Types of fastenings for floor joists. Adjustable floors Adjustable floor with plastic bolts

Knows that there are several most common methods for leveling the floor level in an apartment. And one of them is to use adjustable floors. The use of concrete screed is gradually losing popularity. This work requires considerable effort and also involves dampness and dirt. Moreover, installing adjustable floors will take much less time.

One worker per day can independently lay floors on an area of ​​up to 20 square meters. m. Next we will talk in more detail about the advantages, disadvantages and features of assembling adjustable floors.

Design Features

To understand what adjustable floors are, you need to familiarize yourself with their operating principle. The studs rotate around their axis, which allows you to adjust the floor level horizontally. The same principle applies to floors on slabs, which also move due to rotation. This allows you to set the floor as accurately as possible. You can level the horizontal floor almost perfectly.

Such structures will not sag under weight or “play” over time. You can install them on any available surface. Each floor can be covered with several layers of covering (plywood).

Such floors will be an excellent solution for gyms, clubs, office premises and so on. By strengthening the load-bearing studs, the load indicator (up to 2 tons per 1 sq. m) can be increased. The service life of adjustable floors is up to 15 years.

Features of use

Adjustable floors are most often used:

• At stations and server premises;
• under final finishing in the shortest possible time;
• In houses of new construction;
• In houses of old buildings for holding overhaul or reconstruction;
• To raise the floor level to a sufficient level (especially when additional pressure on the main floor is undesirable);
• When installing multi-level floors;
• For carrying out all kinds of communications under the base of the floor.

If you need to level or raise your floors to a significant level, then using adjustable floors is a great solution. After all, you will need a month to lay a concrete screed, while with adjustable floors you can do it in one or two days.

Also, the use of such systems is useful in houses where a distance of up to 15 cm was specially left under the floor for laying communications or insulation. Not all structures will be able to withstand the load of such a layer of concrete. But using adjustable floors will help you raise the level of coverage to 20 cm.

You can also successfully, for example, move plumbing fixtures (toilet or bathtub) and hide bulky communications not under a thick layer of mortar, but under the floor, where they will remain accessible at any time.

The use of such systems is especially popular for country houses or cottages. This gives you the opportunity to hide all communications in one place, where they will be reliably protected from exposure and accessible when needed.

Advantages and disadvantages

Like any similar systems, there are also advantages and disadvantages.

Advantages:

• One worker can install an adjustable floor within one working day;
• The adjustable floor system is lightweight in itself, so it will not be able to put additional pressure on the main floor;
• International testing confirms the quality, strength and durability of such systems;
• Using adjustable floors, you can further isolate the room from outside sound;
• You are given the opportunity to use the floor to hide all communications, which is a plus not only from an aesthetic point of view, but also safely collects them in one place;
• Maximum accuracy when setting the horizontal floor level;
• Various levels that can be used in parallel (up to 20 cm);
• The materials used for manufacturing are tested for purity;
• It becomes possible to quickly correct uneven floors, even if there is a discrepancy of 10–15 cm;

Flaws:

• Adjustable over time. To avoid this, even at the installation stage it is necessary to remove all dust and dirt after drilling holes and driving dowels. It is best to use a vacuum cleaner for this. Also thoroughly clean the first floor surface before laying the second layer. Make sure all dowels and nails are driven in completely. This will prevent the structure from becoming loose. It is also necessary to take into account that wood is natural material, which breathes and is capable of deforming under the influence of moisture or gravity. Over time, creaks will appear one way or another;
• If you raise the floor level over a long distance, additional sounds will be heard when walking on it. For example, the sound from women's heels will resemble the beat of a drum. Installing additional sound insulation will help correct the situation.

All your work depends on the quality of the materials used. Treat their choice with special attention. High-quality timber and plywood will save you from having to dismantle the floor in the future.

For maximum accuracy when setting the floor level, use laser level.

Take care to ensure proper ventilation under the floor covering.

Types of adjustable floors

Depending on the type of construction, adjustable floors are divided into two groups:

• slabs;
• lags.

By using adjustable plates you can raise the floor to a distance of no more than 3 cm. This is not much, but enough to carry out the necessary communications: telephone, Internet, and so on. You can also lay thermal insulation and soundproofing materials under these floors.

Such structures are sheets of thick plywood (several layers of it can be used). Special bushings are inserted into it. The peculiarity of these bushings is that they already have a special internal thread. An anchor for the adjustable floor is threaded into it, which will serve as a level regulator. Then the entire structure is installed on the base and fixed with dowels.

As already mentioned, the difference between such a system is that the floor level is adjusted directly through the holes in the slab (made of plywood or any other suitable material).

To assemble a floor based on adjustable slabs, just follow our tips:

• Drill holes in the plywood sheet;
• Then insert bushings into them, which are pre-threaded on the inside;
• Insert special bolts into the bushings, which will adjust the level of the slab;
• Fix the bolts to the base;
• Turn the bolts until you achieve a perfectly flat floor plane;
• After this, the remnants of the bolts that peek above the surface of the slabs must be cut off with a grinder;
• The final stage of assembly will be laying the next layer of plywood, which will hide the marks of the bolts.

Please note that when laying a new layer of flooring, its seams should not coincide with the seams of the previous one, since this way the structure will not be strong.

Adjustable floor joists are the best alternative today. When using this design, the floor will be raised by at least 5 cm. This distance can be successfully used to isolate the room from sound or odors, as well as to lay all the main communications of the apartment or house.

Such designs are distinguished by their simplicity and speed of assembly, as well as reliability and durability. The log is equipped with special sockets for installing bolts. It is fixed to a special base using dowels. To change the floor level, just rotate the bolt in the desired direction. After the floor plane is completely leveled, a coating is applied to them.

Such floors are often used in newly built luxury buildings, in which all main communications are laid under the floor.

The main advantage of such systems is their strong fixation to wood or concrete base. Other materials can also serve as a base. For example, threaded anchors can be installed on concrete slabs that are hollow inside, wooden beams using self-tapping screws, as well as on brick surfaces with concrete screed using special fasteners or to a wooden floor.

To correctly assemble such a structure, read our instructions:

• Special racks (bolts) are installed in the sockets in the joists;
• Now lay out the logs around the perimeter of the room and inside it. Here it is necessary to take into account the required sagging strength of the structure, which depends on the type of floor covering used. For example, the distance between the logs should be about half a meter. If you use floor tiles, then maintain a distance of no more than 30 cm. To ensure the necessary air circulation, step back one centimeter from the walls;
• Then, through the holes provided in the joists, drill holes in the floor for installing bolts. Their depth should not exceed 4 cm;
• Next, you have to set the floor covering to the required level. Please note that the difference between the sides should not exceed 1 mm. To adjust, use a special wrench that turns the bolts;
• After laying out the floor, hammer in the protruding parts of the dowels or cut them off with a grinder or chisel.

Next, the flooring is installed. To start, use two layers of waterproof plywood. Attach the first layer using self-tapping screws directly to the joists. The next layer of plywood should be installed with a slight deviation from the first so that the joints do not coincide. If using floor tiles, it is better to use waterproof plasterboard as the second layer.

To hide unevenness and gaps between the flooring and the walls, use skirting boards. Experts in some cases recommend installing them after all finishing work.

As you can see, an adjustable floor on studs or on slabs is a pretty good alternative to a conventional concrete screed. Moreover, to install such a structure you do not need to have special construction skills. You just need to be patient and do everything according to the instructions. If you have ever encountered the problem of installing such systems, share your comments under this article.

The new technology involves the use of wooden logs or slabs (sheets of moisture-resistant plywood), which are supported by stand-up bolts screwed into them, usually made of high-strength plastic. By rotating the bolts around their axis, the height of the joists or sheets changes, which allows you to accurately level the subfloor. After leveling the substructure, the bolt is firmly fixed to the base with a dowel-nail. Moreover, the base can be either concrete (monolithic, hollow, base with a screed) or wooden (beam). Sheets of moisture-resistant plywood are usually laid on top of the logs, and any type of floor covering is fixed on them - parquet, parquet boards, laminate, linoleum, carpet, etc. In order to save money, massive boards are sometimes mounted directly on the logs.

Adjustable joists

• Possibility of leveling from 5 cm or more (at no additional cost)
• No risk of flooding neighbors
• Pleasantly warm floor
• High sound insulation (necessary for home theaters)
• Reduced costs for communications (all types of communications, including electricity, can be placed under the floor)
• No dirty or wet work

Adjustable plates

• Mechanical leveling method (without the risk of squeaking or shrinkage)
• Cheaper than concrete
• No dirty processes
• Opportunity step-by-step assembly(if the apartment has furniture)
• Completely cuts out impact noise that will disturb your neighbors
• Assembly speed (from 20 m2 per day!)

Advantages of the system

Such adjustable structures have a number of advantages. First of all, they have advantages over concrete leveling. They are cheaper than a concrete screed if it is necessary to level a surface with a difference in height of more than 3-5 cm. In addition, they allow you to save money when installing a base for plank floor coverings (parquet, parquet boards, laminate), because concrete preparation in this case, it will include not only a screed, but also a self-leveling mixture (do not forget also about the need to create a plywood flooring on top of the screed, on which the plank floor will be laid).

In total, the costs of such preparation will be higher than the costs of installing an adjustable structure. No less important point: the concrete screed acquires the necessary strength within 28 days. While the installation of adjustable supports usually takes less than a week, since one worker installs an average of 20-25 m2 adjustable joists or slabs per day. Moreover, according to VSN 9-94 “Instructions for installing floors in residential and public buildings", the moisture content of the screed should not exceed 5% to avoid deformation wooden floor. Note that European standards require drying the screed to 3-4%. It is a mistake to assume that it dries to this level in 28 days: this process takes longer than the curing process and usually takes several months. There is no direct contact in the design of adjustable supports wooden elements with the base of the floor, and therefore, you can lay logs on top of the concrete floor, and then plywood and parquet without waiting for the concrete to dry completely. In case of overlapping with high humidity, you can lay it on top plastic film, thereby cutting off water vapor, and then immediately begin installing the logs or slabs. Finally, the adjustable design allows air to move under the floor and thereby remove excess water vapor that can lead to warping and rotting of the wood. The supply and exhaust of air is carried out due to the gaps between the floor and the wall of the room (on top it is closed with a plinth, but there is also a gap between it and the floor). The standard size of this gap is 10 mm. If you need to increase the ventilation of the space under the subfloor, you can install decorative grilles in the floor in opposite corners of the room for additional air supply and exhaust. Let us add that in regulated systems It is recommended to use only moisture-resistant plywood (grades no lower?) and logs made of timber chamber drying humidity no more than 12%.

Another advantage of adjustable structures is that they increase the sound insulation of the room: the floor is not monolithic, but contains in its “pie” air gap, which dampens noise. In addition, plastic racks prevent the spread of noise. If it is necessary to significantly increase the sound or heat insulation of the floor (for example, in a home theater or basement), you can lay slabs of wood between the joists. mineral wool. The slabs are laid on metal plates fixed to the joists. The thickness of the insulating layer can be varied, however, there is usually no contact between the slabs and the concrete floor (there remains between them air gap), so in case high humidity the ceiling insulation will remain dry. The next point: height-adjustable structures allow you to lay utility lines (pipes with a diameter of more than 50 mm) and any wiring under the floor covering. Moreover, engineering communications will follow the shortest path, so there will be fewer connecting nodes, which means that the reliability of the system will be higher and the cost of its installation will be lower. One of the problems that arise when using a wooden floor is creaking. Is there a possibility of it appearing in floors along adjustable joists or slabs? Experts say that with high-quality installation of the system there will be no squeaking. It can occur when the floor elements do not fit tightly together, for example, when bolts are screwed incorrectly or the layers of plywood laid on top of the joists are poorly glued. However, with qualified installation, all elements of the system are so rigidly fixed to the base and interconnected that even a slight drying out of the wood, according to experts, will not result in a creaking floor. However, knocking noises in the floor may occur if the concrete base on which the joists rest is made incorrectly: for example, if the screed applied to the ceiling crumbles or cracks. Then it is recommended to remove the bad screed before installing the floor, and also select the correct dowel-nail model for attaching the bolt to the base. Let us add that the maximum permissible load for adjustable structures - at least 3 tons per 1 m2. Their estimated service life is at least 50 years.

Installation of the structure

If it is necessary to raise the floor to a height of 5 cm or more, install a structure of adjustable joists. If the required lifting height is from 3 to 5 cm, then a system of adjustable slabs (plywood) is used. Let's start with the first option. When installing the floor on concrete floor Most often, logs with a cross section of 45x45 mm and a length of 2 or 3 m are used. Their standard pitch is 30 cm between the axes of the bars. When laying the floor on a ceiling made of wooden beams Usually, logs with a larger cross-section are required, the size of which is selected taking into account the pitch of the beams (as a rule, logs with a cross-section of 45x70 mm are used). You can also vary the lag pitch. For each joist there are 5 stand-up bolts for which threaded holes are prepared at the factory. The length of the bolts is usually 100 or 150 mm: it is chosen depending on the height to which the floor needs to be raised. The installation of the structure begins with bolts being screwed into the logs, then the logs are laid out on the base with the required pitch, and holes for the dowel-nails are marked. Moreover, a gap of about 10 mm is left between the logs and the walls. Next, the bars are moved to the side, holes are drilled to a shallow depth, the bars are returned to their place and the dowels are driven through the bolts using a hammer and a punch into the prepared holes. Then they begin to level the joists by rotating the bolts with hex keys (the bolts have a hex groove), using a level. Having completed the alignment, the dowels are driven all the way into the base, and the protruding part of the plastic bolt is cut off flush with a chisel. Then the plywood flooring is installed. According to the recommendations of system manufacturers, the thickness of the flooring should be at least 18 mm. However, some parquet companies recommend installing under parquet, massive board and flooring up to 30 mm thick with a lag pitch of 30 cm. Usually two layers of sheets are laid (overlapping top sheet the junction of the two lower ones) to ensure maximum structural rigidity. As a rule, layers of plywood are fastened using self-tapping screws, however, when laying parquet, parquet companies also recommend gluing upper layer to the bottom. The flooring is installed on top of the plywood.

In the case of floors on adjustable slabs and on joists without ready-made threaded holes, the installation technology is somewhat different. A hole is drilled in the plywood or joist into which a plastic sleeve with a threaded hole is inserted. The sleeve is secured to the joist or plywood with self-tapping screws. Then the post bolt is screwed into the bushing, after which the entire cycle of the work listed above is performed.
Let us add that there are other adjustable designs on the market. In particular, systems where metal stand-up bolts are used, and adjustment occurs using a nut screwed onto them with a support washer. There are also systems with U-shaped metal brackets that “clasp” the lag from the sides and are secured to it with self-tapping screws. The bracket is provided with a number of holes, and after alignment, the screws are screwed into holes of suitable height.

“Adjustable floors on joists or on plywood slabs have obvious advantages over concrete leveling, if we are not talking about an abstract “concrete screed”, but about a base under parquet, parquet board or laminate, which includes a layer of screed, a layer of self-leveling mixture and layer of plywood. Adjustable structures are cheaper than such a base, especially when it is necessary to level a floor with large differences in height. In addition, a concrete screed gains strength within 28 days, while installation of an adjustable floor usually takes from 2-3 days to a week. In addition, utilities and wiring can be laid under the adjustable floor, and, if necessary, heat and sound insulation slabs. However, such a floor itself increases the sound insulation of the room due to the air “cushion” between the floor covering and the ceiling, as well as through the use of plastic bolts.

Technology comparison

Those wishing to level the floor before laying the covering were not too spoiled by the abundance of screed options. Those who wanted to save on materials had to work hard with lining wood chips or adding sand under the joists, or wait a whole month for the cement to harden. Those who did not want to cut costs had to pay a significant amount for a polymer leveling mixture. Adjustable floors have become an alternative to outdated and expensive technologies. Their construction allows you to save money, reduce the duration of repairs, and even do the work yourself.

Is it worth making adjustable floors at all?

The list of advantages of leveling systems with adjustment includes all the priorities inherent in light dry screeds arranged on joists or on point supports with a flooring made of chipboard or OSB panels, plywood, gypsum fiber boards. Excellent ventilation, minimal weight, ability to lay utility networks, etc. The principle of their operation and construction is similar, the only difference is the use of special screw devices. They facilitate and speed up the labor-intensive process of arranging structural elements horizontally, which takes a lot of effort and time from the performers.

Regulating devices consist of plastic support bolts with external threads and an internal cone-shaped cavity and dowel-nails. Plastic bolts are inserted into holes drilled in the joists or slabs. After laying the dry screed elements together with the bolts in their proper place, the leveling structure is attached to the base floor. To do this, a dowel-nail is inserted into the inner cavity of the bolt and driven into it with a hammer.

Fastening with dowels and nails is carried out if the leveling structure is installed on a concrete base. TO wooden floors fastened with galvanized screws.

Regulating devices simultaneously perform three functions:

• serve as reliable supports for the log system or for sheets of plywood;
• work as guides for installing fasteners connecting the subfloor to the base base;
• and most importantly, they help in the shortest possible time adjust the position of the rough flooring in the horizontal plane by simply turning the screws.

The construction technology is so simple that you can build adjustable floors with your own hands. House master, which has nothing to do with construction specialties. You can even make your own adjustable dry screed using the type of factory systems. Difficulties may arise with the purchase of a support bolt made of heavy-duty ABS polymer. However, a number of manufacturers offer leveling structures only with a metal stud bolt, along the external thread of which joists or plates move down/up.

A simplified bolt design for adjustable floors consists of metal rods with external thread. At the bottom they are equipped with elements for fastening to the base floor, at the top with a device for adjusting and fixing the logs or plywood in the required position. There is also an option with metal U-shaped parts attached to the floor and to the joists with screws, but there is a lot more fuss with them and the adjustment is carried out according to a slightly different scheme.

Two technologies for constructing adjustable floors

As mentioned above, either joists or slabs are equipped with support bushing bolts. The choice of a leveling system with adjustable joists or slabs determines the planned height of the subfloor:

• If it is possible or necessary to raise the floor to a height of more than 5 cm, the owner should pay attention to structures with joists;
• If it is undesirable to greatly reduce the space, and you plan to raise the surface by a distance of 3-5 cm, a leveling system with adjustable plates is suitable.

Both use similar adjustable feet to create a level floor surface. Only the support bolts and anchors for the joists are longer, since they have to “go through” and also support the beam. There is a difference in the arrangement of holes for screw devices and in the methods of installing a dry screed.

General preparation rules

To select the type of adjustable structure, we determine the height at which the rough flooring will need to be fixed. We focus on the floor level in the room with a previously laid coating, the thickness of which will need to be subtracted in the calculations. Let's take into account the height and location of underground communications, if any, and the height of the lower plane of the doors. In accordance with the difference between the actual and planned floor surface levels, we select the option of an adjustable system.

Then you will need to measure the room being equipped and draw a plan. Having a simple drawing in hand, it is easier to calculate the amount of material and hardware for fastening, it is easier to determine optimal scheme arrangement of whole and chopped elements.

Regardless of the type of leveling structure, a ventilation gap of at least 1 cm must be left around the perimeter of the room. A similar gap should be between adjacent slabs and between inserts used to equip areas not covered with whole sheets.

In the drawing we “lay out” the slabs with the given dimensions that are available in the factory configuration or for free sale. After all, they will be covered in both cases. We determine the hole drilling step, depending on the coating chosen for finishing installation. To form an ideal dry screed for floor tiles or linoleum, there should be no more than 30 cm between the axes of the holes. The maximum distance between the centers of screw devices is 50 cm when leveling using slabs. When leveled with lags of 45 cm.

If you intend to install a structure with adjustable joists and then lay plank floorboards, there is no need to nail plywood to the aligned joists. The board can be attached directly to the beam, which should not be forgotten when determining the level of the subfloor.

Construction of a floor with adjustable joists

There are mandatory rules for marking drilling points in timber for plastic support bushings:

• to drill the first hole from the end of the log, it is necessary to retreat 10 cm;
• the remaining distance minus 10 cm from both ends must be divided into equal segments;
• between the walls, ends and the side plane of the first log there should be a distance of 1 cm for ventilation;
• the logs are installed at equal distances according to the selected step;
• ordinary logs are positioned so that the edge of each sheet of plywood rests on the timber. Do not forget that you need to leave a centimeter gap between the plates.

Installation and fastening of the joist structure is carried out in accordance with the algorithm proposed by the developers of dry leveling systems:

• At the points marked on the beam, holes are formed with a feather drill for support bushings, which then need to be inserted there and screwed with screws. Flush with the plane of the beam we recess only the outer bolts, with the help of which the adjustment will be carried out.
• We place the lag with bushings in the planned place and, through the internal cavities of the bushings, mark points for dowel-nails on the base base.
• We remove the lag, drill holes in the concrete with a hammer drill 4-5 cm deep at these points.
• We return the lag to its rightful place and insert fasteners into the bushing bolts.
• We hammer in only the outermost dowel-nails with a hammer. We do not hit “all the way”; we will do the final driving after leveling. Ordinary dowel-nails are not fixed at all until the joist is accurately aligned and adjusted horizontally.
• Using a hexagon, we adjust the position by rotating the two outer bolts. We control the actions with a level gauge.
• Found the perfect position? We finally fix the outermost dowel-nails. We screw the ordinary plastic supports all the way into the base floor and hammer in all the fastening elements inserted into the support bolts with a hammer.
• We carefully cut off all excess beams protruding above the surface of the beam with a chisel flush with the upper plane of the beam.

Similarly, we install each element of the floors constructed using adjustable joists. Then we nail or screw the plywood to the beam with self-tapping screws in one layer if the sheet thickness is 18 mm or more, in two layers if we have sheets with a thickness of less than 12 mm. The maximum spacing for fastening the boards is 15 cm. The butt seams of the second layer of plywood should not coincide with the butt seams of the first layer.

Every time after drilling holes in concrete and wood, the floor and adjustment devices must be removed from dust, otherwise the finished floor will creak.

Rules for installing adjustable plywood

Craftsmen leveling floors using adjustable slabs should adhere to the following recommendations:

• The optimal distance from the edge of the sheet to the center of the outer support-sleeve is 6 cm, exceed specified limit it is forbidden.
• After marking the position of the outer bushings, the slab must be divided into equal, preferably square, segments. Maximum length the sides of the square are 50 cm.
• Inserts should be equipped with at least 2 rows of screw supports, regardless of the design pitch.

To shorten and facilitate the marking process, we lay the slabs in stacks. We drill the first sheet of plywood marked on top with a feather drill so that a mark remains on the slab lying underneath it. Using these points we form holes in the second plate, etc.

We carry out further actions by analogy with the technological diagram described above. The only difference is that you will have to adjust not the outer two, but four bolts using a hexagon.

Since mark the attachment points on the base floor through quite volumetric sheet plywood is not too easy, we stand on it with our feet. This way we will fix the plywood and prevent it from moving.

After driving the dowel-nails with a hammer, the installation strength of the fasteners must be checked. Untrustworthy elements must be dismantled and replaced. Before finishing installation The surface of the floor covering must be dust-free. There will be no specks or specks of dust, the adjustable floor will never creak.

If you follow the rules for installing a dry screed, the leveling will be done perfectly and the rough base will last for half a century. Floors will be better preserved if moisture is removed regularly natural ventilation. And the owner will not lighten his own wallet by the very significant amount saved on the services of builders.

We make an adjustable floor on joists instead of a concrete screed

Concrete screed, due to its structure, does not allow the formation of a surface that would be sufficiently smooth, and now, more and more often, mixtures such as “Betonite” or technology are used instead. A good alternative to all these “wet”, and therefore labor-intensive and dirty technologies, is a floor with adjustable joists.

These structures have special adjustable supports for the logs in the form of plastic post bolts. Moreover, the adjustable logs can be raised or lowered along the threads of these post bolts and thus easily adjusted to the level, which guarantees a perfectly level base for the finishing floors, and therefore no creaking floors.

Advantages of an adjustable floor on joists

Compared to leveling with concrete screed, adjustable joists offer the following advantages:

• wet and dirty technical processes are excluded;
• a wide range of floor lift levels from 5 to 15 cm and higher is provided without any additional material and labor costs;
• obtaining cost savings when raising the floor over 7 cm;
• speed of the installation process (100 m2 in two days);
• guarantee of high alignment accuracy;
• increased heat and sound insulation;
• placement of all types of communications in the underground space, which makes it easier to access them during repair or replacement;
• the lightness of the design, making it indispensable in houses where a large load on the floors is technologically unacceptable.

The following are possible design options adjustable lags.

Also read materials:

• Standard set of plastic post bolts and fastening elements for concrete + separately purchased wooden beam under the logs. This option involves the maximum amount of DIY work. It will be necessary to drill holes in the joists, and then cut threads into them with a tap for plastic post bolts.
• Standard set of plastic bushings, post bolts and fastening elements to concrete + separately purchased wooden beam for logs. Unlike the previous option, here, after drilling holes in the joists, ready-made plastic bushings with internal threads are inserted into them, which are attached to the joists with self-tapping screws.
• Standard set of adjustable joists, including wooden joists with ready-made threaded holes for stand-up bolts, as well as a set of stand-up bolts themselves and elements for fastening them to concrete. Plastic post-bolts have internal through cone-shaped holes for passing through them the fastening elements of the post-bolts to concrete (dowel-nails) or wood (screws). Moving down in such a hole, the dowel-nail self-centers along its axis. In the upper wide part of the hole, a hexagon wrench is formed for screwing the stand bolt either into a threaded bushing or directly into a threaded hole in the joist.

Installation of the floor on adjustable joists (video)

The main stages of installing an adjustable floor on joists

Preparatory work

1. The room in which it is planned to install adjustable joists is measured. Based on the measurements, the amount of timber for the logs with a margin for cutting, bolts-posts for installation and dowel-nails for attaching them to concrete are calculated.
2. The level of the floor slab is checked and the final floor level is set taking into account the height of the flooring (plywood, OSB) and the height of the finishing coating.
3. In the logs with the required pitch, through holes are drilled with a feather drill, then, if you do not have threaded bushings, threads are cut into the holes with a tap. If you purchased ready-made plastic bushings, they are inserted into smooth holes and fastened to the joists with self-tapping screws.
4. The stand-up bolts are screwed into the holes of the joists using a hex key - the outer screws in each joist are screwed in completely, and the middle ones - to a small depth.

Important! If the surface of the floor slab under the post bolt is very uneven, it should be leveled with a chisel. The post bolts must be securely attached to the concrete. Minimum distance there should be 10 mm between the floor slab and the joists.

Installation of logs

• First, logs are installed along the perimeter of the room with a distance of 10-70 mm from the walls, the distance between the wall and the ends of the logs is 10-30 mm. When choosing a pitch between lags, you should take into account the dimensions of the flooring sheets (slabs). The edges of the flooring slabs should rest on the joists and end near their central axes. The standard step size between the logs is 400-600 mm, however, to strengthen the structure, this step can be reduced to 300 mm. It is allowed to install cut-off joists supported by two stand-up bolts.
• The outermost bolts in each joist are installed first. They are screwed into the joist to the required depth, controlling the preliminary position of the joist by level, after which all other stand-up bolts are lowered to the level of the slab.
• After this, a thin drill is inserted into all the holes of the post-bolts and holes are marked in the concrete for the dowel-nails.
• The lag is removed and the planned holes are drilled in the concrete. The joist is reinstalled, a dowel-nail is inserted into each bolt-post, which is lowered down the cone-shaped hole and falls exactly into the hole drilled in the concrete.
• Next, lightly recess the dowel-nails in the 2 outer bolts-racks using a hammer. The log is set to the required height by rotating the two outer bolts with a hexagon, controlling the process by level.
• The outer dowel-nails are finally driven into the concrete. Then screw the remaining stud bolts into the joists until they rest on the slab, recess and hammer the dowel nails into each stud bolt.

Using a chisel and a hammer, cut off the protruding ends of the bolts from the upper plane of the log. Check the rigidity of the fastening of the post bolts to the floor slab by pressing on each joist and trying to tear it off (lateral loosening is prohibited).

If any post bolt is not sufficiently fastened to the floor slab, it is unscrewed. Remove the dowel-nail and increase the depth of the hole in the concrete. The holes are cleared of dust and the post bolt is reattached.

If the required rigidity of fastening to the base is not achieved, then use other fasteners. For example, in the form of RDK - a nylon expansion dowel with a screw. The screws in the RDK dowels are tightened using a long bit with a screwdriver or drill. The screw must not be loosened or turned in the dowel thread.

Installation of the floor on adjustable joists (video)

Adjustable logs on metal studs

Let's consider how you can arrange adjustable logs from materials that can be purchased at any building materials store.

Regular steel studs can be used as adjustable supports for joists. The design of such adjustable lags on heels is as follows.

• A standard dry planed timber with a cross section of 50x50 mm is used for the logs. Its adjustable support contains an M 6 pin, two nuts, two washers and an anchor sleeve.
• IN concrete slab a hole is drilled into the ceiling, an anchor sleeve is driven into it against a spacer, into which a pin is screwed.
• The lower (under the joist) nut with a washer is screwed onto the stud. A hole is drilled in the joist with a hammer on top.
• The lag is put on the stud, so that the nut and washer are on its lower side. By rotating this nut you can adjust the position of the joist. The second nut (top) is necessary to fix the log at the set level.

As you can see, the modern construction industry is offering new alternatives to traditional construction technologies. Adjustable – shining example such an alternative that makes it easier and cheaper to install and repair floors.

Currently, the main criteria for flooring subfloors are strength and reliability, since the quality of floor installation depends on them. finishing material. To ensure that the floor is level, experts advise giving preference to adjustable structures that are built along joists.

What you need to know about adjustable floors

• Hollow wear-resistant polymer bolts are used as adjusting elements;
• the adjustable base is divided into two types: by slabs and by logs;
• if plywood is used as the base of the adjustable floor, then the bolts should be attached to the underside of the sheets;
• when laying insulation between concrete base and with an adjustable floor, metal clamps should be secured to the inner surface of the joists;
• the logs should be located at a distance of 25-45 centimeters from each other, and the step under the tiles should be small;
• if there are no hollow polymer bolts, then the fastening mechanism can be made from a hammer-in anchor with a thread. In this case, wooden logs or plywood sheets are clamped to the anchor pin using washers and nuts;
• adjustable floors correct installation can last at least 35 years.

Installation of adjustable floors

An adjustable floor on joists is a floor device located on special boards, under which there is underground space. Thanks to this, the floor surface does not require additional leveling using a concrete screed.

A threaded anchor for an adjustable floor is attached to a base, which can be wood, concrete or dirt. The height of the floor is adjustable due to the ability of the clamp to rotate around its axis.

Anchors are attached to the base depending on the type of subfloor:

• fastening to a concrete slab occurs using polypropylene needle dowels;
• fastening to wooden base occurs using self-tapping screws;
• fastening to the concrete screed occurs using dowel-nails.

The anchor structure performs the following functions:

• adjusts floor height;
• provides load separation;
• enhances the strength of the connection between the subfloor and the adjustable one.

Advantages of adjustable floors

Adjustable floors have many advantages, including:

• Possibility of use as a base for any finishing material;
• possibility of installation on our own, since the work is quite simple and does not cause any particular difficulties;
• lightness of design, thanks to which it can be used when arranging loggias or balconies;
• the possibility of laying communications or an insulating layer in the space between the flooring and the base;
• installing an adjustable floor on joists is a fairly dry and clean type of work, which allows you to avoid staining the walls during work;
• wooden floors can cope well with differences exceeding 15 centimeters;
• the cost of adjustable floors is more affordable compared to concrete screed, which makes them more popular;
• thanks to modern technologies it becomes possible to create a perfectly flat floor that does not create squeaks.

DIY adjustable floors

Adjustable indoor floors

To begin with, you need to attach the logs to the base in increments of 30-50 centimeters, using screwed-in post bolts. Then the logs are leveled by level, for which the stand-up bolts are rotated along the axis using a special key. Finally, plywood is laid on the joists. double layer, and the thickness of each sheet must be at least 12 millimeters. In the event that in the future it will be laid ceramic tile, to lay the top layer you need to use moisture-resistant plywood with a thickness of about 10-12 millimeters.

When installing adjustable plywood using feather drill 16 are made in plywood through holes. Then plastic bushings are inserted into them, into which the post bolts are screwed. After this, you can begin to level the sheets by rotating the bolt stands secured to the base with dowels.

Attention ! To install the floor, you must use logs made of durable wood with a humidity of 12 to 14%. They should not have cracks or knots, traces of mold or rodent damage. The length of the logs is usually 2 meters, and the cross-section is 4.5 by 4.5 centimeters. Before starting work, the material should be treated with special protective compounds. There must be enough air in the underground for ventilation.

The main advantage of such a floor is that it becomes possible to create a perfectly smooth and even subfloor on an unprepared base. Thanks to this, almost any floor covering can be used in the future.

Setting the horizon level using adjustable logs

By erecting a structure of this type, it is possible to mask any systems (ventilation, heating, electrical, etc.). If a “warm floor” system is installed in the room, then its installation, carried out according to this design, will significantly reduce heat loss through the floor and, thereby, significantly save electricity.

Despite the fact that such an adjustable design is characterized by a fairly low weight, it is capable of withstanding heavy loads, which can reach up to 2500 kilograms per 1 square meter. Thanks to this, adjustable floors have found their use not only in furnishing living rooms, but also warehouses, gyms and other premises.

Houses with such a floor structure can be built even on soils in which heavy loads on the foundation are strictly prohibited. If the floor cannot be raised too high, then you can use a special design on adjustable plywood, in which the rise will reach only three centimeters.

The technology for installing it is almost no different from installing logs. The main difference is that instead of joists, naturally, sheets of plywood are used.

Plywood is a material used not only in home life, but also in aircraft manufacturing, shipbuilding, furniture production and many other industries. With the help of plywood, you can easily replace a damaged section of the floor, because it goes well with floor coverings from linoleum, laminate, carpet and parquet. But to avoid any misunderstandings, you need to know how to lay plywood correctly.

Advantages of plywood over other materials:

• the strength of the material is the same in all directions;
• the sheets are quite large;
• the formation of through cracks is completely excluded;
• plywood bends easily;
• transportation of the material does not cause any difficulties;
• has low weight but high strength;
• plywood is characterized by high quality sanding and a hard surface;
• The material is waterproof and odorless.

Adjustable plywood is excellent in cases where the floor has distortions exceeding 15 centimeters, or communications pass through it.

Attention ! When adjusting the floor along the joists, the height of the room usually becomes lower by about 7-8 centimeters, so it is recommended to use it in rooms with high ceilings. In turn, when laying floors on adjustable plywood, the floor rises no more than 3 centimeters, so the second method is considered more effective.

• when choosing materials for leveling floors, you need to look for timber and plywood as much as possible High Quality, since this show significantly affects the result of the work as a whole;
• for ease of installation, it is recommended to purchase a laser level, which will allow you to achieve more accurate results;
• floor slabs and the base must be as strong as possible, not crumble or crumble;
• do not forget about the need for ventilation of coatings;
• To prevent floors from squeaking, during the installation process all surfaces should be cleaned of dust (as soon as the holes are drilled and the bolts are screwed in, the surfaces are thoroughly vacuumed). In addition, the dowel-nails should be nailed as tightly as possible so that the racks do not become loose;

When using this method, the logs are replaced with bushings, inside of which there is a thread (for this, special holes are drilled in the plywood). 6 plastic bolts are screwed into the bushings, which must then be attached to the base using a dowel. To level adjustable plywood key should be used.

First you need to carefully level the first layer of plywood, then install the next layer and screw it with self-tapping screws. Before laying the second layer, you need to carefully overlap the joints of the previous one, which will avoid the formation of seams. Thanks to these actions, the floor surface will become even and smooth.