The nodes of the truss system or what the wooden frame of pitched roofs consists of. Fasteners for the truss system Knots of metal roof trusses

In order for the roof to have high strength and reliability, special attention will be required to be paid to the truss system. In addition to correctly made calculations and drawings, fasteners for rafters and all its elements are of no small importance in the stability of the structure.

Design truss system.

In addition to the load of atmospheric precipitation, the rafters must withstand the weight of the crate and the total weight roofing cake which must be taken into account when choosing a mount.

The truss system is a spatial structure consisting of the following elements:

In order to understand how all parts of the truss system are attached to each other, you need to figure out what nodes it consists of, what fasteners are used in each case and what they are. When assembling the supporting structure of the roof, fasteners, both steel and wooden, are used.

The main nodes of the connection of the truss system

The scheme of fastening the Mauerlat to the wall.

Before connecting the Mauerlat and the rafter leg to each other, the first one will need to be firmly connected to the wall. Mauerlat is a thick beam (15x15), laid along the axis of the wall and parallel to the ridge of the beam, on which they rely rafter legs. The functions assigned to this element of the supporting structure are to distribute the load from the rafters, the weight of the roofing pie and atmospheric precipitation throughout the wall, including internal supports. In other words, the Mauerlat is the foundation for the entire roof. It is laid on the axis of the wall and fixed to it. In this case, there are several connection methods.

Method one. When constructing a roof of a large area along the entire length of the wall, an armored belt is poured, where metal pins are immediately embedded under the M12 thread every 2 m. In this method, there will be studs that pass through the beam through the wall and are attracted to the wall with a nut and pucks. At small area roofs, where there is no heavy load on the wall, do without a Mauerlat and the rafters are attached directly to the studs embedded in the masonry process.

Method two. Another quite affordable way to make the truss system stable is to attach the Mauerlat to the wall with a wire. To do this, you need to lay the middle of the wire between the rows of bricks 3 rows before the end of the masonry. Its length should be sufficient to tie and pull the Mauerlat to the wall. You can also do without the Mauerlat and fix the rafter with wire directly to the wall. But such a connection will give a point load on the wall, which may affect its integrity.

The scheme for attaching the rafter leg to the Mauerlat can be rigid and sliding. The type of connection depends on the shape of the roof and the type of rafters, which can be hanging or layered.

Rigid and sliding connection of the lower part of the rafters with Mauerlat

The main nodes of roof trusses.

Connection nodes in this case will be made of wood and can have several types:

A tooth that has only an emphasis.
A tooth with a spike and an emphasis.
Emphasis directly on the beam.

A single tooth notch is used for a roof with a large angle of inclination, where the angle between the mauerlat and the rafter leg is more than 35º. To do this, you will need to cut a tooth with a spike in the rafter leg, and create a nest under it in the Mauerlat. The use of a spike avoids lateral displacement of the rafters. The double tooth notch is used when installing more gently sloping roofs. The latter method is used extremely rarely.

AT recent times more often wooden mount for rafters is replaced by metal, because it allows not only to get more robust design truss system, but also significantly reduce the work on its installation. Therefore, metal rafter bolts, brackets, plates, clamps, hinges and various corners are used as additional fasteners.

Sliding connection example..

The most used method of rigid connection is driving nails from the sides at an angle into the mauerlat. Thus, internal crossing takes place within it. Further, for the final fixation of the connection, the third nail is driven vertically. Another way to prevent transverse displacement of the rafter leg is to fix it on the sides with metal corners.

The scheme for movable fastening of the rafters in the lower part is used for houses built from logs or timber. Since during operation the truss system is in motion due to a change in its physical properties, i.e., the building shrinks.

The rigid fastening scheme in this case is unacceptable, since such movements can lead to the destruction of the wall. This means that the attachment points need to provide mobility. In such cases, special swivel joints are used, which are called skids or corners with an oblong hole for fasteners. The sliding interface in this fastener achieves two levels of freedom through the free movement of one of the fastener elements.

Nodal ridge connection

The ridge connection of the truss system can be obtained in three ways: butt, overlap and on the ridge beam.

Scheme of the ridge connection of the truss system.

Butt. The upper part of the rafter leg must be cut at an angle equal to the slope of the roof. The opposite leg is also adjusted to the appropriate angle, but with an inclination to the other side. Further, they are interconnected at the top point with the help of a nail, which must be driven into the end of the rafters with the capture of the opposite end. In addition to nails, special plates are used for a more durable connection of joints. Such a fastener can act as wooden plank 30 mm, and a metal fixing double-sided pad. For its installation, bolts or nails are used.

The next two methods will be similar to the first, but have a slight difference. When fastening with an overlap, the upper parts of the rafter leg will be interconnected by their sides. The latter option is carried out by connecting each rafter directly to the ridge beam. In this case, threaded studs with washers and bolts are used as fasteners.

If trusses are used to stiffen the rafter system, then to ensure good resistance to wind loads, it will be necessary to install the required number of diagonal ligaments. The presence of a brace and a brace (rafter leg) in the supporting structure helps the gables of the house to be more stable. The brace is installed by resting the upper part against the corner of the pediment, and with the lower part it rests against the main floor beam. The strut helps to reduce the load on the rafters in the center. Its installation is carried out at an angle of 45º. Diagonal connections are fixed using clamps, corners, plates.

Types and features of metal fasteners for rafters

If earlier masters used as such fasteners wooden elements(bars, overlays, dowels, metal staples, wooden pins, wedges), now such methods are inferior to more modern types. The construction market is big the lineup metal fasteners, which are now much stronger and allow the installation process of the truss system to be made much easier. The manufacturing technology of these elements uses metal, the thickness of which varies from 1.5 ... 3.0 mm, which allows the product to be more resistant to loads compared to any other material. In addition, rafter fasteners are available in any size and allow you to carry out the technological process with great accuracy.

Types of fasteners for rafters.

The metal fasteners of the rafters, which can be perforated and nailed, include:

perforated mounting tape;
corners;
plates;
beam support;
beam support;
wire tie;
self-tapping screws;
bolts with nuts;
corners of the KR;
brackets WB;
fasteners LK.

The use of perforated products allows you to firmly fix the rafters with all parts of the system and provide good rigidity and strength at any angle. They are characterized by the presence of many holes for bolts, screws and self-tapping screws, with the help of which the attachment to the tree is carried out. The size of the product is adjusted by trimming to the desired length and width.

Also fasteners can be nailed. However, the use of this type is possible only in the factory by cutting, which bends the cone-shaped part. This operation is carried out by special machines under pressure.

KR corners have a large number of modified types, which reduce the risk of bolted joint breakage during natural settlement of the structure. Fastening is carried out without the use of special equipment using screws and nails.

Brackets WB are used for fastening the console of the supporting beam when installing wooden floors in houses made of logs or timber. At the same time, the tie-in on the rafter leg is not made, which does not weaken its bearing capacity. The connection is carried out using anchor bolts, nails or screws.

LK rafter fasteners are applicable in under rafter systems where rafters and beams need to be connected. It has the same advantages as WB fasteners, but the process is carried out only with screws or nails. Used in construction wooden houses.

Fasteners in the rafter system play a huge role. It depends on him the strength and duration of operation of the entire roofing pie. Therefore, the choice of type and method of attachment should be treated with great attention.

Fasteners for rafters: the strength and reliability of the roof

In order for the roof to have high strength, fasteners for rafters require special attention. The type of connection will depend on the shape of the roof and the type of rafter system.

Fastening rafters to the Mauerlat: connection methods

Rafters are the main load-bearing structural elements of the roof. Proper and reliable fastening of the rafters to the Mauerlat eliminates the risk of deformation and collapse of the roof under its own weight and external loads.

Basic fasteners

To install the rafter legs on the Mauerlat and firmly fix them, apply different kinds notch (tie-in) and metal truss fasteners:

wire ties;
corners;
plates;
brackets WB;
corner KR;
fasteners LK;
self-tapping screws;
nails;
perforated mounting summer TM;
bolts, studs complete with nuts and washers.

The connection of rafters and mauerlat can be done using brackets. In this case, no tie-in is made in the rafter, so this key structural element is not weakened. Brackets for mounting are made of 0.2 mm thick steel with anti-corrosion zinc coating. The brackets are attached to the wooden beam and rafters with self-tapping screws, nails or anchor bolts.

Fasteners LK allow you to attach the rafter to the Mauerlat, as well as connect other elements of the system. When installing this fastener, anchor bolts are not used.

The use of perforated mounting tape allows you to strengthen the connection node. The perforated tape makes the connection of the rafters with the Mauerlat more durable, does not weaken the supporting structures, as it does not violate their integrity. For its installation, screws or nails are required.

Corner KR and its modifications - widely demanded fastener rafter system. It is used if necessary to securely install the rafter legs on the Mauerlat. The corner adds strength to the connection nodes, increases bearing characteristics design, eliminates the displacement of rafters under high operational loads. The corner does not need to be cut into the wooden elements of the truss system, it is mounted with self-tapping screws or sharp nails (equipped with special protrusions).

Metal fasteners for the truss system must be made of high-quality material with reliable anti-corrosion protection - this guarantees its strength and durability.

In what cases is a Mauerlat required?

Mauerlat is often called the foundation of the roof. This design, made of logs or timber, allows not only to securely fasten the rafters, but also to ensure uniform load transfer to the walls and foundation of the structure.

During the construction of houses from timber or logs, the role of support for rafters is played by top harness walls, installation of additional structures is not required.

For structures whose walls are made of piece materials (brick, foam concrete or aerated concrete blocks, etc.), the installation of a Mauerlat is necessary. This is due to the fact that walls of this type do not cope well with point, undistributed loads. In addition, foam blocks are not strong enough to securely fix the truss system - fasteners under load can be torn out of the block. Thus, the installation of a Mauerlat is required.

To wooden beam, laid on the longitudinal walls of the building or along the entire perimeter (depending on the type of roof) was firmly attached to the base, it is recommended to pre-create a reinforced concrete belt at the top of the walls. In a monolithic beam with a height of 200 mm and a width coinciding with the width of the wall, fasteners for the support beam are embedded. These are anchor bolts or studs with a diameter of 14 mm or more, located strictly vertically. To eliminate the possibility of tearing them out of concrete under high load, the lower ends of the studs or bolts should be bent. Mortgage fasteners are located in increments of no more than 1.5 m.

The use of studs with a diameter of less than 14 mm can lead to deformation of the fastener under loads.

In the beam from which the Mauerlat is mounted, holes should be made corresponding to the location of the studs. The beam is put on the studs, washers are put on the free threaded end of the fasteners and nuts are screwed on. This technology allows you to securely fix the roof base on the wall.

Before installing the timber, it is required to lay a waterproofing layer to prevent damage to the wood under the influence of moisture.

Principles of attaching rafters to Mauerlat

Installation of rafters on a support beam may be required when creating expansion and non-expansion roof structures. The installation of layered or hanging rafters on the Mauerlat is carried out using a rigid or sliding connection. Depending on the design features, the methods of attaching the rafters to the Mauerlat are selected.

A rigid connection implies the complete exclusion of the displacement of elements relative to each other, the absence of such influences as shear, torsion, bending. The necessary rigidity of the connection is ensured if the rafters are attached to the Mauerlat with corners with a support bar, or a special “saddle” cutout is made in the rafter leg. The place of the cutout in the rafter is additionally fixed with self-tapping screws, nails, staples, bolts. In addition, it is necessary to perform a wire twist, which connects the rafter attachment to the Mauerlat and the anchor mounted in the wall.

During the construction of the roofs of wooden houses, a special fastener (“sled”) is used, which allows you to make a sliding connection. The attachment point of the rafters to the Mauerlat with a certain degree of freedom of the rafters makes it possible to avoid deformation of the roof during shrinkage of a house made of timber or logs.

Installation of rafters using a corner

When choosing how to attach the rafters to the Mauerlat, it is necessary to proceed from the design features of the roof. If it's not about wooden buildings, then the joint must be rigid.

If the installation of the rafters is carried out with a “saddle” cut, then the technology of work is as follows:

a cutout is made in the rafter leg so that the horizontal part of the rafter can be installed on a wooden beam, while the angle of inclination of the rafter leg must correspond to the angle of inclination of the slope;
the rafter is fixed with three nails, two of which are driven in on both sides of the rafter leg at an angle (crossing must occur inside the Mauerlat), and the third nail is driven in vertically from above;
additionally, the attachment point is fixed with brackets, wire rod.

Such fastening of the rafters to the Mauerlat provides the necessary rigidity and strength of the assembly.

A fairly common technology is the installation of rafters using a metal corner and a hemmed beam. The rafters are attached as follows:

the rafter leg is cut at the required angle to ensure the slope of the roof slope specified by the project;
along the edge of the Mauerlat, a hemmed beam is mounted, the length of which is about 1 meter, the rafter firmly rests against it along the pressure line - this design eliminates the shift of the rafter leg under thrust loads;
on the sides, the rafter should be attached to the Mauerlat using metal corners - fastening the rafters to the Mauerlat with these elements makes it possible to avoid transverse displacement of the rafter leg;
the finished attachment point is additionally reinforced with wire rod.

The fastening of the rafters to the Mauerlat should be carried out following the instructions, the details of the work technology can be found in the video.

The rafters are attached to the wooden support beam using special corners. The subspecies of the corner of the KR include:

models KR11 and 21 (improved KR1 and KR2) are equipped with oval holes for anchoring, which can significantly reduce the risk of breaking the fastener when the building settles or the structure is loaded;
model KP5 allows you to fasten structural elements with a high load-bearing capacity;
model KR 6 (reinforced angle) is made of 3 mm steel, has an oval hole for anchoring, and is used for mounting heavy structures.

Bearing and auxiliary elements wooden truss structures are also fastened using a KM mounting bracket made of perforated steel. Its advantages include the possibility of fastening with self-tapping screws and screws, the absence of the need to use special equipment for installation.

The KMRP reinforced elbow is used for 90° connections. Its use allows you to reliably install wooden rafters on the support bar. The angle can be adjusted.

Proper fixation of the rafter legs on the Mauerlat is a guarantee of durability and reliability of the roof structure. The scheme for attaching rafters to the Mauerlat may be different, but there are general installation rules:

it is important to ensure a snug fit of the planes of the wooden elements, which requires accurate and accurate cuts and cuts;
using bolted connections, it is necessary to install washers or metal plates in order to avoid sinking the nut into the wood - this can lead to the destruction of the fastener.

It is forbidden to use linings, as they deform over time, which leads to improper distribution of loads on the roof and entails deterioration in performance, destruction.

Fastening rafters to the Mauerlat: how to fasten, attachment point, methods

Learn how to attach rafters to the Mauerlat. Types and methods of connecting rafters, a diagram of Mauerlat fasteners and rafters along with a video.

How to choose the right fasteners for mounting the truss system

The frame of the truss system and the foundation of any roof is the Mauerlat. AT wooden houses its functions can be performed by the upper crown of the log house, and a powerful base made of timber is mounted on brick and concrete walls.

Mauerlat mount

1. In houses made of glued laminated timber or logs, Mauerlat is not required. If the height of the bearing walls is not enough, an additional mauerlat crown is laid. For its fastening, forged brackets and steel pins (thorns) are used.

2. Mounting the Mauerlat on brick walls possible in several ways:

- in the process of laying load-bearing walls to a depth of 3 or more upper rows of bricks, studs with a diameter of at least 14 mm are immured. The lower end of the stud should be bent at a right angle in the shape of the letter "L". The length of the free part of the hairpin should be 3-4 cm more than the thickness of the Mauerlat;

- on the final stage masonry bearing walls poured reinforced belt. “L”-shaped studs or anchor bolts with a diameter of at least 14 mm are embedded in it. The length of the open part of the fasteners should be 3-4 cm greater than the thickness of the Mauerlat.

The distance between the studs (anchor bolts) is selected as a multiple of the pitch of the rafters and is equal to 1.0. 1.5 m

Before installing the Mauerlat, a layer of waterproofing material must be laid on the stone walls.

Rafter fastening

1. Houses made of logs or timber shrink during operation, and their geometric parameters change. In such conditions, the roof must have some independence. With rigid fastening of the truss system, the roof wooden house warps, and roofing materials are destroyed. In the worst case, this can lead to the destruction of the frame of the house, so the joints of the rafters are made movable.

The rafters in the ridge can be attached in two ways:

– movable connection with M16 bolt;

- connection with a lamellar hinge. In this case, on each rafter with 4 M10 bolts. M12 are attached by two steel plates. The role of the hinge is performed by the M16 bolt.

The fastening of the rafters to the Mauerlat is carried out using the so-called “sled”. The bracket and bracket are fastened with nails, while the rafter has the ability to move slightly relative to the Mauerlat along its longitudinal axis.

2. If the house is made of brick or cinder block, apply rigid mount rafters. In this case, the ridge connection is performed in the following ways:

- fixed butt joint. In this case, the rafters are fastened with nails, and the entire assembly is reinforced with an additional steel or wooden lining - a crossbar. The crossbar is attached to the rafters with M10 bolts. M12 or nails, respectively;

- a fixed connection with a half-tree tie-in. In this case, the rafters are connected with an M16 bolt, and the knot is reinforced with a crossbar.

The rafters are fastened to the Mauerlat using reinforced steel corners. M10 bolts are used to fasten the corners. M12 and nails.

Clamps, wire ties and mounting perforated tape are used as additional fasteners for fixed assemblies.

All threaded connections are made using metal washers or plates.

When fastening structural parts with nails, the following rule must be observed: the length of the nail should be 2-3 times the thickness of the element being punched.

How to choose the right fasteners for mounting the truss system

For novice craftsmen building a house with their own hands, the truss system is perhaps the most complex design. The largest number questions are caused by methods of fastening individual elements and used fasteners. The stability and durability of the roof largely depends on these nodes, so we will talk about them in more detail.

Fastening rafters to Mauerlat

The reliability of the roof structure directly depends on how correctly its entire supporting system will be mounted. And its main elements are rafters. The whole system consists of rafter legs that support and burst additional elements, such as struts, crossbars, side girders, support posts and guy wires. The rafter legs are connected on the ridge beam from above, and their lower edges very often rest on the Mauerlat, fixed on the side load-bearing walls of the building.

Fastening rafters to Mauerlat

Since the biggest load falls on the Mauerlat, it is made from a powerful beam. Its cross section is determined by the massiveness of the entire truss system, but basically the size is from 150 × 150 to 200 × 200 mm. This load-bearing element is designed to evenly distribute the load from the entire structure of the roof and roof onto the load-bearing walls of the building. The rafters are fastened to the Mauerlat different ways. They are selected locally depending on the type of truss system (which can be layered or hanging), its complexity and massiveness, on the magnitude of the total loads to which the entire roof structure will be subjected.

Varieties of connecting nodes "rafters - Mauerlat"

First of all, there are sliding and rigid fastenings of rafters to the Mauerlat.

1. Sliding mounts consist of two separate elements, one of which has the ability to move relative to the other.

These mounts can be of different designs - closed and removable.

Closed sliding mount

The closed mount consists of a corner, which is attached on one side to the Mauerlat, and on the other side has a special slotted eye. A metal loop with holes for fastening to the rafters is installed in it. Thanks to the free, not fixed vertical side of the corner, the fastening allows the rafter to move slightly if necessary, without causing a deforming effect on the walls of the building.

Movable sliding fastening of open type

The open mount is arranged according to the same principle, and differs only in that the metal loop is not inserted into the eye, but simply the upper part of the vertical shelf of the corner is bent down after installation, thereby fixing the connection.

Video: an example of installing a movable mount on a rafter leg and Mauerlat

2. There are many more types of rigid fasteners. They are selected depending on the massiveness of the wooden structural elements and the method of installing the rafters on the Mauerlat.

Various hard mounts

This includes metal corners. different sizes, LK fasteners, which will securely fix the rafter, installed with the gash, without damaging it with fastening screws or nails.

LK fasteners are produced in several sizes, so they can be matched to any bar or board thickness. The thickness of the metal from which these fasteners are made is 2 mm, no matter what size they are. Depending on the size, fasteners have a different designation.

It should be noted that these fasteners are suitable not only for connecting rafters on the Mauerlat - they are also used to fix the "floor beam - Mauerlat" nodes.

LC mounts in action

The main advantage of this fastener is the maximum rigidity and reliability of the connection of wooden elements.

The fastening of the rafters with a gash on the Mauerlat with the help of corners is carried out on both sides, which provides the required rigidity.

Corner with reinforced rib at the bend

There are corners designed for attaching rafters without cuts. They have higher shelves and are screwed with a large number of self-tapping screws. They are made from metal with a thickness of 2; 2.5 or 3 mm.

Fastening rafters to the Mauerlat with corners

KP 11 and KP21 are improved corners, often marked as K P1 and KP2. These elements have an oval-shaped anchor hole, which reduces the risk of bolt breakage in the event of structure shrinkage.

KR series corners

КР5 and КР6 are corners used for fastening elements on which a large bearing load falls. The corner to K P6 is also equipped with an oval hole, and it is recommended to use it when creating a truss system on a new house, which will still shrink. These models are in demand for the installation of structures that have a lot of weight.

Corner to K M is made of perforated steel and is used for fastening rafters with a large section. It is especially suitable for wooden buildings. This corner fixes the structural elements very reliably, and when using it, it is not necessary to cut the rafters into the Mauerlat - it is enough to cut the correct angle at the first.

Reinforced corner KMRP series

The KMRP corner is used to fasten parts of the truss system at right angles, including rafters with Mauerlat. It also differs from conventional angles in that it has an elongated hole, which allows displacement during shrinkage without damaging the fixing bolt. It can be used in a design where it is impossible to cut one element to another.

KMRP corners are produced from 2 mm thick steel. Three varieties are produced:

Another option for fixing the rafters on the Mauerlat is to install them between two boards, sawn at a certain angle, and additionally fixed at the bottom with metal corners or LK mounts.

Attaching a rafter between two boards

This fastening of the rafters gives good rigidity and reliability. This method is well suited in cases where the rafter needs to be fixed at the right angle, lifting it above the horizontal plane of the Mauerlat, but fixing it to the vertical outer side.

The method of attaching the rafters to the Mauerlat, made of timber, is not too large section. It is carried out by reinforcing the bar with wooden linings having the required thickness.

Fastening with reinforcing lining

Pieces of boards are attached to the Mauerlat with nails or self-tapping screws, in those places where the rafter legs will be installed.

In this case, cutouts of the desired configuration and depth are made in the rafters. The rafter legs are securely fixed to the wall with the help of steel wire, which is fixed to a driven steel crutch.

Fixation with wire twist

In addition to the above methods of fastening, the rafters are nailed to the Mauerlat using brackets. It should be noted that this method is quite common and has been used for a very long time. With proper fixing of these elements, the truss system will last for many years.

Fastening "the old fashioned way" - staples

Staples may have different size, are driven into different places connections.

Another fastener that is used as an auxiliary is the TM perforated tape. It is used to strengthen the fastening unit if necessary, its additional fixation.

Often metal perforated tape comes to the rescue

In some cases, this element can be indispensable, so it also cannot be excluded when installing rafter legs on the Mauerlat.

Features of truss systems

The rafter system is selected depending on the location of the load-bearing walls of the building. Each of the systems has its own additional retaining or tightening elements.

Varieties of truss systems

Rafters

The system with layered rafters is characterized in that it has one or more reference points, in addition to the load-bearing walls. In this regard, a significant part of the load is removed from the side walls.

Laminated rafters supported by a capital partition

In the form of additional retaining elements, side racks and "grandheads" are used that support the ridge and are fixed to the floor beams. And the beams themselves, in turn, simultaneously serve as puffs for the structure, and also lighten the load from the truss system on the load-bearing walls.

Rafters with sliding fasteners

Laminated rafters are most often attached to the Mauerlat with sliding joints that can move when the walls shrink or deform, leaving the roof structure intact. This is especially important to take into account in new buildings, since any newly built building necessarily shrinks under the influence of temperature fluctuations and ground movements.

hanging rafters

Hanging rafters are called due to the fact that they do not have other supports, in addition to the two side load-bearing walls. It turns out that they seem to hang over the internal space of the building. In this case, the entire load from the roof frame structure falls on the Mauerlat.

Rafters in a hanging type system

For fastening hanging rafters to the Mauerlat, rigid fasteners are used with no degree of freedom of movement, since the frame structure has only two points of support.

To remove part of the load from the walls of the building, additional elements such as struts, “headstocks” and puffs-crossbars are used, which pull the system to the ridge bar and evenly distribute the load on all walls. Crossbars are installed parallel to the floor beams and pull the rafters together. Without these additional details, the design can become unreliable.

Calculation of the installation of rafters

In order for the rafter system to be reliable and durable, in addition to best way connection, you need to choose the correct step for the location of the rafter legs. This parameter is selected depending on the size of the rafters (their cross section and length between the support points), as well as on the roof structure.

In this table, you can get information about the necessary parameters for the installation of a reliable truss system.

A few rules for attaching rafters to the Mauerlat

In order for the fasteners to be reliable, it is necessary to follow a number of rules that are provided for this process:

If metal connecting parts are used for fastening, then they must be fixed to wooden connecting elements with the utmost care - high-quality self-tapping screws of the required length.
If the rafters will fit into the cuts in the Mauerlat, then the dimensions must be precisely verified. This will ensure a tight, reliable installation of the rafters in the prepared gash, which should have a depth of ⅓ Mauerlat. However, it should be remembered that such a rule will be valid only if the Mauerlat is made of a powerful bar with a cross-sectional size of at least 150 × 150 mm.

Washed down on the Mauerlat

In order not to weaken the Mauerlat, most often the cuts are made in the rafter leg itself at the desired angle, and in addition the knot is then fixed with corners. Washed down should not in this case exceed ¼ of the thickness of the rafters. This mount is rigid and can be used in a hanging rafter system.

In this embodiment, washed down is done on the rafter leg

When using bolts to fasten rafters with slopes, puffs and other wooden elements, it is necessary to install a washer or metal plate, in order to avoid flooding the nut into the wood and, consequently, weakening the structure.
Fastening rafters to the Mauerlat only with nails or self-tapping screws is considered unreliable, so it is imperative to use corners or other metal fasteners of various configurations.

Wide range of metal fasteners

When installing rafters on wooden walls, whether it is a hanging or layered system, it is recommended to attach them to the Mauerlat with a sliding fastener, especially if the roofing material is heavy enough.

Fastening rafters to the Mauerlat - how to do it right?

One of the most important connecting nodes in the roof structure is the fastening of the rafters to the Mauerlat. There are several approaches to solving this problem. December 12, 2017
Specialization: facade finishing, interior finishing, construction of dachas, garages. The experience of an amateur gardener and horticulturist. He also has experience repairing cars and motorcycles. Hobbies: playing the guitar and much more, for which there is not enough time :)

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

Frame elements

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

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

Main knots

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

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

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

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

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

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

Here are all the main nodes wooden structures the roofs that form them.

Additional

Additional details include:

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

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

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

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

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

A few words about the types of systems

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

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

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

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

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

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

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

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

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

One last thing about fasteners

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

Rafter / Mauerlat;
Skate knot.

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

Connection of rafters and Mauerlat

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

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

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

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

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

Connection of rafters and ridge run

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

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

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

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

Conclusion

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

December 12, 2017

If you want to express gratitude, add a clarification or objection, ask the author something - add a comment or say thanks!

At the stage of building a house, special attention should be paid to the roof. The reliability of the entire structure will largely depend on how reliably, correctly and efficiently it will be done. One of the important details of the roof is the truss system, which holds finishing material, insulation, waterproofing and other elements. For gable roofs of houses, hanging rafters are often used, the design and components of which, as well as installation, are described in this material.

Rafters are the main load-bearing element of a pitched roof, which takes on the main load experienced by this structure. The rafter system is of two types - hanging or layered. You have to choose between them, based on whether there are internal walls in the structure under construction, which can serve as a support for parts of the roof. The hanging rafter system is used if there are no such walls, and here only external walls buildings. That is, these rafters do not have a central support as such and rest on the wall on one side, and on the opposite rafter on the other. The fastening of individual elements is carried out using slotted spikes, nails, anchors or metal plates.

Hanging rafters are usually used to cover spans with a width of 7-10 m. The scope of application can be different - such a system is used for the construction of roofs in warehouses, industrial buildings, residential buildings.

On a note! The maximum distance between the walls, which allows the use of a hanging rafter system, is 14 m.

Despite the fact that such rafters are installed at a slope, they do not act on the walls like spacers - they transfer only vertical loads. This can be achieved through the use of stretch marks made of timber, located at the base of the roof.

On a note! The tightening between the legs of the rafters is located the higher, the greater the load it experiences.

Rafter elements are made of timber, boards or logs, metal. AT without fail before starting installation work, the material must be treated with special protective compounds that will provide the tree long term services. They will protect it from fungus, mold. If the material is treated with fire-fighting compounds, then the house will gain additional protection against fires.

What does the hanging rafter system consist of?

This type of system has several constituent elements. And it is necessary to get acquainted with them in order to understand the purpose of each of them and not to get confused in concepts.

Table. The constituent elements of the system.

Element	Description
	This is the basis of the system. It is thanks to them that it turns out to form the shape of the roof, slopes. They are created from a bar (or board) with a section of 50x150, 100x150 mm and are placed in increments of about 60-120 cm. The dimensions and pitch chosen will directly depend on the parameters of the roof, its design features, and the calculated load.
	The place where two roof slopes are connected. Usually there is an additional ridge beam.
	With the help of these elements, representing beams horizontally located between the rafters, the rafter legs are tightened and strengthened. Due to the puffs, the load experienced by the rafter legs is compensated.
	A kind of puff, which is located near the roof ridge. It is made of a very durable timber, as it experiences a colossal level of load.
	A beam, which is installed on the upper part of the load-bearing walls, rafters rest on it. It helps to distribute the weight of the entire roof along the perimeter of the building, which makes it possible for the foundation and walls to experience the load evenly. For manufacturing, a bar with a section of 100x100 or 150x150 mm is used. Interestingly, it may not always be used - some types of roofs are equipped without it.
	An element that is installed under the roof ridge and is designed to support a long draw.
	These structural details are used for buildings that have too large spans between load-bearing walls. They are necessary to support the rafters, providing them with a minimum bending load, that is, they will not allow them to bend and sag.

Bar prices

Types of structures

There are five main types of roof structures of this kind that can be obtained on the basis of hanging rafters and can be used in construction. They differ in the presence of some structural elements, configuration, etc.

The simplest option is triangular articulated arch. Its shape is triangular, the puff here is under tensile load, and the rafters are under bending. Such a scheme is used only if the height of the ridge is at least 1/6 of the entire span between the walls, otherwise it will not function correctly. Quite often used in the construction of attics. In this case, two rafters are joined and connected to each other in the ridge part. At the bottom, the triangle can be connected with a long puff. The system can only be used if the span between the walls is no more than 6 m.

Slightly different from the above system - articulated arch with headstock. In this case, the design has a support in the form of a headstock installed under the ridge. Due to the tightening, it works in tension. The headstock can be made of either metal or wood. The system is used if the spans between the walls are 6 meters or more. The headstock will not allow the puff to sag - it acts as a kind of suspension and allows you to adjust the degree of deflection of the horizontal part.

Articulated arch with puff that is raised, is usually used when planning the construction of attics and spacious attic spaces - that is, where the ceiling height is important. In this case, puffs will be installed at the top of the rafters. And the higher the puff is located, the greater the tensile force it perceives.

If the support is a fixed hinge element, then the structure will be called arch with crossbar. Here the roof is attached to the Mauerlat by forming a tooth on the rafters. The bolt itself resembles a small puff, but in this case it works not in tension, but in compression. Rafter legs are fixed quite rigidly.

Arch with struts and headstock resembles an arch system with a suspension. Here, during the installation of the rafters, struts are used, which ensure that the structure is relieved of excess stress. The option is suitable for closing spans with a width of 9-14 m.

On a note! Any scheme for the design of hanging rafters involves accurate calculations that will clarify all external and internal loads.

The rafter system is quite difficult to install, sometimes its parts are assembled directly on the ground, and then rise to the roof. But also rafters can be mounted right on the spot. In general, the hanging rafter roof is the most simple option, therefore, it is often made by novice builders or independently.

Perforated plates used for attaching rafters

Prices for various types of fasteners for rafters

Fasteners for rafters

Ways of fastening rafters

These structural details can be fixed in two ways.

Bolt and clamp, where in this case the end part of the rafter is cut off, and she herself is placed on the beam in the place where the notch is made. The fastening of individual elements is carried out with the help of bolts. They are connected so that the attachment point is perpendicular to the upper part of the rafter. Sometimes clamp systems are used for connection.
double tooth. The method is applicable if the slope of the roof slope relative to the horizontal is less than or equal to 35 degrees. In this case, two stops are made on the beam, a special hole is made in the rafter leg, and a spike is cut out at the place of the extreme stop on the beam. In size, these elements must correspond to each other.

System design

To correctly create a system layout, it is important to consider:

rafter installation step;
load on the structure and structure;
section of rafters;
material that will be used to create the roof;
construction type;
roof pitch angles
the dimensions of the building as a whole;
climatic conditions of the region.

The more accurately the calculation is made and the more correctly the rafter system is designed, the stronger and more reliable the whole structure will turn out. For convenience, you can use the existing online calculators, which is important for those who are not friends with the exact sciences, or for beginners.

Video - Roof truss system, what you need to know for proper design

Installation rules

Installation of hanging rafters must be carried out in compliance with certain rules. Only in this case it will be possible to make a correct and stable design. The work rules are as follows:

Installation of hanging rafters

For the construction of the truss system, certain tools and materials may be required. The list below is quite approximate, but can be used as a basis during preparation for the start of work.

Tools for creating a rafter system:

a hammer;
axe;
jigsaw or hacksaw;
building level, twine, tape measure;
thread with a load (plumb line);
pencil, ruler.

Prices for popular models of jigsaws

As necessary materials, you can directly list the beams and boards for rafters, self-tapping screws and nails, anchor bolts, waterproofing material, antiseptic compounds for wood processing.

Sigma-Extra - outdoor work, antiseptic for wood

Consider the installation process of the truss system step by step.

Step 1. All wood material is processed antiseptics that prevent the development of decay processes, the occurrence of fungus and mold. Prior to installation, the material is well dried.

Step 2 Building material is delivered to the top of the building.

Step 3 A mauerlat is nailed along the perimeter of the load-bearing wall, consisting of two boards of such a width that they can cover the entire upper part of the wall with themselves. It is recommended to lay a layer between the Mauerlat and the wall waterproofing material(for example, roofing material). This will seal the joint, protect the material from moisture and reduce drafts in the future.

Step 4 Next, beams are created from the timber, which will be attached to each pair of rafters in the lower part. They are attached to the Mauerlat and connect two load-bearing walls together. You can temporarily move along them during the work, and boards that are used to create rafters are also folded on them.

Step 5 To form the top of the roof, a ridge beam is cut out. It should have a length from one part of the future roof to another and be parallel to the long load-bearing walls.

Step 6 The required roof height is determined - the level at which the ridge beam will be attached. The angle of inclination of the slope is recommended to be done within 25-45 degrees. You can find out the angle of the roof and the length of the rafters using the Pythagorean theorem. To do this, you need to measure the distance from the ridge, the height of the roof and the distance to the outer wall.

Step 7 The ridge board is installed at the place of the future docking of two rafter legs.

Step 8 From the prepared lumber, future rafters of the desired length are measured and cut. They will be attached with the selected pitch to the ridge board and Mauerlat.

Step 9 To make it possible to attach the rafters to other elements, special triangular cutouts are made. To do this, the board is installed so that one side lies on the ridge board, and the other on the Mauerlat. The cut mark is applied. Next, the marked sections are cut.

Step 10 The second rafter is prepared in the same way. Now they should be docked with each other. To do this, the boards are moved as close as possible to each other, markings are applied indicating the place of the cut. The cut is made and the boards can be joined.

Step 11 The rafters are attached to the Mauerlat using metal corners and self-tapping screws. With the help of them, the boards are also fixed on the roof ridge.

Step 12 Two rafters are interconnected using metal plates and self-tapping screws. Thus, the first two structures are installed, which will be located at the edges of the roof.

Step 13 In order to make it easier to evenly install other rafters, a rope is stretched strictly horizontally between the extreme structures.

The process of installing rafters

Step 15 If necessary, the rafters can be reinforced with puffs that are attached to two joining rafters.

Video - Installation of the truss system

Video - Installation of rafters

Video - Using a crossbar (screed) for rafters as an interior element

Hanging rafters are considered a fairly simple design compared to other types of truss systems. But there should be no rush during their installation. It is important to remember that at the slightest skew, all work will go down the drain, so you need to work carefully and carefully.

The truss system is the skeleton of the roof. It is she who is responsible for the strength of the roof, its reliability and resistance to stress. At self construction at home, you need to know how to properly make the attachment points of the truss system so that the roof is reliable and safe.

The device of the truss system

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

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

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

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

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

Types of truss systems

Rafters can be hanging and layered.

Hanging lean on the walls and create a spacer. To reduce it, puffs are made at the base of the rafters, which connect the rafters and form triangles with them. Hanging systems various types are used for houses with a width of not more than 17 m. Depending on the width of the building, they arrange them differently.

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

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

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

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

How to connect the parts of the truss system

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

Mounting Methods:

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

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

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

Mauerlat mount

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

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

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

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

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

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

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

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

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

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

Ridge connection

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

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

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

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

beam knot

The rafters are attached to the beams as follows. the main task fastenings - to prevent the rafters from sliding along the beam, therefore various techniques are used.

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

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

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

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

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

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

The main parts of the roof structure

Before proceeding directly to the analysis of the topic of the article, it is necessary to indicate what elements (details) the roof structure. We list all the main details 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 emanating from the truss 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, it is they who form the slopes and bear all the loads acting on the roof structure.

Skate run. This is the uppermost beam, installed horizontally. Its purpose is to support the upper ends of the rafter legs. It is he who 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 it cannot be said that others are less important. It's just that these three elements form the structure itself. The only thing to add is that in some roof structures there is no ridge run. It's just that the upper ends of the rafters rest against each other. This type of rafters is called hanging, and with a ridge run layered.

In order for the roof structure to be the most reliable, it is necessary that the roof nodes are correctly connected. In this case, the force of the acting loads and their direction must be taken into account.

How to connect the elements of the roof structure

More recently joining timber roofing carried out with the help of notches. That is, they cut the elements of the roof structure in order to connect them along one fairly wide plane. Therefore, so that the roof details do not reduce their strength characteristics, as well as their bearing capacity, they were selected with a sufficiently large cross section. And it's not economical. That is, the larger the cross-section of lumber, the more expensive it is.

Today, the technology of fastening nodes and parts of the roof structure has changed dramatically. To do this, use bolts, dowels or metal perforated profiles. The latter are made of galvanized steel, which makes it possible to operate 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 node. The photo below shows some of these fasteners.

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

Let's now look at how fasten parts roof structure to each other. In principle, there are two types of connection: Mauerlat-rafter, rafter-ridge run. The remaining parts are connected parallel to these joints. They will also be talked about.

Mauerlat and rafters connection

There are actually a huge number of fastening options, from ordinary nails to 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, where a wire with a diameter of 6 mm is inserted. They also make a hole 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 against the Mauerlat. The connection is actually strong and reliable, but the process is laborious.

Can be used instead of wire metal tape 3 mm thick. She simply wraps two connected elements and through the strip is attached to them with self-tapping screws, more often with nails. In the latter case, there is no need to drill through holes in the metal. note that in the bottom photo the mount is held to reinforced belt anchor, which increases the strength and reliability of the connection.

On our website you can find contacts of construction companies that offer turnkey calculation and roofing services of any complexity. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".

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 it is tightly pressed against the plane of the Mauerlat and the rafter leg with its mounting shelves. Fastening is carried out with screws or nails.

Fasten the corners it is possible not only with self-tapping screws or ruff nails. There is another more reliable option where bolts are used. True, holes will have to be made under them, which increases the costly time for carrying out this type of work. But in this case, the quality is above all. 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 rafter.

And another mounting option - on the slider. This is a special type of fastener, 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 is done specifically so that the rafters can move relative to the Mauerlat during the 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 a ridge run

The second main node of the wooden roof - joint between rafter leg and ridge beam. In fact, the ridge roof truss assembly is very complicated, because two rafter legs and a beam are joined on it. In this case, all the elements are located in different planes, meaning the rafters and timber. This means that more than one fastener will have to be used to connect them.

To connect the 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 from 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 a different type of fastening. Only corners are used here. This option is used if a board with a thickness of 50 mm is installed as a ridge beam.

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

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Pay attention to all of the above options for connecting 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 mounting lock, consisting of several plates that are bolted together. 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 run . That is, the rafter legs in the upper part (ridge) rest against each other. In order for them not to disperse different sides, the rafters are interconnected by a horizontal puff. The latter is a board located at any distance in height: from above, below or in the middle.

It should be noted that hanging rafters not assembled separately on the roof. Farms are collected from them on the ground, which in ready-made installed on the roof of the house. In this case, all elements of the farm are interconnected by perforated plates.

Video description

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

Other types of knots

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

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

Under the ridge beam is also installed vertical support posts, which are attached to each other by perforated plates. But in some roof structures, a completely different approach is used to solve the installation of a ridge run. Under the beam, jibs are mounted from the bars, which are fixed 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. It is not difficult to do this, while the masters use several technologies, where they use various additional fasteners.

Video description

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

Roof structures are several varieties of their forms. Almost all models have a large number of identical elements. But among them there is one design that differs significantly from the others. This is hipped roof. Its distinctive feature is that the rafters are connected upper edges to one point, which is called the 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 mounting perforated metal profiles U-shaped.

Conclusion on the topic

In fact, we have considered only a small part of the connecting nodes for attaching the roof truss system. But even on their example, the variety of parts and assemblies becomes clear. That is, the roof structure is a complex system, consisting of a large number of different elements and parts that are interconnected in different ways.