Elements of fastening of the truss system. Assembling a wooden skeleton: methods for attaching rafters

For a durable and reliable roof, it is important to make all the nodes of the truss system with high quality. What this means, we will analyze right now.

The rafter is the skeleton of the roof, on which the inner and outer skin, insulation, waterproofing and other elements are held. Also, very often they are used as the basis for communication. Huge loads fall on the roof and, accordingly, the rafters, which can reach 200 kg / m 2. This is the weight of building materials, snow with foliage and other debris. And what about gusts of wind?

Roof rafters as a basis for communications

When carrying out repair work, this system must withstand not only the weight of a person, but also the necessary equipment. Moreover, all these parameters are strictly individual and depend on a number of factors, ranging from the configuration to the climatic zone. However, in any case, the roof and all its elements must be sufficiently reliable, and only then can we feel truly protected.

First you need to familiarize yourself with the terminology. The Mauerlat can rightly be called the foundation of the entire system. It is a beam on which the structure is attached. Its main function is to evenly distribute the loads on the walls. But the beam on which the crate is fixed is called the rafter leg. This is the most important element that determines the angle of inclination of the slope and the general appearance of the roof. Between themselves, the rafter legs fasten the run. It is located both on top and on the side. Depending on this, there are ridge and side runs. At the bottom of the leg are fixed with a puff.

Mauerlat for fastening the truss structure

Thanks to the struts and racks, the rafter beams are located as stable as possible. Edged boards are stuffed perpendicular to the legs - crate. It serves as the basis for the roofing material. And the junction of the roof slopes is usually called the ridge. A continuous crate is stuffed on it to make this part of the roof as reliable as possible. Continuation of the rafter legs - filly. They are located under an overhang that protects the walls from precipitation. Very often, it is these structural elements that begin to rot first, since they are most susceptible to the negative effects of the weather, while the legs themselves can serve for a very long time. The reliability of the entire structure depends on how high quality absolutely each attachment point will be. We will talk about them in more detail.

This concept combines a number of structural elements, as they consist of crates, racks and braces. In fact, this rigid structure is the skeleton of the roof. Depending on the size and personal wishes, there are four types of farms. If the width of the house is from 12 to 24 m, then the most suitable would be a segmented or trapezoidal shape. For larger structures, up to 36 m wide, a polygonal one is suitable. But the classic triangular one will be an excellent solution for the construction of houses with a width of 9–18 m.

Roof trusses of different sizes

The material also plays a huge role. The most commonly used wood. In this case, the beams are mounted by cutting and subsequent fixing with nails, self-tapping screws and other fasteners. However, the use of a tree is not relevant in all cases. So, if the span length exceeds 16 m, then trusses with stretched metal racks will be more suitable, since it will be difficult to ensure reliable fastening of wooden elements in this case. The combined type is also popular, in which both wooden and metal parts are used at the same time.

The ridge is a horizontal rib at the junction of two slopes. There is a layered and truss system of a hanging type. In the first case, the skate is mounted on racks parallel to long walls. It is very important to ensure the maximum adjoining of the rafters to the ridge; for this, appropriate cuts are made. Fixation is done with nails.

Skate at the junction of two slopes

If we are talking about a hanging structure, then the ends of the rafter legs are connected in pairs. To ensure such a pairing, the end of each beam is cut at an angle equal to the slope of the roof. Next, the rafters are connected by cut planes and fixed with nails hammered at an angle. It is imperative to close the junction with a metal plate or a wooden lining.

Pair connection of rafter legs

When connected with a notch in half a tree, maximum strength is achieved. To do this, at the junction, the rafter legs are connected to the ledge. Then a hole for a 14 mm bolt is drilled. Further fixation is achieved by bolting. When it comes to a sliding system, in this case the ends of the legs are connected by means of metal plate hinges.

This is the next attachment point for truss systems, which you need to dwell on in more detail. There are two technologies for fixing beams to the Mauerlat. Rigid fastenings exclude any shifts, vibrations, turns, torsion and other manipulations. To achieve a similar effect, a drink is made on the leg. Further, the connection is additionally fixed with nails, wire, self-tapping screws and other auxiliary elements. Usually, several nails are hammered at an angle so that they cross inside the Mauerlat. And then another nail is driven vertically.

Washed down on the legs for attachment to the Mauerlat

Sliding mounts are obtained thanks to special fasteners. There is one, two or three degrees of freedom of this conjugation. Such a connection is great for wooden houses, as a rigid fixation during shrinkage can be severely damaged. Such a mobile connection can be provided in several ways. The leg rests against the Mauerlat with a hemmed bar or sawn tooth and is rigidly fixed with a metal corner. Thus, the rigidity of the fastening in the horizontal plane is achieved. At the top, the legs are connected by notches, while a bevel is made on a horizontal platform to provide a sliding connection.

Sliding fastening elements

If only one nail is driven in at the place of fixation to the Mauerlat or special flexible plates are used, then the pairing will turn out to be sliding in this part of the truss system.

Now let's focus on the typical nodes of the wooden truss system. The peculiarity of such a roof is the presence of hips. This type has a number of advantages. They are more durable, since the load is distributed evenly over the entire surface, they are not afraid of strong winds and precipitation, and they are economical. However, they are more technologically complex.

Typical hip roof nodes

This roof consists of two long trapezoidal slopes, while they do not cover the entire area, triangular hips are installed at an angle from the ends of the building. In this case, typical elements appear - additional sloping rafter legs, from which end slopes are formed. The connection of diagonal beams can be different. Both hanging trusses and a layered structure fixed to the Mauerlat are popular.

Roofing from trapezoidal slopes and triangular hips

If the rafters of the slopes rest on the ridge, then the sloping legs should be adjacent to the console of the ridge run. It is very important that the console outlet is not less than 100 mm, but not more than 150 mm. The lower part of the diagonal rafters is fixed to the Mauerlat or a special beam on the wall of the house. Sometimes a wooden bar is used to make rafter legs, in which case the slanting elements are fixed to a special board (surfboard) fixed on the farm. But the installation to the extreme hanging farm is done by means of a sprengel. At the same time, cuts are made on the beams of the legs at an angle corresponding to the slope of the hip slope.

In order for the constructed building to serve for more than one year, it needs both a reliable foundation and a strong roof system that resists the vicissitudes of the weather. The roof must withstand heavy loads with dignity: heavy snowfalls, sharp gusts of wind, torrential downpours. The roof truss system is best suited for this.

Roof trusses and its types

The truss system is the basis of the roof, which focuses on the load-bearing elements of the structure and also serves as a frame for various types of roofing materials: insulation, waterproofing, various coatings.

The dimensions and design of the rafters depend on:

• purchased material;
• the size of the building;
• dimensions of the house;
• building material for rafters;
• individual preferences of the customer;
• roof loads relevant for a particular region.

The rafter system has:

• crate - bars, in a perpendicular direction, fit on the rafter legs;
• screeds that perceive tensile forces;
• wooden racks, located in a vertical position;
• mauerlat - a bar, the installation of which is carried out along the wall, the rafters focus on it;
• rafter legs are a kind of wooden beams that take on the main load of the roof.

Each of these factors is very important, because it is necessary to understand what type of truss system will be best suited for a particular situation.

When it comes to low-rise buildings, wooden structures are the most common. In many cases, three types of truss trusses are used: hanging rafters, layered rafters and a mixed rafter system.

Characteristics of hanging rafters

Hanging rafters are the most elementary type of truss systems, their characteristics:

If the roof of the house is of complex construction, the types of rafters can be alternated. For example, in the presence of supports or the middle main wall, they install layered rafters, and in the absence of such elements, hanging rafters.

Features of layered rafters

For a layered rafter system, the house must be additionally equipped with a load-bearing wall located in the middle. There are layered rafters according to the following features:

The design of the combined system is the most complex, since it includes parts of two other types of rafters - hanging and layered. It is used for mansard roofing. The walls of the rooms, which are located on the second floor, form vertical supports, these supports are also intermediate racks for truss beams.

Part of the rafters that connect one end of the uprights functions as a crossbar for the slopes located on the side, and for the upper part of the structure they are a puff.

At the same time, the horizontal bars perform the following functions: for the upper slopes - a Mauerlat, for the side ones - a ridge beam. To increase the strength of the roof, struts are mounted that connect the side slopes and vertical racks.

The combined sling system is the most complex and time-consuming to manufacture, but these shortcomings are fully compensated by an increase in the bearing qualities of the roof in the absence of extra supports, especially when there is a need to cover significant spans in the building.

You can increase the bearing qualities of the roof using a mixed truss system

Rafter trusses for various types of roofs

During the construction of a certain building, truss systems of one kind or another are necessarily used, and the type of roof will completely depend on the design of the future structure.

Rafter truss for a gable roof

A gable roof is a common roof construction for residential buildings that have no more than three floors. Preference is given to just such a design because of the technical characteristics of the inclined shape of the truss system, and also due to the fact that installation work is carried out easily and simply.

The truss system of a gable roof includes two rectangular inclined planes. The upper part of the building from the front side resembles a triangle. The main components of a gable roof are the Mauerlat and rafter legs. In order to properly distribute the load on the rafters and walls, struts, crossbars and racks are mounted, thanks to which you can create a durable, rigid, elementary and easy installation scheme for a gable roof structure.

A gable roof is considered the simplest roof system; it is used for residential buildings no more than three floors.

On top of the rafters, you can mount a sparse crate or a solid one, and then attach a bituminous coating, tiles or some other type of material to it. The rafters and sheathing itself are usually made of beams or boards, which are fastened with nails, bolts or metal fittings. Metal profiles can be used as rafters, due to which significant spans overlap. There is no need to use extra racks and struts.

The device of the truss system for a gable roof allows you to evenly distribute all the existing load along the perimeter of the building. The lower ends of the system focus on the Mauerlat. They are fixed with metal fasteners or staples. By the angle of inclination of the bars for the rafters, you can determine at what angle the roof slopes will be inclined.

The truss system for a gable roof allows you to evenly distribute the load from the roof along the perimeter of the building

Rafter system for a hip roof

When arranging a system for a hip roof, you will need to install different types of rafters:

• conjurers (shortened);
• side;
• hip main;
• sloping (diagonal elements that form a slope in the shape of a triangle).

The rafter legs located on the side are made of board, and they are mounted identically to the details of a traditional pitched roof with a layered or hanging structure. Hip main rafters are layered parts. For sprigs, boards or bars are used, which are attached not only to the Mauerlat, but also to the diagonal beams.

To install this type of construction, the angle of inclination is accurately calculated, as well as the cross section of the sloping beams. The dimensions of the parts also depend on the length of the span.

So that the hip roof does not deform from a heavy load, you should accurately calculate the angle of inclination of the diagonal beams for the rafters

Observe symmetry when installing diagonal beams for rafters, otherwise the roof is deformed from a significant load.

Rafter system for sloping roofs

A broken roof is a construction with rafters, which consist of several separate elements. Moreover, they should be located at different angles relative to the horizon. And since the lower rafter part is almost vertical, the attic of the building receives additional space, so that it can be used as a living space. The device of this type of roof is carried out during the construction of a four- or gable rafter structure.

Professionals need to calculate a four-pitched rafter system, but a gable broken roof can be made independently, since its installation is very simple. To do this, it is necessary to install a support frame, which should consist of runs, as well as racks. Horizontal parts are fixed with hanging rafters. But to the Mauerlat, the supports of the sloping roof are fixed with shortened legs of the rafters.

The assembly of rafters for a broken gable roof can also be performed by non-professionals, since the installation of such a roof is very simple.

"Cuckoo" in the roof truss

The so-called cuckoo on the roof is a small ledge that is located on the attic floor. Here is a window for better illumination of the attic room. The installation of the "cuckoo" is carried out carefully, while controlling the parameters of the entire structure: the depth of the cut, the angle of inclination and other factors. However, before that, the necessary measurements are made.

The first stage of work begins with the installation of a power plate (a beam with a section of 10x10 cm, which is needed to support the lines). The truss system acts as a skeleton for the roofing material. To stiffen the structure, spacers are used, which are mounted between the two legs of the rafters.

After the installation of the truss truss is completed, a sheathing is laid, the type of which depends on the roof covering purchased. The installation of the crate is done continuously or with a certain step. Boards, OSB and plywood sheets are usually used for it. In addition, the installation of roofing material must be identical throughout the entire roof.

The main difficulty in installing such a rafter system is the location of the internal corners. In these places, snow can accumulate, which means that the load will increase, which is why a continuous crate is made.

"Cuckoo" on the roof is called a small ledge on the attic floor, under which there is an additional window

Chalet roof truss truss

A feature of a device of this design is the removal of visors, as well as overhangs outside the house. In addition, there must be rafters and beams for the roof, which extend up to three meters on the sides of the building. Each of these elements is fixed with a bracket to the wall of the building in the lower part. Next, tie the edges of the beams. They serve as a support for covering the roof of the building.

But when creating large overhangs, it is necessary to install the reinforced belt in parallel with the installation of the Mauerlat studs. It is necessary to make anchors that help fix the consoles. In this case, the rafters will be perfectly fixed with anchors and, in addition, tie-ins.

To carry out the side cornices, a ridge beam is made, after which beams are taken out at the Mauerlat level, which must be identical to the length of the ridge. The truss is based on these structural details, and in the future - building material for the roof.

When designing a building, the angle of the roof-chalet is calculated based on the characteristics of the local climate and other factors. With a slope angle of about 45 °, the load from snow is not taken into account, since with this option it will not linger on the roof. At the same time, the sloping roof will withstand the load from the snow, but it is necessary to install a reinforced roof truss. Before installing the roof-chalet, a building project is prepared, because the originality of the roof itself, as well as long cornices and its overhangs, oblige this.

The roof in the style of a chalet is characterized by visors, taken out several meters outside the house.

Roof truss designed for soft roofing

Soft roofing is done in various ways, but there are common characteristics in the technological methods of its construction. Initially, you need to prepare. When equipping a roof for a house made of foam concrete or other material, a Mauerlat is first installed, then a cut is made under the ceiling beams in increments of up to one meter in the upper crowns of the building. The distance between the boards is calculated based on the type of rafter structure.

1. Mount individual parts of the rafter system. To completely eliminate the risk, the boards of the rafter legs on the ground are attached with screws. After creating a truss truss, it is raised to the top of the building.
2. All elements of the rafters are fixed with ceiling overlap, internal boards, jibs, and also crossbars. Further, this basis for the roof will become a single whole structure.
3. The next stage is a crate, which is installed under a soft roof with small gaps or no gaps at all. Gaps of no more than 1 cm are allowed. Quite often, leveling plywood is installed on top of the boards. Its sheets are laid according to the brickwork method. The resulting joints do not align with the gaps between the plywood and the board.

If the length of the boards of the crates is not enough, then the joints of the parts must be located in different places. In this way, areas that have been weakened can be correctly distributed.

Self-manufacturing of the truss system

Before the installation of the truss system begins, the Mauerlat must be fixed to the longitudinal walls with anchors. Next, you need to decide on the desired section of the legs for the rafters, depending on the distance and their length. If there is a need to increase the length of the rafters, then connect them with various fasteners.

When using different insulation, you need to choose the ideal distance between the elements of the rafters in order to reduce the number of thermal insulation scraps.

Installation of the truss system must be carried out in the following order:

1. A template is made according to which the farm is assembled. 2 boards are taken, corresponding to the length of the rafters, and connected to each other from only one edge with a nail.

   
   A rafter template called "scissors" will help you quickly assemble the entire roof truss system

2. You get a design called "scissors". Its free edges are placed on supports at the points of contact of the rafter legs. The result should be the final angle, that is, the angle at which the roof slope will be tilted. It is fixed with several long nails and transverse boards.
3. A second template is made, thanks to which the cuts on the rafters are installed. It is made from plywood.
4. Special mounting cuts are cut out on the rafters (a prepared template is used for this purpose) and connected at an angle of inclination of the slope. You should get a triangle that rises to the roof along the stairs. Next, it must be attached to the Mauerlat.
5. Initially, two side gable rafters are mounted. Their correct installation in the vertical and horizontal plane occurs due to temporary struts attached to the rafters.

   
   For the correct installation of the entire rafter system, the first pair of rafters is installed on the roof

6. A cord is stretched between these tops of the rafters. It will indicate the future skate and the level of other rafters located in the gap.
7. Raise and mount the remaining rafters at the initially calculated distance, which should be at least 60 cm from each other.
8. If a bulky construction of rafters is provided, then it is additionally strengthened with struts, supports, and so on.

   
   The bulky construction of the rafters is additionally reinforced with struts and supports.

9. On special supports, a ridge beam is installed, to which not only short, but also diagonal and intermediate elements of the rafters are attached.

   
   Proper fastening of the ridge beam ensures the reliability of the entire rafter system

Typical nodes of a standard truss system

The structural strength of the rafters depends on the ideally selected section of the boards, as well as on the high quality of the rafter units. The connection of parts for the roof structure is done in accordance with established rules.

The main typical nodes in the truss system:

• supporting knot of rafters on the Mauerlat;
• ridge;
• a node for combining the upper puffs and the entire truss system;
• fixing the strut, rack, as well as rafters and beams.

After the design of the rafter system has been chosen, it is necessary to draw up a plan in which to select all the nodes. In each design, they are made in different ways, since it depends on different nuances: the type of roof, its size, and the angle of inclination.

A rafter from a profile pipe is a metal structure that is assembled using lattice rods. The very production of such farms is a very time-consuming process, but also more economical. Paired material is used for the manufacture of rafters, and scarves are connecting elements. The construction of rafters from profile pipes is assembled on the ground, while riveting or welding is used.

Thanks to such systems, any spans are blocked, but it is necessary to make the correct calculation. Provided that all welding work will be done with high quality, in the future it remains only to transfer the structural elements to the top of the building and assemble them. Bearing rafters from a profile pipe have many advantages, such as:

Crossbar in the truss system

Rigel is a fairly broad concept, but in the case of roofs it has a certain meaning. The crossbar is a horizontal bar that connects the rafters. Such an element does not allow the roof to "burst". It is made of wood, reinforced concrete, and also metal - it all depends on the type of structure. And the crossbar serves to distribute the load exerted by the truss system.

It can be fixed in various places between the legs of the lines. There is a direct pattern here - if the crossbar is fixed higher, then the timber for its installation must be selected with a large cross section.

There are many ways to fix the crossbar to the truss system:

• bolts;
• nuts;
• studs with washers;
• special fasteners;
• nails;
• mixed fasteners, when different types of fasteners are used in parallel.

Mounting exists with a tie-in or overhead. In general, the crossbar is a design unit, as, indeed, the entire roof sling system.

The crossbar in the truss system is designed to reinforce the roof structure

Rafter system fastening

To ensure the reliability of the rafter system, it is necessary to initially find out how they are fastened to the supporting roof and the ridge. If fastening is done to prevent deformation of the roof during shrinkage of the house, then the rafters are fixed on top with a hinged plate or a nut with a bolt, and on the bottom with a sliding support.

Hanging rafters need a tighter and more reliable fastening in the ridge, so in this case you can apply:

• overhead metal or wooden plates;
• cutting method;
• connection with long nails.

In the layered system, the rafter legs are not connected to each other, since they are attached to the ridge run.

The rafters are fastened to the Mauerlat by cutting down, which is done in the rafter leg. Thanks to this method of fastening, the support of the roof will not be weakened. Cutting is also done when installing rafters on floor beams. In this case, the cut is also made in the support beam.

Video: how to make rafters with your own hands

Thus, a perfectly matched system of rafters and their structural characteristics will help create the basis for a reliable roof for your home.

The truss system is the skeleton of the roof. It is she who is responsible for the strength of the roof, its reliability and resistance to stress. When building a house on your own, you need to know how to properly make the attachment points of the truss system so that the roof is reliable and safe.

The device of the truss system

The truss system consists of many elements, each of which performs its task.

• Mauerlats are responsible for distributing loads on the walls. These beams take on the weight of the entire roof and lie on the walls.
• rafter legs- these are inclined beams, which create the necessary angle of inclination of the roof.
• Runs are horizontal beams that hold the legs together. There is a ridge run, located at the top, and side ones, located with slopes.
• The puffs are located horizontally and do not allow the rafter legs to part, forming rigid triangles with them.
• Racks and struts(rafter legs) - additional elements on which the rafter legs rest. They rest on the beds.
• Lying - a horizontal beam located under the ridge; racks and struts rest on it. The task of the bed is to redistribute the point load from the racks.
• The ridge is the junction of the roof slopes.
• Sheathing - bars or boards that are stuffed perpendicular to the rafters. Roofing material is laid on it. The task of the crate is to distribute its weight.
• Overhang - an elongated edge of the slope that protects the walls from precipitation. If the length of the rafter legs is not enough to create an overhang, additional elements are used - filly.

The device of the truss system is shown in the figure.

Also, truss trusses are distinguished in the roof device. This is a solid knot consisting of rafter legs, stretch marks, racks and struts (braces, braces). The farm can be not only triangular, but also trapezoidal, segmental or polygonal. Which type of farm to choose depends on the size of the house. If the distance between the walls is 9-18 m, then a triangular truss will do. For houses with a width of 12 to 24 m, trapezoidal or segmental trusses are used. If the width of the building is greater (up to 36 m), then polygonal trusses are used.

The main attachment points for the roof truss system are beam, ridge and Mauerlat.

Types of truss systems

Rafters can be hanging and layered.

Hanging lean on the walls and create a spacer. To reduce it, puffs are made at the base of the rafters, which connect the rafters and form triangles with them. Hanging systems of various types are used for houses with a width of no more than 17 m. Depending on the width of the building, they arrange them differently.

If the width of the house is not more than 9 m, then the rafters are supported by a vertical bar - the so-called headstock. She is under the skate.

If the width of the house is from 9 to 13 m, struts are additionally installed, which at one end rest against the rafter legs, and at the other end against the headstock.

With a house width of 13-17 m, two vertical posts are used, connected at the top with a crossbar (fitted), as in the figure.

Sloped rafters rest on a load-bearing wall or columns inside a building. With this method, the rafter has three or more support points. The layered type of truss system creates less load on the walls of the building and is more durable; it is used for buildings of greater width. Such roofs can be arranged in different ways, depending on the location of the internal walls, they can be symmetrical or asymmetrical.

How to connect the parts of the truss system

To connect wooden elements to each other, nails, bolts, studs, as well as metal plates and corners are used to strengthen the knots. Additionally, wooden bars or plates are used.

Mounting Methods:

• teeth into a thorn
• point-blank teeth
• stop at the end of the crossbar.

The use of metal fasteners does not reduce the bearing capacity, since they do not need to be cut in, in contrast to fastening, for example, by the method of teeth into a tenon.

Rafters can be not only wooden, but also metal. For fixing metal rafters, various corners, brackets, mounting perforated tape, plates, bolts with nuts or self-tapping screws are used.

Mauerlat mount

If the wall is concrete, then a reinforced stiffening belt is made in its upper part, in which studs are provided. Mauerlat will be attached to them.

Rafters to the Mauerlat can be attached in two ways: rigid and sliding.

The first way is more popular. For fastening, special corners with a support bar are used. There are several ways to attach the rafter to the Mauerlat.

• Each rafter is nailed with three nails: two of them must be crossed, and the third is located vertically.
• Fastening with a bracket: one end of it is hammered approximately into the middle of the support beam, and the other is turned 90 degrees and hammered into the rafter.
• Fastening with wire rod: a clamp is made from a wire folded in 4 rows, with which the rafter is screwed to the beam. Instead of wire, a special perforated tape is also used. Sometimes this method is used in addition to other fastening methods.
• With the help of corners: the corner is screwed with screws to the Mauerlat and the rafter leg. It is better to use corners with two rows of holes and a stiffener.

The disadvantage of the hard method is that when the building settles, damage to the walls is possible. Therefore, rigid fastening is used in brick buildings.

The sliding method implies that the rafters are connected to the Mauerlat with such fasteners that do not prevent their movement within certain limits. This method is used in wooden buildings that can settle. With the help of special fastening methods, it is possible to achieve that the rafter will have one, two or three degrees of freedom. In the latter case, a special hinge is used.

One degree of freedom means that the rafter can turn in a circle. In this case, they are fastened with one nail or screw. The two degrees of freedom are circular rotation and horizontal displacement. For this, the rafters are attached to the Mauerlat with metal brackets. Special corner-sleds are also used.

With a sliding connection in small buildings with a not very heavy roof, the fastening is done without cuts. If the building is large, it is recommended to do this knot with a gash on the rafter leg.

Important! Washed down is cut out on the rafters, and not on the Mauerlat, so as not to damage or weaken the beam.

In this case, the fixation can be either rigid (with emphasis on the beam) or movable (with a tooth on the outside). Sometimes, instead of sawing out a tooth, an additional bar is used.

Ridge connection

After the rafter leg is fixed on the Mauerlat, they move on to the ridge attachment point. This connection can be made in three ways: butt, to the ridge run and overlap.

For butt fastening, the rafters are sawn in the upper part at an angle equal to the slope of the roof, and connected with nails (150 mm), driving them into the upper planes of the rafters, so that the nails enter the end of the opposite rafter. For strength, a metal plate or wooden plate is attached, which is also nailed or attached with bolts.

When attaching to a ridge run, a ridge beam (run) is additionally laid between the rafters, this method is more laborious.

When fastening with an overlap, the rafters located on opposite sides overlap each other and touch the side surfaces. They are connected with bolts, nails or studs.

beam knot

The rafters are attached to the beams as follows. The main task of fastening is to prevent the rafters from sliding along the beam, so various techniques are used.

1. In the heel of the rafter, it is necessary to cut a tooth and a spike, and an emphasis of the appropriate size is cut out in the beam.
2. From the hanging edge of the beam, the attachment point should be 25-40 cm away.
3. The mounting socket should be 1/4 - 1/3 of the beam thickness deep.
4. Together with the tooth, a spike is cut out, which prevents the rafter from moving sideways. Such a connection is called a "tooth with a spike and an emphasis."

If the roof is flatter (its angle of inclination is less than 35 degrees), then the rafters are fixed in such a way that the area of ​​​​their contact with the beam increases. Then use the following methods:

When creating a truss system for a roof, it is important to remember the following.

• All wooden elements are treated with an antiseptic and a refractory compound before installation.
• The thickness of any wooden part should not be less than 5 cm.
• Rafters without racks and struts are not made longer than 4.5 m.
• Mauerlat should be located strictly horizontally.
• Racks and struts are recommended to be done as symmetrically as possible.
• You can not add elements to the calculated truss system - this can lead to the appearance of loads where they are not needed.
• At the junction of wood with stone (brick) masonry, waterproofing is needed.

Properly made truss system is the key to the reliability of the roof. It is the rafters that take on the entire weight of the roofing materials and resist wind loads. Therefore, it is very important to build a truss system in compliance with the technology.

The rafter system is the frame of the roof of the house, which bears and evenly distributes the weight of the roofing pie, sometimes reaching up to 500 kg / m2. The reliability of this kind of skeleton depends on three factors: the accuracy of the calculation, on the basis of which the number and cross section of the supporting elements are selected, the material from which it is made, and also on the correct fastening technology. Knowing how to properly fix the rafters, you can significantly increase the bearing capacity of the frame, making it more durable and reliable. Installation errors, on the contrary, lead to noticeable strength losses and roof deformations. In this article we will talk about the main types and methods of fastening, with which you can install the rafters with your own hands.

The truss frame of the roof of the house is a system of interconnected supporting elements made of wood or metal, which give the structure a shape, slope, and also evenly distribute its weight between the bearing walls. Its main component is the rafter legs, which are angled beams that are connected in pairs along the slope, forming a ridge at the top of their connection. There are two main types of rafters:

• Layered. Rafters are called supporting elements, which in the roof structure have two points of support - on the ridge run and the Mauerlat. This type of rafter system is used in structures that have one or more load-bearing walls inside, on which the rafters can be “leaned”. This fastening of the rafters allows you to unload them through the use of additional vertical supports.
• Hanging. Hanging elements are called elements that have only one point of support, located where the rafters are attached to the wall or Mauerlat. The hanging type truss system experiences a load not only in bending, but also in bursting, therefore it is reinforced by horizontal compensating elements (crossbars, puffs, contractions).

Note! In most of the most popular truss systems, the rafters are attached to the Mauerlat. Mauerlat is a massive bar or beam with a section of 150x150 mm or 200x200 mm, laid along the load-bearing walls of the structure, on which the rafter legs will subsequently rest. It softens the pressure on the walls of the house, and also evenly distributes the weight of the roofing cake. You can attach the Mauerlat to the upper belt of the walls using anchor bolts or embedded metal studs.

Main connecting nodes

The rafter frame is called a system because all its elements are closely interconnected and fixed, as a result of which the roof structure acquires a stable shape, rigidity and high bearing capacity. Each connecting node between its parts is a weak point that can easily be deformed under load, so all fastenings must be carried out strictly according to the technology. Experienced craftsmen distinguish types of connections in the roof structure:

1. Fastening rafters to the ridge beam. This connecting node is typical only for layered truss systems, in which the upper part of the rafter leg rests on a ridge run, mounted on vertical posts. The rafters can be fastened to it with the help of metal plates, nails or sliding sliders.
2. Fastening rafters to the Mauerlat. The most important fastening unit of the rafter frame is the junction of the Mauerlat beam with the rafter legs. You can fix the rafters on it with nails, metal corners or wooden bars.
3. The connection of the rafters to each other. To lengthen the rafter legs, if the length of the slope exceeds the standard length of lumber, they are assembled from several elements interconnected with nails, glue or metal linings.
4. Connection of rafter legs with auxiliary supporting elements. In the design of the truss frame, the rafters can be connected to a puff, crossbar or struts to increase rigidity, strength and bearing capacity.

Please note that any cuts made to attach the rafters to beams, mauerlat or other structural elements of the frame lead to a decrease in their strength, so experienced craftsmen recommend connecting them together using corners and overlays.

Fixation methods

When deciding how to attach the rafters to the Mauerlat or ridge run, it is necessary to choose the right mounting hardware. The modern construction market has a huge assortment of fasteners of various designs and sizes. The main criteria for choosing fasteners are the material used to make the rafters, their cross section, as well as the type of load to which they are subjected. There are the following ways of fastening rafters:

Experienced craftsmen believe that the most reliable way to fix the rafters is to use metal corners that firmly connect the wooden elements to each other, rigidly fixing the angle between them. The corner that overlaps the joint between the rafter leg and the ridge beam or Mauerlat serves as a kind of spacer between them.

Varieties of fasteners

Wood is a natural material that, in the process of leveling moisture and drying, shrinks significantly, due to which the linear dimensions of the structure change. That is why experienced craftsmen recommend building a roof for timber and log houses, a year after construction, when the shrinkage process passes from an active to a passive phase. If you fix the wooden elements of the frame rigidly, then after drying the roof of the house may be deformed. Therefore, the following types of fasteners are used to connect the rafters:

Interestingly, there are several options for combinations of movable and fixed connecting nodes. The most common are truss systems with one rigid and two sliding fasteners, which provide sufficient mobility with high strength and rigidity of the structure.

Types of fasteners

Among experienced roofers, disputes do not subside, the more efficient it is to fasten rafters to floor beams and Mauerlat. However, in most cases, the catch is that in these conditions it is more practical to use nails or self-tapping screws. Both of these fasteners have their own advantages and disadvantages:

• Nails are good because only a hammer is needed to drive them, which is in every household. However, some masters complain that it takes too long to hammer them manually. It is worth recalling that special serrated nails are used to fix the rafters, which securely adhere to the wood.
• To assemble the rafter frame, galvanized self-tapping screws are used, which are not afraid of corrosion. Due to the thread, they are firmly screwed into the thickness of the wood, securely fixing the elements together. Screw them quickly and conveniently with a portable screwdriver. The disadvantage of this type of fastener is that during dismantling, removing self-tapping screws from wood is long and dreary.

Most experienced roofers agree that it is better to use galvanized ruff nails to fix the rafter legs, the length of which is 5-3 mm longer than the thickness of the lumber. Properly selected fasteners are the key to high-quality and long-term fixation of the roof frame, which will not be afraid of either mechanical stress or wind load.

Video instruction

Experienced builders are well aware that during the construction of the truss system there are no nodes that would not play an important role in ensuring the strength of the structure. This, among other things, also applies to the methods of attaching the rafter leg to the Mauerlat. We will not dwell on the characteristics of the Mauerlat itself, the methods of its construction and the methods of its fastening. The initial data for all options for attaching rafters to Mauerlats are standard - they must all be made in accordance with the requirements of existing building codes and regulations.

It is necessary to briefly clarify one more question - it is not always possible to attach rafters to Mauerlats.

When and why it is impossible to use this method of fastening the truss system?

On complex hip or gable roofs with different slope angles.	Why? The angle of the rafter (or filly, if it is of insufficient length) from each roof slope will be different. This means that problems will arise during the installation of the eaves of the roof. If you wish to make the cornice the same width around the entire perimeter of the building, it will be located at a different height on each wall. If you want to make all the cornices at the same height, then each wall will have a different width. You need to remember school lessons about triangles. It goes without saying that both the first and second options for the building are unacceptable. On such buildings, the rafter legs should be attached only to the floor beams, this is the only way to make the cornice the same width around the entire building. And if the roof is with a bay window, then the option of attaching the rafter legs to the Mauerlat does not even make sense theoretically.
During the reconstruction or repair of old or dilapidated buildings.	Experienced builders immediately determine the angles of inclination of the slopes. If at the points of their intersection the lines of roofing form a right-angled triangle, then the slope of the slopes is the same, if the waves of the coating do not match, the rafters will have to be fixed on the beams.
The upper rows of load-bearing walls are in such a deplorable state that it is very difficult to attach a Mauerlat to them with the necessary strength indicators.	You have to either disassemble several rows of bricks and lay them again or concrete a special reinforcing belt around the entire perimeter of the building, and only after such work is done, firmly fix the Mauerlats. Practice shows that doing such work is economically unprofitable, and it takes much more time than installing load-bearing beams on the ceiling.

We figured out this issue, now we should consider a few general recommendations regarding the fastening of rafters.

Recommendations for fastening rafters	Description	Illustrations
The rafters should never be sawn or notched deeper than one third of the width.	Remember this rule once and for all. On the net you can find examples of washing down rafters almost to half the width, this is a gross mistake. The question is, why take a board 150 millimeters wide for the rafters, so that later in the most loaded place “cut off” half of it? What bearing capacity will it have? Moreover, this rule applies not only to the attachment point of the rafters to the Mauerlat, but to absolutely all fixation points of the truss system.
For each node, at least two methods of fixation must be used simultaneously.	In addition to notches, use metal brackets or corners; supplement notches that do not inspire confidence with special resistant boards, etc.
Use templates only if you are absolutely sure that all dimensions and distances around the entire perimeter of the building are as identical as possible.	There is no such certainty - adjust each rafter leg separately.

And we figured out this topic, now we can already consider the most common ways of attaching rafter legs to the Mauerlat. We will talk about three: sawing with an emphasis (hard), sliding and layering methods.

Rigid fastening of rafters

The most reliable, most time-consuming and most versatile method can be performed by cutting or by sewing retaining bars onto the rafters. First, consider the option of cutting the rafters.

Do not worry if, as a result of cutting out your leg, the slope of the slope changes slightly. The main thing is that all the rafters lie on the same line. Before washing down the rafter leg, you need to take the dimensions of the place where it fits to the Mauerlat, and this is quite difficult. We will not perform various mathematical calculations, it is long and useless, and in practice no one bothers with such a head.

Step 1. We offer two options: make one universal template for all legs at once or make cuts for each separately.

If everything is fine with the position of the Mauerlat, then it is better to make a template, if there are problems, then you will have to prepare each rafter separately.

The template can be made from cutting boards, a piece of fiberboard, or thick cardboard. Draw a line on it at the bottom edge at a distance of no more than 1/3 of the width of the rafter leg. On all rafter legs, draw the same parallel line, mark the places where the rafters fit the Mauerlat, and draw a line perpendicular to it.

Now you need to trace the angle of the vertical and horizontal planes of the notch for one fit to the Mauerlat over the entire surface. Let's say right away that it will not be possible to achieve the ideal option, but the loose fit of the planes of a few millimeters does not play a critical role. Attach the template to the end of the Mauerlat beam at an angle of slope. The point of intersection of the vertical and horizontal lines must be exactly opposite its corner. Draw the resulting triangle, cut out the drawn part.

Step 2 Check the correctness of the template in several parts of the Mauerlat, walk along both sides of the building. If necessary, slightly change the angle of the sawn part, you need to achieve the most accurate fit of the notch around the entire perimeter.

Step 3 Attach the template to the rafter, the point of the angle of the upper stop should be on all rafters at the same distance from their ridge part.

Step 4 With an electric saw or a hand saw, cut the cut across the fibers of the rafter leg.

Sawing very carefully, do not reduce the width of the remaining intact rafter with a cut. With insufficient experience with electric tools, it is better to use hand saws. Let it take more time and effort, but the likelihood of marriage is significantly reduced. And if you take into account the time for rework, then the loss of labor productivity from a hand tool will not be so large.

Step 5 At an angle, select the second slice.

Attention: this is the most difficult job. Sawing such a surface with an electric saw is undesirable, the risks of intercession are high. You need to work with an ax, the ax must be very sharp. Working with an ax will require not only skill, but also physical strength. By the way, the ability to work with an ax (and not at the professional level) will always come in handy when building a wooden bath.

Step 6 Check the template made seat, if necessary, correct it. You can prepare seats for the entire set of rafter legs at once, or you can perform work in turn. It all depends on your skill and accuracy of installing the Mauerlat.

Step 7 Put the rafter leg in place, fix its position. For fixing, you can use homemade staples, metal corners or other durable devices.

Thus, you need to put the two extreme rafters, pull the rope between them in the lower part and put the next ones in turn. Be prepared that for some rafters you will have to adjust the heel sizes several times. The more practical experience you have, the less often you will have to remove / put the rafter leg to fit. During the installation of the truss system, each pair of legs should be temporarily fixed with various wooden braces or struts. Temporary fastening is removed only after stuffing the crate under the roof finish.

Edged board prices

edged boards

Fastening the rafter legs with a stripe of a thrust bar

For small baths, we recommend using this method - much easier and faster. As for the mechanical stability of the structure, it depends on the conscientiousness of the performance of all work. Even very inexperienced builders can use this method of fastening the rafters, it makes it possible to move the rafter legs in any position until they occupy the correct position and fix the knot in place.

Step 1. Install the gable rafters in place, temporarily fix their position.

Step 2 From a wide board, cut a piece at least 40 cm long. Determine the angle of inclination of the butt end in the Mauerlat. The upper horizontal notch on the board can be omitted, it does not carry any load. The rafters will hold the vertical load. In order to increase the area of ​​\u200b\u200btheir emphasis in the Mauerlat, it is necessary to saw through the seats in them to the width of the rafters.

There were no pieces of durable boards - nail two thin rafters on both sides. We only recommend planting them on one through hardware (optimally long bolt), you should not loosen the rafters with a large number of nails or self-tapping screws.

Step 3 If you have boards on both sides of the rafter, then you can not use additional methods of fixing the element from side overturning. If the board is on one side, then you will need to fix them with metal corners or staples.

It should be said that each truss system on any building is carried out by craftsmen with individual differences. It all depends on their experience and preferences. And you may not follow our recommendations exactly, make original decisions on the spot, taking into account the characteristics of the bath and the availability of building materials.

Work on fastening the rafters should always be done with a rope, the ridge and lower legs should be controlled. If there are height problems, then put wooden stops on the Mauerlat, to prevent slipping, nail them with small cloves or self-tapping screws.

Prices for a set of hardware

set of hardware

According to this method, a truss system is built in wooden log cabins.

The fact is that the log house must stand under the roof, during which time it shrinks. Shrinkage, as a result, slightly changes the position of the truss system, in the case of rigid fastening of the rafter legs, either deformation of the truss system will certainly appear, or the stability of the upper row of the log house will be disturbed. It is this row that plays the role of the Mauerlat. In order to increase the area of ​​\u200b\u200bsupport for the rafters and Mauerlat, you need to remove the sharp edge of the latter. Otherwise, heavy loads will cause the beam to be pressed into the corner of the Mauerlat, and the truss system will begin to change its position. This will be done unevenly along the perimeter of the log house - the rafters can significantly disrupt their original position, the roofing will become wavy. And this can violate its tightness, as a result, leaks will appear with all very negative consequences.

Sliding rafters can only be installed when the rafter system has an emphasis in the upper part on the ridge beam and vertical stops; to enhance the stability of the structure, it is desirable to additionally install braces or stocks. A specific decision should be made taking into account the size of the bath, the material of construction and the architectural characteristics of the roof.

Very important: if you intend to fix the rafter legs using a sliding method, then the fixation assembly of the upper ridge parts should be done on a hinge. In the upper part, the rafter legs should oscillate in the axial direction, which makes it possible for them, depending on the shrinkage of the bath, to change the angle of inclination of the truss system. Thus, possible vertical loads are extinguished.

Step 1. Install the ridge beam in size. It should be located exactly in the middle of the bath, otherwise the angle of inclination of the slopes will not be the same. What difficulties are caused by the unequal angle of inclination of the slopes during the construction of cornice overhangs, we have already described in the article above.

Step 2 Start the installation with the installation of the extreme gable rafters.

For sliding fastening, you need to buy special clamps, you need to install them on both sides of each rafter.

Sliding support for rafters - dimensions

Step 3 Take the dimensions of the rafters along the length, determine the specific places for their installation.

Step 4 To increase the plane of contact between the rafter leg and the Mauerlat, remove the corner of the beam. You can shoot the corner around the entire perimeter (difficult and long) or only in the places where the rafter legs rest. To do this, make two cuts in the Mauerlat at a distance slightly greater than the width of the rafter board.

With a chisel, carefully remove the wood in the cut, trim its surface. We advise you not to neglect this advice, such a simple installation method will make it possible to significantly increase the stability of the entire truss system. In addition, it will not be necessary to apply other methods for the stability of the system to longitudinal wind loads.

Step 5 Carefully place the rafters on the prepared seats, fix with floating metal mechanisms. They must be installed in such a position that most of the protruding node allows the rafters to go down, it is in this direction that shrinkage occurs.

Step 6 Between the extreme gable rafter legs, pull the ropes on the slope of the cornice overhangs, mount all the remaining rafters along the rope. If necessary, adjust the length of the structures. Simultaneously with the legs, fix the ridge parts of the rafter legs with a swivel joint.

Such a device of the truss system is considered the least stable. Despite the fact that the forces expanding the rafter legs are much less than the bending forces, the sliding legs are the weakest node of the entire structure.

Practical advice. At the slightest doubt about the stability of the constructed truss system, reinforce it. It does not matter in what way the system is strengthened, the main thing is that it always has a fairly large margin of safety and reliability. Remember that reinforcing a structure after a problem is discovered is much more difficult than doing all the work in a timely manner.

There is another kind of sliding method, it is more reliable in strength, but only suitable for baths made of rounded bursa or round whips - a sliding method with a gash in an arc.

Making it a little more difficult, each rafter at the point of contact with the upper crown of the log house must be cut in an arc. For sawing, it is better to use an electric jigsaw. The depth of cut is no more than 1/3 of the width of the rafter. The mark can be removed from the end of the timber, the rafters can be made all the same. Such a connection has an additional degree of freedom, but at the same time excludes axial movements - the reliability of the entire truss system increases.

Scheme - rafters with sliding support and cuts

sliding support prices

sliding support

It is used in the case during the production of repair work on roofs of complex construction or insufficient length of available lumber for the manufacture of rafters. Of course, the rafters can be connected and in this way increase the length. But builders do not advise doing these things; at the slightest opportunity to avoid the connections of the rafter legs, you need to use them. In addition to the fact that each connection requires a lot of time and labor, it always significantly reduces the strength of the rafters. We repeat once again - always the bearing characteristics of the connected rafters are much less than the whole ones.

It is better to use the layered method during the construction of the rafters, and with the help of ordinary fillies, make the roofing part of the eaves.

Step 1. Measure the exact length of each rafter until the end part stops in the Mauerlat. Determine the angle of inclination of the thrust plane.

Rafter rafters - schemes

Make a drink along the marked line. If the width of the rafter leg allows, then it is recommended to wash down with a tooth. The tooth will prevent the rafters from sliding on the Mauerlat. If this is not possible, then at the bottom of each rafter leg, stubborn boards about 40 centimeters long should be added. Boards are attached to the rafters with nails or screws.

Step 2 To prevent lateral vibrations and overall strengthening of the joint, the rafters are additionally fixed with metal corners or brackets. Driving large nails into the end is not recommended due to the high risk of cracking the wood.

Step 3 Next, you need to do fillies for cornices. For this, edged boards with a thickness of more than 30 millimeters are suitable. Cut them to length, taking into account the expected overhang of the eaves, and nail them firmly to the rafter legs. All work must be done only under a rope stretched between the extreme gable rafter legs.

Prices for metal corners

metal corners

For the rafter system, choose only the highest quality materials, this is not a design that you can save on. Many ordinary architectural elements have several additional components of load-bearing structures, they complement and insure each other. The rafters work "alone", in case of violation of stability, no other elements take on the load.

Try to make knots of rafters with Mauerlat in those places where there are no natural malformations of wood, including healthy knots. The hardness of the knots themselves is large, but swirls of wood fibers form around them, and they no longer have high rates of physical strength.

Do the markup, and especially the cropping, very carefully. To correct errors, you can use various linings, but this is highly undesirable.

And the last. You can find recommendations to install the truss system on your own without helpers. Some of the simplest types of truss systems can be done alone. The only question is, why is it needed? Why risk your health if there will be no savings in time and money in the long run. And the quality of the connection of all nodes will suffer significantly.

Video - Fastening rafters to the Mauerlat, sliding support

Video - Installation of rafters

Video - Assembly of rafters

Video - Quick installation of the truss system