Using a sliding support for rafters. Sliding support for rafters: design features Sliding lathing in a wooden house

The usual rigid system of attaching rafter legs to the mauerlat or the upper crown of a wooden frame using staples, nails or corners does not always justify itself. In many cases, the rafter beam must be able to move relative to the walls. To ensure this displacement, a sliding support for the rafters is used.

The design of the support unit, in which the rafter beam has free movement at the point of its support on the wall, is used mainly in the construction of wooden houses. The walls of a log house made of solid wood after assembly and during operation are subject to significant deformations and change their geometric characteristics. Not only wood with natural moisture, but also laminated timber shrinks to one degree or another. An ordinary log house can become 15% lower after being placed under a roof and the first snowy winter. Moreover, the walls can settle by significantly different amounts, resulting in a distortion at the top, in the roof area.

The roof rafters are attached to the upper crown of the log house made of rounded logs through sliding supports

During operation, slight deformations also occur. If the house has a central wall, it settles to a greater extent than the outer ones when the house begins to heat. This is explained by a decrease in the volume of wood due to a decrease in its moisture content. There are also seasonal deformations. During the rainy season, the walls of the house become a little higher, and in winter, when air humidity is minimal, they “shrink out.” Moreover, the southern wall dries out faster after rains, that is, the amplitude of changes in the height of the walls is not the same, the house “walks.” Temperature and humidity deformations occur in solid wood buildings throughout the entire life of the house.

The estimated change in the length of the rafter beam due to greater shrinkage of the central wall of a wooden house

A four-wall log house (there is no central wall) may have another problem. Logs that are constantly subject to stress can gradually bend. The rafter system, if it is not rigidly assembled and does not have a closed loop like a truss, exerts not only vertical, but also horizontal pressure on the walls. The rafters can bend the central parts of the walls outward, and the log house will acquire a “barrel-shaped” outline in plan. And the roof will sag at the ridge. The presence of a cut with reliable locks located across the ridge (five-walled) will eliminate this problem or reduce it.

In addition, the wooden rafters themselves, if they have not been subjected to technical drying, will lose moisture and become shorter.

If you attach the rafters rigidly at the point of support to the wall, the deformations of the structure will be transferred to the roof. As a result, a roof that looked perfect during installation may, after some time, sag in the center, the planes will become crooked, bumps and depressions will appear, and the end and wind planes will lose their evenness.

To prevent the deformations of the walls from being transferred to the roof, the rafter system at the points of interface with the walls must be able to move while maintaining its shape. This task is provided by the sliding support for the rafters. The maximum effect from the use of such supports is achieved when constructing houses made of solid wood with central walls parallel to the ridge of the roof.

Main design characteristics

The function of the sliding support is to clearly fix the rafter beam to the wall and the mauerlat in a vertical plane and the possibility of its displacement along its own axis.

The sliding support consists of two elements. One is a guide (bar), which is attached to the rafter beam. The second is a corner with a support platform, fixed to the upper crown of the log house or mauerlat. The angle is equipped with a loop that engages with the guide, but does not prevent it from moving within certain limits.

The sliding support consists of two elements

The amount of deformation may vary. The support guide element limits possible movement. There are supports on sale with the ability to move to varying degrees.

The possible sliding amplitude of the rafter leg depends on the length of the free section of the support guide bar. These three options allow for an offset of 90 to 160 mm

The supports are made of steel at least 2 mm thick. The height of the angle is usually 90 mm, the width of the plates is 40 mm. Factory products have a galvanic anti-corrosion coating. Fasteners made of ordinary steel must be protected from rust by painting with oil paint.

Application of sliding supports

The support platform must be mounted on the upper crown strictly perpendicular to the axis of the rafter beam, in the sliding direction. It is recommended to initially install the angle loop at the bottom of the sliding bar.

The rafter beam will sit down, so when installing the plank and corner are positioned in this way. The drawing indicates “shrinkage reserve”.

Metal elements are fastened only with screws with anti-corrosion coating.

Incorrect installation. The platform should be located on the upper crown at an angle, perpendicular to the axis of displacement of the rafter beam. In this case, the plate will jam or the corner will tear off from the crown.

In addition to the described advantages, the use of sliding supports makes it possible to simplify the design of the rafter system. There is no need to make complex cuts to the rafter beams and the top crown to provide support. If the house is built from timber or hand-cut logs, it is enough to plan a platform at the crown for attaching the support at the desired angle. In a structure made of rounded logs, this is even simpler: a square is used to measure the perpendicular on the roof element, and at the point of intersection of the log and the beam, a place for attaching the support is obtained.

Hinged ridge design

To prevent the rafter legs from moving apart, the rafter beam must have one or more support points in the middle, on the ridge or next to it. When the walls are deformed, the angle of articulation of the rafters in the ridge may also change. To prevent the roof plane from bending, a sliding (hinge) connection is also used in the ridge.

The ideal “sliding” rafter system. The ridge rests on the central wall. A hinge made of metal plates connected by a tie is much more reliable than a conventional bolt.

Other uses of sliding supports

A sliding support can be used wherever it is necessary to ensure the movement of elements of wooden structures. In particular, when installing partitions and linings in wooden houses. For example, in the bathroom of a wooden house it is planned to decorate part of the wall with ceramic tiles. To do this, it is necessary to sheathe the wall with sheet material (gypsum fiber board, gypsum plasterboard, OSB), having previously made a frame. Moreover, the frame must be “floating”, because the walls can settle over time and undergo seasonal deformation. If the lining is not extended to the ceiling, and the frame posts are secured to the wall on sliding supports, the problem is solved.

Gone are the days when towers were erected without a single nail. The architects of wooden architecture did not use fasteners in the form of those elements that are relevant in modern construction. However, the study of the foundations and principles of ancient architectural heritage led to the invention of reliable connecting elements for arranging the roof of a wooden or brick house or log house. These include, in particular, sliding supports for rafters.

Effective fasteners for wooden roofs

The invention of an effective support for fixing rafters to a load-bearing structural element, a mauerlat, or a ridge, greatly facilitated the work of roofers. The roof frame consists of many elements of different functional purposes, interconnected. A wooden frame changes under the influence of natural conditions, it can become 15% lower due to shrinkage, it can swell from rain, and dry out in frosts. The geometry of the walls of the house also changes, unevenly and in all seasons. The heating season, the rainy season, and the summer drought undoubtedly affect the condition of the wood, especially if the house has five walls.

Sliding support for rafters is a fastening element that prevents deformation of the roof, preserving its original reliability and strength. The monolithic rigidity of the rafter system, which occurs when fastening with staples, nails, and self-tapping screws is used, under the influence of vertical and horizontal loads leads to either sagging or arching of the roof, deformation that cannot be eliminated by simple repairs. Fastening with a sliding support provides play for moving the rafters relative to the beam or mauerlat. That is, rafter slides, as they are popularly called, provide compensation for roof distortions caused by changes in its geometry during drying, swelling and other processes.

Advantages of using a crawling structure

The sliding supports used to fasten the rafters provide, first of all, a reliable connection between the base of the structure and the roof. Provide the ability to move wooden roof structures while maintaining the strength and tightness of the structure. Other advantages that are typical for supports for rafters of this type:

• simplicity of the device;
• reliability of fasteners;
• ease of use and installation;
• durability;
• low cost.

A log house, with a rafter structure assembled using sliding supports, the surface of which is treated with an anti-corrosion compound, can stand for at least a hundred years in any area with any climatic conditions, winds, frosts and high temperatures, without losing its strength and suitability for habitation.

Features of fastening rafters in a wooden house

Rigid or beam support during the construction of a roof structure is especially not desirable in a wooden structure. The inevitability of changes in the geometry of the rafters under the influence of moisture requires the creation of the ability to move the rafters along the support. Sliding rafters in a wooden house provide reliable fastening and free movement of the rafter beam at the junction with the support.

Wooden houses are subject to shrinkage to varying degrees. The degree of shrinkage is determined by the material from which wooden houses are built:

• beam;
• laminated veneer lumber;
• simple chopped log;
• rounded log.

The highest degree of shrinkage is characteristic of houses made of solid wood; laminated timber is the least susceptible to deformation. The gain or loss of moisture in wood leads to a change in the geometry of the rafter system, and this process is characterized by unevenness and multidirectionality. A special fastening design at the connection points of the rafter legs with the support using a device that allows the roof to move while maintaining its geometry ensures the integrity and reliability of the roof.

Types of sliding supports

A movable, sliding fastening of the rafters to the base is the only possible way to prevent roof deformation. All such crawling supports have the same design principle. They consist of a fixed base, which serves as a guide, and a movable element in the form of an angle that crawls along this base under the influence of longitudinal or transverse load.

Support for rafters is:

1. Open type;
2. Closed type.

It is believed that an open type support, a collapsible fastening device consisting of a stationary guide, which is mounted to the rafter leg and a crawling angle, with fastening to the Mauerlat, is much more convenient to install. Its use will not cause any difficulties even for a novice roofer. It has varieties according to the number of holes for fastening and the stroke size from 60 mm to 160 mm. The maximum value of this parameter is more effective, as it provides better rafter mobility.

The support for closed rafters is distinguished by the fact that it is non-removable. The monolithic one-piece structure of the device is mounted in assembled form in the same way as the open-type support described above. The corner is attached to the Mauerlat; it is equipped with a loop through which a guide attached to the rafter is threaded. Obviously, extreme precision is required when installing a closed support; precise dimensions and calculations are required. On the other hand, fastening with a closed type support ensures the most efficient operation of the roofing system.

Separately, it is worth highlighting the popularity of such a name for a roof fastening element as a sliding support for rafters kucis. Depending on the model, it has a stroke length of:

• 60 mm;
• 120 mm;
• 160 mm.
  Kucis is manufactured from low-carbon steel 08PS in accordance with GOST 14918-80 for perforated elements. The sliding support has high strength characteristics and can withstand heavy loads. Its standard sizes:
• at least 2 mm thick;
• width – 40 mm;
• in height – 90 mm.

The length dimensions provide a rafter stroke range of 60 mm - 160 mm.

Floating or sliding technology of the rafter system

The development of modern architecture and the creation of extraordinary, striking examples of individual housing construction have led to the birth of new technologies. The construction of a roof, a protective dome of a house from the vagaries of nature, is an important stage of construction that determines the comfort of life. Therefore, to create complex roofing systems that use floating rafters, or sliding rafters as they are also called, precise calculations are required. Calculations should reflect the angle of inclination, the volume of roofing material, and other components of a particular type of roof.

Sliding (sloping) rafters are used for the following types of roofs:

• attic;
• tent;
• hip and half-hip;
• multi-forceps complex;
• spire;
• domed.

That is, complex types of structures that need to be calculated. This is a job for specialists; amateurs have nothing to do in these matters; even an online calculator will not help in determining the basic volumes of roofing material.

The sliding support of the rafters is connected to the Mauerlat, and at the top rests on the ridge girder. The sliding rafters are connected to each other by a knot, the angle of which can vary depending on the subsidence under load, so they do not slide off the roof, but slide a certain distance under load, keeping the entire roof structure intact.

The basis of a wooden roof of a house is a frame that holds the roofing covering on itself. It contains a large number of elements, each of which is necessary and intended for a specific function. One of them is a sliding support for rafters, which serves to prevent deformation of the roof during shrinkage of a wooden house when its geometry changes.

Shrinkage of a wooden house

In one year, the log house can become lower by 15%. The average shrinkage is 8%. However, it can occur unevenly, which negatively affects the condition of the rafter system. The size of the wooden structure changes all year round. During the rainy summer season, the wood swells, and in winter the material dries out. In addition, walls gain and lose moisture in different ways, depending on the lighting and wind rose. If there is support on the central load-bearing wall, the deformations between it and the outer walls are significantly different, which also affects uneven changes in the geometric dimensions of the house. During the heating season, the walls, especially the central one, decrease in size due to drying out.

If there is no central wall, even greater problems can arise. If the rafter system is not assembled as a truss, its rigidity is significantly lower. As a result, not only vertical but also horizontal loads act on the walls. Under the influence of pressure, they can bend outward, and the house in plan will take the shape of a barrel. In this case, the roof is deformed and sag at the ridge. "Pyatistenka" allows you to get rid of this problem or significantly reduce it.

Application of screw jacks

To compensate for settlement processes and seasonal movements of the house, screw jacks can be installed. They should be located on all vertical supports in the house. By tightening the jacks, the movements of the log structures are compensated for.

Purpose of using sliding supports

It is not always advisable to rigidly fasten it to the Mauerlat or to nails, staples, etc. If the frame of the house can shrink, it is necessary to create the opportunity for the rafters to move relative to the supports. Previously, this was done using forged wire, which created a connection with a certain degree of freedom of parts of the structure.

Since then, technology has changed, and more advanced devices have been used, such as sliding rafter supports. It is attached to the walls as follows:

• to the upper crown of the log house;
• to the top frame of the frame structure;
• to floor beams;
• to the Mauerlat.

Why are the supports made sliding?

The sliding support makes it possible to compensate for distortions of the roof frame during its operation. When wood dries, the geometric dimensions of structures change. At the same time, the width of the house decreases, but due to sliding along the floor beam, sagging or expansion of the roof, leading to subsequent leaks, does not occur. The reason for precipitation getting inside may be different, but the influence of deformations from shrinkage should never be underestimated.

Advantages of sliding supports

• Creating a reliable connection between the base and the roof.
• Ensuring mutual movement of wooden structures during shrinkage of the base, maintaining the strength and tightness of the roof.
• Simplicity of the device, reliability and durability.
• Low cost and the ability to make it yourself from scrap materials. In this case, the steel plates must be at least 2 mm thick and protected on top with an anti-corrosion coating.

Design features of rafters

A pair of gable roof rafters is made according to one sample. The connection in the ridge is made end-to-end, with a gap or overlap. The rafters are connected to each other by a metal plate with bolts and nuts. The main design feature is the creation of sliding fasteners in the lower supports. The rafters are placed on the Mauerlat on top or with a mortise to fix the structure in a vertical plane.

The sliding support for the rafters, which serves as a fastening element, is made of two parts:

• strip fixed on the rafter leg;
• a corner with a loop attached to a supporting beam (mauerlat or support beam).

There is an even simpler option for how a sliding support for rafters can be made (photo below). For this, a corner with a slot is used. It is mounted on the rafter along its axis, and in a slot with a gap there is a bolt head screwed into the body of the Mauerlat.

This support for rafters (sliding - Kucis 120x40x40) costs only about 25 rubles apiece and is easier than others to install.

The devices are made of galvanized steel plates. They are attached to one or both sides of the rafters. The double-sided option is preferable for roofs with high wind and snow loads and low weight of the roof structure. Fasteners are used with an anti-corrosion coating so as not to damage the wood. The stroke length depends on the expected displacements and ranges from 6 to 16 cm.

Open and closed supports

Open-type sliding supports for rafters (“sliders”), consisting of two parts, can be made with your own hands, but you should use a template. All parts must be adjusted to size. An open connection consists of a curved plate (mounting strip) and an angle with holes for fastening (at least five).

When closed, the bar is inserted into the corner holder with the ability to move, but cannot be removed from it and is non-removable. The assembled structure allows for higher quality installation. If forces arise to separate the rafters from the mauerlat under the influence of wind loads, the loop can unbend, and the closed sliding support of the rafters has greater strength.

Important! It is advisable to make a rafter system with the ability to slide relative to the base only for a symmetrical gable roof. This is its advantage, since it increases reliability at low cost. The supports can also be used for a pitched roof.

for rafters: dimensions

The support includes two components - a guide plate and an angle. The amount of permissible movement of the rafter leg depends on the size of the product.

The popular sliding support for Kucis open and closed rafters has a plate width of 40 mm, a support height of 90 mm, and a length of up to 160 mm. The metal for the plates is taken with a thickness of 2-2.5 mm. They are cold-formed from low-carbon steel with good ductility. Hot zinc coating provides protection against corrosion. When purchasing uncoated products, they should be painted so that the material does not rust.

The corner is attached to the support beam. If its surface is round, prepare a flat area for installation by grinding the wood on a log to the size of the L-shaped part of the part. The photo below shows a similar sliding rafter support closed (Paz). Both types of products are made by stamping and are inexpensive.

The guides are attached to the rafters in the extreme position to provide maximum movement. Since the angle of inclination relative to the ridge changes when the roof shrinks, it is necessary to make a hinge in the upper part of the rafters. Special perforated plates can be used here.

Installation

A sliding support for rafters when installing a roof frame is used as follows.

• Rafters are made of boards 150-200 mm wide and 50 mm thick. If the length is insufficient, the rafter leg is lengthened by adding an overlap with a chaotic arrangement of fastening elements to prevent cracking.
• A purlin is installed on top - a load-bearing beam located horizontally and perpendicular to the sliding rafters.
• In the lower part, the rafter legs are fixed on cuts made in the Mauerlat. In this case, their jamming is not allowed. But at the same time, the cuts should keep the boards from lateral distortions. The presence of a Mauerlat evenly distributes the load across the entire building. In its absence, the local pressure on the walls from the rafters becomes greater.
• Fasteners of suitable sizes are selected depending on the range of rafter displacement.

• A platform is prepared for the corner on the support log.
• The angle is attached perpendicular to the log to ensure free movement of the plate.
• The guide is inserted into the loop of the corner and attached to the rafter along its axis. Installation is done in the lowest position, since the wall below will shrink and decrease in size. In this case, the rafter leg will move down.
• The rafter boards are connected at the top in a hinged manner.

Conditions that guarantee the strength, reliability and durability of the roof

• Compliance with the necessary mechanical properties and dimensions of sliding supports for rafters.
• The location of the guide support is parallel to the axis of the rafter, and the angle is perpendicular to ensure reliable sliding.
• The cross-section of the boards for the rafters should not be less than 150x50 mm.
• The roof frame must be treated with an antiseptic and fire-resistant compound.
• Maintaining the correct proportions of the roof frame.
• Manufacturing of the entire rafter system according to the template.
• Creating a hinged ridge connection.
• The extension should be done alternately in the lower and upper parts.

Sliding support for rafters: application for other purposes

Wood shrinkage compensation is not only used on roof frames. It is used wherever it is necessary to create the ability to move parts of wooden structures, for example, when constructing partitions in wooden houses. If you need to decorate a bathroom wall with ceramic tiles, you cannot simply cover it with sheet material.

It is necessary to install a “floating” frame, fixed on top with sliding supports, and then attach drywall to it, on which the tiles will be glued. Moreover, the sewing is not done all the way to the ceiling. When the walls deform, the frame will remain motionless and the cladding will not collapse.

Conclusion

Sliding supports for rafters in wooden houses are necessary to prevent the roof from deforming when the house shrinks. It occurs especially actively in the first years after construction (about 8%). Correct installation of the rafters will ensure the constant tightness and strength of the roof.

A sliding support for rafters is a necessary part of the frame of any roof with inclined slopes.

Sliding supports or slides are a kind of fastener that allows the rafters to slide along the crossbar on which they are attached.

This is necessary so that during the shrinkage of the house the rafters do not get torn out “with meat”.

Application area

Over time, the building shrinks. This process is uneven - some walls shrink faster, others slower.

This leads to a change in the angle of inclination of the slopes. These changes must be taken into account at the stage of installing the roof. Sliding supports allow the rafters to be movably secured.

Sliding holders attached to the skates allow the rafters to rotate relative to the crossbar on which they are attached.

It is more difficult to create a movable connection at the heel of the rafters, since this part must be able not only to rotate, but also to move parallel to the wall.

If the rafters are fixed motionless on a building prone to shrinkage, then after some time these roofing elements will deform, which will lead to the destruction of the entire structure.

By providing the rafters with at least a slight rotation and the ability to move along the wall, you can get rid of this problem. It is important that the rafter holder does not lose its strength.

Previously, rafters were secured in a sliding manner with burnt wire, which was simply tied to the rafter leg to the crossbar.

The wire secured the rafter and at the same time allowed it to move a few centimeters.

Now, for the same purpose, sliding supports for rafters are used - industrially manufactured hardware.

Such fasteners are more convenient to install and stronger than wire. It is securely fixed to the Mauerlat or ridge.

If the parts of the rafter system are made of laminated veneer lumber, then sliding supports become the only way to securely secure the rafters.

The holder is fixed to the area along the displacement of the crossbar. To do this, a small area is ground off on the timber. The stationary part of the holder is fixed to the resulting flat area.

Sliding supports are installed on both sides of the rafter; on flatter roofs it is permissible to use one fastening for each rafter.

In a layered system, sliding holders are fixed to the mauerlat, ridge and intermediate supports.

Sliding bearings can be divided into two types.

Open - such a holder consists of two parts: a guide and the mount itself.

The guide is fixedly fixed to the rafter - this part is a curved metal plate, at one end of which there are holes for threaded fasteners.

The guide includes a movable part of the sliding support, which is called the “angle”. He should be able to move along the guide at a distance of 6 to 16 centimeters.

The closed sliding support is installed assembled. There is a holder hole on the corner - a bar is inserted into it and both ends are fixed to the rafters motionless. In this case, the rafters will be able to move both left and right and up and down.

Manufacturing of sliding supports

Roofing fasteners are used in unfavorable conditions. In some cases it comes into contact with water. It may be exposed to condensation formed in the under-roof space.

Therefore, sliding supports are made of durable metal - alloy steel - and coated with an anti-corrosion zinc layer with the addition of alloying substances that increase the corrosion resistance of the coating.

Strong and reliable hardware increases the load-bearing capacity of the rafter system.

The sliding holders themselves are made by cold stamping from steel 08 PS. The low carbon content in the metal allows for high-quality stamping of products. To increase strength, the part is deoxidized.

If the fastener does not have a galvanic coating, then it must be coated with a layer of oil paint before installation.

General rules for the operation and installation of sliding rafter systems:

• sliding rafter systems can be installed on a building of the correct geometric shape;
• there are moving parts in the system, therefore, before the installation of the roof begins, the perimeter of the box is measured and checked for compliance with the project;
• the rafters themselves are made according to the same template - this allows you to get the same parts;
• in sliding rafter systems, the moving unit is usually made on the mauerlat, and sometimes also on the ridge ceiling;
• to create movable units, studs and screws are used as connecting axes;
• long spans are covered with extended lumber, and the connection is made overlapping using brackets or self-tapping screws;
• when building lumber, mounting holes are made in them in advance;
• the distance from the mounting holes to the edge of the board is at least 10 centimeters;
• to ensure the strength of the connection, holes are drilled in a chaotic manner;
• each support of the sliding rafters is installed parallel to the previous one and at an angle of 90 degrees to the supporting beam - this will provide protection against jamming of the moving elements;
• sliding supports are fixed perpendicular to the rafter;
• the sliding support is attached with nails or self-tapping screws with an anti-corrosion coating;
• the length of the rafter stroke in the support must correspond to the calculated value of the displacement of the walls during shrinkage;
• insertion into the Mauerlat cannot be made deeper than 1⁄4, so as not to weaken this most important part of the rafter system.

As a rule, sliding supports are available in the following sizes (in centimeters):

• 9x9x4;
• 12x9x4;
• 16x9x4;
• 27x9x4.

Hinge rafter joint over ridge log

There are several ways to secure rafters to a ridge log:

• end-to-end;
• overlap;
• on a chase and/or ridge beam.

When fastening end-to-end, it is impossible to make a sliding fastening of the rafters. The upper ends of the rafters rest against each other and are fixedly fastened with metal plates that will not allow them to move.

When fastening the rafters to the purlin, they are not only fastened end-to-end over the ridge, but are also placed in the cut on the ridge beam and purlin, that is, the rigidity of the rafter fastening increases.

If the rafters are attached to the ridge beam using the end-to-end and purlin methods, then a sliding support is installed at the junction of the rafters with the mauerlat.

You can do this in one of the following ways:

• make a cut on the rafters and lay them on the mauerlat;
• connect the elements obliquely with two nails;
• secure with one nail, driving it from top to bottom into the Mauerlat through the leg;
• use steel plates with holes instead of nails;
• secure the leg to the Mauerlat using a bracket;
• release the rafter leg beyond the wall and secure it with a fastening plate;
• use special fasteners - slides.

All these fastening methods will allow the rafter to rest on the base beam, but when moving the frame elements, the parts of the rafter system will be able to move, which will prevent subsidence and deformation of the roof or the upper part of the walls.

For a movable connection, the overlap method is suitable. In this case, you can use a hinged connection rather than sliding supports.

The rafters above the ridge beam are connected not by their ends, but by their sides and are fastened to each other with a bolt or pin, which allows them to move relative to each other in the vertical plane.

Step-by-step algorithm for installing sliding elements on the Mauerlat:

1. in the upper part of the mauerlat, cuts are made with a depth of approximately one quarter of the height of the beam;
2. a rafter leg is inserted into the cut - it must fit firmly into the gap prepared for it;
3. to the right and left of the rafter leg are secured by open-type sliding supports, one on each side;
4. First, the guides are secured by screwing galvanized screws into the holes located at the ends of the part.

Important: the guides are not screwed to the top or side plane of the Mauerlat, but to its edge. To do this, the edge is first cut off so that a flat area is formed in place of the right angle.

The sliding support is secured on the other side of the leg in the same way. That's it, the movable rafter assembly is ready.

When working with a power tool, it takes no more than three minutes to secure one sliding support, and ten minutes to install the entire moving unit, including working with an electric saw.

What happens if the rafters are fixed motionless in a building subject to shrinkage? The consequences for the building will be the most dire. The shape of the deformation will depend on the type of roof.

For example, with a gable roof, after the facade and pediment shrink, a through gap is formed between the wall and the roof, into which a hand can easily pass.

But it’s even worse if the side walls settle - in this case, the slopes will acquire a concave position and the entire roof will have to be redone again to return it to its normal appearance.

Sliding rafters allow the roof frame to sag simultaneously with the shrinkage of the gables, which helps keep the walls intact.

Sliding fasteners designed for rafters can be used not only in roofing work, but wherever movable joints are required: in the construction of wooden partitions, finishing the walls of wooden houses with tiles, etc.

The mobility of roof fastenings is used in the construction of multi-pitched roofs made of materials that shrink.

First of all, we are talking about the wooden elements of the roofs of wooden houses.

Connections with several degrees of freedom allow you to create a balanced design.

Despite all its mobility, it must be strong so that it can be used in areas with soil fluctuations, as well as where there is a harsh, snowy and windy winter.

Purpose of moving connections

Wood shrinkage, which occurs for natural reasons, is the main reason for the misalignment of the entire roofing system.

Minor deformations will occur in any case.

They are mainly associated with seasonal weather changes.

So, for example, when the heating is turned on (this is usually 5-6 months in a row), the walls of a wooden house are subject to shrinkage more than in warm, dry weather.

In this case, the central wall is more likely to settle than others.

And this is due to a decrease in its volume with loss of humidity.

Noticeable deformation occurs during the rainy season (mainly in autumn) and during the cold season (winter).

In autumn, constant high humidity leads to an increase in the volume of walls.

In winter, the walls dry out due to minimal humidity, reaching almost their minimum size.

If the rafters are rigidly attached to the wall, the deformations of the wooden house will in any case be transferred to the roofing system.

And then, a measured and clearly calculated roof (except, of course, for the mobility of the joints) will shrink in the center.

Another possible option is that bumps, irregularities, and noticeable depressions will appear along the entire plane of the roof.

Not only will such changes negatively affect the condition of the entire house, but it is also impossible to eliminate the defects without completely dismantling the roof.

Therefore, in order to avoid such a negative result (the investment of money during construction is practically the same for both sliding and monolithic supports), it is best to equip the system at the points where the supports are attached to the walls with elements that can move slightly.

When creating a roof project, you need to rely on what kind of house it will crown, as well as the area in which it will be used.

Any movable support has a fixed frame of movement.

Features of sliding joints

It is advisable to use sliding joints in places of high humidity, as well as when condensation forms when water gets under the roof slopes.

Any wooden house will change its physical properties for several years after construction.

In any case, it is necessary to make a gash on the rafter leg so that it fits tightly into the mauerlat (for information about what shape and depth it can be, read the section “Installing sliding joints”).

More about .

The answer to the question of which is better: ondulin or metal tiles can be found at. How to compare which is cheaper and how to finally choose.

About the design of a hip roof - a beautiful and elegant design. Calculation of a hip hip roof, photographs of the varieties of these roofs.

The rafter junctions require a certain freedom of movement.

This can be achieved in three ways:

1. On the sides of the leg, long nails are driven into the log.
2. You can drive one large nail on top.
3. For fastening, it is sometimes advisable to use metal brackets or plates.

Whatever the method of fastening, the rafter must be extended to the required length beyond the wall.

The sliding joint gains the ability to move due to its design features.

Types of moving connections

The method of fastening the main structural elements of the rafter system varies depending on the type of system.

The fastening elements themselves are made of low-carbon steel, hot-dip galvanized.

All sliding joints that can be used in modern construction are divided into two types:

1. Open connections.
2. Closed connections.

For complete fastening of movable joints, it is important to determine the uniform distribution of the load on the walls of the building.

It is necessary to take into account the weight of the rafters and the total weight of the entire roof.

Open connection

There are only two open elements here.

The first is the guide, which must be attached to the rafter leg.

The guide is a steel plate, curved and having holes at the edges.

There may be two or three at each end.

The stroke length of the moving element has a minimum value of 60 millimeters and a maximum of 160.

An angle is a fixed part of an open type sliding joint.

It can have a maximum of five holes.

Closed connection

A closed sliding joint cannot be disassembled into individual elements.

This is only a monolithic single structure.

Its installation on the roof is only possible in assembled form.

The fixed part of the system is made in the form of a corner.

Its long side has a holder into which the fastening bar is threaded.

If logs and boards, theoretically, can be prepared independently, it is best to buy rafter connections ready-made, in quantities determined for high-quality roof installation.

Photos of sliding supports for rafters

Purchasing connection elements

The roofing system, like all other construction elements, must be calculated in advance.

To select elements, it is worth knowing that the percentage of shrinkage of logs in a wooden house, where the beams have a diameter of 195 millimeters, is 6%.

This indicator is accurate for the first year of operation.

Over the next 3 -5 years it will be 2 - 4%.

To select sliding joints, it is worth determining:

• what is the approximate weight of the entire roofing covering;
• expected snow and wind loads on the roof.

These indicators are enough for selection.

They are attached to each rafter.

The average price for one connection is 100 - 180 rubles.

You can buy these elements in construction stores or at construction bases.

There are also Internet resources that sell products online, including those for roofing.

Naturally, it is also possible to purchase sliding joints there.

Installation

Sliding supports are two parts: a guide and a bent plate.

During operation, the guide slides within the bent plate.

A priori, they must be mobile.

But it is important that it does not come off the mauerlat (load-bearing log) under any load on the roof.

Sliding joints are always attached perpendicular to the rafters.

Therefore, the cut in the beams should be made at an angle of 90° to the rafters.

The design features of the installation of sliding elements are as follows:

1. A semicircular cut is made on the support of the rafter leg.
2. One or two spikes are installed (the number depends on the angle of the roof), which relieve the load from the entire rafter system.

There is another way to attach sliding joints.

Special cuts are made in the load-bearing log to 3/4 of its diameter.

This creates small friction over a large area, which makes it possible to hold a heavy structure in strong winds and under heavy snowfall.

This method of fastening sliding joints is advisable when the roof slope is small, as well as when intermediate supports are required for additional fastening.

Installation of the sliding system can be done with self-tapping screws.

The roof, which contains sliding joints, must be correct and geometrically correct in shape.

Installation of rafters should take place only after checking the perimeter of the objects and its compliance with certain dimensions.

All rafters must be the same size.

This will make installation much easier.

And minimizes the “fitting” of elements.

Using movable joints, not only rafters and walls are attached, but also ridge joints.

True, there are slightly different elements here, but the principle of operation is very similar to sliding joints.

To prevent jamming of the moving systems, each support of the sliding rafters must be secured parallel to each other and perpendicular to the supporting mauerlat.

Operation of roofs with movable joints

You can streamline the physical, natural processes during the operation of a wooden house with a wooden roof by installing a roof with elements of a sliding system.

The wall located directly under the ridge is more susceptible to subsidence.

And smaller - the outer, outer walls of the house.

A properly designed roof of a wooden house can withstand significant snow loads (up to a one and a half meter snow layer), provided that movable joints are present in all structural connections.

Twice a year (after winter and before it) it is worthwhile to inspect the connecting elements of the system.

This will ensure that the system not only has not lost its strength, but also remains strong.

If any screws come out of the holes, it is better to tighten them or completely replace them.

The roof of a wooden house with a sliding joint system should not be insulated inside.

Firstly, this will enable the elements of the system to fulfill their purpose.

Secondly, this will make it possible to inspect the connecting elements.

Sliding support for wooden rafters can be used in the roofs of wooden houses that are operated in more severe climatic conditions.

A properly designed system will enable the roof to be strong and withstand large amounts of snow, as well as soil vibrations and strong winds.

Moreover, the installation of such a system practically does not increase the cost of the entire roof.

Video about the sliding connection of rafters.