Fastening the log to the concrete floor with anchors. Guide for fixing the lag to the concrete floor

Tsugunov Anton Valerievich

Reading time: 4 minutes

Preparation of materials and tools

Before starting work, you need to stock up on everything you need. Considering that you will have to work with wood and concrete, the list necessary tools will be as follows:

pencil;
building level;
roulette;
perforator drill;
devices for working with wood (planer, hacksaw or circular saw);
screwdriver or a set of screwdrivers;
fasteners (usually self-tapping screws, dowels and anchor bolts).

Having prepared the tools, you can go to the nearest construction market for material. Usually lumber sellers, pursuing personal gain, are advised to purchase expensive types of wood, referring to the reliability and long service life of the material. You don't have to fall for this trick. For your purposes, spruce, fir and pine may well be suitable. Wood grades of category B or BC are quite suitable, the moisture content of the material should not exceed 18-20%. Wherein appearance, color and even evenness of parts do not play a big role. The only thing you should pay attention to is the absence of mold and traces of the bark beetle.

The cross section of the log depends on the thickness of the flooring and insulation. Experts do not recommend using a beam with a cross section of less than 20 millimeters as a lag.

Installation process

It should immediately be clarified that the use of logs under the floors is advisable only in apartments with high ceilings. This floor installation technology quite strongly “steals” the height of the premises. So, the installation of the lag occurs according to the following scheme:

or a concrete base is recommended to be leveled. Otherwise, the elements will not be in the same horizontal plane. Accordingly, they will need to be leveled by laying plates. This can lead to the fact that the floors in the apartment will creak.
On the base you need to lay a layer, or treat the concrete with a special mastic. In the first case, the use of soft materials should be avoided. Over time, they will sag, and the floor will no longer be reliable and monolithic. For a waterproofing layer, roofing felt or plastic film is perfect.
Logs are treated with an antiseptic composition and cut according to the size of the room.
The installation process begins with the installation of a log at two opposite walls. These elements are aligned using the building level and immediately fixed to concrete floor. Then a string is stretched between the installed lags. It will serve as a guide for the installation of the remaining elements.

The remaining lags are laid. The distance between the elements directly depends on the thickness of the future.
A heater is poured between the lags. For this, ecowool or roll materials can be used. In the second case, you need to mount the material as tightly as possible without leaving gaps between the layers.
A layer of vapor barrier is being laid. This necessary condition to protect the insulation from external influences. The vapor barrier can be attached with a stapler, the joints must be glued with adhesive tape.
You can lay a layer of plywood. This will serve as the basis for the installation of the floor covering.

In order for the floors to serve for a long time, it is necessary to strictly observe the step between the laid parts. You can use a table for this.

Anchors

This method is used not only for fastening elements, but also to give the structure additional strength. Pulling the anchor out of the concrete base is quite problematic, so it can be difficult to dismantle such a structure. Anchors are installed, like self-tapping screws, by drilling through holes. A locking element is inserted into the concrete, into which the bolt itself is screwed through the log. In order for the bolt head to "drown" in the wood, the holes must first be countersunk.

Metal corner

Another way of mounting wooden elements on a concrete base. To do this, you will need a corner made of galvanized metal. The installation process looks like this: the corner is attached to the log with a self-tapping screw (the fasteners must go into the tree by at least 3 cm). Then, with a self-tapping screw through the dowel, the corner is attached to the concrete surface.

When building houses made of wood, builders often ask themselves the question of fixing a beam to a concrete floor, because these are two different material, which means that the mounting technique will be different. A wooden beam is fixed using two methods: overhead installation and rigid fixation. Fastening the log to the concrete floor will not only increase the thermal insulation of the premises, but also hide possible unevenness of the concrete coating.

Appointments

Before installing a decorative coating on the floors of buildings and structures, beams are fastened to the surface from a concrete solution. Using logs, a high quality frame is obtained, suitable for further laying of coatings. In addition to the fact that the bars are an intermediate structural element, they also have the following purposes:

provide the room with additional air flow;
create sound absorption in the room;
increase thermal insulation, thereby reducing heating costs;
allow you to hide engineering communications;
create uniform loads on the foundation;
provide the surface with a smooth structure, which is necessary for the finish coat.

To attach logs to a concrete surface, first you need to observe a certain gap between them. A board with a thickness is used, from which the step size will be repelled when laying the beams on concrete. So, a board, the thickness of which is two centimeters, is fixed on the beams in increments of 200 mm.

How to choose the right material?

In order not to miscalculate with the choice of material, consider the following points:

price;
section in lags;
grade;
the tree from which the logs are made;
length.

If the budget is limited, it is not necessary to buy expensive wood. Fir, spruce have no less service life, if the material is processed correctly. It is not necessary to choose a flat surface and solid color, these figures are irrelevant. However, it is important to pay attention to the humidity, which should not exceed 20%. The material is kept at home for a year before use, this will allow the lag to take the humidity of the room and dry out.

Tools

To attach lags to concrete surface, you need to use tools, both for wood and for concrete. The following tools are used:

jigsaw;
perforator;
chisel;
anchors, self-tapping screws.

For the installation of an anchor frame for floors with lags, the following tools are used:

hacksaw;
building level;
perforator.

You can fix the adjustable frame in a concrete field using the following tools:

chisel;
finisher;
laser level;
drill and drill;
hammer.

To fix the concrete floor to the lags, choose fasteners based on the budget. Self-tapping screws are cheaper than anchors, but the latter are more reliable. Anchor fasteners allow you to attach wooden beam to the floor surface, pressing it, this is important when erecting a massive concrete surface.

Mounting methods

To fasten the log with a concrete floor, two types of beam laying are used. One of them is the lack of fixing the lags to the floor. This method provides structural rigidity by fastening the lag to each other using a board. The disadvantage of this method is the possibility of shifting the floor covering. In order not to encounter such a problem, the lag is fastened to the surface with anchors, corners or self-tapping screws.

Another way of fastening is to fasten the lags to the concrete surface. Installation includes application thermal insulation materials and floor leveling solutions. This lag installation option will save on expensive insulation materials.

self-tapping screws

Fastening the beams into the concrete pavement using self-tapping screws significantly reduces the price of the structure and simplifies the installation work. To do this, holes are made through the board with a drill, and points are marked through them at the base of the floor. This is necessary to make recesses in the coating and screw in the screws. The installation step should be within 4-8 centimeters. The distance between the holes is affected by the design being made. Self-tapping screws are used long, depending on the thickness of the beam, but it should not be less than 0.5 cm. Experienced builders advise choosing self-tapping screws that have a so-called neck, which means that there is no thread in front of the cap, which allows you to better attract the board to the floor surface .

Anchors

When used in the construction of an anchor, a greater resistance against pulling out is provided. Which justifies the high price of the material. Their use is relevant in the construction of heavy structures with a large load on fasteners. Installation of anchor fasteners on a concrete surface is carried out according to the following instructions:

Holes are made in the board with the help and marks are marked on the concrete through them. I make the same holes in the log, so that later I can hide the bolt heads in them.
Using an anchor, reliable fastening of beams is provided.
Next, the locking elements of the anchor are placed in the resulting holes in the floor base, after which the bolt is screwed into them.
The length of the fastener is different, and can vary from 45 mm to 200 mm. The thickness of the beams affects the length and diameter of the anchor fastener.

corners

Fixing wooden bars with corners is as follows:

One of the sides of the corner is attached to the wooden base with screws. The depth of insertion should be at least 0.3 cm.
When fastening, you need to rest the free side of the corner on the floor. It must be fixed with the help of the same method as fastening anchors and self-tapping screws, i.e., make through marks and insert dowels into them and screw in self-tapping screws.

Installation of a floor base using adjustable logs is relevant today due to its significant number of advantages. These include:

exclusion of surface irregularities;
the flaws of the base of the floor in the form of cracks are hidden;
soundproofing and thermal insulation are provided;
protection against fungus and rot is obtained.

Highly reliable fastening is obtained due to the presence of plastic bolt-racks, which are a fastening and adjustable element. This design allows you to make a wooden floor on a concrete base of decent quality in a short time.

A significant advantage of this mount is the possibility of adjustable log. This happens due to the ventilation features of the mount. Using adjustable logs, it becomes possible to hide engineering communications. And possible thermal insulation will reduce heating costs.

The device of a floor on logs from a bar is a very practical and easy way to get a functional flooring. In such a floor, you can install any base for the floor, lay heat and sound insulation, hide any engineering communications such as electrical wiring or a heating system.

It also creates conditions for freer air circulation in the room. In addition, a perfectly leveled surface is obtained, on which any final decorative coating can be placed without the risk of its deformation.

There is nothing difficult in installing such a coating, installation can be done on your own without the involvement of specialists, and hence additional costs. The price of this kind of work, taking into account the cost of all materials, will suit almost everyone. As a result, a structure is obtained that does not overload the foundation of the house or the ceiling between floors, but can itself withstand significant loads.

When considering this question, doubt will inevitably arise whether it will be possible to securely fasten together such different physical properties materials. In this material, we will consider fixing the log to the concrete floor.

What is the floor on the logs

The floor on the logs is a structure consisting of several functional elements:

bars;
fasteners;
Black flooring.

Proper installation involves rigid fastening of all elements relative to each other in order to avoid displacement, deformation and permanent creaking of the floors. True, opponents of this method argue that the rigid fastening of the beam destroys sound insulation and contributes to the destruction of the screed.

As for the first doubt, it can be easily dispelled by studying how the lag is laid. Indeed, a rigid connection can create sound transmission bridges. But at the same time, a special shock-absorbing layer is laid under the base of each beam, which has the property of sound absorption.

Some more noise is “eaten up” by the insulation laid in the cells. In addition, solid concrete conducts sounds quite poorly, unlike wood, so it is unlikely that the noise level will noticeably change after the repair.

Ideas about the possibility of destruction are also unfounded, since a well-made screed does not crumble when trying to fix the logs. If the screed began to fall apart even before trying to fix the logs, then it needs to be removed and the floor refilled, since such a base will not provide high-quality flooring.

Another argument in favor hard mount- the inability to independently check how well the materials are dried. Floating (not bonded to other elements of the system) laying will allow you to maintain the highest level of sound insulation. But insufficiently dried logs will eventually bend and distort the entire complex structure.

The floating floor receives a margin of safety literally under its own pressure. In the lattice, assembled from the bars, a heater is installed, a rough flooring is laid on top. But still, it is better to give preference to rigid fixation of the log from the timber.

First of all, it is necessary to choose the maximum quality materials. Coniferous trees are perfect for this task. It is necessary to ensure that its humidity is not more than 18%. After buying the bars, you should give them a little rest, leaving them to lie in the room where the floor is planned to be laid. During this time, the wood will get used to the new conditions. After that, the material must be treated with antiseptics and liquids that impede the combustion process.

After making sure that the tree is ready, you need to prepare the floor. It is cleaned of debris and dust, all cracks are sealed, bumps and protrusions are knocked off. Then you need to take care of waterproofing to protect the tree. Suitable special mastic, roll materials and even ordinary thick film.

It is required to lay substrates under the logs. You can make them yourself from thin pieces of wood, plywood or plastic, and also buy already finished materials in a hardware store. Make sure that these elements do not sag or deform, as gaps that are detrimental to wood can form because of this.

When laying, you need to make sure that the logs rise perpendicular to the sunlight falling from the window. Such laying will allow to achieve uniform heating of each beam, which will reduce the likelihood of material distortion.

If rather strong and thick sheets are chosen as a black coating, then the bars can be laid with a fairly large step. It must be assumed that the average width of the space between the lags is about half a meter, and the extreme bars are placed at a distance of a couple of centimeters from the walls.

The crate after assembly must be placed horizontally. If desired, you can level the floor with a cement-sand screed, but the design of the logs allows you to lay them on the floor without additional leveling. Instead of a screed, it is enough to put pre-prepared substrates in the right places.

Each support at the bottom must be padded with a piece of rigid material that is not subject to deformation (for example, linoleum). Soft materials will “fall through” over time and lead to squeaks and noises.

Among the necessary tools:

Perforator (or a drill with a special mode);
fasteners;
Tools for preparing timber and other elements.

Legs can be fixed in several ways. Each owner chooses the method that is clearer to him or more affordable for the budget. Can choose:

self-tapping screws;
anchors;
corners.

Self-tapping screws are the simplest and cheap way. Enough to drill in the bars through holes and continue them into the grounds. A dowel is inserted into the hole, inside which a self-tapping screw is screwed, which should go a few more centimeters into the base.

Anchors are, in essence, almost the same self-tapping screws, only with a much greater margin of safety. They not only firmly attract the floor, but also have resistance to tearing.

It is unlikely that the floor will ever be subjected to such loads, but the method, nevertheless, remains quite popular. Two or three anchors are enough for one room in the apartment. Their length ranges from 4.5 to 20 centimeters, it is better to choose those that go to the base of the floor by 5-6 centimeters.

Metal corners are fixed on the log with one side, and on the floor with the help of self-tapping screws or anchors on the other.

There is also such a solution to the issue as the acquisition of a regulated system. It will cost more than all the listed options, but the height of the structure can be adjusted almost perfectly. The system includes special plastic bases and self-tapping screws, which are screwed in at the right level, and then the excess is cut off from above.

At the final stage, it is desirable to lay a vapor barrier layer on top of the timber. And on top of the resulting result, plywood or boards are laid. The result is a perfectly even surface on which any decorative flooring can be laid.

Keep in mind that in wooden houses fastening logs from a bar to the floor is not worth it.

Laying a wooden floor on a concrete base is a common way to create a warm, well-ventilated structure that can serve as a finishing coat when using tongue and groove boards or be an excellent base for a finishing cladding material. At the stage of manufacturing such a floor, the question arises: what is the best way to fix the lag to the concrete floor? This will be discussed in today's material.

Despite the fact that the advantages of creating a flooring with lags rigidly fixed to the base are obvious, there are opponents of this method, who argue that in this way it is possible to damage the integrity and violate the sound insulation of the room due to the formation of acoustic bridges at 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 well-made screed does not change its integrity when drilling holes in it with a drill.

Regarding sound insulation: a rigid structure transmits sound waves, but given that insulation material is laid between the lags, which dampens sound, 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 from below.

One of the nuances of wooden flooring along the logs is the possibility of a creak, which becomes audible even to the neighbors below. This occurs when the structural elements (beams, logs and fasteners) are displaced relative to each other. With a rigid fixation of the lag to the concrete base, these troubles can be avoided.

Important! If the logs are not rigidly fixed, and their humidity declared by the seller is not true, then soon, due to the warping process of the wood, the floor structure will begin to deform and shift.

Proponents of the rejection of rigid fastening of the log prefer floating floor structures when the flooring is not fixed to the supporting structures. In this case, it is necessary to carefully approach the choice of lag material. The stability of the floating structure will be given by a special fastening of the bars to each other - in the form of a lattice, in the voids of which insulation material is placed.

The process of creating high-quality flooring along the logs depends on the right material. Coniferous wood is most preferable, as it resists moisture better, contains natural antiseptics in its composition, and therefore is resistant to the formation of fungus, and also belongs to durable types of wood.
The moisture content of the timber should not exceed 18%. Before laying, the timber must undergo an acclimatization period of several days and get used to the microclimatic conditions in the room where it will be used. If during these days some logs begin to show signs of warping, then they are rejected and not used in the floor construction.
Before laying, the logs are treated with an antiseptic and fire retardant. It is better to do this before installation, because it is more convenient to process the whole product.
It is important to pay attention to the choice of the direction of laying the log relative to the sun's rays - the bars are laid across to ensure their uniform heating. Where the strength of the flooring is important (in rooms with high traffic), the logs are placed across the movement.
The distance between the lags is selected in accordance with the thickness of the rough flooring. The larger it is, the greater the distance between the lags (40 - 50 cm). The distance from the wall to the beam should be 2 - 3 cm.

Materials and tools

Work on laying the floor on the logs does not require specialized equipment and tools. You will need to prepare:

Perforator drill.
Screwdrivers or screwdriver, hammer.
Measuring tools - tape measure, level, pencil.
Fasteners, depending on the method of fastening.
Wood processing in the course of work is carried out using a planer, hacksaw or circular saw.

You will need to purchase waterproofing material, taking into account the overlap on the walls along the perimeter of the room by at least 15–20 cm.

You should not take to heart the assurances of lumber sellers that the more expensive and higher the grade of wood, the more reliable and durable the logs made from it will be. For flooring, you can completely do with spruce, fir or pine.
You can safely purchase wood of grade B and BC, provided that its moisture content does not exceed 18%. Minor external defects and the shade of the material can be ignored.
The main condition is the absence of traces of vital activity of insect pests (bark beetle) and mold on the surface of the wood - even its minimum amount should be a signal to refuse to purchase wood from this batch.
The choice of the beam section occurs in accordance with the chosen thickness of the flooring and the upcoming loads.

Mounting methods

There are several of the most common ways of attaching a lag to concrete. Each of them has its own characteristics.

Fastening the lag with self-tapping screws

This method of fixing the lag, although it is the simplest, is not suitable in every case. The process is simple:

A hole is drilled in the concrete base for a plastic dowel.
A hole for a self-tapping screw is also drilled in a wooden element.
The dowel is placed in concrete hole, hammering with a hammer, and fix the log by immersing the head of the self-tapping screw into the body of the wood by a few millimeters.

The step that is taken when attaching the lag in this way is at least 50 cm.

Table 1. Installation of a wooden floor with a lag fastened to self-tapping screws

Illustration	Description
	Explicit defects on the concrete surface are sealed with mortar or mounting foam.
	The concrete base is dedusted and debris is removed from this surface with a vacuum cleaner.
	The floor is primed with a solution with antiseptic additives.
	Logs are pre-treated with antiseptics and fire retardants.
	Logs are laid in increments of 50 cm.
	Plastic wedges are placed under the log and with their help the element is set to the desired height.
	The height of the lag is controlled using a building corner or tape measure and a laser level.
	Drill a hole for the screw.
	Screw in a self-tapping screw.
	The wedges must be fixed in a predetermined position with foam.

	Lay a layer of vapor barrier.
	Fix OSB boards.

Fastening the lag with anchor bolts

Fixing the log with anchors is a durable and reliable method. Additional structural rigidity is provided by pulling the beam to the surface of the base.

The anchor is a more powerful fastener than a dowel, it is able to withstand high loads. When installing such a floor, you can be calm in its reliable fixation to the concrete base. According to the technology of work, fastening a beam to an anchor is similar to fixing to self-tapping screws. Preliminarily, holes of the required diameter are drilled in the base and lags. A hole is made in the wood so that the bolt head can be hidden.

The number of fasteners is calculated taking into account the fact that an average of 4 anchors will be required to fix one beam. The bolt in the locking element, inserted into the hole in the concrete, is carried out through the wood. The length of the anchor bolts varies from 45 to 200 mm. When choosing it, 6 cm is added to the thickness of the timber for penetration into concrete. The recommended anchor bolt diameter is 10 mm.

The popularity of anchoring is due to a more rigid fixation. wooden structure. With this fastener, you can rely on the containment of wood before the deformation process, if it has not been dried sufficiently.

Table 2. Anchor installation

Illustration	Description
	After the anchors are driven into the concrete base, using a 13 wrench, you will need to stretch each anchor nut to secure it more securely. In this case, do not apply too much force so as not to break the thread.
	After that, a bottom nut is screwed onto each anchor and a washer is installed on which the lag itself will be laid. Nut is installed reverse side and screw, guided by the markings on the wall.
	Throw a puck on top.
	In the lags, a hole is drilled under the anchor's head and under its body, taking into account the spacing of the anchors.
	The lags are baited on the anchor.
	Screw the top fixing cap of the anchor.
	The nut is tightened in accordance with the level value.
	The excess fastener is cut off with a grinder.
	Insulation is laid in the space between the lags.
	Sheets of plywood are fixed to the lags.

Fastening the lag with the help of corners

If the height of the lag exceeds 10 cm, then they are used for fastening metal corners. The corner shelf is fixed to the concrete base with dowel-nails, and to the log - with self-tapping screws. In this case, the corner is used to fix the position of the wooden element, and the load is distributed to the spacers.

Table 3. Lag installation

Illustration	Description
	Before attaching the corner to the log, drill a hole for the self-tapping screw. For the strength of the connection, the self-tapping screw is immersed in 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 introduced under the logs, which will fix the logs at the required height and ensure ventilation of the structure.
	The bars are also fixed with corners to the floor.
	Wooden flooring is made of grooved boards.
	To fix the board at an angle, drill a hole for a self-tapping screw.
	The board is fixed with a self-tapping screw immersed in the groove at an angle of 45 degrees.

Adjustable lags

Adjustable log system is the most in a simple way devices of a flat boardwalk in a room with a concrete base having a significant height difference. Anchors in this design are replaced by plastic posts, which are attached to concrete with dowels. The convenience of using plastic racks lies in the fact that you can adjust their height and the level of the lag location using special rotating bolts. Excess racks protruding above the surface of the log after adjustment are cut off.

Modern manufacturers offer universal racks that allow you to produce perfectly even plank flooring in a room with a large height difference, regardless of the section of the beams. Installation takes place 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 automatic tilt angle correction up to 5%.

No modern material does not fully replace the traditional wooden floor. True, its installation is fraught with some difficulties (the need for the correct selection of wood for the log, their strictly horizontal installation, careful fitting of the flooring boards), however wooden floor there is still no alternative in terms of environmental friendliness.

Wooden floors have always been highly valued. It is natural, attractive and safe.

It would seem that floorboards can be laid directly on a leveled screed, however, logs are necessary to sufficiently ensure normal floor ventilation and the most optimal heat exchange in the room. Of course, laying a perfectly even screed will simplify the task of installing a floor log, so the very first preparatory work when installing a wooden floor, there should be maximum leveling of the base.

Required materials, tools and fasteners

As for the question of how to fix the logs, it should be said that not every type of wood is suitable for their manufacture. best material for them are coniferous trees: spruce, fir, pine and larch. As a rule, a material with a cross section goes to the bars, in which the aspect ratio is 1: 1.5. In addition, before you start fastening the log, the boards and beams must be thoroughly dried. The wood moisture index should not exceed 20%. It should be noted that the installation of a wooden floor is advisable only in rooms with high ceilings.

For high-quality fastening of the log to the concrete base, a thorough approach to the choice of tools and fasteners is also needed. In the work it is necessary to use:

To install the log, you will need a hacksaw, a building level, a screwdriver, self-tapping screws, a construction pencil, etc.

tools for woodworking (planer, circular saw or hacksaw, drill, etc.);
screwdriver or screwdriver;
perforator (well, if there is a universal tool that can hammer, drill, and screw);
self-tapping screws with a section of 6 mm with plastic dowels (plugs should be driven into concrete by 6-8 mm, and the length of the fastener depends on the thickness of the bars) or anchor screws, whose dimensions depend to the same extent on the cross section of the bar.

The choice of fasteners depends on your preferences and the thickness of the wallet, but it must be said that the anchor fastening is much more reliable than the dowel, since the anchor shank, when screwed into the concrete body, bursts its sleeve and tightly fixes the fasteners. Nevertheless, it is often enough to use polypropylene dowels with self-tapping screws to fix the floor lag, since most coatings will not have to experience extreme mechanical stress.

For the waterproofing device, roofing material is required.

In addition to the listed tools and fasteners, the log must be prepared for the device:

waterproofing agent (roofing material and similar rolled bituminous materials);
primer mixtures for processing screed and wood;
antiseptic compounds (you can always pick up multifunctional products in the store, which will significantly speed up the process of processing the bars).

You should stock up on pieces of plywood, chipboard or wood, which may be needed as linings for logs to the floor to level the plane.

Operating procedure

So tools and Consumables prepared. You can start attaching the lags. Work is carried out in the following order:

Make sure that concrete screed dry, and treat it with a primer.
Lay a waterproofing layer on the screed. Its adjacent sheets should be laid with an overlap of 10 cm.
Glue the edges of the vapor barrier tapes with bituminous compound or adhesive tape (depending on the material of the water-repellent membrane).
Treat the bars with an antiseptic.
Cut the logs according to the dimensions of the room and spread them over the floor surface. It is desirable that only 1 beam is used for each log. Joints are allowed with large sizes rooms when the length of the timber is not enough. The location of the joints on adjacent beams should not match. They must be spaced apart from each other by at least 0.5 m. There must be a support under the joints.
Put 2 extreme logs at opposite walls. Place the rest of the bars perpendicular to them. The distance between adjacent lags depends on the thickness of the flooring. The stride range ranges from 40cm to 100cm (more on that below).
Fasten the extreme lags. Using a hydraulic level and a chopping cord, set the end bars. Drill holes in them and in the concrete base, insert fasteners and fix the logs in concrete. The fastening step with self-tapping screws is from 50 to 80 cm, and the anchor screws are screwed in every 1 m.
Attach the cross joists to the floor. For better orientation, pull a cord between the extreme bars.

It is desirable that there are no linings under the bars, but with an uneven screed, they cannot be dispensed with. Make sure that the pads fit snugly into the space between the timber and the screed. If there is a bulge under the log on a concrete base, lightly trim the edge of the beam adjacent to this place with a planer or chisel.

Only when performing these procedures, the floor will not creak under your feet in the future.

Now back to the question of the step between the lags. Its dependence on the thickness of the floorboards is as follows:

floor thickness 2 cm - the distance between the lags is 30 cm;
for a board of 2.5 cm, the step is 40 cm;
for 3-centimeter boards, the distance between the bars will be 0.5 m;
for 35 mm, a 60 cm step is required;
40 mm boards are placed on logs, the distance between which is 0.7 m;
for 45 mm flooring, a step of 80 cm is provided;
under the floorboards with a thickness of 5 cm, the logs are attached at a distance of 1 m from each other.

Under the plywood floor, the distance between the lags is calculated a little differently. A pitch of 40 cm is enough for a 15 or 18 mm decking, and for 22 mm plywood, a spacing of 60 cm between the bars is suitable.

After mounting the bars, you can fill in expanded clay between them or lay another heat insulator. Until it's laid flooring, you can lay some communication lines. Before installing the floor on the logs, it is advisable to lay a vapor barrier film.

Laying beams on the ground

There are cases when the bars under the floor have to be laid not on a concrete base, but on the ground. To fix the logs in this way, it is necessary to clean the soil from the top layer and carefully compact it. It would be even better if the surface is covered with rubble. The backfill layer can be up to 5 cm. After leveling the rubble, waterproofing is laid on the ground.

On the walls of the building, it is necessary to mark the horizon along which the logs will be installed. Markings are made using a laser or water level and a chopping cord. First of all, bars are installed along 4 walls. Logs are placed on stands made of bricks, boards or other materials. All wood products must be treated with antiseptic compounds, and roofing material must be laid between the logs and supports. There should be a wooden spacer between the brick stand and the floorboard. Its thickness cannot be less than 25 mm. The distance between the extreme beams and the walls should be at least 2 cm. Threads can be pulled between opposite walls, which will serve as guidelines for mounting the beams.

Now the rest of the lags are attached. Their location should be perpendicular to the direction of the floorboards. It is recommended to lay the support bars transversely to the direction of lighting through the window opening. The step between the lags during their installation on the ground depends to the same extent on the thickness of the flooring, as well as when fastening to concrete. The cross section of the beam must correspond to the distance between the walls of the room (span):

for a 2-meter span, a beam of 110 x 60 mm is used;
if the walls are located 3 m apart, bars 150 x 80 mm are used;
4 m - 180 x 100 mm;
5 m - 200 x 150 mm;
6 m - 220 x 180 mm.

The use of logs shorter than the span when they are installed on the ground is highly undesirable.

Adjustable lags

Need to talk about modern means lag level adjustment. Manufacturers produce special racks that can change the height of the beams from 10 to 25 cm. Such devices are very useful when installing a wooden floor on an uneven base. They are threaded racks attached to the ceiling with dowels and nails. Changing the height of the beam is carried out by screwing or unscrewing the threaded rod, fixed in the desired position with a lock nut. Supports for timber can be inserted into holes drilled in its body. Often they are equipped with corners with holes through which self-tapping screws are screwed into the logs.

Despite the apparent complexity, setting the log is not so difficult. If you do not violate the installation technology, then the wooden floor will serve for many years without the slightest creak and deflection of the floorboards.