Installing a wooden floor along joists on a concrete base is a common way to create a warm, well-ventilated structure that can serve as a finishing surface when using tongue-and-groove boards or be an excellent base for finishing facing material. At the stage of manufacturing such a floor, the question arises: what is the best way to attach the joists to the concrete floor? This is what we will discuss in today’s material.
Despite the fact that the advantages of creating a flooring with joists rigidly fixed to the base are obvious, there are opponents of this method who claim that in this way the integrity and sound insulation of the room can be damaged due to the formation of acoustic bridges in the places where the fasteners are installed.
If the screed is destroyed during drilling, then this indicates its poor quality and should serve as a signal to dismantle it completely and fill in a new one. A high-quality screed does not change its integrity when holes are drilled in it using a drill.
Regarding sound insulation: a rigid structure transmits sound waves, but if you consider that insulating material is laid between the joists, which dampens the sound, then this statement can be considered controversial. In addition, concrete is much denser than wood, and therefore the sound that is transmitted through the acoustic bridge to the concrete base will not reach the neighbors below.
One of the nuances of wooden flooring over joists is the possibility of creaking, which can be heard even by neighbors below. This occurs when structural elements (beams, joists and fasteners) are displaced relative to each other. By rigidly fixing the joist to the concrete base, these troubles can be avoided.
Important! If the logs are not firmly fixed, and their humidity stated by the seller does not correspond to reality, then soon, due to the process of warping of the wood, the floor structure will begin to deform and shift.
Proponents of abandoning rigid fastening of joists prefer floating floor designs, when the flooring is not fixed to the supporting structures. In this case, it is necessary to approach the choice of lag material very carefully. The stability of the floating structure will be ensured by the special fastening of the beams to each other - in the form of a lattice, into the voids of which insulating material is placed.
The work of laying floors on joists does not require specialized equipment and tools. You will need to prepare:
Will need to purchase waterproofing material taking into account the overlap on the walls around the perimeter of the room by no less than 15 - 20 cm.
There are several most common ways to attach joists to concrete. Each of them has its own characteristics.
Although this method of fixing lags is the simplest, it is not suitable in every case. The process is simple:
The step taken when attaching the logs in this way is at least 50 cm.
Table 1. Installation of a wooden floor with fastening joists to self-tapping screws
| Illustration | Description |
|---|---|
 | Obvious defects on the concrete surface are repaired using mortar or foam. |
 | The concrete base is dusted off and debris from this surface is removed using a vacuum cleaner. |
 | The floor is primed with a solution with antiseptic additives. |
 | The logs are pre-treated with antiseptics and fire retardants. |
 | The logs are laid in increments of 50 cm. |
 | Plastic wedges are placed under the joist and with their help the element is adjusted to the desired height. |
 | The height of the logs is controlled using a construction angle or tape measure and laser level. |
 | Drill a hole for the self-tapping screw. |
 | Screw in the self-tapping screw. |
 | The wedges must be fixed in the specified position using foam. |
 | |
 | Lay a layer of vapor barrier. |
 | The OSB boards are fixed. |
Fixing lags using anchors is a durable and reliable method. Additional rigidity of the structure is provided by attracting the timber to the surface of the base.
An anchor is a more powerful fastener than a dowel; it can withstand high loads. When installing such a floor, you can rest assured that it is securely fixed to the concrete base. According to the technology of work, fastening timber to anchors is similar to fixing it to self-tapping screws. First, holes of the required diameter are drilled in the base and joists. A hole is made in the wood so that the head of the bolt can be hidden.
The number of fasteners is calculated taking into account the fact that an average of 4 anchors are required to fix one beam. The bolt into the locking element, inserted into the hole in the concrete, is driven through the wood. The length of anchor bolts varies from 45 to 200 mm. When choosing it, 6 cm is added to the thickness of the beam for penetration into concrete. The recommended diameter of the anchor bolt is 10 mm.
The popularity of anchor fastening is due to more rigid fixation wooden structure. With the help of this fastener, you can count on restraining the wood before the deformation process if it has not been sufficiently dried.
Table 2. Anchor installation
| Illustration | Description |
|---|---|
 | After the anchors are driven into the concrete base, using a 13mm wrench you will need to tighten each anchor nut to secure it more securely. However, you should not use too much force to avoid stripping the thread. |
 | After this, a lower nut is screwed onto each anchor and a washer is installed on which the log itself will be laid. The nut is installed reverse side and screw it in, following the markings on the wall. |
 | A puck is placed on top. |
 | A hole is drilled in the joists for the anchor head and under its body, taking into account the spacing of the anchors. |
 | The logs are attached to the anchors. |
 | Screw in the top fixing cap of the anchor. |
 | The nut is tightened in accordance with the level value. |
 | Excess fasteners are cut off using a grinder. |
 | Insulation is laid in the space between the joists. |
 | Sheets of plywood are fixed to the joists. |
If the height of the logs exceeds 10 cm, then metal corners are used for their fastening. The corner shelf is secured to the concrete base using dowel nails, and to the joist - with self-tapping screws. IN in this case the corner is used to fix the position of the wooden element, and the load is distributed on the spacers.
Table 3. Installation of logs
| Illustration | Description |
|---|---|
 | Before attaching the corner to the joist, drill a hole for the self-tapping screw. To ensure a strong connection, the self-tapping screw is immersed into the wood at an angle. |
 | A hole is drilled in the concrete floor for the dowel. |
 | The dowel is immersed in the hole and the self-tapping screw is screwed in. |
 | A beam is inserted under the logs, which will allow the logs to be fixed at the required height and provide ventilation to the structure. |
 | The bars are also fixed to the floor using corners. |
 | Wooden flooring is made from tongue and groove boards. |
 | To fix the board at an angle, drill a hole for a self-tapping screw. |
 | The board is fixed using a self-tapping screw inserted into the groove at an angle of 45 degrees. |
The adjustable joist system is the most in a simple way installation of a level boardwalk in a room with a concrete base that has a significant difference in height. The anchors in this design are replaced with plastic posts, which are attached to the concrete using dowels. The convenience of using plastic racks is that you can adjust their height and the level of the logs using special rotating bolts. Excess posts protruding above the surface of the joists after adjustment are cut off.
Modern manufacturers offer universal racks that make it possible to produce a perfectly flat plank covering in a room with a large difference in height, regardless of the cross-section of the beams. Installation proceeds as follows. The supports are installed on a concrete base.
The logs are laid and, focusing on the level, they set the horizontal plane, adjusting the location of the beams using a special rack mechanism.
Universal racks are equipped with an automatic tilt angle correction system up to 5%.
Modern construction technologies make it possible to use effective ways to regulate the floor level and level it. If previously only a concrete screed was used for this, the creation of which is characterized by a long duration of work, a huge amount of dirt and significant costs, but today the role of such a rough foundation is played by adjustable floors, which can be easily and quickly installed with your own hands.
With the help of an adjustable floor, you can level the surface if the base is uneven.
There are a few in various ways, allowing you to create adjustable floors with your own hands and thereby raise the surface to a height of only three millimeters, which is important for apartments in multi-storey buildings that do not have a high ceiling height anyway. Adjustable floors are also very beneficial for old houses, where the floors may not withstand the installation of a heavy concrete screed.
The main feature of adjustable floors is that such floors can be lowered or raised using a special system of stands or pads. That is, you can achieve the ideal result by simply adjusting the height of the bolts, and end up with a smooth, beautiful base, suitable for laying any type of flooring: from expensive solid boards and parquet to simple linoleum.
Special anchors are used as support, that is, metal rods and bolts that have a stepped hole for attraction to the base. The dowels are driven in only after all the joists have been installed.
The advantages of adjustable floors include the following:
You can adjust the floor in several ways, including:
Leveling the floors in both options is carried out by freely moving the bolts along the axis down or up. In this case, the system can be attached to any base:
In this case, the anchors take on the responsibility of adjusting the height, ensuring the connection between the ceiling and the structure, and a significant part of the load.
Installing an adjustable floor involves the following steps:
If you use several layers of plywood, you must ensure that the joints and seams of one layer do not coincide with the joints of the second, otherwise the necessary strength and reliability of the entire structure will not be achieved.
When laying on joists, it must be taken into account that the joints should be located on the surface of the joists, and not between them.
Installing an adjustable floor using plywood or using joists involves performing the same steps, the only difference is that in the first case, the plywood itself or the selected material is laid directly on the bolt posts, and in the second, the plywood is laid on the already leveled joists .
The assembly of an adjustable floor may depend on a number of features that must be taken into account before installation. So, if the future floor covering is laminate or parquet, then the step of wooden logs can be fifty centimeters, but for linoleum and floor tiles the step cannot be less than thirty centimeters.
For wooden floors It is better to use moisture-resistant plywood.
Also, during installation the following conditions must be met:
For flooring, only moisture-resistant plywood is used, which can be laid in one or two layers. Moreover, for one layer the thickness of the sheet cannot be less than 11-12 millimeters, and for two layers - nine. Often, when laying a double layer, factory-glued plywood is used, which has a kind of lock for ease and reliability of installation.
It is necessary to take into account that maximum thickness for such double flooring should not exceed twenty millimeters. Instead of plywood, you can use fiberboard and chipboard sheets, moisture resistant drywall large thickness, OSB boards, cement bonded particle boards. All gaps between the wall and the subfloor are subsequently covered with baseboards after the floor is finished.
Adjustable floors have gained popularity due to their relatively simple installation compared to screeds, as well as a fairly wide range of applications. For rooms where the ceiling height is quite low, such floors are a godsend!
Similar designs are also used for dilapidated houses, where the floors simply cannot withstand the enormous weight of the concrete screed, but lightweight wooden joists and plywood sheets allow all leveling work to be completed quickly and without much dirt.
Adjustable floors are also installed in offices and other commercial premises when it is necessary to carry out quick and relatively inexpensive work on leveling the floor and masking utility lines.
Today, an adjustable floor is a very beneficial technology for almost any room, which provides high-quality and quick leveling using environmentally friendly materials and does not require wet construction processes. Moreover, create adjustable floors without using professional builders, quite simple.
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.
An adjustable floor on joists is a floor device located on special boards, under which there is an 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:
The anchor structure performs the following functions:
Adjustable floors have many advantages, including:
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, a double layer of plywood is laid on the joists, and the thickness of each sheet should 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, 16 through holes are made in the plywood using a spade bit. 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.
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 living rooms, but also in 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 households, but also in aircraft construction, shipbuilding, furniture production and many other industries. Using plywood, you can easily replace a damaged area of the floor, because it goes well with floor coverings made of 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:
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 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.
Floor slabs with adjustable posts
Disadvantages of adjustable floors
Characteristics of adjustable ground on logs
Possibility of selecting adjustable soil
Types of floors with adjustable brackets
Floor design with adjustable flags
Floor coverings with adjustable supports
Tips for Installing Adjustable Foot Structures
Modern flooring options include adjustable flooring in the latest designs.
The day system, installed on mobile brackets, makes the floor surface completely flat with minimal physical effort.
Manufacturers produce several versions of so-called “adjustable floors,” depending on the purpose of the specific space, the design height of the floor covering, and the condition in which the underlay is placed.
If it is necessary to raise the floor level to the desired height in order to accommodate various services below the surface, a DNT structure with adjustable footrests can be installed. They ensure not only perfect uniformity of floor coverings of all materials, but also allow the installation of a frame when the floors between the floors in the house are wooden elements.
The upper form is capable of raising the covering to a height of 5 centimeters or more, which depends on the cross-section of the logs and the dimensions of the polymer screws. The system can be attached to wooden or cement floor or to another type of foundation.
When it is necessary to solve the problem of leveling rough ground without losing the height of the space, the adjustable bottom structure on the plates can be adjusted.
It is used to prepare the base for laying, for example laminated or parquet panels, provided that the difference in height does not exceed 2 mm with 2 linear meters. The maximum amount of lifting of the floor covering in this case does not exceed 5 centimeters, which corresponds to the thickness of a standard concrete screed.
The parameters of the adjustable DNT structures allow a short time create a strong and durable floor with excellent thermal and sound insulation of the room. In this case, there is no need to deal with dusty and wet processes, as in the case of installing cement sand. The DNT system costs no more than traditional leveling options such as semi-dry or concrete screeds or Knauff flooring.
If the soil rises 5 centimeters or more, you can save a large number of when preparing a rough base for finishing.
As for the disadvantages of this design, they may arise if the requirements for proper operation were not met during installation.
DNT adjustable floors with high quality installation provide a reliable and durable base for everyone finished materials for the floor. It will not only be possible to move on foot, but also to travel by car.
If the DNT system assembly fails or wrong type fastening elements for an adjustable flag, the soil will become unusable within a short period of time.
The structural solution of such floors has the following characteristics:
You just need to buy quality materials and supplies of some tools.
This allows for space-saving and at the same time impervious floor coverings.
This is why this option is ideal solution for areas where cleanliness is required.
Although adjustable structures have many benefits, many property owners are hesitant to install them during renovations.
On modern market Consumers are offered two types of flooring:
The main difference between these varieties is the difference in height.
When installing systems on logs, the amount of lift is 5 centimeters or more. As for the adjustable plate design, it can be raised by a maximum of 3 centimeters.
Installation work related to the installation of adjustable systems on logs and boards is carried out using similar technology that allows you to do it yourself.
The seals for them are made from plan rays.
The size of wooden elements usually does not exceed 50x50 centimeters. First you need to prepare your tools and building materials.
To install the floor, you need:
At the first stage, preparatory work is carried out:
If necessary, build utility lines.
Otherwise they must be executed independently. At least 5 holes must be made at a distance of 2 meters. This simple operation is performed by drilling with a flared top. To ensure installation rigidity, it is necessary to drill slightly smaller than the diameter of the bolt.
During the installation phase, the following measures are taken:
In this case, the difference between them depends on the type of floor area. When the floor plan is covered with linoleum or slab, the distance between the beams should be up to 30 centimeters. Leave at least an inch of space between flags and walls to ensure proper ventilation.
The hole must be securely fastened so that the structure does not move.
During the surface smoothing process:
This applies a rule and a key that needs to be adapted.
At the final stage, complete the following tasks:
The choice of materials depends on the purchased flooring. Typically the flooring is made from slabs made from plywood, rarely using DSP or GVL slabs, with linoleum or laminate on top.
This option is used if the height of the floor surface does not exceed 3 centimeters.
In such a narrow space it is unlikely that communications can be hidden, but telephone cable and Internet wiring will be available. This type of installation technology is similar to the procedure for installing adjustable floors on logs.
It is necessary to prepare a set of adjustable presses on plates, consisting of sheets of plywood (other building material), posts, bushes, self-tapping screws.
You will also need: a hammer, a drill, a level (water or laser).
The work begins with the preparatory stage:
If it has a 1.5 x 1.5 meter sheet, it should be approximately 9. One of the holes should be placed in the middle of the plywood or other material. Four holes rotate in each corner and 4 in the middle of the sheet. For this reason it is possible to provide reliable connection plywood.
Installation of panels should be carried out in the following order:
Use a special drill bit with an extended tip.
They lead them halfway.
At the adaptation stage, the following measures are taken:
Proceed to the final stage:
To successfully install this type of flooring system, you will need to:
The fact that uncleaned debris, plastic cutouts, sawdust from the last floor covering can lead to pulleys and noise.
This is the same dowel, but stronger. Anchors provide a secure and permanent connection. They not only hold the stick in place, but at the same time attract it to the ground, which, in addition to being rigid, also transmits rigidity.
There was no noise during operation of the coating.
If you need to move the link after installation is complete, a few strips of cover can be removed and then put back on.
Often, people associate floors with joists with something old, creaky, rotting and obsolete.
Of course, there are now many advanced technologies for floors that make it possible to insulate, waterproof and raise the floor level to a greater height, if the design requires it. However, one should not exclude good old logs - the solution is simple and, with high-quality installation, will eliminate the disadvantages typical of such floors.
The most undeniable advantages adjustable floors are the ability to raise the floor level to a greater height without increasing the overall weight of the structure and the speed of installation, in comparison with various screeds and self-leveling floors.
The big advantage is that there are no wet processes and therefore no need for drying. Insulation of such floors also does not cause any problems - polystyrene foam, extruded polystyrene foam, mineral wool, all these materials are acceptable. In comparison with self-leveling, floating screeds there are no requirements for insulation high requirements according to the density of the insulation and it is possible to select a budget material.
When pouring screeds up to 5-10 centimeters thick, the advantages of lags are not relevant, however, situations often arise when the floor level needs to be raised by 15 centimeters or more. Such heights may be required when there is a large difference in floor slabs, during partial renovation of an apartment, where it is necessary to join the old floor on joists.
Of course, there are screeds with the addition of expanded clay, various floating screeds that allow you to raise the floor level and at the same time insulate.
As a rule, the cost of materials and work increases, and if a 5-centimeter screed is 1.5-2 times cheaper than an adjustable floor, then with layers of more than 10 centimeters, the cost of the lag remains the same, which cannot be said about wet screeds.
The disadvantages of flooring with joists include the risk that the floor will creak; in an aggressive, humid environment, wood is not so durable. The issue of squeaking is practically reduced to zero when choosing high-quality, dried logs and the correct fasteners.
Many people are confused by the possibility of laying tiles on such floors - this problem can be solved, the joists are installed in sufficient quantities to eliminate significant deflections in the canvas, and gypsum fiber is laid over the canvas.
Gypsum fiber serves as a damper; even with large fluctuations in the size of the canvas due to changes in humidity, gypsum fiber is quite stable and does not provoke the tile to snap.
The material of the canvas laid on the joists is quite diverse: from the most budget chipboard to two-layer plywood. Planed boards, lining and OSB - you see, a very wide choice for flooring with joists.
Let's summarize: in renovations where standard screeds and self-leveling floors do not cause high loads the ceilings and layers are quite thin - adjustable joists are not relevant.
Where you need to raise the floor level by 10+ centimeters, the logs become very practical solution. Important high-quality installation, it will prevent squeaking, sagging and other typical wooden floors Problems.
Companies engaged in adjustable floors They exaggerate their professionalism and the uniqueness of their technology too much. I will try to dispel some myths, because I worked in this field for several years.
Let's look at the important points in installation.
To attach the logs to the concrete base, it is the anchors that are needed; plastic dowels are not able to cope with the loads to which the logs are subjected.
The so-called plastic bushings, which are screwed into the joist and attached to the concrete, are very inconvenient to install; they can only be purchased from those who professionally install floors. Naturally very expensive. In addition, they have questionable reliability; the bushing is attached to the concrete base with a dowel-nail.
The most reliable fasteners can be assembled yourself, despite the cunning marketing of “sex companies”. However, the components for the rack are usually available in most stores.
So, homemade fasteners for adjustable joists. The base is an expansion anchor (drive-in), it holds tightly in the concrete and is easy to install, it can be made of steel or brass, the anchor expands due to a screw-in bolt.
Brass is preferable. The product is suitable for M10 or M8 threads; other components are selected based on the selected diameter. The next element is a bolt, the diameter of which is suitable for the anchor and the corresponding length; the higher the logs need to be raised, the longer. Instead of a bolt, you can take long studs and cut them to the desired length, but you need a special tool to screw in the studs.
Two nuts with washers (preferably reinforced) are screwed onto the bolt, and the joist is actually clamped between these nuts/washers.
The resulting fastener is very reliable and easy to use.
It does not pull out even if the joists were made of raw wood, the joist guides it when it dries, and the anchor holds it.
Usually a 50 by 40 mm block is used, but if the height allows, you can take a thicker block. In thicker bars, fasteners to the base can be used less often.
As a standard, a 3-meter log is attached to 7 anchors. The logs are set at intervals of 30-40 cm, depending on the material of the covering sheets.
The logs should be chosen drier and without too many bends and screws. The worse the lag is dried, the greater the likelihood of squeaking in the future. Ideally, dry, planed bars, planed after drying, are suitable, but finding them is not always easy. Usually in stores they sell planed “wet” and then dried naturally bars, they have a bent shape. You can use them, but you should carefully choose those that are smoother.
Let me note that the logs do not have to be planed and smooth, preferably straight and not “screwed”. You should also avoid knots; if the hole with the anchor hits a knot, the joist will significantly lose its strength.
Prepared logs can be treated with an antifungal compound; this will not interfere in potentially damp areas.
Materials can be varied, from rough to finishing. For subsequent finishing, you can lay a regular edged board - this option is more suitable for a private home.
Sheet materials are suitable for both private and apartment building. It can be plywood, chipboard, OSB. All these materials are considered rough, with subsequent installation of linoleum, laminate and parquet board. With additional gypsum fiber flooring, tiles are laid.
TO finishing coating applies batten, lining.
Their further finishing consists of sanding and painting (although it is often useful to do this before installation).
As a sheet material, I would like to mention plywood - it is strong, durable and tolerates moisture well. Due to the different orientations of the veneer layers, plywood is less susceptible to variations in size.
There is, however, one unpleasant drawback: in most cases, the thickness of the sheets may differ slightly by 1-2 mm, and the difference may be present at different ends of the same sheet. Because of this difference, for linoleum flooring, for example, you will have to putty the seams. However, despite this, plywood is considered the best material for adjustable floors - 10 mm plywood in two layers is the most durable solution.
Plywood no thinner than 18 mm is placed in one layer.
A concrete base is required to securely fasten the anchors. Typically, in commercials, fasteners for joists are installed in a perfectly leveled cement-sand screed (CSS). But the reality is that for real work Leveling the base is not required this time; moreover, usually the screed does not have sufficient strength to reliably hold the anchor.
If in your case the installation will be carried out for some reason on the central fiber substation, then you should drill down to the concrete. Or check the strength of your tie by tightening a test anchor.
Preparation consists of cleaning, foaming and caulking various cracks to avoid drafts. You should also mark the location of future logs; this is done on the walls, where the middle of the log will be. When marking, you should take into account the centimeter gaps of the sheets from the walls so that the seams clearly fall in the middle of the joist.
The easiest way to mark is this: first, mark the logs on which the sheet joints will be, and only then distribute the remaining logs between the seams so that the distance between them does not exceed 30-40 cm.
I would like to note: usually all the lags are made parallel; at seams perpendicular to the lags, additional lags are not required for connecting sheets; more on this later. Of course, the logs can be set as you like, they can be longitudinal or transverse, the point is that there is no need to make extra crosshairs.
From my own experience, I was convinced that it is more convenient to drill holes for bolts and countersunk nuts in place. If you make holes with countersunk holes in advance, you eliminate the possibility of moving the fastener; this may be necessary when the fastener hits a weak spot in the concrete, a covered void, etc.
This is my personal opinion; it is certainly possible to drill holes in the joists in advance. I will describe my method, and it’s up to you to decide which is more convenient and practical. This method is not relevant with ready-made fasteners purchased in online stores - there you need to tighten the lowest nut to fix the anchor.
The joist is laid in the marked place, a hammer drill is used, and a hole is drilled directly through the joist in the concrete base. Having drilled, the anchor is immediately inserted without washers and nuts. This will prevent the jog from moving during further drilling. I would like to note that in panel and monolithic houses, in most cases, the thickness of the ceiling is no more than 10 centimeters, so drilling more than 5 cm is highly undesirable, be careful! Having drilled, you need to clean the hole with the same hammer drill in drilling mode so that all the crumbs come out.
In this way, all the joists are drilled and the bolts are tightened in the anchors. The fasteners are securely fixed in the concrete, but the logs have free movement up and down.
After tightening the anchors, the bolt heads are cut off and the joists are pulled off.
Screw one nut onto each protruding stud and put one washer on. It is not easy to screw a nut onto a sawn bolt, so it is useful to have a small file on hand; trimming the sawn edges will make it easier to screw on the nut. Next, holes for the upper nuts are drilled into the joists, they are put back into place, the position of the joists is adjusted using the lower nuts, and they are tightened from above with a second nut and washer.
It is most convenient to adjust the lag using a laser level. A tubular wrench is convenient for tightening the upper nuts, and an open-end wrench for adjusting the lower nuts.
After all the adjustments, the studs sticking out above the joists are cut off. The installation of the logs is complete. If insulation was planned, the insulation is laid and foamed. Excess foam is cut off and the floor is ready for laying.
The most important thing in flooring is to align the sheets so that the seams fall in the middle of the joists. It may happen that the seams will be significantly displaced, if the sheet does not fit onto the joist by at least a centimeter, you will have to change the layout of the sheets or make additional seams; twisting the joist is much more problematic. The seams running across the logs are pulled together from below with a bar or the same sheet material.
It is important to leave a 5-15 mm gap from the walls, the canvas will have room to expand if something happens, this will in some cases avoid the floor creaking.
When laying plywood, an unpleasant phenomenon may occur: the screws may not fit into the canvas and burst, the result is not a tight fit and a squeak may appear in this place.
In the place of the broken screw, you need to tighten a new one, stepping back a few centimeters. If the screws break too often, there are two options: take thicker screws instead of 3mm, for example 6mm, or before tightening, make a countersink with a drill slightly larger than the diameter of the head.
That's all, I hope I gave comprehensive information.
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Wooden floors are the warmest, most environmentally friendly and beautiful of all types of floors because:
There are certain design features laying plank floors.
This is the laying of logs - wooden beams - on a supporting structure with a certain step. To understand how to make a floor on joists and choose the most suitable option For specific conditions, you need to find out what types of wooden floor structures there are.
In private housing construction they are used various materials load-bearing and enclosing structures, they are built on different types soils, which determines the choice of foundation.
Once the house is erected, the question of how to install the logs so that the floor is strong and stable is decided. This will depend on the size of the room, because even for a room with an area of 1x1 m, support for the logs is needed in the middle. Therefore, you need to decide whether to choose as a base for the logs support pillars or the foundation of intermediate walls.
Installation of floors on joists along beams and support posts
As a support for the logs, a frame of beams is installed along the inner perimeter of the foundation.
For support between the beams, intermediate pillars are installed every 500-600 mm. Technologically it looks like this:
The logs are laid, supported by bars around the perimeter and pillars between them, so that their ends do not reach the basement wall or grillage by 2-3 cm (this is necessary to expand the tree).
The joists must overlap the support by at least 10 cm.
Grillage is top part foundation of the house. It can be “low” - somewhat recessed relative to the “zero mark” - ground level. Or “high” - raised above the ground. If the foundation is piled, a grillage is made to tie together individual columns - piles in single design and to serve as a foundation for the intermediate walls of the house.
The section of the log, depending on the load exerted on the floor, will be 10x20 or 15x20 cm.
Their length, preferably, should be enough from one wall to the other of the room.
The pitch between the logs will depend on the width of the insulation used - this will make the installation process more convenient (the optimal size is 1 m).
There is an opinion that before fastening the logs should lie in the room for several days and only then can they be fixed.
Before making the floor on joists, communications can be laid between them.
It is necessary that the insulation is 5-7 cm below the joist level.
This is necessary so that there is a gap for ventilation between the insulation and the finished floor layer. It is better to calculate the dimensions of the insulation and the log immediately in order to follow the technology when laying (the insulation layer can be 10-15 cm).
If, however, the height of the logs is not enough for a ventilation device, counter battens can be placed on them, which should have the same width as the logs.
Self-tapping screws 3-4 cm long are used for fastening.
It is pressed tightly against the insulation and fixed with a stapler to the sides of the logs.
Between the ends of the finished floor and the wall you need to leave a gap of 1-2 cm, left for the thermal expansion of the wood, which will then be covered with a plinth.
To ventilate the underground space with an uninsulated base, holes are left in it for ventilation, which...
b. covered with protective nets to prevent rodents. In summer, the goal of ventilation and drying is achieved, but in frosty conditions the underground becomes very cold, cooling the floor too. Therefore, it is recommended to close the vents for the winter.
A more suitable option is when the base is insulated from the inside or outside, and the ventilation is internal - the ducts are led into the room and hidden behind the baseboards.
It differs from installation on poles in the design of the foundation.
A strip foundation is placed under each wall and thus divides the entire basement space into separate rooms.
All installation steps are repeated, only the logs will rest on the foundations of the intermediate walls or beams attached to them.
Since air flow is needed for underground ventilation, it is difficult to organize it in intermediate rooms.
To allow free passage of air, through holes are made in the walls, and ventilation ducts are installed in the structure of the enclosing walls, taking air from the room.
It is clear that in this case there is no need to ventilate the floor from below, just as there is no need to lay the subfloor as a substrate for the insulation.
But it is still necessary to arrange soundproofing and, at the same time, insulation. The better this is done, the warmer the floor will be and the less voices and the sound of a hammer drill coming from the lower floor will be heard.
The logs are laid parallel to the short side of the room. Their size depends on the layer of insulation that is supposed to be laid under the floor.
If the floor slabs are not completely level, the horizontality of the joists can be achieved by using a level and placing pieces of plywood under the joists.
The cavities between the joists are filled with insulation or filled, for example, with expanded clay.
A sheet of polyethylene or penofol-type insulation is placed on top of the insulation, which will reflect heat inward and is stapled to the sides of the logs. The remaining space of 1.5-2 cm will serve to ventilate the space underneath.
Then the finished floor is laid along the joists, with the obligatory arrangement of gaps between the covering and the wall.
01/18/2014 at 20:01
Attaching joists to the floor: pros and cons
Log laying technology
Fastening the joists with self-tapping screws
Using Anchors
Fastening joists with corners
Attaching adjustable joists
Quite often in residential premises the floor is built on joists, which allows the use of any type of insulation and sound insulation, as well as various materials for the subfloor.
This way you can make any surface flat and lay the necessary communications under the floor. Installation of this floor is quite simple, and with economic point From a perspective it is not very expensive.
The result is a structure with a small load on the base. And of course, when installing such a floor, the question arises: is it necessary to attach the logs to the floor and, if this is necessary, then how to attach the logs to the concrete floor.
In this article we will give answers to these questions.
According to opponents of fastening, these actions can destroy the screed, and where the beams and the base are connected, sound insulation is broken and sound bridges are formed, which the neighbors below will not be happy about.
And those who believe that fixation is necessary share their experience: all the work done to repair the floor was in vain due to deformation of the joists.
Is everything really as they say? Regarding the destruction of the screed, if the screed is quite strong, then you will not be able to break it with a drill when drilling a hole.
And floor repairs can only be done if there is a solid foundation. If the old screed begins to collapse, then it must be removed.
The problem of violation of sound insulation remains controversial.
Rigid structures can actually transmit sound. However, insulating material is placed in the space between the joists, which has soundproofing characteristics. A gasket with shock-absorbing properties is placed under the joists, which also prevents the spread of sound.
The sound bridge, which is formed at the attachment point, transmits vibrations to concrete, which is a fairly dense material and, unlike wood, does not conduct sound well.
Consequently, neighbors below will not notice changes in noise levels before and after repairs.
The floor on the joists is constructed from beams, fasteners, and rough flooring. When all components are displaced relative to each other, a creak occurs, which is unlikely to please the neighbors. You can prevent the appearance of unpleasant sound by firmly securing the joists to the floor.
Another argument in favor of fastening is the fixation of the lag. When it comes to the degree of drying of the wood, buyers are forced to trust the seller’s words, since it is impossible to find out by simple inspection.
Over time, poorly dried timber may warp, eventually the coating will move, and the whole complex design the floor will be skewed.
For those who are wary of attaching logs to a concrete base, you can organize a floating floor. In this case, the flooring is not attached to the supporting structures. This will provide excellent sound insulation, but it is necessary to use well-dried joists.
They won't warp over time.
The beams are fastened to each other in such a way as to form a lattice. This design will make the floating floor more stable. Insulation is laid in the gap between the beams, and a subfloor is built on top.
As a result, the entire structure is pressed to the floor under its own weight. Over time, such a floor will not change its shape and will serve for a long time.
In most cases, the installation of logs on a concrete base is carried out with their fastening to the floor, since there are many more arguments in favor of this than the possible disadvantages.
Let's look at how to install joists on a concrete floor step by step:
You can use timber made from softwood. Its humidity should not exceed 18%. The purchased beams must be allowed to acclimatize for several days in the room where the floor is planned to be made. Logs that begin to bend should be set aside and not used in the floor installation.
The wooden components of the future structure should be treated with a fire retardant and antiseptic, which will prevent the appearance of mold and insects.
For this purpose, materials are used in the form of rolls, hydrophobic mastics, impregnating compounds, and dense film.
Wood can become deformed due to temperature changes, but when laid in this way, all logs will be heated evenly. In rooms such as hallways, logs must be laid across the movement. This will give the floor greater strength.
The greater the thickness and the higher the strength, the farther apart the logs are laid. As a rule, the distance is approximately 40-50 cm.
The logs closest to the wall should be located 2-3 cm from it, and others - depending on the size of the room.
There is no need to screed, since the use of lags allows you to level even a very uneven floor. If the beam is below the required level, then substrates are placed under it.
It is important that the material used is not soft. Otherwise, after some time it will sag due to the pressure acting on it, as a result a gap will form, which will ultimately lead to the appearance unpleasant sounds, such as creaking.
After completing the construction of the structure from the logs, all that remains is to fasten them to the floor.
There are the following ways to attach joists to a concrete floor:
The choice of fastening method depends on financial capabilities and personal preferences.
Such fasteners for joists as self-tapping screws are the simplest and inexpensive option, but at the same time guaranteeing excellent results.
It is necessary to drill symmetrical holes in the joists and base. Then dowels are inserted into them and screws are screwed in.
The distance between the holes can vary between 40-80 cm depending on the case.
The length of the screw should be equal to the thickness of the timber plus 5-6 cm.
You can use self-tapping screws with threads that do not reach the head. They allow the joists to be better pressed to the floor.
To obtain reliable and long-term fastening, you can use anchors for floor joists. In addition to holding the beam in one place, they also attract it to the surface, giving the entire system additional rigidity.
In essence, the anchor is a dowel, but much stronger.
Its advantage is its high pull-out resistance, so it is used when installing very heavy structures that create a large load on the fasteners. The probability of the floor on the joists being completely torn off from concrete base, approaches zero, so fastening can be done with self-tapping screws. However, anchors are quite often used for these purposes.
So, how to secure joists to a concrete floor using anchors? This method It is carried out similarly to fastening with self-tapping screws.
Identical holes are made in the beams and concrete floor. To prevent the bolt head from sticking out, it must be hidden without damaging the wood; for this, the logs should be countersunk beforehand.
Typically, 3-4 anchors are required to secure one joist within a room.
The locking element of the anchor should be inserted into the hole in the floor, then a bolt should be screwed into it through the beam.
Anchor bolts are produced in various lengths: 45-200 mm. When choosing the length, you should take into account the thickness of the log plus 6 cm for penetration into the base. It is recommended to purchase anchors with a diameter of 10 mm.
Another fastener is used for the floor joists - a galvanized metal corner.
One side of the corner is attached to the beam using self-tapping screws. The self-tapping screw should enter the wood 3-4 cm and preferably at an angle, this will increase the strength of the connection.
The other side of the corner should rest against the floor.
It should be fixed using the methods described above, that is, using dowels with self-tapping screws or anchors. Instead of corners, you can take a U-shaped profile.
Installation of an adjustable system is simpler and will make it easier to obtain a perfectly flat surface. In this design, instead of anchors, plastic racks are used, which are screwed into wood and fixed to the base using dowels (for more details: “How to make adjustable floors on joists with your own hands”). By rotating special bolts you can set the required height. After the joists are adjusted, the protruding part of the bolts must be cut off.
Conclusion
IN wooden house It is not recommended to fix the joists to the floor. And if a concrete screed is used as a base in the room, then in this case is it necessary to attach the logs to the concrete floor or not. In such a situation, fastening will not be superfluous. Everything is done quite simply, the main thing is to use high-quality materials and strictly follow all the rules.
Then the design will be reliable and will serve for a long time.
In the case where floor joists need to be installed in a building with wooden floors As a rule, no questions arise. But what to do in a situation when we're talking about about slab floors or monolithic concrete? For these purposes, special screws for joists are used, which have a number of differences from conventional screws used in construction work.
There are two ways to attach the joists to the floor: using regular screws and special screws with adjustment. Many experts prefer conventional fasteners, which have a more modest price and are more convenient to use. Simple long screws or anchors reliably fix the joists to the floor, but they have a significant drawback.
Anyone who has at least once encountered the installation of floor structures knows how important it is to maintain precision in this work. If the ceiling is perfectly flat, then setting the joists in the same plane with millimeter accuracy is not at all difficult - even an inexperienced craftsman can handle this. But, unfortunately, in our houses and apartments, floors with a perfectly horizontal surface are very rare, and when placing beams that will become the basis for the floor covering, you almost always have to resort to labor-intensive and responsible adjustments. That is why, most often, when installing joists, adjustable screws are used, which make it possible to level structural elements if necessary and at the same time provide the most reliable fixation.
Adjustable screws used to install floor joists most closely resemble studs in appearance, having double-sided threads. But unlike studs, such a screw has a thread for a nut on one side, and a thread for a construction dowel on the other. The screws can have different lengths and diameters, and their choice depends on the height to which the joists need to be raised and what load will be placed on the floor structure in the future. Complete with such support screws, which are also called dowel-studs, 3 nuts and three washers of the corresponding diameter are used.
Installing the logs on the adjustable screws is as follows:
In most cases, adjustable joist supports are used as a simple and affordable alternative to cement-sand screed. This design of wooden floors is ideal if it is necessary to minimize the load on the floor - unlike screeds, screws with nuts and washers weigh very little. This method is also well suited for rooms in which it is not possible to perform “wet” processes. Fastening the joists with adjustable screws can be done as quickly as possible and you can immediately begin laying the floor, while the option with a screed will require additional time for it to harden. If you plan to install “warm” floors, the described solution is the most optimal - it provides access to communications if repairs are necessary and is equally suitable for both water and electrical systems. The space under the floor can also be used for laying various communications, of course, taking care of them fire protection and waterproofing.
This method of installing logs has one drawback - such floors do not tolerate high humidity. In this regard, screw-adjustable floors are not used in rooms with high humidity such as toilets and bathrooms.
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