid along the perimeter of the external (main) walls of the building. The presence of a Mauerlat is provided for securing the lower ends of the rafters to it.
• Sill- an element similar to a Mauerlat, but laid along the inner wall of the building. Vertical posts are fixed to the bed.

Types of rafter systems

From wood you can assemble many options for trusses and, accordingly, rafter systems. But all of them can be divided into two types: hanging and layered.

Hanging rafter systems

Suitable for rooms without interior walls. Trusses made up of rafters rest solely on the outer walls; there is no need for additional support. That is, hanging rafters cover one span, 6-14 m wide.

An obligatory part of hanging trusses, in addition to the rafter legs connected at the top at an angle, is a tie - a horizontal beam connecting the rafters. The tie becomes the basis of the “triangle” of the truss. In most cases, it is located at the bottom of the structure, connecting the lower ends of paired rafters. But raised-pull designs are also used. And also with its modified version - a crossbar, which looks like a raised tightening, but works on compression, and not on tension, like a true tightening.

The need to use a Mauerlat depends on the presence of the tie and its location in the farm. If the tightening is located at the base of the rafter legs, then the Mauerlat is not needed. During installation, the truss is supported on the external walls through the existing tie, which at the same time becomes a floor beam. If the tie is raised upward or a crossbar is used instead, then the Mauerlat must be included in the diagram as the basis for attaching the rafters to the upper edges of the walls.

As additional elements in a hanging system, headstocks and struts are used. They serve to strengthen the truss when covering wide spans.

The headstock in appearance resembles a vertical post running from the center of the tightening to the top point of the truss (ridge part). In fact, the headstock is a suspension, the function of which is to support a pull that is too long (more than 6 m) and prevent it from sagging.

In tandem with the headstock, with an even greater increase in the tightening length, struts are used - diagonal beams. They are rested with one end against the rafter leg, and the other against the headstock. In one farm, two struts are used, on both sides of the headstock.

In country houses and small private houses, hanging rafters made of wood are good because they allow you to create spacious attic rooms no partitions inside. Of course, we are talking about schemes where there are no struts and headstocks. Their presence imposes on the developer the need to divide the attic into at least two rooms.

Layered rafter systems

The layered structure of wooden rafters is used for rooms with internal main walls, which serve as additional support for the system. In this case, the distance between the external walls (total overlapped span) can be within 6-15 m.

Rafter trusses necessarily consist of rafter legs supported on the outer walls and a vertical drain supported on the inner wall. If there are two internal walls, two studs can be used in the scheme.

Unlike a hanging system, a layered system must have a Mauerlat to which the rafter legs are attached. The racks crash into a kind of mauerlat - a bench. This is a timber laid on top of an internal supporting wall.

For a span of 6 m or less, the simplest layered truss is used, consisting of two paired rafter legs and a stand. The construction of wooden rafters with an increase in span requires the addition of additional details to the diagram, such as contractions and struts (rafter legs).

The contractions are similar to the ties in hanging systems, but they are always located above the base of the rafters. The main purpose of scrum is to increase the stability of the system.

For stability, struts, also called rafter legs, are also provided. The strut supports the rafter leg, that is, in fact, it becomes an additional (third in a row, after the Mauerlat and ridge girder) support for it.

Layered wooden rafters are the most common for private residential buildings and cottages. As a rule, such buildings have one or more internal main partition walls, which can become a support and additional support for a strong rafter system.

Methods of fastening rafters to the Mauerlat

The attachment point of the rafters to the mauerlat is one of the most important; the functionality of the rafter system and its ability to bear loads depend on its correct execution.

There are two types of such fastenings: rigid and sliding. The choice of one of them depends on the scheme truss structure. Replacing a rigid fastening with a sliding one or vice versa, as well as insufficient provision of the required degree of shift of the rafter leg, will lead to the fact that the circuit will “break” and will not work.

The rigid fastening ensures a strong, motionless connection between the rafter and the mauerlat. Shift is not allowed, but the rafter can be rotated at the hinge. Such fastening is organized in two main ways:

• by cutting the rafter beam into the mauerlat and further fixing the assembly with corners, staples, nails;
• using metal corners and a support bar.

A sliding fastening (or, as roofers call it, a “sliding fastener”) is of a slightly different type and functionality. It allows the rafter leg to move relative to the support. Of course, this shift will not be noticeable to the eye, but will allow the rafter system not to deform during the natural shrinkage of the walls of the house. Sliding fastening is especially necessary during construction wooden log houses. It is also implemented in the construction of houses of any other type, if required by the design and calculations of wooden rafters.

To provide the rafter leg with a small range of movement relative to the Mauerlat, special fastening elements are used - sliders. Structurally, they consist of two metal elements, the first of which is static, and the second is capable of moving relative to the first. There are two types of sliding mounts: open and closed types.

The open-type slider is a prefabricated structure consisting of two separate parts: a static guide bar and an angle with a bend at the top. The guide is threaded into the bend of the corner and fixed on the rafter leg, the corner is attached to the mauerlat. When changing the geometric dimensions of the building, the guide can move relative to the rigidly fixed corner by 60-160 mm.

Sliding mount closed type its properties are exactly the same. The design changes a little; it is no longer collapsible, but solid. The corner, which is attached to the Mauerlat, has a loop in the central part. A guide is inserted into it, which, in turn, is attached to the rafter leg.

What both fastening options are (sliding and rigid) is shown in the video:

Another important component of the rafter truss is the rafter attachment point in the ridge part. In private housing construction, the following fastening options are most often used for these purposes:

• overlap;
• end-to-end;
• using a half-tree cut.

Overlapping fastening is considered the most simple option. The upper edges of paired rafters are simply placed on top of each other. Then a hole is made at both ends and the connection is secured with a pin or bolt and nut.

To make a butt connection, the upper ends of the rafter legs are cut off at an angle to make it possible to align the sawn surfaces. Fastening is carried out using nails, which are driven into the end of the ridge part through both rafter legs. To further secure the nail joint, use wooden horizontal pads or metal plates, which are placed over the connection on both sides of the truss.

A half-tree connection involves preliminary cutting out notches at the upper ends of the rafters to half the thickness of the beam. This allows you to combine the rafters in the ridge, like parts of a designer, without increasing the thickness of the ridge assembly (as happens with an overlap connection). After combining the parts, they are fixed with nails, bolts or dowels.

In addition to the methods described, there are other, less common ones. For example, a tongue-and-groove connection. It is not popular, as it requires great professionalism from the carpenter. The essence of the fastening is that a groove is made in one rafter, and a tenon is cut out on the other. The tenon and groove are combined and fastened with a nail or dowel.

One of the possible connections of the rafters in the ridge (end-to-end, through the ridge purlin) is discussed in the video:

Advantages and disadvantages of wooden rafters

However, working with wood and installing wooden rafters does not present any particular difficulties. In addition, there are other advantages of using wood as a material for rafters:

• low cost of wood;
• universal availability;
• relatively light weight, simplifying installation;
• there is no need to use heavy construction equipment;
• versatility, the ability to be used on buildings made of any material, regardless of bearing capacity foundation.

The disadvantages of choosing wooden rafters are minor, but they also need to be known in person before starting construction:

• the need for treatment with protective agents that prevent fire and rotting of wood, as well as reducing its “attractiveness” to various insect pests;
• the use of wooden rafters is possible only on spans up to 14-17 m; for wider spans it is recommended to use metal or reinforced concrete;
• slightly reduced service life compared to metal or reinforced concrete trusses.

Thus, all the shortcomings are features rather than real negative aspects. This explains such a widespread use of wooden rafters in private housing construction.

Every day new houses appear on earth, which are built according to absolutely different technologies. By trial and error, people choose the optimal design for themselves that will serve them for a long time and with high quality. The choice of roof construction system is one of the most important issues resolved in the process of designing a house. Currently, the roof truss system, which has been used for quite a long time and has many advantages, is becoming in demand.

The rafter system is the load-bearing structure of the roof, which is the basis for the tightness of the roof and the stability of the walls. That is, how durable the house will be depends on the quality work done in this direction. This is a roof frame, which consists of a number of interacting parts.

Elements of the roof truss system

This is a rather complex structure, and the importance of each of its component parts should not be underestimated. Here's what it's usually made from:

1. Rafter, or rafter leg. This is a beam that is used to form the angle of inclination of the entire roof. In addition, the rafter is also a support for the roof. The choice of material from which the rafter leg will be made must be taken seriously, because it will be affected by the wind, the weight of people, and precipitation. Therefore, these elements of the rafter system are made from boards with big size sections, especially in the vertical direction.
2. Puff. This is a beam or board connecting the rafters, which are located on opposite slopes. It is located horizontally and does not allow the rafters to creep apart.
3. Run. This is a beam that serves as a support for the rafters at the top or in the middle.
4. Rack. This element is used to support the purlin or rafters. A rack is a component of the system, located vertically; walls often serve as support for it.
5. Mauerlat. This is the beam most often square shape, support for the lower part of the rafters. Mauerlat is laid along the entire perimeter of the building on the walls.
6. Wind beam. This element connects the rafters to each other, forming a roof slope. We are talking about a board that is attached at an angle to the rafters from the attic. The wind beam prevents the rafters from moving in strong winds.
7. Strut. The roof rafter system requires the presence of timber, which should support the rafters so that they do not sag. The strut is attached at an angle to the vertical elements of the building.
8. Sprengel. This is a beam made of logs or timber, thanks to which the entire structure is strengthened. Its location is horizontal. The sprengel is located on adjacent walls; it would be correct to install it perpendicular to the bisector of the angle that these walls create.
9. Filly. This is a board that is attached to the rafters, namely to their lower part. The main role of this element is to create an overhang of the roof.
10. Narozhnik. This is a rafter, but shortened, resting on one side on the mauerlat, and the other on the diagonal leg.

Features of the gable roof rafter system

A gable roof is the most common type of roof for houses up to 3 floors inclusive. Installing such a roof is not at all difficult; you can do it yourself. This installation of the rafter system assumes the presence of two rectangular planes inclined towards each other, which make the upper part of the structure triangular.

Gable roofs mainly consist of rafters and mauerlats. There are layered and hanging rafter systems of this type of roof. With a layered system, the rafter legs cover the roof and have a span of up to 7 m. If it is necessary to cover a larger span, they resort to installing intermediate supports, which increases the span length to 12-15.5 m. Layered rafters have supports on the top of the walls or on the crown log house The middle and lower parts of the rafter legs serve as support.

A suspended roof truss system is a structure in which the rafters rest on load-bearing walls, with no intermediate beams. This type of roofing is acceptable for houses in which the walls are made of lightweight material. The advantage of the hanging system is this: it is excellent for forming long spans. To make the structure strong, purlins, struts, and racks are used.

Rafter system of a hipped roof: advantages and disadvantages

The hip roof is one of the most popular for modern private houses. It has a number of advantages:

• hurricane resistance;
• resistance to deformation;
• good protection of building facades from precipitation;
• beauty of appearance.

However, there are also disadvantages of such a rafter system:

• the design is more expensive than a gable one;
• slopes reduce the area of ​​the attic;
• It is very difficult to install a four-slope rafter system yourself.

Main fastenings of the roof rafter frame

To know how to properly make a roof frame, you need to understand what the main components of the rafter system are. The main nodes are as follows:

1. Attachment point to the beam. The rafter leg must be attached to the beam using a tooth with a tenon (in the rafter) and a socket (in the beam). In this case, the nest should have a depth that will be 25-30% of the volume of the beam. If we are talking about a roof with an angle of less than 35°, a knot with two spikes is used. To create the structure, metal screws, nails, angles, bolts, as well as wooden scarves, tenons and beams are used.
2. Mounting point to the Mauerlat. For fastening, a cut or saddle is made on the rafter, then the connection is fixed using nails, staples and wire. Two nails are crossed together, and the third is forgotten between them in the center. This is how the rafters of the gable roof and the Mauerlat are fastened.
3. Ridge connection unit. Can be mounted end-to-end, overlapping and on a ridge beam. Most often this is done with an overlap, in this case the rafter legs touch each other not with their ends, but with their planes. Fastening occurs using a pin, nails or bolt.

Video with errors during the construction of the rafter system. You can't build like this:

An example of calculating the rafter system of a conventional gable roof

Build rafter roof It’s quite possible to do it yourself; it’s important to be able to correctly calculate the amount of materials needed for this work, as well as take into account all the essential nuances.

Need to consider specific example calculating the roof truss system, and then everything will become completely clear. So, let’s take a house 4 m wide and 6 m long. In this case, the angle of inclination of the rafters is 120°. It will be implemented that there is 1 m between the rafters. 0.5 is the allowance for the roof canopy.

• Find the height of the central support: 0.5x(Width of the house)/tgY/2=0.5x4/1.73=1.2 m.
• Calculate the length of the rafter leg. The size of the rafters for the roof is: 0.5x(Width of the house)/sinY/2+0.5=2.8 m.
• Roof area: (House length)x(Rafter length)x2=33.6 m². This is the number of sheets of metal tiles you will need for the roof.
• Let's calculate the length of the beam: 2x(Length of the rafter leg)+(Width of the house)+(Height of the central support)=75.5 linear meters.
• Since the length of the house is 6 m and the distance between the rafters is 1 m, it will be necessary to have 7 rafters.

Installation of rafters

You should start working with beam floors. To understand how to install rafters on the roof, you need to understand the installation options. If you do not plan to use the attic as housing, you can take 50x150 mm boards. If you need to make an attic, you need a 150x150 mm beam, which will be installed on the load-bearing walls of the house.

The rafter installation process involves the following steps:

1. Preparation of structural elements. For this purpose, boards and beams are made the right size using a circular saw.
2. Marking of all components of the structure according to templates.
3. Assembling the roof truss system according to the markings. After completing this work, all elements should be marked.
4. Sockets are selected in rafter legs and other elements. All fastenings are made using nails, screws, self-tapping screws, metal corners, dowels and wire.

Rafters with small spans can be assembled off-site at special enterprises and purchased in this form. Thanks to this, the roof frame is made much faster.

It is not for nothing that the rafter system is chosen for roof installation, because it is simple and reliable. Knowing the algorithm of actions, you can create a durable roof that will protect from wind, cold and precipitation.

Video on installing the rafter system:

One of the main elements in building a good and durable house is a high-quality rafter system for the roof. The rafter structure must be made of quality materials, because it bears a huge load from the weight of the finishing roof and the load of weather conditions.

Before you start installing a truss structure, you need to understand what types, principles and rules for installing trusses exist.

Factors influencing the choice of rafter structure

The rafter structure is the basis of the roof, which is supported by supporting elements and is the basis for all building materials used during installation.

The parameters and structures of the rafters are determined by a number of factors:

• Purchased material
• Design size
• Personal choice of the customer
• Roof loads in different regions.

The roof truss consists of:

• Lathing
• Screed
• Wooden racks
• Mauerlat
• Rafter legs.

All of the above factors directly influence the choice of the type of rafter structure.

Types of structures

The following types of rafter structures are often used:

Hanging rafter structures. Are the most simple types designs.

Layered rafters. When choosing this system, you should take into account the need for an additional load-bearing wall located in the center of the building.

Mixed systems. This system is more complex, since the installation uses two of the above types. Often used for attic spaces.

Rafter structures for various types of roofs

For a specific type of roof, a specific type of roof truss is used. Let's take a closer look at each of the structures:

Rafter system for gable roofs

This system consists of two rectangular inclined planes. The entire structure looks like a triangle from the end of the building. The main elements are the sling legs and the Mauerlat.

To evenly distribute the load on the slings and walls, building materials such as struts, crossbars and racks are used. With the help of these elements a durable, tough, simple circuit truss structure for gable roofs.

At correct installation structure of the rafter system, the entire load is distributed evenly over the area of ​​the building.

Hip roof rafter systems

During installation it is necessary to mount different types rafters The rafters are placed on the side, made of boards, installation occurs in the same way as when installing traditional pitched roofs.

Beams installed diagonally must be symmetrical so that the roof does not deform from any loads in the future.

Self-installation of a roof truss

Before starting work, it is necessary to calculate the rafter system, the amount of building materials, thermal insulation and other additional consumables.

Mounting is carried out according to the following algorithm:

• We make a model from which you will assemble the structure. This requires the presence of two boards that correspond to the length of the slings; they need to be connected with nails from one edge.
• Get a design called “scissors”.
• We are installing the second model, with the help of which the cuts on the slings will be installed. For this template you will need plywood.
• Cutting out the cuts special purpose on the rafters. We connect them at the slope angle of the slope. We attach the resulting triangular template to the Mauerlat.
• First, we install two side front slings.
• We stretch the cable between these tops of the rafters. Let us denote by this the ridge, as well as the points of the remaining rafters, which will be located in the gaps.
• Raise and install the remaining rafters
• For bulky structures we use additional reinforcing struts and supports.
• We install ridge bars.

To install a correct and reliable design on the Internet you will find a huge number of photos of the rafter system with step by step guide actions.

Fastening of the truss structure

In order for the rafter system to be reliable, you must first determine the methods of attachment to the load-bearing roof and ridge.

When using fastening to prevent distortion of the roof during shrinkage of the structure, use a hinge plate or nut with a bolt and a sliding support to strengthen the rafters.

For hanging rafters, an additional plate of wood or metal is used, they are secured using the cutting method and connected with nails.

Based on the above, you can ideally select a sling system and install a reliable and durable roof.

Photo of the rafter system

The roof of the building protects it from cold, rain and wind. This is as important an element as the outer walls and foundation. The rafter system is the supporting frame of the roof. It takes on all the loads: from structures, from snow and wind. To avoid problems during operation, the roof structure of the house must be strong and reliable. Do-it-yourself installation of the rafter system should only be done after careful preparation and studying all the necessary information.

Roof and roofing

Before you start installing the roof of a private house, you need to distinguish between two concepts. Non-professionals are often confused, but builders clearly distinguish between the definitions of roof and roofing. The roof is the entire structure that separates the building from the street above. The roof structure of a private house includes rafters, all other load-bearing elements, thermal insulation material, and roofing.

Rafters - load-bearing roof structures

The roof is the top part of the roof. She is also roofing covering . The installation of a roof requires careful selection of materials. After all, the reliability of waterproofing and comfort of living will depend on it.

System requirements

To properly install a rafter system with your own hands, you must take into account a certain set of rules. Without taking them into account, the structure will not be able to effectively resist negative impacts from outside.

First of all, it is worth considering strength. All elements must withstand the load without destruction. The design of the roof truss system requires preliminary calculation load-bearing structures according to the first limit state. It is he who checks the elements of the rafter system for strength.

The second requirement is rigidity. The maximum deflection is taken into account here. The roof structure of a wooden house or any other should not sag too much. The permissible deformations in the middle of the span are equal to the length of this span divided by 200. Before construction begins, the structure of the rafter system must be calculated according to the second group of limit states - for rigidity.

Do-it-yourself roof raftering is done taking into account that the structure is light in weight. Otherwise, the load on the walls and foundations increases greatly. It is for this reason that wood has become widespread as a base material. The wooden rafter system has sufficient strength, but weighs relatively little. Attention should be paid not only to the roof structure, but also to choosing the right roofing material. It shouldn't be too heavy. Ceramic tiles has lost its popularity not only because of the cost, but also because the roof of the house, its walls and foundations must be reinforced for it.

Special requirements are placed on the quality of the material. The production of wooden elements should be made only from good raw materials. It is worth considering the following recommendations:

• For the main elements, grade 1 or 2 wood is used. Grade 3 can only be used for sheathing and other small parts.
• It is recommended to make rafter structures for pitched roofs from coniferous trees. They are more resistant to rot and other problems because they contain resin. With the same cross-section, the permissible span for hardwood will be less.
• Before starting work, all elements must be treated with an antiseptic. This stage of preparation allows you to prevent many troubles in the future. You can also treat the wood with fire retardants if desired. This will increase fire resistance.
• It is better to purchase wood from the northern regions, which is harvested in winter. This material is of the highest quality.

Parts of the structure

The rafter system diagram includes many elements. To understand drawings and correctly perceive information, you need to know at least the basic ones. So, what is the roof made of?

First of all, these are the ridge, cornice and slopes. These elements are the main parts. The ridge is the topmost part of the structure. Cornice or overhang - bottom. Stingrays are inclined surfaces, which are located between the ridge and the cornice.

The construction of a rafter system requires knowledge of load-bearing elements. These include:

• Mauerlat - timber that is laid along the edge of the walls of a building. The Mauerlat is needed to evenly transfer the load from the rafter legs, which are supported pointwise. Typically, timber with dimensions of 150x150 mm or 200x200 mm (for large buildings) is used for its manufacture.
• Rafter legs are inclined beams that transfer the load from the roof's own weight, snow and wind to the mauerlat. Such beams are usually installed from the ridge to the eaves. But during construction hip roof elements appear that have only one of the specified points. They are supported on a ridge or on a cornice. Such details are called spigots. They usually have the same cross-section as the rafters. In fact, sprigs are rafter legs cut off on one side.
• Purlin - a beam on which roof elements rest. The purlin can be installed under the racks. Another option is a ridge girder (crossbar). The rafters rest on it at the top point. The cross-section of the purlin depends on its span, usually 200x200 mm.
• Sloping legs are only needed for hip roofs. They are diagonal rafters resting on the mauerlat at the corners. The cross-section is assumed to be enlarged, usually 150x200 or 100x200 mm.
• Design wooden roof assumes the presence of puffs, struts and racks. They are designed to reduce the load on the main elements. When building a house with your own hands, it is important to remember that the racks cannot be supported on the floor span. Installation is only possible on underlying walls or on purlins spanned between walls. Such elements can be mounted on the ceiling only if it is designed for such a load and reinforced in the required area.
• The lathing is needed to make a base for the covering. For metal tiles and seam roofing, the sheathing can be sparsely made of boards 32-40 mm thick. For bitumen shingles you need a solid base made of boards 25-32 mm thick or moisture-resistant plywood.
• In order to make the cornice overhang, install fillies. They become an extension of the rafters. The filly is attached to the rafters for a length of at least 1 m. The cross-section of the element is usually taken to be 50x100 mm.

Another element of the rafter system is a truss. This is a one-piece structure that consists of rafters, tie rods, struts and racks, rigidly connected to each other. The truss has a triangular shape, and inside it is divided into several smaller triangles, which provides it with good stability.

Roof shapes

Roofs of pitched roofs are different forms. It is worth highlighting here:

Types of rafters

There are two designs:

• with layered rafters;
• with hanging rafters.

Installing a roof on a wooden house is only possible using the former. This is caused by two rules:

• hanging rafters must be firmly attached to the mauerlat;
• V wooden house The rafters must be hinged to the mauerlat.

These two statements contradict each other, so the rafter system of a wooden house can only contain layered elements.

Layered beams are elements that rest on the Mauerlat at the lowest point and on the ridge girder at the top. This allows you to reduce the horizontal thrust that acts on the walls when the rafters try to move apart and take a horizontal position. Elements can be reinforced with racks or struts. In this case, contractions can be placed through one pair of legs.

Hanging tanks are supported only at the lowest point on the Mauerlat. At the top they just rest against each other. To prevent the system of wooden elements from moving apart, tightening must be done. It is better to install them on each pair of legs. This option is characterized by a strong thrust effect on the external walls, but it allows you to get more free space inside the attic.

Connections

Before you make a rafter system with your own hands, you need to carefully study the nodes. To build your home, you shouldn't save time or money. Only in this case the result will please you for many years.

Mounting points for the roof truss system that deserve special attention, are represented by the following:

• fastening the Mauerlat to the wall;
• fastening the rafters to the mauerlat;
• fastening the rafters at the top point;
• splicing rafters along the length.

Mauerlat to the wall

This node can be performed in several ways. The choice largely depends on the wall material. The construction of a building made of brick, block or concrete allows the use of the following methods:

• on the wire;
• on staples;
• on stilettos;
• on anchors with the installation of a monolithic belt along the edge of the wall.

Rafters to the mauerlat

Fastening is carried out in two ways:

• rigid for buildings made of brick, concrete or concrete blocks;
• hinged for wooden houses.

Rigid fastening can be with or without a notch. It is recommended to do the cutting on the rafters, and not on the mauerlat, since this weakens it. In both cases, the leg is rigidly fixed with nails, screws, staples or metal corners.

For hinged fastening, a special part is used - a slide.. They allow the beam to move without obstacles when the walls of the building shrink.

Additionally, the rafter legs are attached to the wall. This is necessary to prevent the roof from being blown off by the wind. For fastening, use a twist of two wires with a diameter of 4 mm, fixed to the wall with an anchor or a ruff. In a wooden house, twisting can be replaced with staples. Fastening is carried out on each beam or through one.

At the ridge level

The layered elements rest on a ridge girder with a notch. Additionally, a board overlay is made on both sides. An overlay is also needed for hanging elements. It can be wooden or metal with holes for screws.

Splicing rafters

There are several methods for splicing roof rafters with your own hands. The choice between them largely depends on the experience of the master. The splice point is located at a distance of 0.15 span lengths from the support. In this case, not only the ridge girder and the Mauerlat are considered supports, but also the struts and racks.

There are five ways:

• butt joint;
• oblique cut;
• overlap;
• compound legs;
• paired legs.

To build quality roof, you need to carefully study the technology, choose the right type of rafters and methods of connecting elements at important nodes. This is especially important when building a rafter system with your own hands.