Wooden roof designs series. How are roof units connected to each other?

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

Roof trusses and its types

Rafter system- the base of the roof, which places emphasis on the load-bearing elements of the building and also serves as a frame for various types roofing materials: insulation, waterproofing, various coatings.

The dimensions and design of the rafters depend on:

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

The rafter system has:

• sheathing - beams laid perpendicularly on the rafter legs;
• ties that absorb tensile forces;
• wooden racks located in a vertical position;
• mauerlat - a beam, the installation of which is carried out along the wall, the rafters rest on it;
• rafter legs are a kind of wooden beams that bear the main load of the roof.

Each of the above factors is very important, since it is necessary to understand what type of rafter system will be optimally suited for a particular situation.

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

Characteristics of hanging rafters

Hanging rafters- this is the most elementary type of rafter systems, their characteristics:

If the roof of the house complex design, types of rafters can be alternated. For example, if there are supports or a middle main wall, layered rafters are installed, and if there are no such elements, hanging rafters are installed.

Features of layered rafters

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

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 attic roofing. The walls of the rooms located on the second floor are formed by vertical supports; these supports also serve as intermediate supports for the rafter beams.

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

At the same time, the horizontal beams perform the following functions: for the upper slopes - the Mauerlat, for the side slopes - the ridge beam. To increase the strength of the roof, struts are installed that connect the side slopes and vertical posts.

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

You can increase the load-bearing qualities of the roof using a mixed rafter system

Roof trusses for various roof types

When constructing a certain building, rafter systems of one type or another are necessarily used, and the type of roof will completely depend on the design of the future structure.

Rafter truss for gable roof

Gable roofing is a common roof construction for residential buildings that have no more than three floors. Preference is given to this particular design due to the technical characteristics of the inclined shape of the rafter system, as well as due to the fact that installation work is carried out easily and simply.

The rafter system of a gable roof includes two rectangular inclined planes. The upper part of the building from the end side resembles a triangle. The main components of a gable roof are the mauerlat and rafter legs. In order to properly distribute the load across the rafters and walls, struts, crossbars and racks are installed, thanks to which you can create a durable, rigid, elementary and lightweight structure for installing a structure for a gable roof.

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

You can install sparse or solid sheathing on top of the rafters, and then attach bitumen coating, tiles or some other type of material to it. The rafters and the sheathing itself are usually made of beams or boards, which are fastened with nails, bolts or metal fasteners. Metal profiles can be used as rafters, thereby covering significant spans. There is no need to use extra racks and struts.

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

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

Rafter system for hip roof

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

• narozhniki (short);
• lateral;
• hip main;
• obliques (diagonal elements that form a slope in the shape of a triangle).

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

To install this type of structure, the angle of inclination, as well as the cross-section of the slanting beams, are accurately calculated. The dimensions of the parts also depend on the span length.

To hip roof not deformed from heavy load, you should accurately calculate the angle of inclination of the diagonal beams for the rafters

Maintain symmetry when installing diagonal beams for rafters, otherwise the roof will deform under significant load.

Rafter system for a sloping roof

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

Calculate four-slope system rafters are needed by professionals, but you can make a gable sloping roof yourself, since its installation is very simple. To do this, it is necessary to install a support frame, which should consist of purlins and racks. Horizontal parts are fixed with hanging rafters. But the supports are attached to the Mauerlat sloping roof shortened rafter legs.

The assembly of rafters for a sloping gable roof can also be carried out by non-professionals, since the installation of such a roof is very simple

"Cuckoo" in a roof truss

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

The first stage of work begins with the installation of the Mauerlat (beam with a cross-section of 10x10 cm, which is needed to support the slings). The rafter system acts as a skeleton for the roofing material. To impart rigidity to the structure, spacers are used, which are mounted between the two legs of the rafters.

After installation is complete roof truss lay the sheathing, the type of which depends on the roof covering purchased. Installation of the sheathing 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 when installing such a rafter system is the location of the internal corners. Snow can accumulate in these places, which means the load will increase, which is why a continuous sheathing is made.

A “cuckoo” on the roof is a small protrusion on the attic floor, under which there is an additional window.

Chalet roof rafter truss

The peculiarity of this design is that the canopies and overhangs are moved outside the house. In addition, there must be rafters and roof beams extending up to three meters on the sides of the building. Each of these elements is secured 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 studs for the Mauerlat. It is necessary to make anchors that help secure the consoles. In this case, the rafters will be perfectly fixed with anchors and, in addition, with mortises.

To carry out the side cornices, a ridge beam is made, after which beams are placed at the level of the mauerlat, which must be identical to the length of the ridge. The truss, and subsequently the building materials for the roof, rest on these structural details.

When designing a building, the angle of the chalet roof 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 flat roof will withstand the load from snow, but it is necessary to install a reinforced roof truss. Before installing the chalet roof, a building design is prepared, because the originality of the roof itself, as well as the long eaves and overhangs, oblige this.

A chalet-style roof is characterized by canopies placed several meters outside the house

Rafter truss designed for soft roofing

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

1. Install individual parts of the rafter system. To completely eliminate risk, boards rafter legs They are attached to the ground with screws. After the roof truss is created, it is raised to the top of the building.
2. Secure all elements of the rafters to the ceiling, internal boards, jibs, as well as crossbars. Further, this base for the roof will become a single whole structure.
3. The next stage is the sheathing, which is installed under the 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 method brickwork. The resulting joints are not aligned with the gaps between the plywood and the board.

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

Self-production of the rafter system

Before the installation of the rafter system begins, the mauerlat must be secured to the longitudinal walls with anchors. Next you need to decide with the required section legs for 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 rafter elements in order to reduce the number of thermal insulation scraps.

Installation of the rafter system must be done in the following order:

1. A template is made according to which the truss is assembled. Take 2 boards corresponding to the length of the rafters and connect them together at just one edge with a nail.

   A template for rafters called “scissors” will help you quickly assemble the entire roof rafter system

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

   For proper 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 ridge and the level of other rafters located in the gap.
7. Raise and install the remaining rafters at the initially calculated distance, which should be at least 60 cm from each other.
8. If a bulky rafter structure is envisaged, then it is additionally strengthened with struts, supports, and so on.

   The bulky structure of the rafters is additionally strengthened with struts and supports

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

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

Typical components of a standard rafter system

The strength of the rafter structure depends on the ideally selected section of the boards, as well as on High Quality rafter nodes. The connection of parts for the roof structure is done according to established rules.

The main typical units in the rafter system:

• rafter support assembly on the mauerlat;
• ridge;
• unit for combining the top ties and the entire rafter system;
• securing 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 highlight all the nodes. They are made differently in each design as it depends on different nuances: type of roof, its size, angle of inclination.

Rafters from profile pipe is a metal structure that is assembled using lattice rods. The production of such farms itself is a very labor-intensive process, but also more economical. For the manufacture of rafters they are used paired material, and the gussets are connecting elements. The structure of the rafters from profile pipes is assembled on the ground, using riveting or welding.

Thanks to such systems, any spans are blocked, but the correct calculation must be made. Provided that all welding work is done efficiently, in the future all that remains is to transfer the structural elements to the top of the building and assemble them. Load-bearing rafters made from profile pipes have many advantages, such as:

Crossbar in the rafter system

Crossbar is a fairly broad concept, but in the case of roofs it has certain value. The crossbar represents horizontal beam, which connects the rafters. This element prevents the roof from “expanding.” 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 rafter system.

It can be fixed in various places between the legs of the slings. 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 rafter system:

• bolts;
• nuts;
• studs with washers;
• special fasteners;
• nails;
• mixed fastenings when used in parallel different types fasteners

The fastening is available with a mortise or overhead. In general, the crossbar is a design unit, as is the entire system of roof slings.

The crossbar in the rafter system is designed to strengthen the roof structure

Fastening the rafter system

To ensure the reliability of the rafter system, you must first find out how they are attached to the supporting roof and ridge. If a fastening is made to prevent deformation of the roof when the house shrinks, then the rafters are secured on top with a hinge plate or a nut and bolt, and below with a sliding support.

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

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

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

The rafters are attached to the mauerlat using the cutting method, which is made in the rafter leg. Thanks to this fastening method, the roof support will not weaken. Cutting is also done when installing rafters on floor beams. In this case, a cut is also made in the support beam.

Video: how to make rafters with your own hands

Thus, an ideally selected rafter system and its design characteristics will help create the basis for reliable roof for your home.

Private construction is unique in that most developers try to build a building with an individual feature. All possible design tricks, advice from friends and acquaintances can be used here, but no matter what the house is, it is very important to install the main components. If it is built from wood, then the log house can be purchased at finished form, and as for the roof, everything is more complicated here. Nodes wooden structures Roofs are the most important part of construction. They must be executed perfectly correctly so that the building serves you for as long as possible.

Wooden roof knots

If you have ever been present at the construction of the roof of a house, then you probably know that the rafter system is a kind of skeleton of the roof. The roofing pie, covering, with reverse side possibly sheathed facing material. Over their entire service life, rafter legs support colossal weights, which under some conditions can reach up to 200 kilograms per 1 square meter. This value can be achieved if the owners do not maintain the roof and enough water has accumulated on it. a large number of debris, leaves and snow.

At the time of construction of the roof, it must support the weight of several workers and their equipment. Such a load is purely individual, because it is difficult to predict exact figures if you do not know how much the workers will weigh or what equipment they will take with them. Therefore, very often roofs are constructed in such a way that no matter how high the load, it can withstand it. Only in this case will work and further operation take place in a calm and safe manner.

The next most important element is called the Mauerlat, or in other words, the support beam. It is a kind of foundation for the entire roof. This element must be durable, so in most cases it is prepared using conifers wood The Mauerlat can be attached to the wall in many ways, but the most popular and simplest are: fastening using embedded parts or anchors. For the first method, during the construction of walls, special metal parts are laid and released at the end.

The support beam holds the rafter beams, which means it bears their weight and the load that they can withstand. The calculation for selecting rafter elements is quite simple and at the same time complex. It’s very easy to calculate one equation, but it’s not always possible to discover all the nuances and insert them into the formula, so many developers simply take products with a large cross-section and don’t bother. This is partly true, but what if this is not enough. This problem can be solved with the help of all kinds of spacers and supports.

If you are faced with a voluminous roof, then the matter will not do without struts and racks. Thanks to these elements, the rafter legs feel as stable as possible. An important part of the entire system is the sheathing. It can be arranged using a discharged or continuous method. If the roofing material is hard, then you can use the first, and if it is soft, then only the second. As a rule, the discharged sheathing is packed over the eaves overhangs in a continuous manner, thereby increasing the stability of the entire overhang and making it stronger.

The ridge unit is a very important part of any roof. It not only protects two planes from dust and moisture, but also allows moist air to leave the attic. This is especially important when the coating or something in roofing pie completely isolates materials from moisture. The moist air has no choice but to begin to condense and destroy all elements of the rafter system.

IMPORTANT: Before the device wooden elements it is very important to process them protective compounds. Antiseptics protect the structure of lumber from rotting and the proliferation of harmful microbes, and fire retardants increase resistance to fire.

Rafter truss

On large slopes you cannot do without trusses. This design differs from an ordinary roof in that there are racks and braces that increase maximum load on wood several times. Often the farm is installed throughout the roof, but sometimes it can also occur locally.

It is advisable to install a roof truss if the width of your house is in the range from 12 to 24 meters. As a rule, trapezoidal or segmental trusses are installed on buildings with large volumes. When the width of the building is even greater and this value does not exceed 36 meters, then a polygonal one is suitable. Standard designs with a width of 9 to 18 meters, they are content with a triangular one.

In addition to the shape of the roof truss, it is very important role plays the material from which it is made. In most cases this is wood, but metal can also be used. Self-tapping screws or nails are used to fasten lumber together. In cases where the span length is more than 16 meters, a combined truss is best suited. It includes elements of wood and metal.

Nuances of fastening rafter legs

As you already know, the components of wooden roofs are the most important component of the construction of a building, and what could be more important than fastening roof frame. Rafter legs can be attached to the support beam in two ways.

• Tough
• Sliding

In the first case, you will get the most stable connection, which deprives the structure of all kinds of shifts, vibrations, turns and similar manipulations. This can be achieved by sawing or cutting. After the leg is inserted into the created slot, it is fixed using nails, wire, anchors or any other fasteners.

Sliding docking looks completely different. It has three degrees of freedom of conjugation. It is worth immediately noting that this method of fastening is most rationally used in wooden houses, since they are characterized by large shrinkage, as a result of which rigid units can be seriously damaged. To create such a fastening, you will need to rest the rafter leg against the mauerlat, where the tooth connection was previously arranged or nailed additional beam. Such parts are connected using a metal corner. As for the upper part, here the connection is made with the same notch, and the edge is cut along an oblique so that a sliding connection is ensured.

IMPORTANT: If you are not satisfied with rigid or semi-rigid freedom, you can install special flexible plates, thereby achieving a completely sliding joint.

Ridge knot

As I said earlier, the ridge is one of the important components of any rafter system where two slopes are joined. As a rule, it is located in the very top part of the roof, but there are also structures where there is more than one ridge, for example, an attic roof, there are 3 of them at once.

Rafter legs are almost always created so that they fit as closely as possible to the ridge element. This will provide better protection from dust and precipitation.

In the roofing business, there are two types of rafter systems. The first is layered, and the second is hanging. If we consider the first, then the connection here occurs by cutting into half a tree. This technique ensures maximum strength. As for the hanging rafters, here their lower part is joined in pairs. This can be achieved by cutting each beam at a certain angle, which is equal to the roof slope. After this, they are applied to each other with saw cuts and mated with nails so that each fastener penetrates through the cut into another beam.

You can often find ridge elements with a perforated body. Small holes do not allow small rodents and birds to enter the attic, and the quality of natural ventilation increases several times.

Complex parts of a hip roof

The hip roof is suitable for almost all types of buildings, so it is best to sort out all the difficulties on it. Distinctive feature hip design Obvious is the presence of hips. This rafter system boasts the following advantages:

• Durability. Due to the correct load distribution, rafter elements are subject to less pressure, therefore they are at relative rest.
• Low windage. The material on such a roof is very difficult to lift even by the strongest winds.
• Resistant to all types of precipitation.
• Cost-effective option for large structures.
• The optimal angle of inclination allows the use of almost any roofing materials.
• The hip roof is quite voluminous, so attic can be equipped living room. To create additional lighting, you can insert light windows into the slopes, which will also serve as auditory windows.

The weak point can be attributed to the rather difficult device.

The appearance of the roof includes only a few paired figures: a trapezoid and a triangle. They are opposite each other, so the rafter system can be considered symmetrical. In places where these slopes touch, sloped rafters are installed. They can be connected to the rest of the system using trusses and a layered structure.

The slanted beams in the lower part are attached to the mauerlat, or beam, which is placed on the inner wall. The support goes to the ridge from above, so the legs must be adjacent to the ridge girder.

Any roof must be laid in accordance with the rules and regulations of the construction industry. This is the only way to achieve a high-quality and safe design. When working at height, remember safety precautions.

December 12, 2017
Specialization: facade finishing, interior decoration, construction of cottages, garages. Experience of an amateur gardener and gardener. We also have experience in repairing cars and motorcycles. Hobbies: playing the guitar and many other things that I don’t have time for :)

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

Frame elements

All parts of rafter systems can be divided into two types:

• Basic. These parts form the roof frame, called the rafter 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 additional elements is to increase the rigidity and strength of the frame.

Main nodes

So, the main components and parts of the rafter system include the following elements:

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

It must be said that on a gable roof, the Mauerlat may not be located along the perimeter, but only on the side walls, since on end walls pediments are located, representing a continuation of the wall;

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

Rafters can be lateral (main), diagonal (installed at the junction of the slopes hip roofs) and shortened (diagonal rafters rest on the Mauerlat);

• Roof trusses. They are formed by paired (reciprocal) rafter legs. It must be said that trusses are present on all pitched roofs except single-pitched ones, since they do not have reciprocal rafters;
• Ridge knot. It is the top of the truss, i.e. formed by the junction of two CHs. The ridge unit, like the trusses themselves, is absent only on shed roofs.

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

Additional

TO additional details can be attributed:

• Run. This is a horizontal beam that connects all CHs within one slope;
• Ridge run. It is the same horizontal beam as a regular purlin, but which runs in the ridge unit, i.e. connects simultaneously two legs of each truss.

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

• Tightening (crossbar, contraction). It is a beam that connects two response legs, preventing them from moving apart. We can say that tightening removes the thrust load from load-bearing walls;

• Supports. They can support rafters, all types of purlins or tightening. The supports transfer the load to interior walls buildings, columns or ceilings;
• Struts (rafter legs). They are inclined supports, which have the same function as the vertical posts. The only thing is that they support only the legs, i.e. are one of the elements wooden trusses. The rafter legs transfer the load to the load-bearing elements of the building or to the ceiling;
• Fillies. These elements form the overhang of the slope if the SNs do not extend beyond the walls. Essentially, they prolong CH, i.e. are their continuation.

These are all the elements that make up the frames of pitched roofs.

A few words about the types of systems

So, we have dealt with the knots, now let's look at the main types of rafter structures. There are several of them:

• Single-pitch. As I already said, these structures do not have trusses. The slope angle is formed due to different heights walls on which the SNs are laid, or due to the purlin, which is laid on racks installed on one of the walls;

• Gablesloped. Layered rafters are rafters that are supported by posts 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 gable ones, 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. Represent gable structure, each CH of which is divided into two parts and located at a different angle. Skates, i.e. The upper legs form a gentle slope, and the lower legs form a steep slope. This design allows you to increase the attic space, as a result of which it can be used as an additional floor.

Typical broken (attic) systems have racks on which the upper and lower SNs rest. The counter posts are connected to each other by ties ( attic beams ceilings).

There are also semi-attic structures, which are essentially ordinary hanging systems gable roof. The only thing is that their fastening with the Mauerlat is usually made sliding (movable), which allows you to increase the deflection of the CH, and thereby reduce the thrust load on the walls.

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

Lastly about fastenings

Finally, I propose to consider how connections are made between the main components such as:

• Rafter/mauerlat;
• Ridge knot.

Other details special attention do not deserve it, since their joining most often occurs by cutting down the mating area (to increase the contact area of ​​the parts) and laying on steel plastic/corners, which are fixed with screws. Sometimes fasteners are not even used, i.e. the parts are attached to each other with screws without any overlays.

Connection of rafters and mauerlat

The attachment point for the leg and the power plate can be made in several ways:

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

• Tooth and thorn. This method is usually used to attach the CH to the tie. Its principle is based on the fact that a tenon is selected at the end of the sawed-down CH, and a groove is selected at the tightening. In addition, the leg itself rests on the so-called tooth, i.e. a protrusion in the tightening that takes on the spacer load.

It must be said that in Lately tooth-and-spike type fastenings are rarely used, since it is much easier to use special fasteners, the same corners and plates;

• By washing it down. In this case, the SN is sawed down 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 transmitting the spacer load. It must be said that instead of sawing, you can fasten a block, as shown in the diagram below.

Connection of rafters and ridge girder

The connection between the CH and the purlin can be made as follows:

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

• I started drinking. This is the simplest and most common method, the principle of which is based on sawing down the CH for maximum fit to the beam. In this case, fixation is carried out with a steel angle.

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

Conclusion

We have found out what parts rafter systems consist of, what types they come in and how their main elements are connected. If I missed any points or something is unclear to you, write comments, and I will be happy to answer your questions.

December 12, 2017

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The roofing system is a part of the roof structure with outside, which is supported by a supporting structure. It includes sheathing and rafter system. The triangle underlying this system must be rigid and the most economical structural element, which contains fastening points for roof rafters.

The main characteristics of the rafter system components

The main fastening points of the roof truss system are shown in Fig. 1. They imply the presence of a rafter leg (mauerlat - 1), a rafter leg (ridge girder - 2), a stand (tightening - 3). The design of the rafter system is the main load-bearing element of the roof.

All roof fastening units must have sufficient strength, this should eliminate a significant degree of risk associated with roof collapse. The consequences of a mistake made when connecting elements can be the most unpredictable.

Figure 1. Main fastening units of the roof truss system: 1 – Mauerlat, 2 – ridge girder, 3 – tie-downs.

First, the rafters are installed on the Mauerlat if the building has brick walls. Similar units are provided for concrete blocks; then it is necessary to create a reinforced concrete stiffening belt, and studs must be inserted into its structure. Their location should be at a distance of 1 to 1.5 m from each other, and their diameter should be more than 14 mm. The top of the studs must be equipped with a special thread.

The Mauerlat is drilled, making holes that are necessary for fastening the elements on it. Each hole must have a size that matches the diameter of the stud, and its pitch must correspond to the distance between the studs. A nut is put on each protruding end of the stud and tightened, which ensures the strength of the connection between the Mauerlat and the wall. The rafters should be connected to the Mauerlat in such a way that they do not weaken bearing capacity.

Description of the main fasteners for installing the rafter system

If during the construction of a house a rounded log or beam was used, then it is not necessary to create an armored belt. produced at top beam or on a log wall. For this purpose, connections between the Mauerlat and the rafters are used different ways cut (inset).

What fasteners are used to secure metal rafters:

1. Plates.
2. LK fasteners.
3. Corners.
4. Brackets WB.
5. Self-tapping screws.
6. Varieties of the corner of the Kyrgyz Republic.
7. Wire ties.
8. Perforated mounting tape TM.
9. Bolts and nuts.
10. Brackets WB.

If brackets are used to connect the rafters to the mauerlat, then they are not inserted into the rafters, which helps strengthen the load-bearing capacity. Usually metal brackets are produced, and the metal is galvanized and has a thickness of 0.2 cm. The brackets are reinforced with nails, anchor bolts or screws.

You can use the LK fastener to create fastening points not only for rafters with a Mauerlat, but also for other various elements, components of the roof structure. The LK fastening element is fixed to the wood, like brackets, with the exception of the use anchor types bolts

Mounting perforated tape allows you to strengthen the connecting nodes during the construction of roofing systems. It is used not only to create stronger units, but also to strengthen elements for additional use in order to impart rigidity or strength to the system as a whole. The perforated mounting tape is secured with screws or nails, so it is used to strengthen the structure of the rafter system of any roof, the integrity of which will not be compromised.

Using KR corners and their various modifications, the fastening points are strengthened so that they can effectively participate in connecting the mauerlat and rafters. Providing adequate strength to roofing units is permissible when using corners, which allows increasing the load-bearing characteristics of the roofing structure.

The use of metal connecting elements does not involve inserting corners into the roofing system. This will not cause a decrease in the load-bearing capacity of the roofing system. You can use corners for connections using screws or nails, the protrusions of which resemble a ruff.

How are the nodes connected in the ridge part?

There are three main types of fastening in the ridge parts of a roofing system:

1. Butt connection.
2. Fastening based on a ridge girder.
3. Overlapping ridge joint.

For the purpose of fastening, the first method is to cut off the ridge part from the upper edge at an angle that is the same as the angle of the roof slope. Then it is rested against the required rafter, which should also be cut at an angle, but on the opposite side of the roof. A special template is sometimes used to trim corners.

The nails for connecting the rafters under the ridge must be 150 mm or larger in size; you will need two of them. Each nail is driven into the rafters at the top at the appropriate angle. The sharp end of the nailed nail usually enters the cut of the rafter on opposite sides. Strengthening the ridge joint can be achieved by placing a metal plate on the side or a wooden overlay on it so that it is enough to tighten it with bolts or nails.

The connection in the second way, that is, through a ridge girder, involves strengthening the rafters on the ridge beam. The purlin is one of the additional support beams or beams, which supports the rafters. It is located parallel to the ridge or mauerlat. The method differs from the previous one in that a ridge beam is laid between the rafters, which are cut at an angle, which is a labor-intensive process, therefore this method used less frequently.

The more common method is similar to the first, but it differs in that the fastening is done overlapping, and the joint method is not used. The rafters should be in contact with their ends, and not with their side surfaces. The rafters should be tightened with a bolt or pin or nails. This connection is used by many masters in practice.

In general, it is possible to install rafters on a Mauerlat by creating structures for roofing rafter systems that are either spacer or non-spacer. This determines the choice of the appropriate method of connecting the Mauerlat and rafters, which can be similarly strengthened to the ridge.

The main disadvantages when installing rafter system fastening units

The problem of choosing a method for attaching the rafter system to the structure of the building is very important when creating attachment points. Often, when creating nodes, the Mauerlat serves as a support for the rafters. The Mauerlat beam is fastened “tightly” using anchor bolts to the reinforced stiffening belt.

A possible drawback is the unanchored stiffening belt, which can lead to the overturning of the mauerlat beam and disruption of the stability of the roof rafter system. The roof becomes loose and the roof slides down. Due to incorrect placement of anchor bolts or incorrectly made holes, the fastening is no longer effective.

If the nuts are screwed with overtightening onto the bolts, then the fastening unit becomes fragile and is subject to rapid destruction. To create a fastening point, twisted wire is sometimes used.

When constructing a rafter system, the safety of connections must be observed.

For example, if the truss structure is combined with the floor without taking into account the load-bearing capacity of the attic floor, then this is the most dangerous moment that can lead to the destruction of the building.

If the tie is replaced with a precast reinforced concrete floor beam intended for bending, then the use of precast reinforced concrete beams should be effective due to their rigid fixation in reinforced belt rigidity of the floor, which is constructed using reinforcement cage. Its axis must go in the same direction as the acting forces.

At the same time, the presence of shortcomings in the process of creating a rafter system, which is the load-bearing wooden structure of the floor, often arises due to a misunderstanding of the functions performed by the tie and crossbar throughout roofing system. The tie differs from the crossbar in that it is a longitudinal beam, and the crossbar is a transverse beam.

The construction of a rafter system involves the creation of a spacer system that works on the principle of divergence at the bottom of the planes, which occurs under the influence not only of their own weight, but also of the load that falls on the line of intersection of the planes, which should be prevented by a transverse beam, that is, a tightening.

When starting to install a roof, you should clarify all the points associated with making certain mistakes that arise when performing work on installing a rafter system. The construction of the roof of a house is associated with possible difficulties and shortcomings that do not allow achieving the set goal.

All kinds of wooden buildings, both residential and utility, remain in demand, even despite the wide range of modern building materials. During their construction, competent roof construction plays an important role, since only in this case the buildings will be truly warm and durable.

Wood has always been used as a building material. Wherever forests predominated, it was the most reliable and available material for local residents. They not only built houses from wood, but also covered them with roofing. Wooden roofing copes well with the functions of moisture and heat protection, not to mention exclusive appearance. Wood roofing still occupies a leading place among roofing materials today.

Types of wooden roofing

For the installation of such a roof they use various materials made of wood:

• Shingles look like thin planks made from alder, spruce and aspen. It is laid in layers, maintaining a checkerboard pattern. There can be four or six layers. Shingles are an excellent heat insulator and do not allow noise to pass through. Condensation does not accumulate under such a roof, so additional ventilation is unnecessary.
• Shindel are split planks with irregular shape. As it is also called, wooden shingles are laid with an overlap in a checkerboard pattern. To make the material, hard wood is used, for example, larch or Canadian red cedar.
• The ploughshare, spade-shaped planks, is well known to us from images of royal chambers or boyars' mansions. Even today, domed and hipped roofs are usually covered with this material.
• Shingles are planks that are cut with a saw. This is a fairly versatile material and is suitable for roofs of various configurations and areas.
• Tes, as the name suggests, are boards that are hewn directly from a tree trunk. Therefore, the structure of the wood is clearly visible on them. The main raw materials for them are conifers.

Advantages and disadvantages

Among the advantages of this coating, we first note its environmental friendliness wooden roof.

• its device does not require the use of high-tech equipment and complex tools;
• the coating is completely sealed;
• there is no need to lay a vapor barrier layer;
• under such a roof it is warm in cold weather and cool in hot weather;
• light weight;
• excellent sound absorption:
• exceptionally long service life - about one hundred years.

Of course, there is of this type coatings and imperfections, e.g.

• high price level;
• complexity of installation;
• low fire safety.

However, they do not in any way affect the desire of homeowners to have a really beautiful and environmentally friendly home.

Installation Features

A wooden roof is the result of several manufacturing operations. To perform them, you need tools for woodworking, as well as special devices. Its durability and stability are largely due to competent organization installation work: whether it’s convenient equipment or the quality of connections between wooden roof structures.

During the installation process, various methods of connecting parts are used, for example, simple nails, spikes, or others.

Let's consider the structure of the main components of a wooden roof : locks, notches, tenons.

Carpenter's Castle. The joints of wooden parts acquire strength, thereby increasing the rigidity of the structure. There are two types of locks

• onlay. They are the simplest to implement. In everyday life, you can more often hear another name - half-tree, since the sampling on a workpiece in the form of a rectangle is carried out to half its thickness. Overlay parts can be connected at an angle of 90˚, T-shaped or crosswise. After joining the workpieces, they are fastened either with nails or dowels, or with glue. The fastening option depends on the expected loads at the junction;
• into the frying pan. This is a more difficult option to execute, but, on the other hand, these locks are resistant to high operating loads. To connect parts of the same thickness, use a simple frying pan. On one of the blanks a trapezoid is cut out from the end, on the other - a nest, similar in both shape and size. If a simple frying pan is supplemented with cutting, then it will also be possible to connect parts with different thicknesses. In this case, the depth of the nest should correspond to the thickness of the first workpiece.

Tenon connection- the most aesthetically pleasing, but their execution requires high qualifications. It consists of two elements - a spike and a socket or eye, located on two parts. The tenon is a protrusion that is located at the end of the first and fits into the eye on the second. The tenons and sockets must be adjusted so that the wood fibers do not collapse when they fit tightly into each other. If the fit is too tight, the wood in the spaces between the joining elements may peel off, but if it is loose, the result will be a weak joint.

Rafter notches used in the construction of rafter legs. The method of making cuts of this type has some peculiarities, since the rafter and floor beams are located at an angle. When constructing roofs, stops and so-called frontal notches are more often used, since they are very reliable and at the same time they are not difficult to perform.

This is a type of connection where forces from one part are transferred to another part without intermediary working connections. If we are talking about installation loads, then to transfer them it is necessary to install auxiliary metal fasteners: bolts, brackets, pins or others.

On a note

When constructing a wooden roof log houses, nodes roofing performed using the same fasteners.

Installation technology

• Board roofing. It is laid in two ways:

1. transverse, which involves laying boards parallel to the ridge;

2. longitudinal, the boards in this option are laid parallel to the gable eaves of the slope.

Laying is done:

• in one row. Each subsequent board overlaps the previous one by 50 mm;
• two rows. The middles of the boards of the next row should be aligned in this case with the joints of the boards in the previous one. For residential buildings, it is recommended to use double-row installation.

In the upper part of the plank covering it is necessary to provide a special groove designed to drain water.

• Shingle roof. Installation of shingle coverings (shingles, shingles, ploughshares) is more complicated and more labor-intensive. Typically, roofing elements are fastened using nails, preferably copper.

On a note

For some types of wooden coverings, the tenon and groove fastening principle is used.

A shingle roof is assembled onto a solid or sparse sheathing made of timber with a cross-section of at least 50 mm. The pitch of the sheathing should be equal to one third of the length of the shingles. For outbuildings, two-layer masonry is used, for residential buildings Three-layer is more suitable.

Important points about the device

• Wood coverings, as a rule, placed on pitched roofs with an inclination angle of at least 25˚.
• On outbuildings it can be flat. Such a roof requires the presence of a waterproofing layer, say, made of roofing felt. The waterproofing material is laid on a flat base made of sheet material. In extreme cases, it can be laid out from boards, maintaining a gap between them of no more than 10 mm.
• By traditional technology Wood covering devices, waterproofing is optional. Nevertheless, today many craftsmen still recommend laying membrane films under the coating.
• The membrane is spread over the rafters, then a counter-lattice made of timber is placed on top of the waterproofing layer on the rafters. Then the sheathing under the main flooring is assembled along it.
• On steep slopes, it is enough to apply waterproofing only in problematic areas of wooden roofs, for example, on valleys, along eaves, in places where pipes pass, etc.
• Installation of shingles begins from the middle of the eaves. The elements of the initial row are laid as tightly as possible, and they should protrude beyond the cornice.
• Each subsequent row is laid with such an overlap as to cover the joints of the previous two.
• Roof ridges are decorated with special ridge elements. They are laid overlapping and fixed along the lower edge with nails.

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