Installation of rafters is one of the key stages in the construction of the roof. To prevent the rafter system from deforming and collapsing under high loads during operation, the rafters must be properly fixed.

Calculation of the pitch of the rafters

When designing the truss system, special attention is paid to this issue. The strength characteristics of the roofing system depend on the section of the rafters and the step of their installation.

The pitch of the rafters is the distance between adjacent rafters. The minimum pitch of the rafters is 60 cm, the maximum is more than 1 meter. A simplified version of the calculation of the pitch of the rafters involves the use of a table:

The length of the slope along the eaves must be divided by the rafter step selected in the table, then add one to the resulting value and round up to an integer. The resulting result indicates the required number of rafter legs per slope. Then the length of the slope along the eaves should be divided by the calculated number of rafter legs - the final number corresponds to the value of the center distance between the rafters.

This calculation method is general, it does not take into account the specifics of roofing and the type of insulation used. If it is planned to lay a roll or slab heat insulator, it is recommended to adjust the pitch of the rafters to the size of the material. It should be noted that the width of the cotton insulation should be 1-1.5 cm more than the span between the rafter legs.

When determining how far to put the rafters, you should also pay attention to the recommendations for installing the selected roofing.

Material preparation

Do-it-yourself installation of rafters requires not only knowledge of the process technology, but also the correct preparation of the wooden elements of the system for installation. Rafters are made of edged boards or timber, the section of lumber is selected at the design stage of the roof. The tree should not have cracks, wormholes or other damage.

Rafter legs should be made of well-dried softwood to prevent their deformation.

Wooden elements must be treated with fire retardant and bioprotective compounds. Before proceeding with the installation, it is necessary to decide on the method of attaching the rafters to the Mauerlat or beams, with the type of ridge connection. In accordance with the project, metal and wooden fasteners are selected, including:

• plates (made of metal or wood);
• bolts or studs with nuts and wide washers;
• nails, self-tapping screws, staples, etc.;
• wire rod.

Types of rafters and features of their installation

When erecting the roof of a house, hanging or layered rafters are used. In some cases, a combination of both may be used. Hanging ones rely only on the walls of the building, and layered ones require the installation of additional supporting structures, so this option is primarily used if there is an average load-bearing wall or supporting pillars inside the building box.

The lower part of the rafters abuts against the Mauerlat, respectively, the walls of the structure must have sufficient width for the installation of a special supporting structure made of timber with a section of 150 × 150 mm. The upper part of the layered rafters rests on the ridge run. Thus, the installation requires the installation of a run, for which racks should be mounted on the middle wall or poles.

Hanging rafters rest only on the walls. This design can be mounted both on the Mauerlat and on thin walls without laying the Mauerlat. In this case, the floor beams protruding beyond the plane of the wall on both sides of the building serve as a support for the lower part of the legs. Hanging rafters are connected by a jumper (puff, crossbar) which relieves bursting forces. When covering large runs, truss trusses are reinforced with additional elements to enhance the rigidity of the structure. When installing hanging rafters on a Mauerlat, a low puff can serve as a floor beam.

Before you put the rafters, you need to mount the scaffolding. This makes it possible to provide the necessary safety and convenience of work.

Installation of the upper ends of the rafters

When choosing how to install rafters, it is important to evaluate the complexity of the work and the weight of the truss structures. If the assembled truss has a relatively low weight, or it is possible to use lifting equipment, then it is easier to assemble the structures on the ground, and then lift and mount on the roof. If the elements of the system are heavy and have to be lifted manually, then the trusses are assembled on the roof. The installation technology of roof trusses is described in the video instructions.

The connection of the upper ends of the rafters can be performed in different ways. First of all, this is a butt mount. On the opposite rafter legs, cuts are made at the desired angle. Then the rafters are docked with the resulting ends and fastened to two nails. The connection is additionally reinforced with a wooden or metal lining.

The overlap of the rafter legs is carried out using bolts or studs with wide washers and nuts. In this case, the rafters are in contact with planes.

If the rafter system is mounted on a wooden house with gables made of timber or logs, it is required to install the rafters on the walls using sliding fasteners in order to avoid deformation of the roof during shrinkage of the structure. Accordingly, in the ridge part, the rafters must be connected in a special way: the rafter legs must be located with a gap, and they are fastened with a special movable metal connecting element.

In the presence of a ridge beam, installation of truss trusses on the ground is not required - the rafter legs are installed one at a time and attached to the ridge run.

The ridge run must be located strictly horizontally so that the rafter system evenly distributes the load experienced by the roof.

Methods for installing rafters on walls

The lower ends of the rafters are attached to beams or mauerlats. Hanging rafter trusses mounted according to the template rise to the roof. First of all, extreme farms are installed. In the tightening, two or three holes are required to attach the rafters to the beams laid on the upper crown of the log house.

If hanging rafters are mounted on a stone building, it is required to use special fasteners - the so-called "ruff", made of durable steel. This fastener is driven into every fourth row of brickwork. With the help of loops extending from the ruff, you can fix the beams. It is recommended to use a solid beam as a Mauerlat - in this case, the load will be evenly transferred to the walls.

On buildings made of brick or other material that is not prone to shrinkage, the rafters should be fixed rigidly. To do this, a cutout is made in the rafter leg, the lower part of which must lie firmly on the Mauerlat. The rafter is fixed with three nails (two are driven in on both sides at an angle, and the third is vertically on top) and tied with wire. A connection can also be used with the help of corners and a support bar that prevents the rafters from shifting.

Proper installation of rafters involves making a fire break at the point where the chimney passes through the roof. If, during its arrangement, the installation of a special rafter system is provided, this should be taken into account when installing a shortened rafter leg (from the Mauerlat to the chimney structure). The distance between the structural elements and the pipe must be at least 130 mm.

+9

The arrangement of a gable roof is considered a very practical and right decision in the construction of a residential or commercial building. This option combines the relative simplicity of execution and reliability, ease of maintenance and long service life. In this material, we will talk about how to install a gable roof truss system with your own hands, what are its varieties, and how to calculate the dimensions of its individual elements. Our step-by-step instructions will allow you to deal with any complications that may arise in the process.

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

• ease of calculation;
• various versions;
• saving materials;
• the 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;
• ease of preventive maintenance.

Varieties of gable roofs

Consider the main types of roofs with two slopes, the truss system in which will differ slightly in execution.

Symmetrical gable roof

This is the simplest gable roof, however, 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 insulation layer do not affect the choice of roofing material. Thick beams of rafters have a sufficient margin of safety, so they will not sag. In addition, spacers can be installed at your discretion.

Among the disadvantages of this option, one can only note a too sharp angle of the slopes, which makes it difficult to use the attic floor and creates “deaf” zones that have no use.

Roof with two asymmetrical slopes

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

Broken roof with external or internal break

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 such components:

• Mauerlat. It is a durable bar made of oak, pine, larch or other strong wood, which is laid around the perimeter on the 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 whole structure is created from such elements (read also: ""). Connecting at the top point, two rafters form a farm. They are made from logs or durable bars.
• puff. This part serves to grip the rafters and ensure their rigidity.
• Runs. In those places where the rafter legs are joined, a ridge run is attached, on which the skate will subsequently be mounted. And with the help of side runs, the frame of the rafters is given additional strength. The expected load determines the size and number of such elements.
• Rafter rack. This is a vertical beam that partially takes over the weight of the roof. If the gable roof scheme is simple, then one such beam is placed in the center. For a long span, three bars may be required - 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 a sloping roof, racks are placed on the sides to make room for movement. Beams are placed in the center and sides if there are two rooms.
• Struts. These are rack supports. If significant winds and precipitation are expected in the winter, longitudinal as well as diagonal racks are installed.
• Sill. A rack for rafters rests on it, and struts are also attached.

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

The installation scheme of the gable roof truss system will greatly facilitate all construction work. How such a scheme will look depends on the type of roof.

Please note that the material for the truss system must be of the highest quality, treated with flame retardant and antiseptic agents. There should be no knots or cracks on the beams for rafters, Mauerlat and racks. Only a small number of knots are allowed on the crate, firmly seated in the wood.

Calculation of frame elements for a gable roof

The rafter system of a simple gable roof consists of a set of triangular trusses - this form gives the structure maximum rigidity. Such figures are the easiest to calculate. However, if the slopes have a different shape, irregular rectangles are obtained. In this case, they are divided into simpler forms and calculations are carried out for each element separately. At the end, all data is summed up.

Please note that the more complex the shape of the roof, the more trusses and other details will be required to ensure its strength. All of them increase the total mass of the roof, which, if calculated incorrectly, can damage the load-bearing walls.

The load on the rafters according to the scheme

There are three types of load:

• Constant. This is a value that will not change throughout the lifetime of the roof. This category includes a lot of roofing material, insulation, hydro and vapor barrier, lathing, additional roofing parts, as well as interior decoration of the attic. That is, the summed value of the mass of the elements will be the expected load. Its average value is 40-45 kg/m 2 , but not more than 50 kg/m 2 . It is desirable to provide a margin of safety equal to 10% of the total mass.
• Variable. This refers to the intensity of precipitation, the load from snow and wind, which can vary significantly depending on the time of year or weather conditions.
• Special. This group includes extreme natural phenomena - earthquakes, tornadoes, strong winds. In these cases, the margin of safety is made significantly larger than usual.

We determine the slope of the slopes before installation

The slope of the slopes is calculated based on the type of roofing material:

• soft roof - from 5º to 20º;
• slate, ondulin, tiles, corrugated board - from 20º to 45º.

Note that the sharper the slope, the more material will be required for roofing.

Rafter pitch and length

As a rule, this value for residential buildings ranges from 60-100 cm. Here the type of roofing material and the total mass of the roof matter. The number of rafters per slope is calculated by dividing its length by the step size plus one. For the entire roof, the value is doubled.

The length of the rafter leg is calculated using the Pythagorean theorem. If the maximum beam length of 6 meters is not enough, it can be extended with other segments.

Rafter section

You can determine the cross section of the rafters based on the following data:

• wood type;
• type of material - logs, beams and so on;
• rafter length.

Here are the approximate dimensions of lumber for a truss system for a gable roof:

• mauerlat, section 10 × 10 or 15 × 15 cm;
• puffs and rafter legs, 10 × 15 or 10 × 20 thick, in some cases a bar with a section of 5 × 15 or 5 × 20 cm is used;
• for struts and girders - beams 5 × 15 or 5 × 20 cm, based on their width of the rafters;
• racks - section 10 × 10 or 15 × 15 cm;
• beds, section 5 × 10 or 5 × 15, based on the thickness of the racks;
• crate, section 2 × 10 or 2.5 × 15 cm - the value is determined by the type of roofing materials.

Varieties of truss systems

There are two main types of truss systems for roofs with two slopes - hanging and layered. Let's describe each of them separately.

hanging rafters

The installation of a gable roof with hanging rafters is advisable only with a roof width of 6 meters. Such rafters are mounted on a ridge run on one side, and on a load-bearing wall on the other. They experience bursting forces, which is the main feature of a gable roof with hanging rafters. The puff for them can be made both from wood and from metal. If you install puffs from below, then they perform the function of load-bearing beams. It is extremely important to firmly fasten the puff, since it also experiences a bursting force. Tightening is needed, first of all, to prevent damage to the load-bearing walls - otherwise they may fall under the pressure of heavy rafter legs.

Rafters

In this case, the size of the roof does not matter. The assembly of this type of truss system assumes the presence of a bed and support posts. Part of the load is transferred to the bed, which is laid parallel to the Mauerlat. It turns out that the rafters are adjacent to each other at the top point and are additionally supported by a rack. In such a system, the rafter legs experience only bending force. They are mounted much easier than hanging ones. True, support racks are required.

Combined type

Often, the roof is given a rather complex shape, which requires the construction of mixed-type truss systems. Professionals recommend drawing up a detailed diagram with calculations for each element of the rafter system, so that the data is always at hand during the work.

Do-it-yourself installation of rafters for a gable roof

Laying Mauerlat on the walls

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

With a lack of material length for the Mauerlat, several pieces can be spliced. At the same time, the edges are sawn at 90º and joined with bolts - wire, dowels or nails are not suitable.

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

• symmetrically in the center;
• offset in the desired direction.

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

It is worth taking a responsible attitude to the process of attaching the Mauerlat, since in strong winds it must withstand a particularly heavy load.

As fasteners for Mauerlat, you can use the following consumables:

• Anchors, which 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 fastener that is used almost always.

Assembly of trusses or trusses

Farm assembly can be done using one of the following methods:

• Beams for rafters are assembled and mounted directly on the roof of the building. This process is quite laborious, since all measurements, trimming and coupling of the bars will have to be done at a height. However, you can do it on your own, without the involvement of technology.
• Trusses or truss 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 hand, due to the large weight of the structure, lifting it up will require special equipment.

Please note that it is worth starting the assembly of truss pairs only after marking. And if you make a template in advance, for which you take two boards equal to the length of the rafters, and connect them together, then all pairs will turn out to be exactly the same.

Installation of rafters

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

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

Now you can mount the remaining pairs in compliance with the calculated step between them. In cases where pairs are assembled directly on the roof, a ridge run is attached between the two end trusses. Subsequently, rafters are installed on it.

The order of installation of halves of rafters according to the opinions of professionals may differ. Some prefer to lay the bars in a checkerboard pattern so as not to overload the foundation and walls during work. Others tend to install pairs of rafters in series. Be that as it may, rafter legs may need props and racks - it all depends on the size of the roof and the shape of the trusses.

Skate mount

A ridge is an element that is formed by attaching rafters at the top point. As soon as all the details of the truss system for a gable roof are installed, it is necessary to perform a major fixing of all structural elements.

Lathing installation

The presence of lathing is mandatory in the construction of 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 during work.

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

• soft roofing is laid on a continuous crate without gaps;
• for a metal tile, a crate is needed with a step of 35 cm (between the two lower rows - 30 cm);
• slate and corrugated board can be laid on the crate in increments of 44 cm.

Results

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

The truss system is one of the essential components of any roof. In order for this system to perform the functions assigned to it, it is necessary to think over its design in advance and carry out competent installation. About how to put the rafters with your own hands, and will be discussed in this article.

Correct calculation of rafters

Before you put the rafters, you need to determine two parameters at the design stage of the structure:

• The thickness of the rafter legs;
• Rafter installation step.

To simplify your task, you can use the following data:

1. The length of the rafters is 3 m. With a section of 8x10 cm, the optimal pitch of the rafters is 120 cm, and for bars with a section of 9x10 cm, the pitch should be increased to 180 cm.
2. The length of the rafters is 4 m. The section is 8x16 cm - a step of 100 cm, 8x18 - a step of 140 cm, 9x18 - a step is 180 cm.
3. The length of the rafters is 6 m. If beams with a section of 8x20 cm are used, then the step between them should be 100 cm, and for beams with a section of 10x20 cm, a step of 140 cm is best suited.

To determine the number of rafters per slope, you need to do the following: first, the length of the slope along the eaves is divided by the pitch of the rafters, the resulting value is increased by one and rounded up to whole numbers. By dividing the length of the slope by the calculated number of rafters, you can find out the center distance between the rafter legs.

The calculation technology described above is not universal - for example, it does not take into account the features of the selected roofing and thermal insulation material. When using slab or roll insulation, the rafter pitch should be adjusted to the standard dimensions of the material. For materials based on mineral wool, it is necessary to reduce the distance between the rafters by 1-1.5 cm - such materials are held between the rafters due to bursting force.

Preparation of materials

In order for the truss frame to be of sufficient quality and reliability, it is necessary not only to properly install it, but also to correctly approach the issue of choosing materials for its arrangement. Typically, rafters are made from edged boards or timber with a pre-calculated thickness.

When choosing lumber, you need to pay attention to their quality - wood should not have noticeable structural damage, such as cracks or deep scratches. In addition, a good tree must be sufficiently dried so that excess moisture does not further accelerate the process of destruction of the truss system.

Before you mount the rafters, you need to impregnate them with antiseptic and flame retardants to increase protection. The next step, which indirectly concerns the technology of mounting rafters, is the choice of the method of their fastening.

The following materials can act as fasteners for installing rafters:

• Metal or wooden plates;
• Bolts or studs complete with nuts and washers;
• Self-tapping screws, nails or staples;
• Rolled wire.

Types of rafters for the roof

There are two main types of truss systems - hanging and layered. The rafters used in them are called exactly the same, and in some situations both types of rafters are combined to create the most effective design.

Features of different types of rafters can be described as follows:

1. hanging. Hanging type rafters rest exclusively on the walls of the building. As a rule, to reduce the load, a Mauerlat is mounted on the upper part of the walls, which acts as a supporting element for the rafter legs. However, you can do without it if there are reliable floor beams protruding beyond the perimeter of the building. The reduction of bursting loads in hanging rafters is provided by various jumper options. In the case of large spans, the truss frame can be further reinforced to increase rigidity.
2. Layered. Laminated rafters, unlike the previous ones, are installed using additional supports, which imposes certain restrictions - such a structure can only be created if there is a load-bearing wall or other supporting elements inside the building. The lower part of the layered rafters, however, rests on the Mauerlat, so the walls must be thick enough for its installation. The upper part of this type of rafter is attached to the ridge run, mounted on vertical racks.

Installing the top edge of the rafters

Thinking through the design of the truss system, it is imperative to keep in mind its total weight and the complexity of installation. If the frame in the end is not very heavy, then it will be much easier to assemble it on the ground, and then raise it to the roof on your own or with the help of special equipment. A structure that has a lot of weight will be much more expedient to assemble directly on the roof.

You can connect the upper parts of the rafters in the following ways:

1. Butt mount. This fastening method assumes the presence of cuts on the joined edges of the rafters. The rafter legs are connected in these incisions and fixed with two nails. In the future, the connection must be reinforced with a plate.
2. Lap fastening. Such a connection is carried out by means of bolts or studs, which are tightened with nuts and wide washers. The rafters converge at one point and are brought to each other by the edges so that they can be fastened.
3. sliding mount. This method of fastening is used in wooden houses. The fact is that buildings made of logs or beams shrink, and sliding fasteners allow you to compensate for it without damage and distortions of the truss system. The rafters in the upper part are installed with a small gap and are connected by movable metal fasteners.
4. Fasteners for a skate. If a ridge run has already been mounted on the building, then it is not necessary to assemble a solid frame - the installation process of the rafters in this case comes down to their alternate fastening to the ridge. The ridge beam must be horizontal so that the existing loads are distributed evenly.

How to put the lower parts of the rafters with your own hands

The lower edges of the rafter legs are installed on beams or Mauerlat. According to the installation technology of wooden buildings, the assembled frame is dragged onto the roof and installed, and first of all, it is necessary to fix the trusses located along the edges of the building. In order for the rafters to be attached to the beams located on the walls of the building, the tightening will have to be drilled at several points.

When arranging a roof on a stone house, special metal fasteners, the so-called "ruffs", will be required to attach the rafters. These fasteners are hammered into every fourth row of brickwork, after which they can be used to mount rafter legs.

If the building is made of materials that do not shrink, then the rafters must be fixed in a rigid manner. Before you put the rafters evenly, a cutout is made in each rafter, thanks to which they will all rest securely on the Mauerlat. The rafters are fixed with three nails and wire. To prevent the rafter legs from moving in the future, you can use the connection from the corners and the support beam.

All the nuances of how to properly fix the roof rafters should be considered and taken into account at the design stage. For example, if there is a chimney, care must be taken that it does not pass in close proximity to the rafter frame. Sometimes in this case, shortened rafter legs are used, located between the Mauerlat and the chimney. The minimum distance from the wooden structural elements to the pipe is 13 cm.

Conclusion

Installation of the truss system is a feasible task, but only if all the nuances are taken into account. That is why, before putting the roof on the house, you need to carefully consider the future design, select high-quality materials and study the installation technology. Competent execution of each stage of work will create a reliable and durable truss frame.

The construction of a reliable truss system is one of the most difficult tasks in the construction of the roof of a country house, cottage or garage. Nevertheless, do not rush to give up - today we will refute the popular belief that such work is beyond the power of a beginner. Knowing the rules for calculating, sawing and installing a roof frame, you can build a roof no worse than specialists. In turn, we will try not only to talk about the device, design and features of the construction of various types of truss systems, but also share the secrets of experienced craftsmen.

Any, even the most seedy roof, is based on a strong power frame, called a truss system. The rigidity of the roof, and hence the ability to withstand even the strongest wind and snow loads, depends on how correctly this structure is mounted.
The truss system is the power frame of the roof, which perceives the entire wind and snow load.

The best material for the manufacture of rafters (trusses) is considered to be a bar or thick board made of softwood. And there is an explanation for this - pine or spruce lumber has a relatively low weight, and the presence of natural resins makes it quite durable. Even if the timber will have a small residual moisture, it will not lead when dried, which is no less important factor than ease of use and long service life.

Depending on the size of the roof, the supporting structural elements can have a cross section from 50x100 mm to 200x200 mm or more. In addition, the length of the roof directly affects the number of rafters, because they are installed in small steps - from 60 cm to 1.2 m.

Structural elements of the truss system

The main requirement that is put forward to a wooden frame is the ability to resist bending and torsion. For this reason, a triangle shape is best suited for timber frame trusses. However, they can consist of several parts:

• rafter legs - the base of the roof frame, which has the greatest impact on the size and geometry of the slopes;
• crossbars (puffs) - boards that pull together a pair of rafter legs;
• runs - transversely installed bars, due to which the rafters are connected into a single structure;
• racks - vertical supports that serve to support the rafter legs or prevent deflection of the runs;
• struts - the same racks, only set at an angle to the vertical;
• beds - boards attached to the floor of the attic, on which supports are installed;
• mauerlat - a support beam installed on the bearing walls, to which the lower parts of the rafter legs are attached;
• filly - pieces of timber or boards that are nailed to the lower ends of the trusses and serve to equip roof overhangs.

Additional elements of the truss system make the roof frame more durable, rigid and stable

When choosing the design of the roof frame, it is important to find the very middle ground that will allow you to get a solid and reliable structure at minimal cost. For this reason, you can deviate a little from the established canons, if it does not concern the rigidity of the entire structure. For example, it is quite possible to do without fillies, and form a cornice overhang due to longer rafter legs. Or use not a solid Mauerlat, but pieces of timber laid only at the attachment points of the rafter legs - it all depends on the engineering ingenuity and experience of the roofer.

Rafter classification

Depending on the design of the roof and the purpose of the attic, the wooden frame may consist of several types of rafters:

Features and varieties of truss systems

To make an informed choice, you need to understand the features of various types of truss systems and know the strengths and weaknesses of each design.

Roof frame with hanging rafters

Since the principle of attaching hanging rafters does not imply additional support points, this design is used for buildings with a width of no more than 6 m. Installation of unsupported trusses involves attaching each pair of legs to opposite main walls, while their upper parts are fixed directly to the ridge run.

The roof frame with hanging rafters transfers only vertical forces to the walls, therefore it has simpler attachment points to load-bearing walls

During operation, a force acts on the hanging rafters, tending to push the structure apart. To compensate for the bursting force, a crossbar made of a wooden beam or a metal profile pipe is installed between the rafter legs. If the attic space will be used for domestic purposes, then the upper jumper is attached as close as possible to the ridge, and the lower edges of the pairs of rafter legs are connected with puffs. Such a scheme allows you to increase the useful height of the attic, without reducing the strength of the frame at all. By the way, if the lower jumpers are made of timber with a section of more than 100x100 mm, then they can also be used as load-bearing beams. It is necessary to ensure a reliable connection of puffs and rafter legs, since significant bursting forces also act on the place of their fastening.

Roof with rafters

Rafter rafters require the installation of at least one support, so they are used for buildings with internal load-bearing walls. The maximum length of a single span should not exceed 6.5 m, otherwise the strength and rigidity of the roof frame will suffer. To increase the width of the roof, the truss system is reinforced with intermediate supports. Even one additional rack allows you to increase the width of the roof up to 12 m, and two - more than 15 m. The rafter system is ideal when a large roof width is required.

The stability of slope trusses can be increased by using a sub-rafter frame with girders, posts and struts. In addition, this rafter system requires much less lumber costs. Versatility, strength and cost-effectiveness have long been appreciated by both construction companies and individual developers, most often using roof structures with layered beams in their projects.

Combined options

Today, the roofs of country houses amaze with the elegance of design, the quirkiness of shapes and the variety of configurations. There is only one way to build such complex structures - by combining both types of truss systems in one frame.
The combination of layered and hanging trusses allows you to get a truss system of any configuration

Even for the construction of not the most complex sloping roof, both truss systems are used at once. The right-angled triangles located on the sides are layered truss structures. And they are connected due to the upper screed, which at the same time plays the role of a puff for the upper hanging rafters.

The procedure and rules for the installation of roof frames

Since two types of roof frames are used in the construction of roofs, we will consider the installation technology for each structure separately. However, before proceeding with construction work, it is necessary to study the methods of fastening structural elements to each other.

Roof construction with hanging rafters

It has already been mentioned above that hanging rafters are most often used in the construction of small or undemanding buildings. A log house in this case is an almost ideal option, since you can do without a Mauerlat. The lower part of the rafter legs is attached to the upper crown or the edges of the ceiling beams (matrices) protruding beyond the perimeter of the walls. In the latter case, the puff must be moved up - this will allow you to put the beam on top of the finishing log and make the attic more comfortable.
To increase the height of the attic space, the puff should be installed as close as possible to the top of the roof

Preparatory work

The geometry of the slopes depends on how well the beams will be prepared for the rafter legs. A cord stretched between nails driven into the extreme beams will help to level the supporting surfaces..

1. It is necessary to cut down the slab, having received flat platforms for the installation of trusses. After that, you should definitely check how accurately they lie in the same plane. This can be done using a long straight rail and a level.
   Before installing the trusses, the supporting surfaces are aligned with the cord
2. After removing excess wood, in each beam you need to make a recess under the rafter spike. You can draw the places of future nests using the same nails and cord as in the previous case. Although the recesses for the rafters can be made both before and after the manufacture of the trusses, experts advise doing them first - this will allow you to try on with higher accuracy and convenience.
   The method of attaching the rafters depends on many factors - the type of support beams, their cross section, the features of the roof overhang, etc.
3. Professional roofers recommend installing an additional reference point in the center of the span of each tong - a vertical rail. One of its sides is used as an axis of symmetry, which will make it possible to monitor the strict observance of the geometry of the structure.
   In order to simplify the process of marking and mounting the roof frame, use vertical rails installed along the center line of the roof

Rafter manufacturing

In order for the rafters to have the same dimensions and configuration, they are made according to a pre-made template. For its manufacture, we suggest using the following instructions:

1. Take two slatted boards and bolt them together to form a drop-down compass design. The threaded connection should not be tightened strongly - the structure should rotate around the top. Be sure to check that the slats are 10-15 cm longer than the rafters - this will be needed to take into account the height of the thrust tooth.
   The simplest template allows you to get roof trusses of the same size and configuration
2. On the rail set as a guide, make two marks. The lower one should correspond to the height of the truss system, and the upper one should be separated from it by the height of the mounting ledge.
3. Install the template on the mat so that the corners of the boards rest against the recesses for the rafter teeth.
   In order for the structure to successfully cope with bursting loads, the thrust tooth at the end of the rafter leg is inserted into a recess on the floor beam
4. Align the axis of rotation of the "compass" with the upper mark on the rail and set aside the height of the spike from the lower corners of the jig.
5. Lower the template down and cut the teeth along the drawn line. After that, raise the device to the roof and insert the spikes into the nests on the mother. Check the coincidence of the sample axis with the lower mark on the vertical rail. If necessary, move the bolt to the desired side and fix the angle between the boards with a cross member.
   Several methods are used to fasten trusses - it all depends on the type of support beams, the design of the roof frame and the section of its elements
6. Having adjusted the template in height, apply vertical abutment lines to each board. In conclusion, measure the length of the crossbar and build a template from the scraps of the boards for making overlays on the tops of the trusses.
   To attach the crossbar to the rafters, linings from pieces of an inch board are used.

After the template is lowered to the ground, it is disassembled and cuts are made according to the markings. In addition, they construct a separate pattern, along which the ends of the rafter legs will be cut. The manufacture and assembly of hanging rafters is most often done below, raising finished structures to the roof. If the weight and dimensions of the assembled trusses do not allow them to be pulled up manually, then the assembly is carried out on the spot. At the same time, the components of the truss system are fixed with nails ranging in size from 100 to 200 mm.

How to install roof rafters

In order to raise and install farms, you will need the help of at least one person. Fitting and setting the rafters on a plumb line alone is an extremely difficult task - you will have to fasten them to the struts more than once and repeatedly descend from the roof to control the deviation from the vertical plane.
With the help of a rafter tooth, it is possible to obtain such a reliable connection that only one nail can be used for the final fixation.

Raising the assembled rafters up, first mount the extreme structural elements, and then the central and intermediate ones. To strengthen the structure, a support is installed under each leg:

Having set the hanging rafters according to the level, they are fixed with temporary struts. After that, the lower ends of the beams are nailed to the mat or floor beams.
Various temporary structures greatly simplify the process of installing rafters by level.

It is not worth resorting to newfangled methods of fixing with the help of various corners and perforated plates. A reliable "old-fashioned" method of fastening with nails 200 mm long or construction staples will be much better both in terms of strength and reliability, and in terms of cost. At this stage, do not worry about the design looking flimsy.. After the remaining elements of the truss system are installed and the crate is completed, the structure will acquire the necessary rigidity and stability.

Video: making and installing do-it-yourself hanging rafters

Features of the installation of layered rafters

The process of manufacturing and installing layered rafters is generally very similar to the construction of a hanging roof frame. The main difference is at the top point and it is due to the fact that the tops of the layered beams rest on the ridge run. In this case, the connection with the latter is performed in several ways:

• simple adjoining apart (in parallel to each other);
• with the implementation of a vertical joint (the same as when connecting the paired legs of a hanging truss);
• by tightly fitting the beams to the upper beam (using a vertical cut or notch).

If the design of the wooden frame provides for the support of trusses on the side girder, then the rafters are joined end-to-end, and recesses are made at the junction with the girder.
For fastening layered rafters, nails, building brackets or linings made of wood and metal are used.

To ensure the strength of the structure, the cuts should not be too deep.. Experts recommend making recesses no more than a quarter of the thickness of the beam or a third of the width of the board.

Individual developers most often resort to installing rafters in the following way:

• the upper part rests on the ridge beam by means of a vertical cut;
• from below, the rafter legs are held by a corner cut.

For marking it is convenient to use a construction square. After the scale is selected, on the sides of the right-angled triangle, the values ​​\u200b\u200bof the rise of the slope and half the span are set aside. Thanks to this, it will be possible to obtain the slope angle of the slope without resorting to mathematical calculations.

For the manufacture of rafters, we suggest using the most convenient method:

At first glance, this method is very tricky. However, even a cursory acquaintance with the given instruction is enough to master it perfectly. Of course, it is possible to set aside the necessary distances and make markings by calculation, however, when calculating angles and distances, it will be much easier to get confused.

It should be remembered that the cuts made in the rafter legs must be exactly the same, otherwise the roof slope will be uneven. To do this, you can use a wooden block as a template. It is only important that its thickness does not exceed 1/3 of the thickness of the workpiece.

For the most common slope angles, there are templates that professionals have already worked on calculating the configuration of. Using one of these patterns, you can significantly simplify the task of marking the corners of the cuts.
Templates with marked corners of the cuts allow you to simplify the process of manufacturing rafters

Assembly and installation of a layered structure

Video: installation of rafter legs of a layered roofing system

Methods for connecting rafter logs

When choosing a beam for overall roof trusses, you have to look for a reasonable compromise between the length and thickness of the rafters. The reason for this is the peculiarities of the standard range of lumber, in which longer beams have an increased section. On the other hand, their use is not always justified both technologically and due to an increase in the cost of the structure. The way out of this situation is to lengthen the rafter legs by splicing. The stiffness and mechanical strength of the beam depends on how correctly the joint is made, so the connection is made strictly according to a certain method.

Oblique cutting method

The method of merging with an oblique cut consists in the fact that inclined cutouts (cuts) are formed on the mating parts of the bars. They should be carried out very carefully - after combining both parts of the timber, there should be no gaps, otherwise deformation will appear at the junction.
When splicing with an oblique cut, there should be no gaps and gaps between the mating surfaces, which can weaken the rafter and cause its deformation

When making cuts, a small transverse section is left with a height of at least 15% of the thickness of the rafter - the presence of the end part will make the connection more durable. To calculate the optimal length of the oblique cut, it is necessary to multiply the height of the beam at the place of the cut by two. The cut is fastened with nails, clamps or bolted connections.

Coupling

To lengthen the rafter by rallying (stitching), the edges of the boards are overlapped and a rack is installed in the center of the junction zone. The fastening of the elements is carried out with the help of nails, which are hammered in according to a certain scheme: Joining the boards by rallying allows you to do without additional overlays, however, it requires the installation of an additional support in the center of the junction area

In order for the beam to successfully cope with operational loads after docking, the length of the rallying section (T) is calculated by the formula T = 0.42 × L, where L is the length of the overlapped span.

frontal stop

The frontal extension connection is that the edges of the individual parts of the rafters are carefully trimmed and butted together. For fastening, linings made of lumber with a thickness of at least 1/3 of the section of the main beam are used. The length of the overlays is determined by the formula L = 3 × h, where h is the width of the board.
When splicing with a frontal stop, a monolithic structure will be obtained only with the correct placement of fasteners

The fixation of all parts is carried out using a nail fight or bolted connections. In the first case, nails are hammered in two parallel rows, trying to place fasteners in a zigzag pattern. The threaded connection is performed in a checkerboard pattern, determining the number of bolts depending on the length of the lining.

Compound length extension

To build up a rafter leg, it is not at all necessary to use both parts of the same section. With a compound build-up, a single element can be lengthened due to two boards that are sewn onto its side planes. The resulting gap is filled with l = 2 × h lumber cuts with a step L = 7 × h, where h, as before, is the thickness of the element being extended.
Composite extension of rafters allows you to attach crossbars, supports and other structural elements in the most convenient way

Tips from experts on the manufacture of rafters and assembly of the roof frame

When starting to independently design and install a truss system, be sure to consult with experienced roofers regarding the features of building roofs in your area. Perhaps their advice will keep you out of trouble and help you save time and money. In turn, we offer several recommendations that will help make the design more reliable and durable:

1. If a minimum cross-section bar is used to make a Mauerlat or top trim, then cuts can weaken it. For this reason, cutouts should only be made at the lower ends of the rafter legs.
2. In order to prevent precipitation from falling on the wooden frame and walls of the house, the roof must have an overhang. For its arrangement, pieces of timber (filly) are used, with which the length of the rafter legs is increased, or larger trusses are made.
3. Connection using cuts at an angle of 90 o cannot be used- in this case, the resistance of the element to load forces is significantly reduced.
4. If the elements of the truss system are connected by threaded fasteners, then wide washers or metal plates are installed under the heads of the bolts and nuts. Due to the increased area, the fasteners will not be pressed into the wood.
5. All wooden parts of the structure must be thoroughly impregnated with an antiseptic and flame retardant.
6. When determining the cross section of the puffs, they are guided by how close they will be to the ridge. The shorter the connecting bar, the greater the load on it and the more powerful lumber and bolted fasteners are used.
7. When determining the cross section of a beam for the manufacture of rafters, do not forget to take into account the thickness of the heat-insulating layer.

Video: recommendations of experts on the correct connection of the elements of the roof frame

Modern materials and technologies allow you to build a roof of any configuration and purpose. Given this diversity, it is simply impossible to consider in detail all the options within the framework of one article. However, based on the basic principles of construction discussed here, you can easily cope with the most complex design. The main thing is to pay attention to the little things, to be attentive and accurate in work. And then the roof will be not only a reliable functional superstructure, but also a real decoration of your home.

It is better to entrust the installation of rafters to specialists, the roof is not the element of the building with which you can experiment. However, it is necessary to know the basics and features of how to put rafters on a house, if only in order to control the quality of work and be able to build a simple truss structure.

How to properly put the rafters on the house - let's deal with the terms!

If most people more or less imagine what a rafter is, then a problem may arise with the rest of the terms found in the case of a roofer. Mauerlat, crossbar, bed, stand, brace, run - it is unlikely to do without the help of specialized literature or an experienced builder! However, if you are reading this article, then you can do without them.

• Mauerlat is traditionally a wooden beam with a section of 15 * 15 cm, which acts as an extreme lower support for the rafters, distributing the load from the rafter junction points to the entire upper wall area. Recently, instead of wood, metal is often used; for Mauerlats, these are channels and I-beams. Mauerlat is installed with a slight indent from the outer edge of the wall and fixed. To prevent rotting and corrosion from below, the beams are insulated with roofing felt or other waterproof material. It is with this element that the installation of rafters often begins.
• Lying - an additional beam to distribute the load from the rafters around the entire perimeter of the walls. They differ from Mauerlats in that the beds are installed inside complex truss structures, that is, they are not an obligatory element of the roof, but only an addition in necessary cases.
• Rack - a vertical bar that reinforces the truss structure from the inside. In turn, girders are installed on the racks, which are supported by struts - inclined beams that support horizontal elements and counteract compression or skew of the structure.
• Run - a horizontal beam that crosses the rafters perpendicularly along the entire length of the roof. Three types of purlins can be distinguished in the roof structure - ridge purlins (on which the rafters converge at the top of the roof), side purlins and Mauerlats, which are described above.
• Crossbar - a beam that is installed between the rafter legs, increasing the strength of the structure and its stability. Usually the cross section of the crossbars is 10 * 15 cm.
• Rafter legs or rafters - beams on which the roofing is directly installed. Rafter is also a common name for the entire truss structure. For this element, a bar with a section of 10 * 15 cm is used. For the manufacture of a plank rafter system, a pine board with a section of 50 * 150 mm or 60 * 200 mm is used.

Before installing the elements, it is necessary to accurately calculate their number, as well as take into account possible loads on the rafters: they can be one when installing slate, others for tiles and third for.

For example, a shed roof, built from a minimum number of elements, can easily withstand sheets of metal or slate, while under the tiles, over time, the rafters can deform, bend, which means that you will need to additionally strengthen the structure with racks or struts, and also use beams with a large cross section .

How to install the rafters - layered or hanging?

Rafter structures are divided into two groups - layered and hanging. Hanging rafters are usually built on the roofs of buildings without internal load-bearing walls. The hanging structure rests on the ridge run and Mauerlats, and is fastened at the bottom with puffs that prevent the rafters from moving apart under the influence of the load. It should be noted that much more timber is spent on hanging rafters, since this ensures their stability. You can save wood on plank rafters, since log options take 15-20% more timber.

Sloped rafters are installed on those buildings that have load-bearing walls inside, since this type requires a minimum of three support points. Layered elements can block the span with a maximum length of up to 6.5 meters. If there is a need to increase the width of the covered area, then this can be easily achieved by installing additional supports: with one additional riser, the width can be increased to 12 meters, and with two - up to 15!

Depending on the section of the beams that are used for the manufacture of rafter legs, the spacing of the rafters varies from 0.8 to 1.2 m. The construction of the rafter frame, including runs, racks and struts, provides special stability to the rafter legs. This type is most often used in private construction, since on the one hand, a strong and reliable roof is obtained, and on the other hand, layered rafters are very economical- wood on them, in comparison with hanging ones, is needed many times less. Quite often, a roof is constructed by combining both types.

How to put rafters on the roof - what for?

To begin with, guided by detailed instructions, as given in a separate article, calculate how much material you need. Before installing the elements of the truss structure, they must be treated with compounds against fungi, insects and flame retardants that prevent ignition. Having spent money on these compounds before putting the rafters on the roof, you will extend their service life by decades.

How to put rafters on the roof - step by step diagram

Step 1: Installing Mauerlats

The most important connection in the layered versions is the place where the rafter leg rests on the Mauerlat. It is with the fixing of the Mauerlat that the installation begins. To do this, metal pins are pre-concreted in the walls, which go deep into the walls by at least 40 cm. Wire twists with a diameter of at least 6 mm will also be suitable for the same purposes.

Step 2: Making the layout

Raise up two beams, which will be rafter legs. Cut out notches on the left and right legs to rest against the Mauerlats, do not forget to mark for yourself which side of which beam belongs to. Install the bars, joining them at the top to make marks for the notches at the top. Notches are needed in order to make a connection with an emphasis, and not an overlap - this is considered extremely unreliable even with strong reinforcement with nails.