One of important stages The construction of the roof is a sliding rafter system. It is necessary to take the fastening of elements very seriously. That is why it is necessary to know how sliding rafters are attached and what they are needed for.
It is important to understand that the slightest inaccuracy or omission can lead to damage and destruction of the roof.
Therefore, the sliding support must be made to the highest possible quality.
Preparation of the necessary elements of the rafter system
Before construction begins rafter system you need to prepare its individual elements:
- The ridge is the topmost element of the roof structure. In order to make it correctly, after installing the very first element, it is necessary to make a template based on it, based on which the subsequent elements of the ridge will be manufactured;
- If you plan to build a large house, you may need to lengthen the boards. To do this, you need to make holes for the bolts in the docking board. The distance between the end of the joining boards and the nearest holes was at least 10 centimeters. Holes must be drilled using a drill to avoid damaging the wood. It is worth considering the fact that due to too frequent drilling, cracking of the board may occur. Therefore, it is necessary to drill in a random order.
What you need to know when calculating the rafter system
When calculating the system, it is necessary to prepare in advance for possible loads on the roof that may occur in the future: the weight of the roofing itself, as well as wind or snow loads.
Do not forget about wood shrinkage: with a log cross-section of 195×195 mm, the shrinkage along the eaves and gables can be about 6%.
Installation of rafter system elements
After all the calculations have been made and the elements have been prepared, it’s time to start.
Elements that make up the system
- supports the rafter legs on the eaves overhang;
- support the legs of the rafters on the intermediate beams.
Each element is fastened separately.
Fastening elements of the sliding rafter system
In order to secure the roof ridge, it is necessary to use special joining plates. Using them will not pose any difficulties, everything is simple here.
To support the rafters to the intermediate beams, you need to use special sliding elements.
The sliding rafter support must be mounted perpendicular to the rafters themselves. To do this, you need to provide an angle of 90 degrees, which can be achieved by making a precise cut in the bars above the main part of the sliding elements. This will help you install correctly.
The rafter system provides for the installation of a sliding element in the most extreme position, which is capable of ensuring maximum movement of the rafters during the process of shrinkage of the building.
Under such circumstances, wood shrinkage will not have any effect on the rafter system, and after the process has stabilized, it will be possible to begin laying a permanent roofing covering that can last for many years.
The sliding rafter system is most often used in the construction of houses made of logs or timber, in which noticeable shrinkage occurs from the very beginning. It is worth noting that the technology for fastening the rafter legs to the frame is especially important for a log gable.
The overall shrinkage of the height of a house can sometimes reach up to 10%. Since the shrinkage of such premises occurs unevenly, it affects the dimensions of the structure.
In order to determine, you need to proceed from the weight of the roof that is being built. In most cases it is used edged board, which is no more than 200 mm wide and its thickness is 50 mm.
How to avoid negative consequences during installation
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.
To avoid sagging of the roof or expansion of the walls of the log house, it is not at all recommended to rigidly fasten the legs of the rafters to the mauerlat. It is necessary to attach the rafter legs to the frame using special brackets, which are made of 2 mm steel and equipped with an angle, thanks to which the support can slide. You can purchase them in specialized construction stores, their price is quite low.
The guide ruler requires fastening parallel to the rafters. The corner on the log should lie perpendicular. This technology will prevent the rafters from skewing during shrinkage of the building. It is necessary to fix the corner at the level of the ruler, which can allow the rafters to slide along its entire length while shrinkage occurs.
If any force is applied to the rafter, which is resting against the beam, its end will slide along it, which may result in the rafter slipping and the destruction of the entire roof.
What needs to be done to avoid such slipping?
To avoid negative consequences, you need to securely fasten the rafters using special connections. Possible options:
- stop at the end of the beam;
- tooth with emphasis;
- tooth with a spike and stop.
Connections must be made with one or more teeth. The quantity depends on which one. This fastening of the rafters to the beams will reduce the pressure by transferring it from one to the other.
One-tooth connection method
If the angle of inclination of the roof is large enough, it is best to make beams using a single tooth. It makes sense to use this mount if the angle between the rafter and the beam exceeds 35 degrees. Actions required:
- You need to make a tooth with a spike in the rafter leg.
- In the beam itself, you will need to cut out a stop in which there will be a socket for the tenon, the depth of which should be 1/3 - 1/4 of the total thickness of the beam. If the nest is deep enough, it may weaken.
- The cutting must be carried out at a distance of 30-40 cm from the edge of the hanging beam, and it is necessary to prevent its end from chipping under the load that will be created by the rafters.
A tooth with a tenon is made in the heel of the rafter, and a stop with a socket for the tenon is cut out in the beam.
The tenon and stop tooth is a single tooth that can be combined with tenons. They will help prevent lateral movement of the rafter leg.
If the roof is flatter, that is, its angle of inclination is less than 35 degrees, it will be necessary to increase the area of support of the rafter leg on the beam.
Options for cutting with two teeth
To do this, you need to cut with two teeth. There are several options here:
- two stops: with and without a spike;
- a lock with several spikes;
- two stops with spikes.
The first option is carried out in the following steps:
- a stop is cut for one tooth;
- for the other, a tenon with a stop is cut out in the beam;
- for the second tooth, an eye with a stop is cut out in the rafters.
- a stop for the first tooth is cut out.
It is worth considering that the teeth must be cut to the same depth. At different depths cutting, you will need to cut the first tooth with a tenon at 1/3 of the total thickness of the beam, and the second tooth at 1/2.
Another method of fastening, which is less common, is the end-to-end connection. To do this you need:
- cut out a persistent tooth in the rafter leg;
- place one tooth plane on the very edge of the beam plane;
- make the second plane of the tooth rest against the cut that was made in the beam (the depth of the cut should be 1/3 of the total thickness of the beam).
How to fasten the elements of the rafter system
Using a sliding rafter system means installing timber rafters onto the roof ridge logs. The connection is made overlapping or butt using nails or bolts and steel plates.
In order to make connections to the rafter system, the following fasteners are used:
- everything made of wood is attached using plates, dowels, bars, overhead or insert triangular gussets;
Modern construction technologies allow the construction of a variety of types of buildings, but the most promising option remains roofs with several slopes. In the case when the building is erected from wood, deformations caused by shrinkage may occur, which means that a movable fastening will be required to maintain the strength of the roof. IN similar situations Usually a sliding support for rafters is used, which is the subject of this article.
By using a multi-degree-of-freedom connection, a balanced design is obtained that can compensate for shrinkage and maintain the necessary strength to withstand snow and wind loads. Sometimes similar types of fastenings are used in other situations when it is necessary to fix elements so that they can move among themselves.
Fastenings of this type can be used either in pairs or individually. The second option is preferable for those areas where there are rare strong winds, and the mass of the roof is relatively small. In the case where the wind load on the roof is large enough, the fastenings are located on both sides of the rafter leg.
These elements most often work in conditions high humidity, and may also come into contact with condensation or water that has gotten under the roof slope. In order to avoid premature destruction of the metal, the sliding support of the rafters is made of steel protected by hot-dip galvanizing.
The manufacturing technology for such fasteners is cold stamping. As a rule, low-carbon steel is used as a raw material, for example, grade 08 ps. A small amount of carbon (0.08%) allows this metal to be easily processed, and the strength characteristics of the finished product are increased using the deoxidation method.
All sliding supports existing today can be divided into two categories:
To fix the plate when a log is used instead of a Mauerlat, it is recommended to cut a platform equal to the width of the L-shaped part of the sliding fastening. If this point is not taken into account, in the future the movement of elements relative to each other will be difficult, and kinks or damage may occur due to friction.
Shrinkage of wooden elements occurs due to humidity, temperature changes or other factors, but all these reasons lead to the elements of the rafter system moving, changing their position relative to others. The wall that is located under the ridge settles the most, and the edges of the house, on the contrary, settle less.
Installation of sliding supports is carried out using self-tapping screws with protective covering, otherwise they will become the weakest point of the entire structure, from which destruction will begin. The sliding support for the rafters is installed in such a way that the rafter legs can move freely in a direction perpendicular to the beam. To do this, cuts are made in the Mauerlat, which serve as guides and protect the movable structure from distortion.
Installation of sliding supports is carried out after cuts have been made in the Mauerlat, and the rafter legs have been laid and fixed in the ridge. The length of the sliding supports is selected in accordance with the expected displacement of the rafter legs.
During installation, the guide rail is first fastened, which should be located parallel to the rafter ribs, after which the fixed corner is fixed.
If the corner is attached to the mauerlat using the insertion method, then the depth should not exceed? thickness of timber or log. Otherwise, the strength characteristics of the structure will be too low.
It should be noted that in addition to movable fasteners, there are other ways to compensate for shrinkage characteristic of wooden buildings. An example is a ridge connection, which is created in such a way as to allow the elements of the rafter system to move relative to each other. Of course, someone may say that they used to do without such elements, but the use of twisted wire is less convenient for installation, and in terms of reliability this option is somewhat inferior to the modern method.
The basis of a wooden roof of a house is a frame that supports roof covering. He 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 wooden house when its geometry changes.
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. Resizing wooden structure is happening all year round. On a rainy day summer season 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.
In the absence of a central wall, more big problems. 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.
To compensate for precipitation processes and seasonal movements, houses can be installed screw jacks. They should be located on all vertical supports in the house. By tightening the jacks, the movements of the log structures are compensated for.
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:
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.
Pair of rafters gable roof 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:
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 roofing 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.
Sliding supports for rafters ("slider") open type, 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-separable. 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. Supports can also be used for pitched roof.
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.
Popular sliding support for rafters Kucis open and closed type has a plate width of 40 mm, support height - 90 mm, length - 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.
A sliding support for rafters when installing a roof frame is used as follows.
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 wall in the bathroom ceramic tiles, you can’t just 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, onto 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.
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.
It is, of course, possible to build a reliable wooden house “without a single nail.” At least our ancestors, having no choice, managed to do this.
But does this make sense now?
When inexpensive practical fasteners are available, with which you can build a cottage for a very short time, with minimal labor costs.
All perforated fasteners can be divided into two large groups:
In this article, we will look at products with moving elements, determine their purpose and basic principles of use.
Wooden houses, which are built from solid wood, have one important feature- their walls shrink over time. Shrinkage mainly occurs due to loss of moisture from wall materials (drying). Also, under significant weight, compression of wood fibers and gradual compaction of inter-crown insulation takes place.
All together this results in a pretty decent size change. The wetter the material was, and the more roughly it was processed, the greater the percentage of shrinkage, and the longer its duration can be. For example, the shrinkage of a house made of hand-cut logs can reach 7-9 percent or more (it lasts up to 2-3 years), but if the walls are made of glued profiled timber, then the shrinkage will be about 1-2 percent and it occurs in the first 6-8 months.
In real figures, this will be from 25 to 150 millimeters of loss of log house height per floor. Average figures among other materials (in terms of timing and intensity of shrinkage) are shown by profiled solid timber and dry rounded logs, planed edged timber.
Shrinkage forces homeowners to hold off for at least a season. finishing works. It is precisely because of this that we have to make a sliding knot for window and door openings so that the joinery does not become pinched and crushed.
But the whole problem is that shrinkage does not occur evenly. Higher walls (with gables, for example, or a load-bearing “internal” wall that rises to the ridge) shrink more and take longer to do so. When shrinking, the lower, more loaded crowns become more compacted; the less loaded upper crowns can become deformed when drying and turn out of the wall.
Some of these problems can be solved by using wooden dowels, as well as spring units (“Strength” and the like).
Difficulties arise where the walls of a log house, subject to shrinkage, are tied with other parts and structures that themselves do not change in size and do not lose their original geometry. To non-shrinking elements wooden houses, for example, include:
Fixed vertical structures could be destroyed under strong pressure or could limit the movement of the rims, due to which large through gaps would form in the suspended areas. And, for example, a rigidly assembled roof, which rests on load-bearing wall structures, in the process of uneven shrinkage different walls could be critically deformed.
That is why shrinkage compensators and movable supports are an integral attribute of any modern log house.
This element goes by many other names: “column lift”, “construction jack”, “screw support”, “adjustment stand”, “anchor for vertical adjustment of the column”, “threaded impost”... And there are even several options in nature.
For example, there are models that are installed in concrete while it is being poured, there are models with U-shaped plates...
But the essence and basic principle of operation of this hardware remains the same. We create a gap in advance (based on the predicted percentage of shrinkage) between the walls of the log house and the stationary vertical element. We install a compensator in this gap, thus ensuring the necessary constant supporting moment.
As the walls shrink, we manually (several times, at certain intervals, which depend on the intensity of the shrinkage process) make adjustments - we shorten the distance, let the crowns sit lower.
In the traditional design, this fastener consists of a threaded rod, at one end of which a metal “heel” plate is rigidly welded. Or a nut is welded onto the plate, into which a pin is screwed until it stops. One way or another, it turns out to be a T-shaped thrust knot.
There is always a counter plate with a corresponding hole in the center, which is often reinforced with a powerful washer pad. Some samples can also be supplemented with a guide sleeve.
A nut is screwed onto the stud, on which the counter plate in turn rests. By rotating the nut on the thread, we reduce the distance between the connected elements.
The support plates (they are also called “ladders”) are basically a square with a side of 100 or 120 mm, sometimes 150 mm. Their thickness is usually from 4 to 6 mm, but for super-loaded units there are hardware with plates up to 10 mm thick.
The bodies of both plates are perforated. These are at least 4 holes for the passage of self-tapping screws with a rod diameter of 4.5 mm. Larger holes can also be made here for attaching the shrinkage compensator to the stone base using anchors.
The stud and complete nut can have a working diameter of 20-24 mm on average, or 30-36 or more millimeters for heavy loads. Depending on the predicted load, the diameter of the stud, the area of the ladder and its thickness are selected. Depending on the intensity of shrinkage, a jack with a particular length of pin is selected (usually it is about 15 centimeters, longer options reach 20 centimeters).
Correct screw supports are made from high-quality steel, and to protect hardware from corrosion, all its elements are hot-dip galvanized (can be used outdoors in an open form without painting).
Installing and operating a threaded shrinkage compensator with your own hands is not particularly difficult:
Due to the uneven shrinkage of the various walls of the log house, the elements of the rafter system move relative to each other. The deviation numbers there are not as large as those observed near the walls during vertical shrinkage. But a change in angles, when the geometry of a rafter pair changes on one side by 2-3 centimeters, is not at all uncommon.
If the roof is assembled on rigid connections, then the fasteners from the wood may break out, hardware may break, and the load-bearing lumber may crack.
To eliminate such problems, the rafters of the log houses were never placed on the mauerlat (or upper crown) through stepped cuts, they were not screwed through the corners, and no other options for rigid fastening were made. Usually they tried to maintain a balance between the reliability of fixation and the mobility of the connection. This was achieved using hardened staples installed at certain angles, providing some movement. But more often the entrance was soft wire, which simply tied the rafter leg to the wall.
Now there are perforated fasteners that are reliable and easy to use. Some craftsmen began to use corners with a longitudinal groove for powerful screws or anchors to fasten rafters. These models, of course, are not intended for such a node, since they can jam at any moment, because the rafters not only move up/down along the initially specified line, but the angle at which they are located relative to the wall also changes slightly.
There are special perforated hardware that are designed specifically for this unit. The sliding support is a two-piece T-shaped bracket. One part is a guide bracket that is attached to the rafter leg. The second part is a kind of unequal corner, which is held on one side by a bracket, and the other is attached to the upper crown of the wall. Both parts, being fixed to the wall and to the rafter, are in engagement; they can move forward relative to each other, but they perfectly counteract the “pull-off” forces (which arise under wind loads).
In general, there are two types of sliding supports for rafters (closed and open), but they work approximately the same.
How to install the sliding support:
If the angle between paired rafter legs can change, then it is necessary to arrange their mutual connection accordingly. They are connected at the ridge, so the usual options for implementing this unit (with cutting the rafters) different ways and using perforated plates) will no longer be suitable.
As usual, there are several solutions. One of them is to assemble adjacent rafters with an overlap in the ridge area, and for mutual fixation they can be twisted with powerful bolts.
The second option works in structures where the rafters rest on a ridge girder or on a load-bearing intermediate wall. It consists in using a movable bracket, which wraps its plates around the rafter legs and allows them to move slightly relative to each other. Each bracket of this type can be assembled from four perforated plates and three bolts.
It should also be noted that if roofing system Since the log house contains various auxiliary elements (crossbars, struts, etc.), they must also be connected to the rafter legs and to any stationary structures with the ability to slide. To do this, you will have to use the methods presented in the article in one form or another.
A house made of solid or laminated wood inevitably settles. This is the result shrinkage of wall material (shrinkage), which is most pronounced in the first few years after the construction of the building. But even then the linear dimensions of the wood will fluctuate, due to seasonal changes in temperature and humidity conditions. That is why, even at the design stage of a wooden house, it is necessary to provide special measures to compensate for wall shrinkage, especially if we're talking about O building a house from logs or timber.
House shrinkage is mainly due to the property of wood to dry out when its moisture content decreases. The amount of shrinkage of a log house is determined by many factors. First of all, the moisture content of a log or timber, its original dimensions (primarily thickness), wood type, wood processing technology (primarily drying), operating conditions of the building and its dimensions (the higher the wall, the greater the shrinkage amount), construction season at home (summer, winter), quality of assembly and qualifications of workers (quality and tightness of fit), construction technology (method of connection and type of used).
Moreover, changes in the dimensions of a wooden element are different in the tangential and radial directions, i.e., changes in dimensions along the width of a beam or log are much greater than along the length. In addition, the amount of shrinkage varies depending on the type building material- log, rounded log, beam, profiled beam, laminated veneer lumber, etc.
In principle, data on material shrinkage can be gleaned from, but in practice these data may be far from theory. On average, with calculation of shrinkage amount You can start from the following data:
For example, in the assembly manual log houses HONKA provides the following data:
The difference is noticeable, and in many cases fundamental, because the height of the log house will in any case decrease. To prevent shrinkage from damaging the structure of the building, a number of measures and ways to compensate for it are provided. Let's start with the fact that the very shape of the beam or log profile affects the amount of shrinkage of the walls.
The profile of a rounded log can be supplemented with narrow longitudinal compensation grooves
For example, the profile of rounded logs can be supplemented with narrow longitudinal compensation grooves, reducing stress in the wood and avoiding severe cracking of the log. The number of grooves is from one to three, and one of them is located, as a rule, in the upper part of the log. Thanks to the grooves, the change in profile shape is reduced and, therefore, shrinkage is reduced log walls. The higher the level of technical solutions of a manufacturer of wooden building materials, the more complex the profile of the wall elements it offers.
The log walls themselves do not require special units to compensate for shrinkage, since the log house is a homogeneous structure and all its elements will sink by approximately the same amount. However, there are rigid parts in the building that either do not settle or settle much less than the frame. Therefore, the construction of such parts requires special solutions.
Thus, the house often has vertical elements (pillars, columns, etc.) that serve as support for the higher parts of the house. Adjustment mechanisms are needed to reduce the height of pillars and columns so that their height matches the height of the log house walls. Most often for this use screw mechanisms for shrinkage compensators, special jacks, which are called so - screw jack adjustable shrinkage compensator.
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Wooden posts are rigid elements. To prevent them from interfering with the shrinkage of the overlying log structures, adjustment mechanisms are provided to allow the height of the pillars to be reduced.
The jack is placed in the gap between the vertical and horizontal elements, rigidly fixed to one of them. The size of the gap is selected based on the estimated shrinkage of the building (usually a jack allows you to change the height of the support by 8-10 cm). As the log house shrinks, the screw mechanism is adjusted, thereby changing the height of the column or pillar. The jack can be installed at the bottom or top of the vertical support. From the point of view of shrinkage of the structure, its location is not important. And from the point of view of ease of use, it is preferable to have a jack located below - then you will not need a ladder or scaffolding to complete the work.
The adjusting mechanisms are screw jacks that are installed in the gap between the vertical and horizontal elements, rigidly fastening them to one of them.
The gap between the vertical and horizontal elements is usually covered with a decorative casing, which is removed during adjustment. Sometimes the screw mechanism is left open. How often do you have to reduce the gap? This depends on the type of wall material, profile shape, time of year (seasonal changes in wood moisture content) and log house assembly technology. In some companies the interval between jobs is usually from two weeks to three months, in others it is four to six months. Adjusting each jack takes approximately 15 minutes.
Special technical solutions will also be needed when the log structure is adjacent to a wall or partition of another type (for example, brick or frame), which is subject to less shrinkage. This means that its connection with the log house must be sliding. This connection can be made in different ways. Most often it is carried out according to the “tenon and groove” principle, where the tenon and groove have the possibility of some movement in the vertical direction relative to each other. Usually a groove is made in the wall of a log house, and a tenon in the form wooden block attached to the end of a brick or frame wall. The space between the tenon and groove is filled with heat-insulating fibrous material (etc.). Connection with brick walls, through which capillary moisture can spread, must contain a layer of waterproofing.
Compound frame partition with a log wall: 1. Log house 2. Frame partition 3. Groove |
Connection of a brick partition to a log structure located above: 1. Log house 2. Brick partition 3. Decorative cover 4. Shrinkage allowance 5. Screw jack |
A gap is left between the upper edge of the brick or frame wall and the part of the frame located above for unhindered shrinkage of the latter. The size of the gap is determined based on the calculated shrinkage value (in most cases it is 8 - 12 cm).
Creation of an additional self-supporting brick partition on which the finishing material will be fixed
To prevent the gap from being noticeable in the interior, you can close it with decorative strips that are attached to the frame (and, therefore, go down with it), or you can create a niche in the partition where the frame will settle. At the junction of the upper part of the frame partition to the frame, steel rod elements are usually provided to ensure the rigidity of the structure.
When creating a rafter system, the shrinkage of the log house is also taken into account. So, in the case of using layered rafter legs, the distance between the upper and lower supports may vary. Accordingly, the rafters must be able to move without causing stress and deformation in the building structure.
Layered rafter systems are used in houses where there is a middle bearing wall or columnar intermediate supports. The ends of the rafter legs rest on the outer walls of the house, and the middle part rests on the inner wall or supports.
To do this, the lower end of the leg is secured to the wall using a sliding joint of one type or another. Most often, fasteners are used in the form of two brackets: one is rigidly fixed to the wall, the other to the rafter. These brackets allow the rafter to move relative to the wall.
There is no consensus among experts whether a sliding connection is necessary at the point of support of the upper end of the rafter leg on ridge beam. Some insist that this is a mandatory measure that helps prevent deformation of the rafter system due to shrinkage of the log house. This measure consists in leaving some distance between the rafters converging at the ridge and attaching them to the ridge beam also by means of a sliding (usually hinged) connection. Other experts believe that to compensate for the shrinkage of the frame, sliding fasteners in the place where the rafter rests on the wall are sufficient.
Fastening the rafter leg to the log wall: 1. Rafter leg 2. Brackets that allow the rafter to be displaced relative to the wall 3. Log house
In the case of rafters in the form of trusses, the shrinkage of the frame does not lead to a change in the slopes of the roof slopes. However, it is impossible to rigidly connect gables made of logs or timber with trusses, since the gable walls are higher than the facade walls, and the amount of their shrinkage will be different.
The truss structure must be designed taking into account the shrinkage of the building. Most often, layered rafter legs are used, which rest on one side on the top element of the frame, and on the other on the ridge beam or the wall of the house (when the roof slope is adjacent to the wall). On the ridge, at the point where the rafters of adjacent slopes converge (or at the point where the rafters adjoin the wall), a distance of about 3 cm should be left so that when the roof shrinks, the rafter legs can lower without hindrance.
The fastening of the upper part of the leg itself is carried out using a metal hinge joint of one type or another, which allows you to change the slope of the rafters as the frame shrinks. A sliding fastening is also necessary at the node where the lower part of the leg rests on the wall of the log house. Here, as a rule, a factory-made sliding support is used, thereby allowing the rafter leg to “move” relative to the wall.
Among the structures in a log house that do not change their size are windows and doors. A special system for filling the opening allows you to prevent their deformation due to shrinkage of wood. The window or door frame is not attached to the frame, but to a special casing (frame, casing).
The connection between the box and the walls of the building must be sliding. The design of this unit varies. As a rule, a groove is cut out at the ends of log elements. Mounting bars are inserted into the grooves, securing them at the bottom of the opening. The casing is attached to the bars. The gap between it and the end surfaces of the log house is filled with fibrous insulation (linen, jute, etc.) to prevent freezing in the opening area. A gap is left between the top of the box and the frame element that covers the opening, allowing the frame to lower. Its size is determined by the amount of probable shrinkage of the wall and most often is 5-7 cm.
Installation of the door frame to the casing in wooden house |
To install a window casing, first insert a mounting block into the groove made in the end of the log wall. Then the box itself is attached to the block. Place between it and the wall thermal insulation material |
To avoid heat loss, heat-insulating material is placed in the gap - linen, jute, etc., strips mineral wool, polyurethane foam tapes, etc. It is recommended not to use polyurethane foam for these purposes, which is usually used to seal the window or door frame itself, since it is quite rigid and can deform the structure of the window or door when the frame shrinks. To decorate the gaps at the junction of the filling elements with the frame, external and internal platbands are used.
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A compensation gap is left between the casing and the log house element located above it (on top).
When constructing fillings for window and door openings in houses made of solid and laminated wood, two types of risks are likely. Firstly, the impact of the log wall on the infill elements due to the settlement of the building. This risk is eliminated by creating sliding connections with the parts of the log house that form the opening, by organizing a gap above the infill structure, and by attaching the platbands to the infill elements and not to the walls of the log house.
The second group of risks is insufficient tightness of joints in places of sliding joints. Application polyurethane foam for filling the gaps between the casing and the log house is unacceptable, since the hardened foam will prevent shrinkage, because of this, either the log house will “hang” above the structure of filling the opening, or it will be deformed and damaged. The best decision- the use of thermal insulation of plant origin in the gaps in combination with film protection - a layer of vapor barrier from the inside of the house and a vapor-permeable wind barrier from the outside.
When designing and installing a staircase in a wooden house, it is necessary to take a number of measures to prevent it from being affected by the building’s settlement. The staircase is installed at the final stage of construction, when some shrinkage has already occurred. The base of the staircase (stringer or bowstring) is attached to the upper ceiling using sliding fasteners ( metal corner with a vertical groove, etc.), intermediate fixation to the walls is unacceptable.
Installation of an internal staircase: 1. Screw with washer 2. Angle with vertical groove 3. Floor joist 4. Shrinkage allowance
The shrinkage of the frame should be taken into account when securing the fencing and stair railings.
If the flight of stairs has a platform, then it also cannot be attached to the walls - it should be supported by the racks on the lower floor, and then the shrinkage of the walls will not affect the structure. In addition, during construction work there is no need to bring the upper part of the stairs adjacent to the ceiling into the plane of the floor of the upper floor. It is necessary to leave a gap equal to the calculated shrinkage between the top of the stairs and the floor, which is leveled during the settlement of the floor.
Owners of wooden houses often want to decorate some rooms (for example, tiling a bathroom). To ensure that the finishing layer is not damaged when the log house shrinks, it is fixed to a base, either connected to the log walls with sliding fasteners, or completely independent of the walls. There are many options for sliding fasteners.
Construction of the base for finishing: 1. Log house 2. Frame made of wooden blocks 3. Angle with a vertical groove and a screw with a washer 4. Gypsum fiber or plasterboard boards
One of them involves a frame made of metal profiles or wooden blocks with longitudinal grooves. The frame is attached to the wall with screws through the grooves, and the screws are not tightened tightly so that they can move vertically as the wall shrinks. The finishing base is rigidly fixed to the frame. A gap is formed between the wall of the room and the base equal to the thickness of the frame (usually it is about 5 cm).
If you provide ventilation in the gap (provide the possibility of air flow at the bottom of the structure, and ventilation at the top), this will increase the durability of the wall and base. Between the top edge of the trim and ceiling covering They leave a compensation gap, which is decorated (for example, covered with a suspended ceiling). An undoubted advantage of the base on the frame is the relatively small load on the floor covering. The downside is some risk of deformation of the frame if it is attached too rigidly to the wall or if there is uneven shrinkage of the adjacent log walls of the room. Misalignment can damage the finish. This disadvantage is more often manifested in houses made of chopped and rounded logs of natural moisture than in houses made of laminated veneer lumber.
The frame is in the form of wooden blocks, fixed to the log wall with sliding fasteners. The base for finishing will be fixed on the frame
For rooms located on the first floors of a building with a foundation in the form reinforced concrete slab, there is another solution. The finishing layer can be mounted to additional self-supporting partitions made of half-brick thick ceramic brick or tongue-and-groove gypsum board (a similar structure is often called a “glass”). These partitions are erected at a distance of at least 2.5 cm from wooden walls, making holes at the bottom and top for air supply and exhaust. If the room is made suspended ceiling, then it is attached only to the upper ceiling so that they fall together.
