Floating rafters for the home. Sliding support for rafters - how to attach it correctly. How to use sliding rafters

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

First of all, we're talking about O wooden elements roofs 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 natural reasons- the main reason for the misalignment of the entire roofing system.

Minor deformations will occur in any case.

They are mainly associated with seasonal changes weather.

So, for example, when the heating is turned on (this is usually 5 - 6 months in a row) the walls 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”).

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The rafter junctions require a certain freedom of movement.

This can be achieved in three ways:

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

Whatever the method of fastening, the rafter must be released to desired length beyond the wall.

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

Types of moving connections

Method of fastening the main structural elements 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:

Connections open type.
Connections closed type.

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 total weight 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, rafter connections best to buy from finished form, in a specific way for high-quality installation roofing quantity.

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:

A semicircular cut is made on the support of the rafter leg.
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

Streamline the physical, natural processes during the operation of a wooden house with wooden roof possible when 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 connection 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 correctly calculated system will enable the roof to be strong and withstand a large number of snow, as well as ground 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.

Sliding support for rafters allows you to adjust distortions truss structure, which are formed due to shrinkage of wood during application. The sliding support helps to fix the rafter to the supporting element of the beam, making the product stable, strong and balanced. Builders also use a sliding support to connect loose components together with a fixed base.

The advantages of arranging slides are:

easy installation process that does not require professional knowledge and the use of expensive equipment;
minimizing the cost of hiring builders when arranging the roof, because there is no need to manually balance the roofing system.

Among the disadvantages, experts highlight the susceptibility of rafter supports to influence weather conditions, atmospheric precipitation. Therefore, it is necessary to properly treat the “legs” with a zinc alloy, which increases strength and reduces corrosion properties. This, in turn, allows you to achieve good load-bearing capacity of the product.

Why use a sliding rafter support?

A sliding support for rafters is attached to the mauerlat if it is necessary to erect timber or log structures. As a result, you will not have to deal with sagging roofs and expanding walls of a house made of wood.

Over time, all wooden houses or parts thereof shrink. To avoid weakening and the occurrence of distortions, a sliding support is used, consisting of a bracket equipped with metal and an angle with a loop.

The dimensions of the structure are approximately:

thickness is 2 mm;
the width is fixed at 40 mm;
height reaches 90 mm;
length varies from 90 to 160 mm.

The rafter bears the heaviest load, so the supports are made of durable and reliable material. According to GOST, it is desirable to use low-carbon steel sheets of 08 PS format in production.

How are slippers made?

Buildings are susceptible to shrinkage where prevailing high humidity, temperature changes, the building is in constant contact with condensation or liquid that has penetrated under the slope of the roof material. If the sliding support were made of wood, it would rot and collapse, so today manufacturers create the device exclusively from metal.

During the research, many technologies were studied and tested, but cold stamping turned out to be the only effective one. Low-carbon steel makes it easy to process the material, and its strength properties are significantly increased thanks to the deoxidation method.

Types of slippers

Experts note 2 main types of sliding supports:

Open format - assumes 2 separate parts in the form of components. There are holes on 2 sides of the guides - 2 or even 3, in this case the number depends on the technology adopted by the manufacturer. The difference is also in the stroke size of the moving element - 60 and 90. If we consider the supporting part of the angle, the maximum number of holes can be 5.
Closed system - takes the form uniform design. The plate is attached to the log by cutting a notch, and its width should correspond to the width of the L-shaped area of the sliding fastener. Otherwise, the movement of the parts will be slow, and friction will cause kinks or damage.

Properties of sliding support for rafters

Experts note that a high wall of a house gives a higher percentage of shrinkage, which cannot be said about low parts. In order for the rafters to support the building, and also not to provoke bevels of the walls, which, on the contrary, are devoid of rafters, the following measurements must be made:

The rafters fixed in the ridge must rotate relative to each other. The fastener consists of fixing metal plates on studs.
The lower part of the rafters cannot be fixed to the wall, otherwise the wall structure will warp and stick out.

This problem is solved by a sliding support for rafters, a photo of which can be seen below. The fasteners are placed along the offset of the beam device, for which the wood in the upper part of the beam is ground down. At the exit, a platform should be formed, where the fixed element of the support is fastened from below. During installation, ensure that the shifting power reserve is as large as possible.

Ideally, the sliding support takes its proper place on both sides of the rafter leg, but in some cases only 1 device can be installed.

An alternative to movable fasteners can be another way to level out shrinkage, which builders successfully use when working with wooden houses and buildings. This is a ridge connection that allows parts to move much more convenient option compared to the old way use twisted wire.

Step-by-step installation guide

Sliding supports can be mounted on the timber gables of a building, because the ridge run is fixed in the body of the gable. This trick will prevent the possibility of wall structures expanding due to a change in the angle of the roof after shrinkage.

A strong and reliable connection is achieved by using perforated plate devices that are connected to each other by pins. You can get by by laying the rafters on the rafters at the top of the “legs” and then securing them achieved result studs with nuts and washers.

What features should you pay attention to during installation?

First, let's define what a Mauerlat is. This is the crown of the log house, running along the top; it is precisely fixed to the rafter “legs” with the help of sliding supports. They are made from galvanized steel in sizes 90×90×40, 120×90×40, 160×90×40, 270×90×40, measurements are presented in millimeters. The length depends on the possible displacement of the rafter legs.

In order for the installation to be completed successfully, it is necessary to fix the guide line of the support parallel to the rafter leg. The corner, in turn, is fixed at the top, following the perpendicular to the leg, which ensures the ability to move even with the longest shrinkage length.

The supports are attached to the Mauerlat in one of the following ways: by placing them on top or by cutting them into the body of the Mauerlat. The insertion depth cannot exceed the established ¾ of the diameter of the timber or mauerlat log. If the stated depth is increased, this may cause the roof structure to weaken.

Ideally, for the production of the rafter part, you need to use boards whose cross-section reaches 200×50 mm or 150×50 mm.

Subtleties of operating a roof with moving parts

Upon completion of installation, it is important not to lose sight of the condition of the connecting elements - verification is carried out 2 times a year - upon completion winter period and in front of him. The inspection will help determine whether the structure has lost its strength and strength. If you can see screws coming out of the holes, it is advisable to screw them in deeper or replace them altogether.

Please note that a roof with a connecting system does not imply insulation from the inside, and all because:

as long as the sliding support can properly perform its functions;
nothing prevents the audit from being carried out.

Sliding support for rafters: photos, dimensions, design features

Sliding support for rafters: photos, dimensions, design features Sliding support for rafters allows you to adjust the distortions of the rafter structure that are formed due to shrinkage

Sliding support for rafters: design features

Sliding support for rafters is used when constructing roof structures on wooden buildings. This type of fastening allows you to avoid deformation of the roof due to natural changes in the geometry of the frame during the shrinkage process.

The need to use sliding supports

Rigid fastening of rafter legs to the mauerlat or floor beams using nails, staples and other fasteners is not always justified. If the building frame is prone to shrinkage, it is recommended to allow the rafter legs to move relative to the support. Traditionally, twisted forged wire, which is tensile strength, was used for this. With its help, a reliable connection of the rafters with the upper crown of the log house was ensured, while a certain degree of freedom of the structural elements was provided. Today, for this purpose, a specially designed fastening element is used - a sliding support, this type fasteners are easy to install, reliable and durable.

Free movement of the rafter beam at the point of attachment to the support (floor beams or mauerlat, the function of which is performed by the upper crown of the frame) is necessary, first of all, when building wooden houses. Shrinkage rate building structures depends on the material from which they are made and the degree of moisture in the wood.

Glued laminated timber is least susceptible to shrinkage; solid wood walls are much more deformed natural humidity. A log house placed under a roof can become 15% lower over the course of a year.. It should be taken into account that shrinkage usually occurs unevenly, as a result of which the rafter system, rigidly fixed to the mauerlat or floor beams, can be seriously deformed.

Roof skew can also occur during the operation of the structure. High humidity in the rainy season it causes the wood to swell, and in winter time wood material naturally loses moisture and dries out noticeably: geometric dimensions log houses are constantly changing. At the same time, the walls of the house differ in the rate of moisture gain or loss depending on the degree of sun illumination and the wind rose. If the log house has a central wall on which the floor beams or racks rest ridge girder, it should be taken into account that this wall is also subject to temperature and humidity deformations, and the amplitude of its changes is very different from the indicators external walls– when the house starts to heat up, the central wall dries out greatly.

If you rigidly fasten the rafters to the mauerlat (upper crown) of a four-wall wooden frame, then the load (including snow) can cause the upper logs of the walls to bend outward due to horizontal pressure. Another problem should be taken into account: if the material for the rafters has not been subjected to mechanical drying, the length of the timber (boards) will decrease when dried. In this case, when the rafter legs are rigidly attached to the frame, the roof will noticeably deform over time, which will affect its performance characteristics.

Such difficulties can be avoided by the special design of the fastening points at the junction of the rafter legs with the walls. Special fasteners allows the roof to move without changing its geometric parameters.

Sliding support: design features

Sliding support allows for secure fixation rafter leg on the mauerlat or floor beam, leaving it the opportunity to move a certain distance along its own axis. This fastener consists of two parts:

guide ( metal strip, which is attached to the rafter);
corner with a support platform (mounted on a floor beam, mauerlat or upper crown).

At the top of the corner there is a loop that fits onto the guide. This constructive solution leaves the rafter beam a certain degree of freedom in one direction and over a strictly limited distance, which is determined by the length of the guide.

There are two types of sliding supports: open and closed. The open type design consists of two individual elements. The steel curved plate (guide) is equipped with two or three mounting holes at each end. The fixed part (angle) can have up to five holes in the support area. The length of the fastening stroke depends on the model and can be 60-160 mm. The most popular options include Kucis brand sliding bearings with stroke lengths of 90 mm, 120 mm and 160 mm.

The closed sliding support is a non-demountable structure that is mounted fully assembled. Its fixed part is a corner, on the long side of which there is a holder into which a fastening strip is threaded.

The sliding rafter support is designed for use in difficult conditions: the structure is subjected to high loads and moisture due to contact with condensation or water trapped under the roof slopes. To make the sliding support, steel is used, the thickness of which must be at least 2 mm. The width of the plates is usually 40 mm, and the height of the corner is 90 mm.

Typically, the raw material is low-carbon steel - due to the low percentage of carbon, the metal is easy to process. To increase the strength characteristics of the product, the deoxidation method is used. Products are manufactured using cold stamping technology. Protection of the material from corrosion is ensured by hot-dip galvanizing, which helps prevent premature failure of the fastening.

In the absence of a factory galvanic protective anti-corrosion coating, it is recommended to apply a layer to the sliding support before installation. oil paint to protect the material from rusting. To install sliding supports, it is necessary to use self-tapping screws that are resistant to corrosion - fasteners without a protective layer will quickly fail and cause the destruction of the roof.

Installation of sliding supports

Supports for wooden rafters can be installed in pairs (on each side of the rafter leg), or one at a time. The second option is used if construction is carried out in a region with low snow and wind loads, and the mass of the roofing structure is relatively small. In other cases, it is recommended to install fasteners on both sides of each rafter.

If the rafter leg is mounted not on the mauerlat or floor beam, but on round log upper rim, a flat area should be cut for fastening the fixed part of the sliding support. The width of the platform must correspond to the dimensions of the L-shaped part of the sliding support. This will allow the mount to be securely fixed to the base.

The sliding support must be mounted in such a way that the rafter can move freely in the direction of its axis. To do this, cuts can be made in the Mauerlat, which act as guides and prevent distortion of the structure. Installation of the sliding supports begins after all the rafter legs are connected at the ridge and cuts are made in the mauerlat. The stroke length of the Kucis sliding support (or another brand) is selected in accordance with the calculated parameters of the displacement of the rafters during shrinkage and temperature and humidity fluctuations of the walls of the house. It is important to consider that the insert into the Mauerlat should not exceed 3/4 of its depth, otherwise the roof structure will be significantly weakened.

At the first stage of installing the sliding support, the guide strip is installed on the rafter. It should be located parallel to its ribs and securely fixed with self-tapping screws protective coating. Then the fixed corner is fixed. The initial location of the corner loop is Bottom part guide strip, since the rafter beams sit down during the shrinkage of the house.

The support area should be located strictly perpendicular to the direction of the axis of the rafter leg.

At improper installation the elements of the sliding support will not be able to move freely relative to each other, and the resulting friction can lead to kinks or damage to the fasteners - jamming of the plate or separation of the angle from the crown.

Skate design

When considering the shrinkage of building structures of a wooden house, it should be remembered that under the influence of temperature changes, changes in humidity and other factors, the movement of the elements of the rafter system is uneven. For example, the wall under the ridge settles the most. It must be taken into account that the walls of houses with gables made of timber or logs are more susceptible to shrinkage than the side walls.

Sliding supports allow you to compensate for displacement and make it possible to maintain the geometry of the roof. In addition, this type of fastening makes it possible to significantly simplify the installation of the rafter system - in this case, it is not necessary to make complex cutouts in the rafter legs to ensure reliable support.

In addition to the use of sliding supports, it is worth paying attention to the hinged design of the skate. The deformation of the walls also affects the joints of the rafters in the ridge. Rigid fastening of the rafter legs in the upper part can lead to disruption of the shape of the roof. To avoid curvature of the planes, it is recommended to use special fastening plates for the hinged connection, or fasten the rafter legs in the ridge with an overlap using bolted connection. This will give the necessary degree of freedom of the truss structure.

Sliding support for rafters, floating closed support for rafters on the mauerlat

Sliding support for rafter legs resting on the mauerlat and floor beams. Floating closed rafter support design.

The use of sliding supports for the rafter system

Gone are the days when towers were raised without 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 constructing a wooden or brick house, 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 different elements functional purpose, interconnected. Wooden frame under influence natural conditions changes, can become lower by 15% due to shrinkage, can swell from rain, 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, or 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 simple repair. 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. Provides the ability to move wooden structures roof, 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, in any area with any climatic conditions, winds, frosts and high temperatures able to stand for at least a hundred years without losing strength and suitability for habitation.

Features of fastening rafters in a wooden house

Rigid fastening of the rafter legs to the mauerlat or support beams when erecting a roof structure is especially not advisable in wooden building. 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 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:

The most high degree Shrinkage is typical for houses made of solid wood; laminated veneer lumber 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 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

The only movable, sliding fastening of the rafters to the base possible way 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:

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. Maximum value This parameter is more effective, as it ensures better mobility of the rafters.

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 provides the most efficient operation 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:

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 systems Roofs that use floating rafters, or sliding rafters as they are also called, require precise calculations. Calculations must reflect the angle of inclination, volume roofing material, 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 structures that need to be calculated. This is work for specialists; amateurs have nothing to do in these matters, even here online calculator will not help in determining the elementary 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.

To summarize, the following should be noted. The sliding support for the rafters is an important element of the roof structure. Thanks to the use of this fastener, the effects of wood shrinkage are compensated, and the performance characteristics of the roof are significantly increased. With the help of this element it is possible to create complex roofs with original architectural nuances that decorate the building.

Sliding support for rafters: dimensions, fastening, application

Using a sliding support for rafters. Description of the floating rafter system. Open and closed slides. Dimensions and fastening technology of fasteners.

Sliding support for rafters: how to attach correctly

When constructing the roof of a country wooden house, a structural element such as a sliding support for rafters plays a rather significant role. This article will talk about what it is, how it is used and how this element is installed.

Sliding support for rafters is required in order to compensate for distortions of the rafter structure that occur as a result of wood shrinkage during operation.

Using a sliding support, the rafters are attached to the supporting beam, resulting in a self-balanced structure.

In addition, this element can be used in many other cases where several sliding elements need to be connected to a fixed base.

In addition to strengthening the structure of the rafters, the sliding support has a number of advantages, which include ease of installation, which does not require special skills and tools.

In addition, the sliding support reduces costs manual labor when constructing a roof, since it eliminates the need to manually balance the elements of the roof structure.

When making a sliding support, it should be taken into account that it is exposed to intense influence of various negative external factors, the most significant of which is the environment.

Therefore, the sliding supports of the rafters are coated with zinc melt, which is additionally alloyed with other elements to increase strength and reduce corrosion, which increases the load-bearing capacity of the structure.

The sliding support itself is made by cold stamping from a material with sufficient strength and ductility, such as semi-quiet low-carbon steel grade 08 ps.

Purpose of sliding supports

Fastening rafters using a sliding support

Sliding supports for rafters are designed for attaching them to the mauerlat during the construction of timber and log buildings.

The effectiveness of this perforated fastening is proven by practice: the sliding fastening of the rafters allows you to avoid the “hanging” of the roof and the expansion of the walls of a wooden house.

For all buildings made of solid wood, which include rounded and chopped log, as well as profiled timber, is characterized by natural shrinkage.

Shrinkage of the rafter system of a wooden house can cause weakening and distortion of the structure. Floating rafters, made using sliding supports, help solve these problems.

The sliding support consists of a metal bracket and an angle with a hinge.

It is mainly characterized by standard values sizes:

Thickness – 2 mm;
Width – 40 mm;
Height - 90 mm;
The length can vary between 90 and 160 millimeters.

The rafter system must withstand quite serious loads, so the fastening elements used during its installation, including sliding supports, must be made of reliable and durable materials.

In accordance with GOST 14918-80, low-carbon steel grade 08 PS, which is characterized by fairly high strength, is used for the production of perforated sliding bearings.

In addition, since the roof of any building is subject to various negative atmospheric influences, the workpiece material is additionally galvanized to reduce the corrosive effects.

It should also be noted that the roof installation process is quite low in complexity using the technology of sliding rafter supports, since to attach them to the required structural element It is enough to use only a screwdriver.

Characteristics of the sliding support for rafters

Changing the angle of the rafters over time

Wooden houses shrink during the first years of operation, after which they geometric shapes and sizes gradually change under the influence of changes in humidity and temperature.

In this case, the height of each beam or log changes, resulting in a change in the height of the entire wall, which consists of changes in the height of each individual element.

From this we can conclude that the higher the wall, the more it shrinks during use. The wall located under the ridge has the greatest height, therefore its draft is maximum.

The walls on which the rafters rest, located at the edges of the house, settle less, which leads to a change in the angle of the roof over time.

This makes it necessary to take into account these geometric changes when attaching rafters and giving mobility to joints:

The rafters located in the ridge are made to rotate relative to each other, securing them on both sides with metal plates on studs.
The lower ends of the rafters with your own hands are a particularly difficult case, since during the shrinkage process they not only rotate, but also shift relative to the wall. Therefore, a rigid and motionless fastening of the rafter leg to the wall will cause it to bulge after shrinkage.

The rafter legs should be provided with the possibility of a slight but noticeable rotation and shift along the wall, without reducing the strength of their fastening.

Previously, twisted annealed wire was used for this, with the help of which the top log was tied to the leg of the rafter, which provided both a movable and reliable fastening.

Modern technologies have made it possible to find a more effective replacement this method, which turned out to be the sliding support of the rafters. This mount is more convenient in terms of installation, meets various requirements and allows you to securely fasten the rafter leg to a log or mauerlat beam.

Useful: if laminated timber is used in the rafter system this method is the only one that simultaneously provides the required mobility and reliability.

The fastening is located along the offset of the beam, for which the wood of the upper beam is ground down.

This creates a platform on which the fixed lower part of the support is fastened. When performing installation, the support should be positioned so that its shift reserve is the maximum possible.

Important: the rafter leg, which has intermediate supports between the mauerlat beam and the ridge, should also be secured using a sliding support.

Installation of sliding rafters

Installation of sliding rafters is carried out when the gables of the house are made of timber or logs, and the ridge run is attached to the body of the gable. This is necessary to prevent the walls from expanding as a result of a change in the angle of the roof after shrinkage.

In this case, the rafters for the roof are placed with your own hands on top of the ridge purlin and secured there using a hinge joint, which leaves the possibility of changing the angle at which the legs of the rafters are connected.

To make such a connection, perforated plates are used, connected with studs, or the upper parts of the rafter legs are placed on top of each other and connected with studs with nuts and washers.

In this case, the following conditions are met:

The Mauerlat, which is the upper crown of the frame, is connected to the rafter legs using sliding supports. They are made of galvanized carbon steel, the thickness of which is 2 mm. Typically, sliding supports are made in sizes 90x90x40, 120x90x40, 160x90x40 and 270x90x40 mm. Their length is selected in accordance with the expected displacement of the rafter legs.
When performing installation, the guide line of the sliding support should be fixed parallel to the rafter leg, and the corner should be installed in the upper part perpendicular to the leg to ensure the ability to slide when maximum length shrinkage.
The rafter legs are laid on the mauerlat either from above or by inserting into the body of the mauerlat. The depth of such an insert does not exceed ¾ of the diameter of the beam or log of the mauerlat.
To make rafters, boards with a section of 200x50 or 150 mm are used.
All elements that make up the rafter system should be treated with special bioprotective and fire retardant preparations.

Summarizing all of the above, we can conclude that sliding supports are the most important element roof structures of a wooden house.

In addition to increasing the rigidity of the rafter structure, this element allows you to compensate for the natural shrinkage of wood in the first years of operation of the building.

Sliding support for floating rafters: fastening

447) How is a sliding support for floating rafters made? What is its mounting? This is exactly what we'll talk about.

The need to use sliding supports

Rigid fastening of rafter legs to the mauerlat or floor beams using nails, staples and other fasteners is not always justified. If the building frame is prone to shrinkage, it is recommended to allow the rafter legs to move relative to the support. Traditionally, twisted forged wire, which is tensile strength, was used for this. With its help, a reliable connection of the rafters with the upper crown of the log house was ensured, while a certain degree of freedom of the structural elements was provided. Today, for this purpose, a specially designed fastening element is used - a sliding support; this type of fastener is easy to install, reliable and durable.

Free movement of the rafter beam at the point of attachment to the support (floor beams or mauerlat, the function of which is performed by the upper crown of the frame) is necessary, first of all, when building wooden houses. The degree of shrinkage of building structures depends on the material from which they are made and the moisture content of the wood. It could be:

chopped log;
rounded log;
solid timber;
glued timber.

Glued laminated timber is the least susceptible to shrinkage; walls made of solid wood with natural humidity are much more deformed. A log house placed under a roof can become 15% lower over the course of a year.. It should be taken into account that shrinkage usually occurs unevenly, as a result of which the rafter system, rigidly fixed to the mauerlat or floor beams, can be seriously deformed.

Roof skew can also occur during the operation of the structure. High humidity during the rainy season causes the wood to swell, and in winter the wooden material naturally loses moisture and dries out noticeably: the geometric dimensions of the log house are constantly changing. At the same time, the walls of the house differ in the rate of moisture gain or loss depending on the degree of sun illumination and the wind rose. If the log house of the house has a central wall on which floor beams or ridge girder supports rest, it should be taken into account that this wall is also subject to temperature and humidity deformations, and the amplitude of its changes is very different from the indicators of the external walls - when the house begins to be heated, the central wall dries out greatly .

Such difficulties can be avoided by the special design of the fastening points at the junction of the rafter legs with the walls. Special fasteners allow the roof to move without changing its geometric parameters.

Sliding support: design features

The sliding support allows you to securely fix the rafter leg on the mauerlat or floor beam, leaving it the opportunity to move a certain distance along its own axis. This fastener consists of two parts:

guide (metal strip that is attached to the rafter);
corner with a support platform (mounted on a floor beam, mauerlat or upper crown).

At the top of the corner there is a loop that fits onto the guide. This design solution leaves the rafter beam a certain degree of freedom in one direction and over a strictly limited distance, which is determined by the length of the guide.

There are two types of sliding supports: open and closed. The open-type design consists of two separate elements. The steel curved plate (guide) is equipped with two or three mounting holes at each end. The fixed part (angle) can have up to five holes in the support area. The length of the fastening stroke depends on the model and can be 60-160 mm. The most popular options include Kucis brand sliding bearings with stroke lengths of 90 mm, 120 mm and 160 mm.

The sliding support for rafters is designed for use in difficult conditions: the structure is subjected to high loads and moisture due to contact with condensation or water trapped under the roof slopes. To make the sliding support, steel is used, the thickness of which must be at least 2 mm. The width of the plates is usually 40 mm, and the height of the corner is 90 mm.

In the absence of a factory galvanic protective anti-corrosion coating, it is recommended to apply a layer of oil paint to the sliding support before installation to protect the material from rusting. To install sliding supports, it is necessary to use self-tapping screws that are resistant to corrosion - fasteners without a protective layer will quickly fail and cause the destruction of the roof.

Installation of sliding supports

If the rafter leg is mounted not on the mauerlat or floor beam, but on a round log of the upper crown, a flat area should be cut out for fastening the fixed part of the sliding support. The width of the platform must correspond to the dimensions of the L-shaped part of the sliding support. This will allow the mount to be securely fixed to the base.

At the first stage of installing the sliding support, the guide strip is installed on the rafter. It should be located parallel to its ribs and securely fixed with self-tapping screws with a protective coating. Then the fixed corner is fixed. The initial location of the corner loop is the lower part of the guide strip, since the rafter beam sits down during the shrinkage of the house.

The support area should be located strictly perpendicular to the direction of the axis of the rafter leg.

If installed incorrectly, the elements of the sliding support will not be able to move freely relative to each other, and the resulting friction can lead to kinks or damage to the fasteners - jamming of the plate or separation of the angle from the crown.

Skate design

Wooden house construction long years maintains its leading position. However, wood as building material has some quality characteristics, including a high percentage of shrinkage, which inevitably provokes the development of deformation changes in the structure. It is for this reason that sliding rafter supports are used.

Purpose and scope

The sliding version of the supports allows the structure to easily adapt to configuration changes of various nature, including geometric changes during natural shrinkage.

The process of rigidly attaching a rafter structure to a mauerlat or to floor beams using fasteners is sometimes impractical.

If the frame of the structure is prone to shrinkage processes, it is recommended to allow the legs of the rafter system to move freely in relation to the support.

Previously, during construction, for this purpose, the strongest wire system was used, with which it was used with the upper part of the erected log house. In the conditions of modern house construction, such fastening is carried out with a special fastening element– a sliding support, which is easy to install, reliable and durable. It is worth considering that any movable support is characterized by the presence of fixed frames for performing movements.

Characteristics and dimensions of sliding supports

The sliding supports are perforated elements that are highly effective in preventing hang-ups. roofing structures and the process of expanding walls in wooden housing construction.

The result of shrinkage of a wooden truss structure is a significant weakening of the entire system and the occurrence of numerous distortions. The use of sliding supports for floating rafters minimizes the negative effects of shrinkage. The components of such elements are represented by a metal bracket and an angle with a loop part.

Main parameters:

height - 9 centimeters;
width - 4 centimeters;
thickness - 2 millimeters;
length - 9 - 16 centimeters.

All elements are highly durable and reliable, and installation requires the use of a screwdriver.

Types of supports

Depending on the type of construction, several methods can be used to fasten the main elements. Most often, the material used for the manufacture of such fasteners is low-carbon steel that has undergone a hot-dip galvanization process.

Two types can be used as sliding joints:

open sliding joint type
closed sliding joint type

Full-fledged fastening for movable joints is carried out on the basis of calculations for uniform distribution of the created loads on the walls of the structure. In addition, it is necessary to take into account not only the weight of the rafter system, but also the entire roof being erected.

Open connection option

Characterized by the presence of two open elements: a guide that is attached to the rafter leg and is a curved steel plate with holes and a fixed angle. The number of mounting holes on the guide may vary, and the stroke length is at least six centimeters and no more than sixteen centimeters. The corner has no more than five holes.

Closed connection option

Represents a single and monolithic structure and is installed already assembled. The corner of the fixed part has a special holder on its long side through which the fastening strip is removed. It is advisable to purchase rafter connections in finished form, which will allow for the highest quality installation.

Installation of a sliding rafter system

The basis of the sliding supports are two parts, represented by a guide and a bent plate. During operation, the guide performs sliding, the amplitude of which does not exceed the limits of the bent plate.

In addition to mobility, installation takes into account the reliability of the fastening, which does not allow the load-bearing log to come off under conditions of significant roofing loads.

Sliding joints are characterized by fastenings perpendicular to the rafters, which results in cutting at right angles.

The basics of installation consist of the following steps:

making a semicircular cut on the supports of the rafter legs;
installation of spikes to remove the load from the rafter structure.

Sometimes you can find fastening done in a different way, when special cuts are made at 75% in load-bearing logs. Creating insignificant friction over a large area allows you to keep the system in conditions strong winds and heavy snowfalls. This method is used when there is a small angle of the roof slope or when there are intermediate supports. During the installation process, high-quality, galvanized self-tapping screws are used.

For more information on DIY installation, watch the video.

Let's sum it up

Installation of sliding joints is possible only on roofs that have a correct and geometrically correct shape.

Installation is carried out only after all parameters of the structure have been verified for compliance with dimensions, which will simplify installation work and minimize the need to “adjust” all elements.

Movable connections can be used not only for fastening rafters and walls, but also for arranging ridge connections.

To prevent jamming on moving systems, strictly parallel fastening of all the supports of the sliding rafters to each other and perpendicular to the mauerlat is possible.