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The nodes of the truss system. Strong roof: roof truss system and its types

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 timber. 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 cut 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.

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.
From the hanging edge of the beam, the attachment point should be 25-40 cm away.
The mounting socket should be 1/4 - 1/3 of the beam thickness deep.
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 slope angle 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.

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 along 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.

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.
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.
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:

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
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.
A second template is made, thanks to which the cuts on the rafters are installed. It is made from plywood.
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.
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
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.
Raise and mount the remaining rafters at the initially calculated distance, which should be at least 60 cm apart.
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.
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 from below - 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.

December 12, 2017
Specialization: facade finishing, interior finishing, construction of dachas, garages. The experience of an amateur gardener and horticulturist. He also has experience repairing cars and motorcycles. Hobbies: playing the guitar and much more, for which there is not enough time :)

Any roof is subjected to various loads every day, as it is affected by wind, precipitation, and it also holds the roofing. In order for the roof to cope with all these loads for many decades, it must be properly designed. Therefore, for everyone who wants to do construction on their own, I recommend to figure out what parts and nodes of the truss system exist, and what function they perform.

Frame elements

All details of truss systems can be conditionally divided into two types:

Basic. These parts form the roof frame, called the truss system. Not a single roof can do without them;
Additional. This group includes elements that may be present in some types of roofs, while others do without them. The task of additional elements is to increase the rigidity and strength of the frame.

Main knots

So, the following elements belong to the main nodes and details of the truss system:

Mauerlat. This, one might say, is the basis of all roofing systems, since rafter legs rest on the Mauerlat. Its design is extremely simple, in fact, it is an ordinary bar (a log in log houses), laid along the perimeter of the walls. Its task is to evenly distribute the load from the roof to the walls of the building.

I must say that at a gable roof, the Mauerlat can be located not along the perimeter, but only on the side walls, since there are pediments on the end walls, which are a continuation of the wall;

Rafter legs (hereinafter CH), or simply rafters. These parts are the supporting element that forms the slope and its angle of inclination. They take on the wind and snow load, as well as the weight of the roofing material, and transfer it to the walls through the Mauerlat and other elements.

Rafters are lateral (main), diagonal (installed at the junction of hip roof slopes) and shortened (diagonal rafters rely on Mauerlat);

Rafter farms. They are formed by paired (reciprocal) rafter legs. It must be said that truss trusses are present on all pitched roofs except for shed roofs, since they do not have reciprocal rafters;
Skate knot. It is the top of the roof truss, i.e. formed by the junction of two CHs. The ridge knot, like the trusses themselves, is absent only from shed roofs.

That's all the main knots of wooden roof structures that form them.

Additional

Additional details include:

Run. This is a horizontal beam that connects all CHs within one slope;
Skate run. It is the same horizontal beam as a regular run, but which runs in a ridge knot, i.e. connects two legs of each truss at the same time.

I must say that the ridge run can be installed in several ways - above the junction of the rafters, in the center of the junction, i.e. legs rest on the run, or under the rafters;

Puff (bolt, fight). It is a beam that connects two reciprocal legs, preventing them from moving apart. We can say that the tightening removes the spacer load from the bearing walls;

Supports. Can support rafters, all types of runs or puffs. Supports transfer the load to the internal walls of the building, columns or ceilings;
Struts (rafter legs). They are inclined supports, which have the same function as the vertical racks. The only thing is that they support only the legs, i.e. are one of the elements of wooden trusses. Rafter legs transfer the load to the load-bearing elements of the building, or to the ceiling;
Filly. These elements form the overhang of the slope in the event that the CHs do not go beyond the walls. In fact, they lengthen CH, i.e. are their continuation.

That's all the elements that make up the frames of pitched roofs.

A few words about the types of systems

So, we figured out the nodes, now let's look at the main types of truss structures. There are several of them:

Shed. As I said, these structures do not have trusses. The angle of the slope is formed due to the different heights of the walls on which the CHs are laid, or due to the run, which is laid on racks installed on one of the walls;

Gablesloping. Rafters are called rafters, which are supported by racks or struts that transfer the load to the internal load-bearing elements of the building. The frame of such structures is formed only by trusses, i.e. they do not have diagonal legs.

gable hanging. Hanging rafters differ from layered rafters in that they transfer the entire load from the roof only to the outer walls;

Hip. Unlike gables, at the ends instead of vertical gables they have inclined hips, i.e. end slopes. As I said, the hips form diagonal and short legs;

broken lines. They are a gable structure, each CH of which is divided into two parts and is located at a different angle. Skating, i.e. the upper legs form a gentle slope, and the lower legs are steep. This design allows you to increase the attic space, as a result of which it can be used as an additional floor.

Typical broken (mansard) systems have racks on which the upper and lower CHs rest. The reciprocal racks are interconnected by puffs (attic floor beams).

There are also semi-mansard structures, which, in fact, are the usual hanging gable roof systems. The only thing is that their fastening with a Mauerlat is usually made sliding (movable), which allows you to increase the CH deflection, and thereby reduce the spacer load on the walls.

Despite the fact that the designs of all of the above systems are different, they consist of the same parts that we have already familiarized ourselves with.

One last thing about fasteners

Finally, I propose to consider how the connections of the main nodes are made, such as:

Rafter / Mauerlat;
Skate knot.

The rest of the details do not deserve special attention, since their docking most often occurs by washing down the interface (to increase the area of \u200b\u200bfitting the parts) and lining the steel plastic / corners, which are fixed with screws. Sometimes fasteners are not even used, i.e. parts are fastened to each other with screws without any overlays.

Connection of rafters and Mauerlat

The leg and Mauerlat mount can be made in several ways:

With grooves. In this case, grooves are cut out under the Mauerlat, into which CH is inserted. Then it is additionally attached to the Mauerlat on both sides with a steel corner;

Tooth and thorn. This method is usually used to attach the CH to the puff. Its principle is based on the fact that a spike is selected at the end of the sawed CH, and a groove is selected in the puff. In addition, the leg itself rests against the so-called tooth, i.e. protrusion in the puff, which takes on the expansion load.

It must be said that in recent times, fasteners such as a tooth with a spike are rarely used, since it is much easier to use special fasteners, the same corners and plates;

By washing down. In this case, the CH is sawn so that a right angle is formed at the junction with the Mauerlat, as a result of which the rafter not only rests on the beam, but also rests against its side surface, thus transferring the spacer load. I must say that instead of washing down, you can fix the bar, as shown in the diagram below.

Connection of rafters and ridge run

The connection of CH and run can be done as follows:

With a groove. In CH, two reciprocal cuts are made, as a result of which, after the junction of the rafters, a groove is formed for the ridge run;
Hard pinching. The principle is based on the fact that puffs are installed under the run and above it;

Got drunk on the way. This is the simplest and most common method, the principle of which is based on sawing CH for maximum fit to the beam. In this case, fixation is carried out with a steel corner.

Here, perhaps, are all the main nuances of assembling truss systems.

Conclusion

We have found out what parts the truss systems consist of, what types they are and how their main elements are connected. If I missed some points or something is not clear to you - write comments, and I will be happy to answer your questions.

December 12, 2017

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Roof trusses and its types

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.