Metal rafters for the roof - features of the device and installation. What are the nodes of the truss system? Rafters from round timber knots

The structure of the rafters is the skeleton of the roof, which is obliged to take on and evenly distribute the weight of the roofing materials. If you correctly assemble the wooden frame under the insulation, waterproofing film and top coat, it will be possible to achieve a noticeable increase in carrying capacity truss system.

The main elements of the truss system

The wooden frame of the roof is assembled from parts such as:

mauerlat - a kind of base for roofing elements, attached along the entire perimeter of the building to the upper edge of the outer walls in order to disperse pressure roofing cake;
Mauerlat serves as the basis for the roof frame
rafter legs - irreplaceable details of the wooden skeleton of the roof, which determine the angle of inclination of the slopes and the view of the upper part of the house;
ridge run - a bar fixed in a horizontal position and, like a spine, connecting all the rafters of the roof frame in their upper part;
The ridge run is located exactly in the middle of the building
side run - a horizontal beam, which differs from a ridge run in that it is fixed in the middle of the rafter legs of each roof slope;
puff - a spacer that unites two opposite rafters so that they do not move apart;
Tightening and struts are necessary to properly distribute the load on the Mauerlat
racks - vertical frame elements placed under the ridge and side runs in order to support the rafters and ridge beam, and also, if necessary, substituted under the middle part of the rafter legs;
Racks can support not only the ridge of the roof, but also the rafters
struts - parts that rest against the bed, due to which the rafter legs become more stable;
bed - a bar placed on the upper edge inner wall buildings parallel to the ridge and serving as a platform for attaching racks and struts;
The bed is located on the inner wall parallel to the mauerlat beam
roof ridge - the area of combination of two slopes, along which a continuous crate is installed, necessary to strengthen the described part of the roof;
The ridge is formed in the highest zone of the truss system
filly - elements used in the arrangement of the overhang, when the rafter legs are not long enough;
Fillies lengthen rafter legs
roof overhang - zone timber frame protecting the walls of the house from contact with large quantity atmospheric precipitation;
The cornice overhang is constructed to protect the walls from rain.
lathing - bars or boards nailed perpendicular to the rafters and serving as a platform for attaching roofing materials.
Sheathing boards are laid out perpendicular to the rafters

Main connecting nodes

The main nodes of the truss system are:

roof truss- connection of a rafter pair, extensions, as well as racks and braces;
ridge knot - combination of two opposite rafters;
a link from a Mauerlat and a rafter resting on it;
a module that includes a run, a rack and a bed;
connection of the rafters with a strut and a rack.

The most complex link of the roof frame, according to the author, is a truss truss, which is distinguished by the fact that:

The ridge knot also has several features:

Rafters and Mauerlat become a single link, which is characterized by the following:

A module from a run, a rack and a bed is formed by driving into their joints construction staples, steel dowels or linings from steel strips.

A node of a bed, a rack and a run allows you to share the load between the external and internal walls of the building

Struts, racks and rafters are assembled into a single module, creating cuttings. To ensure that their connection is not weak, construction brackets are used.

A knot of struts, racks and rafters allows you to soften the pressure on the inner wall of the house

Ways of fastening rafters

In the lower part, the rafters can be connected both to the Mauerlat and to the floor beams. Sometimes, for example, during frame construction, they are fixed directly on the wall. And in the upper part, the rafter legs are combined with the ridge. Each labeled node can be created in several ways.

Mauerlat connection

The rigid fastening of the rafters on the Mauerlat guarantees the absence of any displacement of the assembly elements. It is performed by cutting in a certain sequence:

To speed up work, a template is made from a piece of board or thick cardboard. A line is drawn on the workpiece, stepping back from the side edge a distance equal to 1/3 of the width of the rafter, and then the point of contact with the Mauerlat beam is marked, along which a second line is drawn perpendicular to the first.
If the width of the rafter is more than 200 mm, then washed down is done at a depth of 70 mm
Angled roof slope the template is substituted to the edge of the Mauerlat, making sure that the point marked on the piece of wood is strictly opposite the corner of the beam. Two lines are drawn from it with a pencil - vertical and horizontal, as a result of which a triangle is obtained on the workpiece, which is carefully cut out.
The made template is assessed for correctness by putting it on the Mauerlat in several places. If the groove made turned out to be smaller or larger than necessary, then the pattern is made anew, correcting the mistake made.
The template is placed on a horizontally located rafter. The triangle in the pattern is circled with a pencil. The same is done with other rafter legs. At the same time, make sure that the horizontal line of the groove in the pattern is always in the same place on the rafter. Otherwise, notches will be created on different distances from a skate.
The triangles drawn on the rafters are cut out hand hacksaw... The tool is operated slowly so as not to accidentally increase the depth of the groove in the rafter leg. Possessing the skills of working with an electric saw, recesses can be made with this device. True, it must be borne in mind that a tool powered by the mains is much worse at listening to the hand and is able to go to the side.
The triangular cut allows the rafter to rest against the Mauerlat
The correctness of the size of the grooves made is checked with a pattern. If discrepancies are found, the notch is corrected with a hacksaw.
Two extreme rafter legs are placed on top of the house. They are inserted into the Mauerlat with grooves, fixed on the sides with metal corners or brackets.
A rope is pulled along the bottom edge between the two installed elements. Then the remaining rafter legs are attached to the Mauerlat one by one.

The technology of attaching the rafter legs to the Mauerlat with a patch of a thrust bar can be taken into account by builders without experience. With this method of creating a node, as the author of the article noted, it is possible to change the position of the rafters until it becomes completely correct.

To connect the main elements of the roof frame with the Mauerlat with a stripe of a thrust bar, do the following:

During the construction of the roof frame for wooden frame, which always shrinks, they prefer to use the sliding method of attaching the rafters to the Mauerlat. Thanks to it, it is possible to avoid deformation of the truss structure and deterioration in the stability of the upper row of logs, which replaces the Mauerlat.

The choice of sliding rafters is justified only when a ridge beam is provided for the main elements of the roof frame, against which they could abut with their upper part.

When the rafters are fixed on the Mauerlat using the sliding method, certain steps are taken:

The layered method of attaching rafters to the Mauerlat is adopted when the purchased lumber turned out to be shorter than necessary. Also, this method of fixing the main elements of the rafter system is used during the repair of a roof of complex configuration.

When fixing the rafters on the Mauerlat using the layered method, only 3 tasks are performed:

Video: installing rafters

Combination with floor beams

It is possible to fasten the rafters to the floor beams only being sure that the walls of the building will withstand the pressure of the roof frame. Still, in the absence of a Mauerlat, the load on the house is not uniform, but point.

Without fear and doubt, the rafters are attached to the floor beams if they are building a light mansard roof... At the same time, boards with a section of 5x15 cm are used as ceiling beams.

The rafters are not connected to the Mauerlat, but to the beams of the attic, if they know for sure that they will withstand the pressure exerted

To firmly fix the rafter legs on the floor beams, perform the following tasks:

wall mount

If for some reason the rafters have to be fixed directly on the walls, then they will definitely need to be connected with a puff. She, as the author of the article personally made sure, who helped build the roof of the utility room, will remove part of the stress transmitted by the rafters from the house.

Rafters should never be directly connected to the outer walls of the building if they are built from foam or gas blocks. These materials freely transfer their moisture to the wood and are unable to retain fasteners.

On the wall, the rafters can be fixed using a sliding method, but this is not the most reasonable solution.

To securely fix the rafter legs on the walls, it is necessary to take certain measures:

At the right angle, make on the rafters washed down with one tooth.
Install the rafters on the walls with the butt end and drive a nail 10-12 cm long into them.
If necessary, attach metal corners to the sides of the rafters.

Since the roof ridge is under serious pressure from the entire truss system, roofers with extensive experience create a ridge knot in five ways: butt, on a beam, overlap, in a groove, in half a tree.

To create a ridge knot by connecting opposite rafters end-to-end, do the following:

When attaching rafters to a beam, or rather, to a special ridge run, they act in a special way:

When the rafters are connected to the beam, the ridge is not pointed, but flat.

If the ridge knot is made by fastening the rafters with an overlap, then you will need to perform a few simple tasks:

To connect the rafter legs into a ridge knot using a groove, several skillful carpentry actions are performed:

Having chosen the method of connecting the rafters to half a tree, do the following:

Video: building a roof frame with connecting rafters with a ridge run

The construction of the rafter system should not be started until it is possible to understand the features of attaching the rafters to other elements of the roof supporting structure. By the way, among the various ways of fixing the rafter legs, there are options not only for experienced builders.

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

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

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

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

We have dealt with this issue, now we should consider a few general recommendations concerning the fastening of the rafters.

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

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

Rigid fastening of rafters

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

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

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

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

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

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

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

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

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

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

Step 5 At an angle, select the second slice.

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

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

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

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

Edged board prices

edged boards

Fastening the rafter legs with a stripe of a thrust bar

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

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

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

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

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

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

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

Prices for a set of hardware

set of hardware

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

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

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

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

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

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

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

sliding support for rafters - dimensions

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

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

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

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

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

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

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

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

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

Scheme - rafters with sliding support and cuts

sliding support prices

sliding support

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

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

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

Rafter rafters - schemes

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

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

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

Prices for metal corners

metal corners

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

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

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

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

Video - Fastening rafters to the Mauerlat, sliding support

Video - Installation of rafters

Video - Assembly of rafters

Video - Quick installation of the truss system

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.

Construction of the truss system.

In addition to the load of atmospheric precipitation, the rafters must withstand the weight of the lathing and the total weight of the roofing pie, which must be taken into account when selecting fasteners.

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 the rafter legs rest. 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.

Recently, more and more often, a wooden mount for rafters has been replaced by a metal one, since 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 changes 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 truss 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 bottom it rests on 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 craftsmen used wooden elements as such fasteners (bars, slips, 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.

WB brackets are used to mount the console carrier beam on device wooden floors in houses made of rounded 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 bearing structures, since 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 the bearing characteristics of the structure, eliminates the displacement of the 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 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 bar, 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 in the upper part 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 truss 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 we are not talking about wooden buildings, then the articulation should be rigid.

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

a cut 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 with metal corners- fastening the rafters to the Mauerlat with these elements makes it possible to avoid the 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 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 an incorrect 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. V 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 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 a rigid fastening of the rafter system, the roof of a wooden house warps, and the 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.

Everything threaded connections performed using metal washers or plates.

When fastening construction details with nails, the following rule must be followed: 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 structure. The largest number questions are caused by the methods of fastening individual elements and the fasteners used. 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 fastening of the rafters to the Mauerlat is carried out in various 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. Angle to K P6 is also provided oval hole, and it is recommended to use it when creating a rafter 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.

A method of attaching rafters to a Mauerlat made from a beam of not too large a 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 can have a different size, they 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 design may 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 imperative to install a washer or a metal plate on the bolt, in order to avoid flooding the nut into the wood and, accordingly, 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 fasten 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.

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 expand additional elements, such as struts, puffs, crossbars, side runs, support posts and extensions. The rafter legs are connected on the ridge beam from above, and their lower edges very often rest on, fixed on the side load-bearing walls of the building.

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.

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 deforming the walls of the building.

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 installation on the Mauerlat.

These include metal corners of different sizes, LK fasteners, which securely fix the rafters, installed with the help of washed down, without damaging it with fixing 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.

Designation	Size in mm
LK-1L	40×170
LK-2P	40×170
LK-3L	40×210
LK-4P	40×210
LK-5L	40×250
LK-6P	40×250

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.

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.

Designation	The size (length height width, metal thickness) in mm	Designation	The size (length height width, metal thickness) in mm
reinforced corner	105×105×90×2	Reinforced corner KP5	140×140×65×2.5
reinforced corner	130×130×100×2	Reinforced corner KP6	105×172×90×3.0
reinforced corner	105×105×90×2	Reinforced corner KP7	145×145×90×2.5
reinforced corner	50×50×35×2	Reinforced corner KP8	145×70×90×2.5
reinforced corner	70×70×55×2	Reinforced corner KPL1	90×90×65×2
reinforced corner	90×90×40×2	Reinforced corner KPL11	90×90×65×2
Reinforced corner KP1	90×90×65×2.5	Reinforced corner KPL2	105×105×90×2
Reinforced corner KP11	90×90×65×2.5	Reinforced corner KPL21	105×105×90×2
Reinforced corner KP2	105×105×90×2.5	Reinforced corner KPL3	90×50×55×2
Reinforced corner KP21	105×105×90×2.5	Reinforced corner KPL4	70×70×55×2
Reinforced corner KP3	90×50×55×2.5	Reinforced corner KPL5	50×50×35×2
Reinforced corner KP4	70×70×55×2.5	Reinforced corner KPL6	60×60×45×2

A few additional words need to be said about some of the corners shown in the table, since their description requires clarification:

— KR 11 and КР21 are improved corners, often marked as TO P1 and KR2. These elements have an oval-shaped anchoring hole, which reduces the risk of bolt breakage in the event of structure shrinkage.

- КР5 and КР6 are corners used for fastening elements on which a large bearing load falls. Corner TO P6 is also equipped with an oval hole, and it is recommended to use it when creating a rafter 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 M is made of perforated steel and is used for fastening rafters with a large section. It is especially well suited for wooden buildings. This corner fixes the structural elements very securely, 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.

- 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:

Corner designation	Dimensions in mm
	a	b	c
KMRP1	60	60	60
KMRP2	80	80	80
KMRP3	100	100	100

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.

Such fastening 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.

A method of attaching rafters to a Mauerlat made from a beam of not too large a 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 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 can have different sizes, driven in at different junction points.

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

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

It 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.

Rafters

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

In the form of additional retaining elements, side racks and "grandheads" are used, which support 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.

hanging rafters

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.

Hanging system the rafters are spacer, so it puts a lot of pressure on the walls.

Calculation of the installation of rafters

In order for the rafter system to be reliable and durable, in addition to the optimal connection method, 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 (and the 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.

Step of installation of rafter legs in mm	Length of rafter legs in mm
	3000	3500	4000	4500	5000	5500	6000
600	40×150	40×175	50×150	50×150	50×175	50×200	50×200
900	50×150	50×175	50×200	75×175	75×175	75×200	75×200
1100	75×125	75×150	75×175	75×175	75×200	75×200	100×200
1400	75×150	75×175	75×200	75×200	75×200	100×200	100×200
1750	100×150	75×200	75×200	100×200	100×200	100×250	100×250
2150	100×150	100×175	100×200	100×200	100×250	100×250	-

Use, in the article on our portal.

Prices for various types of fasteners for rafters

Fasteners for rafters

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.

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.

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

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.

Video: a few examples of attaching rafters to the Mauerlat

The roof structure will be durable and will last long term, without being deformed by a variety of external influences, if the calculations of all elements are made correctly, correctly select and correctly mount all fasteners.

At the heart of each roof is a large number of beams, rafters, racks and girders, which are collectively called the truss system. Over the centuries-old history of types and methods of its organization, a lot has accumulated, and each has its own characteristics in the construction of knots and cuts. We will talk in more detail about what the gable roof truss system can be and how the rafters and other elements of the system should be attached in more detail.

The design of the gable roof truss system

In the context of a gable roof is a triangle. It consists of two rectangular inclined planes. These two planes are connected at the highest point in single system ridge beam (run).

Now about the components of the system and their purpose:

Mauerlat - a beam that connects the roof and walls of the building, serves as a support for the rafter legs and other elements of the system.
Rafter legs - they form the inclined planes of the roof and are the support for the crate under the roofing material.
Ridge run (bead or ridge) - combines two roof planes.
A puff is a transverse part that connects opposite rafter legs. Serves to increase the rigidity of the structure and compensate for bursting loads.
Beds - bars located along the Mauerlat. Redistribute the load from the roof.
Side runs - support the rafter legs.
Racks - transfer the load from the runs to the beds.

Filly may still be present in the system. These are boards that extend the rafter legs to form an overhang. The fact is that in order to protect the walls and foundation of the house from precipitation, it is desirable that the roof ends as far as possible from the walls. To do this, you can take long rafter legs. But the standard lumber length of 6 meters is often not enough for this. Ordering non-standard is very expensive. Therefore, the rafters are simply grown, and the boards with which this is done are called “fillies”.

There are quite a few designs of truss systems. First of all, they are divided into two groups - with layered and hanging rafters.

With hanging rafters

These are systems in which the rafter legs rest only on the outer walls without intermediate supports (bearing walls). For gable roofs, the maximum span is 9 meters. When installing a vertical support and a strut system, it can be increased up to 14 meters.

The hanging type of gable roof rafter system is good because in most cases there is no need to install a Mauerlat, and this makes the installation of rafter legs easier: no need to make cuts, just mow the boards. To connect the walls and rafters, a lining is used - a wide board, which is attached to studs, nails, bolts, crossbars. With such a structure, most of the bursting loads are compensated, the impact on the walls is directed vertically downwards.

Types of truss systems with hanging rafters for different spans between load-bearing walls

Gable roof truss system for small houses

There is a cheap version of the truss system when it is a triangle (photo below). Such a structure is possible if the distance between the outer walls is not more than 6 meters. For such a rafter system, it is possible not to calculate the angle of inclination: the ridge must be raised above the puff to a height of at least 1/6 of the span length.

But with this construction, the rafters experience significant bending loads. To compensate for them, they either take rafters of a larger section or cut the ridge part in such a way as to partially neutralize them. To give greater rigidity in the upper part, wooden or metal plates are nailed on both sides, which securely fasten the top of the triangle (also see not the picture).

The photo also shows how to grow rafter legs to create a roof overhang. A notch is made, which should go beyond the line drawn from the inner wall upwards. This is necessary to move the incision site and reduce the likelihood of a rafter breaking.

Ridge knot and fastening of the rafter legs to the backing board when simple version systems

For mansard roofs

Option with the installation of a crossbar - used when. In this case, it is the basis for filing the ceiling of the room below. For reliable operation of this type of system, the crossbar notch must be hingeless (rigid). The best way- semi-pan (see the figure below). Otherwise, the roof will become unstable to loads.

Please note that in this scheme there is a Mauerlat, and the rafter legs should extend beyond the walls to increase the stability of the structure. To secure them and dock with the Mauerlat, a cut is made in the form of a triangle. In this case, with an uneven load on the slopes, the roof will be more stable.

With such a scheme, almost the entire load falls on the rafters, therefore they must be taken with a larger section. Sometimes the raised puff is reinforced with a suspension. This is necessary to prevent it from sagging if it serves as a support for ceiling sheathing materials. If the puff is short, it can be secured in the center on both sides with boards nailed to the nails. With a significant load and length, there may be several such insurances. In this case, boards and nails are also enough.

For big houses

With a significant distance between the two outer walls, a headstock and struts are installed. This design has high rigidity, since the loads are compensated.

With such a long span (up to 14 meters), it is difficult and expensive to make a one-piece puff, because it is made from two beams. It is connected by a straight or oblique cut (picture below).

For reliable docking, the junction is reinforced with a steel plate mounted on bolts. Its dimensions must be more sizes cuts - extreme bolts are screwed into solid wood at a distance of at least 5 cm from the edge of the cut.

In order for the circuit to work properly, it is necessary to correctly make the struts. They transmit and distribute part of the load from the rafter legs to the puff and provide structural rigidity. Metal strips are used to reinforce the connections.

When assembling a gable roof with hanging rafters, the cross-section of lumber is always larger than in systems with layered rafters: there are fewer load transfer points, therefore, each element has a greater load.

With rafters

In gable roofs with layered rafters, their ends rest on the walls, and the middle part rests on load-bearing walls or columns. Some schemes burst walls, some do not. In any case, the presence of a Mauerlat is mandatory.

Bezporny schemes and knots of cuts

Houses made of logs or timber do not respond well to spacer loads. For them, they are critical: the wall can fall apart. For wooden houses, the gable roof truss system must be non-expansion. Let's talk about the types of such systems in more detail.

The simplest non-spacer scheme of the truss system is shown in the photo below. In it, the rafter leg rests on the Mauerlat. In this embodiment, it works on a bend, without bursting the wall.

Pay attention to the options for attaching the rafter legs to the Mauerlat. In the first, the support platform is usually beveled, while its length is no more than the cross section of the beam. The depth of the cut is no more than 0.25 of its height.

The top of the rafter legs is laid on the ridge beam without fastening it to the opposite rafter. Two shed roofs are obtained according to the structure, which adjoin (but do not connect) one with the other in the upper part.

It is much easier to assemble the option with rafter legs fastened in the ridge part. They almost never give a thrust on the walls.

For this scheme to work, the rafter legs below are attached using a movable joint. To fix the rafter leg to the Mauerlat, one nail is hammered from above or a flexible steel plate is placed from below. See the photo for options for attaching rafter legs to a ridge run.

If the roofing material is planned to be heavy, it is necessary to increase bearing capacity... This is achieved by increasing the cross section of the elements of the truss system and strengthening the ridge assembly. It is shown in the photo below.

Strengthening the ridge assembly for heavy roofing material or with significant snow loads

All of the above gable roof schemes are stable in the presence of uniform loads. But in practice, this almost never happens. There are two ways to prevent the roof from sliding in the direction of greater load: by installing a brace at a height of about 2 meters or by struts.

Options for truss systems with contractions

The installation of contractions increases the reliability of the structure. In order for it to work normally, at the places where it intersects with drains, you need to attach nails to them. The cross section of the beam for the scrum is used the same as for the rafters.

They are attached to the rafter legs with bots or nails. Can be installed on one or both sides. The knot for attaching the bout to the rafters and the ridge run, see the figure below.

In order for the system to be rigid and not “crawl” even under emergency loads, it is enough in this embodiment to provide a rigid fastening of the ridge beam. In the absence of the possibility of its displacement in the horizontal, the roof will withstand even significant loads.

Rafter systems with braces

In these options, rafter legs, which are also called struts, are added for greater rigidity. They are installed at an angle of 45° with respect to the horizon. Their installation allows you to increase the span length (up to 14 meters) or reduce the cross section of beams (rafters).

The strut is simply substituted at the required angle to the beams and nailed from the sides and bottom. Important requirement: the strut must be cut accurately and fit snugly against the uprights and the rafter leg, excluding the possibility of its deflection.

Systems with rafter legs. Above is a spacer system, below is a non-spacer system. The nodes of the correct felling for each are located nearby. Below - possible schemes for attaching the strut

But not in all houses, the average load-bearing wall is located in the middle. In this case, it is possible to install struts with an angle of inclination relative to the horizon of 45-53 °.

Bracing systems are necessary if significant uneven shrinkage of the foundation or walls is possible. Walls can sit differently on wooden houses, and foundations on layered or heaving soils. In all these cases, consider the installation of truss systems of this type.

System for houses with two internal load-bearing walls

If the house has two load-bearing walls, two rafters are installed, which are located above each of the walls. Beds are laid on the intermediate load-bearing walls, the load from the rafter beams is transferred to the beds through the racks.

In these systems, a ridge run is not installed: it gives expansion forces. The rafters in the upper part are connected to one another (cut and joined without gaps), the joints are reinforced with steel or wooden lining that are nailed down.

In the upper non-expansion system, the expanding force is neutralized by tightening. Please note that the puff is placed under the run. Then it works efficiently (the top diagram in the figure). Stability can be provided by racks, or jointing - beams installed obliquely. In the spacer system (in the picture it is below), the cross member is a crossbar. It is installed above the run.

There is a variant of the system with racks, but without rafters. Then a rack is nailed to each rafter leg, which rests on the intermediate load-bearing wall with the second end.

Fastening the rack and tightening in the rafter system without a rafter run

To fasten the racks, nails for 150 mm and bolts 12 mm are used. Dimensions and distances in the figure are in millimeters.