What are the components of the rafter system? Knots of the rafter system: how to fasten correctly Attaching the struts to the rafters

For a durable and reliable roof, it is important to make all components with high quality rafter system. We'll figure out what this means right now.

Rafters are the skeleton of the roof, which supports the internal and external cladding, insulation, waterproofing and other elements. They are also very often used as the basis for communications. The roof and, accordingly, the rafters are subject to enormous loads, which can reach 200 kg/m2. This is the weight building materials, snow with leaves and other debris. What are the gusts of wind worth?

Roof rafters as a basis for communications

When conducting repair work this system must withstand not only the weight of a person, but also necessary equipment. Moreover, all these parameters are strictly individual and depend on a number of factors, ranging from configuration to 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 foundation of the entire system can rightly be called the Mauerlat. It is a beam on which the structure is attached. His main function– uniform distribution of loads on the walls. But the beam on which the sheathing is fixed is called the rafter leg. This essential element, which determines the angle of inclination of the slope and the general appearance of the roof. The rafter legs are held together by the purlin. It is located both on top and on the side. Depending on this, there are ridge and side runs. The lower part of the legs is secured with a tightening.

Mauerlat for fastening the truss structure

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

This concept combines a number of structural elements, since they consist of sheathing, 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 a segmented or trapezoidal shape would be most suitable. 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 material is wood. In this case, the installation of beams occurs by cutting and subsequent fixation with nails, screws and other fasteners. However, the use of wood is not relevant in all cases. So, if the span length exceeds 16 m, then trusses with stretched metal stands, since it will be difficult to ensure reliable fastening of wooden elements in this case. The combined type is also popular, in which both wood and metal parts.

A ridge is a horizontal edge at the junction of two slopes. There is a suspended and hanging type rafter system. In the first case, the ridge is installed on racks located parallel to long walls. It is very important to ensure maximum contact between the rafters and the ridge; for this purpose, appropriate cuts are made. Fixation is done with nails.

Skate at the junction of two slopes

If we're talking about about a hanging structure, the ends of the rafter legs are connected in pairs. To ensure such a connection, 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 driven at an angle. It is imperative to cover the joint with a metal plate or wooden overlay.

Pair connection of rafter legs

When connecting by cutting into half a tree, maximum strength is achieved. To do this, at the junction, the rafter legs are connected to the ledge. Then a hole is drilled for a 14 mm bolt. Further fixation is achieved through bolted connections. 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 rafter systems, which we need to look at 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 gash is made on the leg. Next, the connection is additionally fixed with nails, wire, screws and other auxiliary elements. Usually several nails are driven in at an angle so that they intersect inside the Mauerlat. And then another nail is driven in vertically.

Washed down on the legs for attachment to the Mauerlat

Sliding fastenings are obtained thanks to special fasteners. There are one, two or three degrees of freedom of this coupling. This connection is perfect for wooden houses, since rigid fixation may be severely damaged during shrinkage. Such a mobile connection can be achieved in several ways. The leg rests against the Mauerlat with a hemmed block or sawn tooth and is rigidly fixed using a metal corner. In this way, rigidity of the fastening in the horizontal plane is achieved. In the upper part, the legs are connected by notches, while a bevel is made on the horizontal platform to ensure a sliding connection.

Sliding element fastenings

If you drive only one nail at the place of fixation to the Mauerlat or use special flexible plates, then the connection will be sliding in this part of the rafter system.

Now let's look at the typical components of a wooden rafter system. A special feature of this 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, and are not afraid of strong winds and precipitation, economical. However, they are more complex technologically.

Typical hip roof components

This roof consists of two long trapezoidal slopes, although they do not cover the entire area; triangular hips are installed at the ends of the building at an angle. In this case, typical elements appear - additional slanted rafter legs, from which the 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.

Roof made of 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 girder. It is very important that the console outlet be at least 100 mm, but not more than 150 mm. Bottom part diagonal rafters are fixed to the Mauerlat or a special beam on the wall of the house. Sometimes they are used to make rafter legs. wooden beam, in this case, the mowing elements are fixed to a special board (beater) fixed to the farm. But the installation to the outer hanging truss is done using a truss. In this case, cuts must be made on the leg beams at an angle corresponding to the inclination of the hip slope.

Rafters and sheathing are the roof frame, which bears the entire weight of the roofing pie, thermal insulation, and snow load, so they must have high load-bearing capacity and strength. The idea of using metal rafters to make the roof structure more rigid is not new, but previously it was used mainly for covering industrial or utility structures. Nowadays, rafter frames and metal profile sheathing are considered a real alternative to wooden roof elements if the length of the slope exceeds 10 meters.

Design rafter frame The roof consists of many interconnected elements that form trusses. The pitch, the cross-sectional size between the rafters and other supports is determined by the calculation of the loads to which they are subjected during operation. The roof frame performs the following functions:

Load distribution. Interconnected nodes, reinforced with corners, evenly distribute the weight of the roof, which can reach up to 500-600 kg, taking into account the snow load. The larger the cross-section of the rafters and the smaller the pitch between them, the greater the load-bearing capacity of the structure.
Giving slope and shape. The rafters, located at an angle to the base of the roof, form an inclined plane of the slopes, so that snow and water do not accumulate on the roof surface.
Forming a base for fixing the roofing material. The finishing coating of the roofing pie is attached to the roof frame. The sheathing acts as a basis for fixing the covering, distributing its weight evenly across the rafters.

Note! What all components, rafters and sheathing of the roof structure should be like is determined by engineering calculations. To determine the required load-bearing capacity of the frame, it is necessary to calculate the total load to which it will be subjected. To do this, add the weight of the roofing material, insulation, waterproofing, maximum snow load with the weight of the rafter system.

Types of rafter systems

The most common material from which the sheathing and rafters of the roof frame are made is wood. However, if the weight of the roofing material is large enough and the length of the slope is more than 6 meters, then the structure turns out to be too massive. Builders have to reduce the pitch between the rafter legs and increase their cross-section, which is why the roof assemblies acquire a lot of weight, increasing the load on the foundation. Unload load-bearing walls and the foundation of the building can be done using stronger but lighter metal rafters. Based on the type of material used, the following types of rafter systems are distinguished:

Wooden. Rafters and lathing made of wood are used for the construction of roofs, the length of the slope of which does not exceed 7-10 meters. The frame elements are fastened to each other using self-tapping screws, nails or movable metal elements. The step between the legs is usually within 50-80 cm.
Metal. Metal roofing frames are made from steel metal profiles with a zinc coating, which is not afraid of moisture. Rafters and sheathing made of this material are light and durable, so the step between them can be increased to 1.5-2 meters. The metal profile is fastened using welding or fasteners. Metal roof components are used for slope lengths of 10 meters or more.
Combined. Rafter frame combining metal and wooden knots, called combined. The combination of support elements made of wood and galvanized steel allows you to make more cheap design, having a high load-bearing capacity, increasing the pitch between the rafters.

Please note that metal and wooden elements frames cannot be connected to each other without a lining of waterproofing material or treatment with an antiseptic drug. Since metal has high thermal conductivity, its proximity to wood leads to the formation of condensation and rotting of the rafters.

Fastening methods

Metal rafters are assembled into triangular, trapezoidal or arched shape. Internal stiffeners are attached to the frame beams, which form corners that significantly increase the load-bearing capacity of the frame. This system allows you to make the pitch between the rafters larger, taking into account the support capabilities of each truss. Fastening the metal elements of the roof frame is performed using one of the following methods:

Fastening by welding. If you weld the parts of the rafter system using welding machine, you can get a rigid structure with high strength and load-bearing capacity. If you correctly calculate the roof, you can lighten the frame and reduce the load on the foundation of the structure. The disadvantage of this method is that only a professional can perform welding using special equipment.
Fastening with bolts. Fixing the rafters with fasteners allows for a less rigid fastening. This method of assembling a rafter frame based on a metal profile is used in private housing construction, where the length of the slopes does not exceed 10 meters. Eliminating welding allows for faster roof installation.

Experienced craftsmen rely on the fact that rafters can withstand more weight than wooden ones, so you can increase the step between them and reduce the thickness of the cross-section of the elements. Moreover, construction stores sell ready-made trusses, fastened by welding, suitable for covering buildings of standard width.

Advantages

Metal rafter frames are used for the construction of roofs of any shape, any slope with a slope of 1-2 degrees. The material from which the rafters and sheathing are made are steel angles, round and round pipes. rectangular section, brands. In order to correctly select the thickness of the frame elements and choose the pitch between them, a calculation of the roof structure is performed, taking into account the permanent and temporary loads that are transferred to the rafter beams during operation. The advantages of a rafter system made from this material are:

Fire safety. Unlike wooden ones, metal frame beams are not flammable, which increases the fire safety of the building.
Easy to maintain. The zinc galvanic coating used to cover the steel corners protects the roof frame from corrosion throughout its entire service life. They, unlike wooden ones, do not require annual treatment with an antiseptic.
Zero waste. Although metal constructions are quite expensive, it is considered cost-effective, since fastening is carried out by welding, and there is practically no waste left.
Long service life. If you correctly calculate the loads, then a metal roofing frame will last more than 100 years, which exceeds the service life of even the most stable roofing coverings.

Professional roofers believe that it is advisable to use welded metal structures for the manufacture of roof rafter frames with a slope length of 10-12 meters. In this case, the main task is to correctly calculate the loads, and then determine the step between the legs in accordance with the climatic characteristics and properties of the roofing material.

Flaws

Despite obvious advantages, metal rafter systems are not the most popular constructive solution in private housing construction. Even a large step between the rafters and sparse lathing when high cost metal cannot make a structure cheaper than wood. The disadvantages of metal rafters are:

High thermal conductivity. Metal has a high thermal conductivity coefficient, so the rafters form cold bridges. From the point of view of energy efficiency, a frame made of metal profiles is not the best solution.
Problematic transportation and installation. When choosing a metal rafter system, take into account that transporting, lifting and fastening long and heavy elements is more difficult than standard-length lumber rafters.
Difficult to install. To lift the trusses to a height and fix them, special equipment is used, the rental or purchase of which is expensive.
Deformation under high temperature. Although metal is considered a non-combustible material, during a fire it is greatly deformed, which usually leads to the collapse of the roof.

To determine whether it makes sense to use more expensive rafter elements made of metal profiles, you need to calculate the roof frame. If the length of the slope exceeds 10 meters and the load is more than 450-600 kg, then installation metal frame economically feasible.

Video instruction

In order for a constructed building to last for more than one year, it needs both reliable foundation, as well as a strong roofing system 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

The rafter 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 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 rafter trusses are used: hanging rafters, layered rafters and a mixed rafter system.

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 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 mansard roof. 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 racks.

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

A gable roof is normal construction roofs 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, and also due to the fact that installation work carried out easily and simply.

Included in the rafter system gable roof includes two rectangular inclined planes. Top part The front side of the building resembles a triangle. Main components two pitched roof- this is 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, installation will be required different types 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 splices, 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 prevent the hip roof from deforming from heavy loads, 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 bottom rafter part is almost vertical, attic room The building receives additional space, thanks to which it can be used as a residential building. The installation of this type of roof is carried out during the construction of four- or gable construction rafters

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 protrusion that is located on 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 they produce necessary measurements.

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 during installation similar system rafters are 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 ledge on the attic floor, under which there is 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 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 done different ways, however, there are common characteristics in the technological methods of its construction. Initially, you need to prepare. When arranging a roof for a house made of foam concrete or other material, first install a mauerlat, then in the upper crowns of the building they make cuts 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.

Install individual parts of the rafter system. To completely eliminate the risk, the rafter boards are attached to the ground with screws. After the roof truss is created, it is raised to the top of the building.
All elements of the rafters are secured to the ceiling, internal boards, jibs, and crossbars. Further, this base for the roof will become a single whole structure.
The next stage is the sheathing, which is under soft roof installed with small or no gaps. 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 on the required leg section 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 different 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:

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
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.
A second template is made, thanks to which the cuts are installed on the rafters. It is made from plywood.
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.
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
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.
Raise and install the remaining rafters at the initially calculated distance, which should be at least 60 cm from each other.
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
A ridge beam is installed on special supports, 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 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. In each design they are made differently, since it depends on various nuances: the 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. To make rafters, paired material is used, and 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 a certain meaning. The crossbar is a horizontal beam that 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 fastening is made to prevent deformation of the roof during shrinkage of the house, then the rafters are secured on top with a hinge plate or a nut and bolt, and below - sliding support.

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

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 done in 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 their design characteristics will help create the basis for a reliable roof for your home.

The pitched roof of a house consists of a large number of parts, each of which is connected to the others in a special way. This connection is called a roof joint. In this article we will talk specifically about connection nodes, how they are carried out, what technologies are used, what fasteners are used.

Main parts of the roof structure

Before moving directly to the analysis of the topic of the article, it is necessary to indicate what elements (details) it consists of roof structure. Let's list all the main parts and indicate their purpose.

Mauerlat. This is a beam that is laid on the walls of the house located along the perimeter of the building. The purpose of the Mauerlat is to evenly distribute the loads coming from the rafter system. After all, if there is no Mauerlat, then each rafter will put pressure on the wall pointwise. And it is in this place that the destruction of the wall structure will occur.

Rafter legs. They are made either from boards with a thickness of at least 50 mm, or from timber. Rafters are the basis of the roof; they form the slopes and bear all the loads acting on the roof structure.

Ridge run. This is the topmost beam, installed horizontally. Its purpose is to support the upper ends of the rafter legs. It is this that forms the ridge of the roof.

These are the three main elements of the roof, which will be discussed further. Of course, these are not all the details of the roof, and we cannot say that others are less important. It’s just that these three elements form the structure itself. The only thing that needs to be added is that some roof designs do not have a ridge girder. The rafters simply rest against each other with their upper ends. This type of rafters is called hanging, and with a ridge girder, layered.

So that the roof structure is as reliable as possible, it is necessary that the roof components are correctly connected. In this case, it is necessary to take into account the strength effective loads and their direction.

How to connect elements of a roof structure

More recently connection of wooden roof nodes carried out using cuts. That is, they cut the elements of the roofing structure in order to connect them along one fairly wide plane. Therefore, so that the roof parts do not reduce their strength characteristics, as well as load-bearing capacity, they were selected with a sufficiently large cross-section. And this is not economical. That is, the larger the cross-section of lumber, the more expensive it is.

Today, technologies for fastening components and parts of roofing structures have changed dramatically. To do this, use bolts, dowels or perforated metal profiles. The latter are made of galvanized steel, which makes it possible to use fasteners for a long time without losing their quality. At the same time, manufacturers offer a fairly wide range of them for each type of unit. The photo below shows some of these fasteners.

It should be noted that perforated profiles gradually replaced all other types of fasteners due to their strength, reliability and ease of fastening operations. After all, to do this you just need to install the profile in the required place and attach it to various details wood screws or ruff nails.

Let's now look at how to fasten parts roof structure to each other. In principle, there are two types of connections: Mauerlat-rafters, rafters-ridge girder. The remaining parts are connected parallel to these joints. He will also talk about them.

Connection of Mauerlat and rafters

Mounting options actually great amount, starting with ordinary nails, ending with perforated profiles. For example, the photo below shows an option where ordinary wire is used as fasteners. That is, a through hole is made in the rafter itself, into which a wire with a diameter of 6 mm is inserted. A hole is also made in the Mauerlat or in the floor beam.

Then the ends of the wire are pushed into this hole and twisted, pressing the rafter leg to the Mauerlat. The connection is actually strong and reliable, but the process is labor intensive.

Instead of wire you can use metal tape 3 mm thick. It is simply wrapped around the two elements being connected and secured to them through the strip with self-tapping screws, often with nails. In the latter case, there is no need to drill through holes in the metal. note that in the lower photo the fastening is carried out to the reinforced belt with an anchor, which increases the strength and reliability of the connection.

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The next type of fastening is a perforated corner made of galvanized steel. The most convenient option, but the most reliable. To do this, the corner is simply installed so that with its mounting shelves it is pressed tightly against the plane of the Mauerlat and the rafter leg. Fastening is carried out with self-tapping screws or nails.

Attach corners It is possible not only with self-tapping screws or ruff nails. There is another more reliable option that uses bolts. True, holes will have to be made for them, which increases the time required for this type of work. But in this case, quality comes first. The photo below shows just such a mounting option. Please note that the corner is attached to the mauerlat with self-tapping screws, and to the rafter leg with a bolt. In this case, one bolt is used to connect two corners located at opposite ends of the rafters.

And another mounting option - on the slider. This is a special type of fastening element consisting of two parts. One is attached to the mauerlat, the second to the rafter leg. In this case, both parts are not tightly connected to each other. This was done specifically so that the rafters could move relative to the Mauerlat during thermal expansion of the lumber. This means that there will be no loads that act on the junction of two roof parts. The photo below shows this connection option.

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Connection of rafters with ridge girder

Second main node wooden roof – joint between rafter leg and ridge beam. In fact ridge knot rafter roof it is very complex because it is where two rafter legs and a beam are joined. In this case, all elements are located in different planes, meaning rafters and beams. This means that to connect them you will have to use more than one fastening element.

To connect rafters to each other they use perforated plate. There are two of them, installed on different sides of the rafter legs to increase strength and reliability.

Perforated corners connecting the rafters to the Mauerlat. There are four of them, two for each rafter leg, installed on different sides.

It should be noted that fastenings can be carried out not only with self-tapping screws or nails. Often masters use bolts for connection paired fasteners.

Pay attention to the different type of fastening. Only corners are used here. This option is used if a 50 mm thick board is installed as a ridge beam.

Another interesting option fastening the rafter legs to the ridge span, for which special perforated profiles complex shape . Essentially, these are brackets into which the rafter leg is inserted. The bracket not only holds the parts together, it supports the rafter, reducing the load on its end.

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Pay attention to all of the above options for connecting the rafters to each other. They clearly show that the ends of the rafter legs are joined tightly to each other, for which they have to be filed at a certain angle. You can do without filing if you use a complex fastening lock consisting of several plates that are connected with bolts. In the photo below this connection option is clearly visible.

Connection of hanging rafters

The rafter system of this type differs from the layered one in that it does not have ridge girder. That is, the rafter legs in the upper part (ridge) rest against each other. To prevent them from moving apart in different directions, the rafters are connected to each other by a horizontal tie. The latter is a board located at any distance in height: above, below or in the middle.

It should be noted that hanging rafters They are not assembled separately on the roof. Of these, farms are assembled on the ground, which in finished form installed on the roof of the house. In this case, all elements of the truss are connected to each other by perforated plates.

Video description

In the video, the master explains how to assemble a roof truss using perforated plates and nails:

Other types of knots

As mentioned above, there are many details in a roof structure. Therefore, we will tell and show a few more important connection points.

If the span of the house is more than 6 m, then a stand is installed under each rafter, which itself should rest against either concrete base, or into the floor beam. In this case, the connection of the rack with the rafter leg is carried out using ordinary boards, as shown in the photo below. Although you can use perforated metal plates.

They are also installed under the ridge beam vertical support posts, which are fastened together with perforated plates. But some roofing structures use a completely different approach to solving the installation of a ridge girder. Under the beam, jibs made of bars are mounted, which are secured to the ridge with special fasteners made of metal. The photo below shows one of the options for this type of fastener.

Very often, when constructing a rafter system, it becomes necessary to lengthen the rafters themselves. This is not difficult to do, and craftsmen use several technologies where they use various additional fasteners.

Video description

The video shows one of the options for lengthening the rafters:

Roofing structures come in several varieties of their forms. Almost all models contain a large number of identical elements. But among them there is one design that differs significantly from the others. This hip roof. Its distinctive feature is that the rafters are connected by their upper edges to one point, which is called a ridge knot.

So, in order to connect the rafter legs to each other, you need a support to which they are attached. There are several ways to ensure high node reliability. The photo below shows one of them, which uses U-shaped perforated metal mounting profiles.

Conclusion on the topic

In fact, we have considered only a small part of the connecting nodes for fastening the roof truss system. But even with their example, the variety of parts and components becomes clear. That is, the roof structure is a complex system, consisting of a large number of different elements and parts that are connected to each other in different ways.

In order for a constructed building to last for many years, it needs both a reliable foundation and a strong roofing system 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

The rafter 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;
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 rafter trusses are used: hanging rafters, layered rafters and a mixed rafter system.

Characteristics of hanging rafters

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

If the roof of the house has a complex structure, the 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.

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

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 layered or hanging structure. Hip main rafters are layered parts. For splices, 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 prevent the hip roof from deforming from heavy loads, 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, the attic space of the building receives additional space, thanks to which it can be used as a living space. The installation of this type of roof is carried out during the construction of a four- or gable rafter structure.

Professionals need to calculate a hipped rafter system, 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 of the sloping roof are secured to the mauerlat with the shortened legs of the rafters.

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.

After the installation of the roof truss is completed, sheathing is laid, 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

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.

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 common characteristics in the technological methods of its construction. Initially, you need to prepare. When arranging a roof for a house made of foam concrete or other material, first install a mauerlat, then in the upper crowns of the building they make cuts 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.

Install individual parts of the rafter system. To completely eliminate the risk, the rafter boards are attached to the ground with screws. After the roof truss is created, it is raised to the top of the building.
All elements of the rafters are secured to the ceiling, internal boards, jibs, and crossbars. Further, this base for the roof will become a single whole structure.
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 using the bricklaying method. 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

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:

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
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.
A second template is made, thanks to which the cuts are installed on the rafters. It is made from plywood.
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.
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
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.
Raise and install the remaining rafters at the initially calculated distance, which should be at least 60 cm from each other.
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
A ridge beam is installed on special supports, 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 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 the high quality of the rafter assemblies. 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.

Rafters made from a profile pipe are 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. To make rafters, paired material is used, and gussets are connecting elements. The structure of the rafters from profile pipes is assembled on the ground, using riveting or welding.

Crossbar in 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 different types of fastenings are used in parallel.

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 you can use:

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 their design characteristics will help create the basis for a reliable roof for your home.