Black floor in a wooden house. Do-it-yourself draft floor: how to prepare the logs and lay the boards? How to make a wooden draft floor on the ground

Many novice builders who have just started building their home are already considering what kind of linoleum or laminate they will lay in the future room.

And soon, before them the question arises - How and on what to lay this linoleum. Of course, we all understand that first you need to make the so-called subfloor - the basis on which, in the future, you can lay any floor covering you like. But, how to make the floor “from scratch” correctly, so that it is reliable, even and, most importantly, warm. You will find the answer in this article.

To make a rough floor with your own hands, you do not need any professional skills or special tools. The main thing you need is good physical strength and a head on your shoulders, as well as some, the most common tool. But more on that later, first you need to decide what building material you will need to purchase for the construction of the subfloor. The choice of materials for the floor on the construction market is now huge, but we will consider the most common option - no less reliable and at the same time not expensive.

We use the following lumber:

- a wooden beam with dimensions of 100 by 150 mm (or 150 by 200 mm) and a length of 6000 mm;
- a wooden block with dimensions of 50 by 50 mm (or 60 by 60 mm) and a length of 3000 mm;
- planed boards 50 mm thick and 6000 mm long;
- OSB sheets with dimensions of 1250 by 2500 mm and a minimum thickness of 12 mm.

As a heater, it is desirable to use basalt insulation (in a simple way, glass wool). To protect lumber from mold and decay, you need to purchase a special solution (antiseptic). You may also need cement mortar during the construction of the floor. Now let's look at all the lumber used separately, as well as what role they play in the subfloor.
Lumber used.

Wooden beams, with dimensions of 100 by 150 mm, are used as load-bearing logs, on which, subsequently, the entire floor in the room will rest.

Bars with dimensions of 50 by 50 mm are designed to accommodate insulation in the floor.

The cost of timber, on average, is about 6,500 rubles per cubic meter. To calculate the total cubic capacity of all bars, you will need to calculate the volume of one bar and multiply by the required number of bars. The volume of any bar is considered as the volume of a parallelepiped.

Choosing the right board
The board plays an important role, therefore it is better to use planed larch as the base of the subfloor. The cost of one cube of such a board is about the same as that of the bars. Cubature is considered similar.

All of the listed lumber should be made mainly from coniferous trees, such as larch, it is less afraid of moisture and dampness, which means it will last longer. By the way, the whole of St. Petersburg, which is already over 300 years old, was built from it!

When buying beams and boards, you will need to take into account that the drier the lumber, the better and more expensive it is. After all, the dried boards will no longer warp and will not go (by helicopter), for example, during the heating of the house. Therefore, lumber is selected based on the following criteria:
- the lower the humidity level, the better, you can take it straight from the dryer;
- timber or board should be smooth, surfaces without significant defects, cracks and delaminations.
Sheets (plates) OSB

These so-called OSB boards complete the construction of the subfloor. Subsequently, OSB panels will serve as the final basis for the flooring. Translated into Russian, OSB is translated as OSB - oriented strand board. The material itself is a board pressed from sawdust.

Over the past 5 years, OSB boards have become increasingly used in the decoration of walls and floors and are considered a fairly good basis for almost all types of finishing materials.

The main advantages of OSB boards:
- high moisture resistance;
– high mechanical strength;
- the material is easy to install.

One sheet of OSB with dimensions of 1250 by 2500 mm and a thickness of 12 mm will cost you about 700 rubles. Many Russian manufacturers sell OSB boards for less than 500 rubles a piece. You should not lean towards a cheaper option, it is cheap OSB panels that have received bad reviews due to their low level of environmental friendliness.
We figured out the materials, now we will find out what tool you will need to install the subfloor. Prepare or buy the following tool with which you can simplify your work as much as possible:

- hammer;
- electric jigsaw;
- hacksaw or electric saw;
- roulette;
- level 1.5 meters long;
- stationery knife;
- nails 50-100 mm long.

Stages of subfloor construction

Let's first figure out how to properly position the lags. Before we figure out the correct location of the lag, let's go back a little to the past. It is advisable to take care of the floor arrangement even before the construction of the main walls of the house, that is, immediately after preparing the foundation. After all, then it will be impossible to fix something in the location of the lag.

First, all the bars (for the first floor) are treated with a special solution (antiseptic) against mold and decay. The fact is that the logs are located near the ground, under the house and will always be exposed to a humid environment.

After laying the beams, check that they do not touch the ground (the distance from the bottom of the beam to the ground must be at least 20 cm). That is why all the space inside the foundation is always cleared in advance.

So, we place the bars perpendicular to the direction of the longest side of the future room with a step of 80-100 cm. The more often you keep the step, the less the floor will wobble and play, but this will require more building materials, respectively, and costs.
We have all the bars with a “rib” to increase the rigidity of the floor and make it as high as possible from the ground level. Agree a room on the first floor with too low windows is not the best option. We have all the logs, strictly in a horizontal position, checking their level from the edges, in the middle and between adjacent bars. If necessary, the edge of the beam can be raised with cement mortar.

The bars should rest with their edges on almost the entire width of the foundation, and their ends should be smeared with cement mortar or closed from the street. It is not necessary to specially fix the logs to the foundation - we just lay them, but so that they stably adhere to the surface of the foundation and do not stagger.

All boards, even before the walls are erected, it is advisable to lay them out on logs and cover them with the same anti-mold solution. You can also adjust them to size and cut a little too long boards, so that later, indoors, it would be more convenient to work with them.

Finally, we make the base of the floor after the erection of the walls. We measure all the boards so that there is a gap of 3-5 mm from the end between the wall and the board. This gap is needed so that the board does not rest against the walls during the shrinkage of the house. We lay the boards perpendicular to the direction of the lag.

We nail each board with nails “weaving”, through one or two logs. You should not hammer three nails into each beam - this will not win you anything. Boards, just do not press hard against each other. The first board lies with an indent of 3-5 mm from the wall, the last one is adjusted in size. You may need to adjust the last board and cut it lengthwise.


For floor insulation we use bars and basalt insulation. To insulate the floor, it is necessary to build a kind of frame in the form of a lattice of bars 50 by 50 mm. In the cells of this frame you will lay a heater with a thickness of 50-60 mm. The insulation in our case comes with plates, but if you don’t like it so much, you can insulate it with soft wool, just keep in mind that for the same soundproofing effect as from plates, you will need twice as much soft wool. For example, if you open a wooden floor in a Soviet apartment, you will see a similar grating, and in rare cases, even with a heater.

The bars must be distributed in increments equal to: the width of the OSB board divided by two, that is, approximately 620-630 mm. Bars are also laid across, here you determine the step at your discretion.

Try to put all the bars in a horizontal level. This can be achieved with small wooden wedges. Wedges are not difficult to make yourself.
Important! We nail the bars to the boards with nails, as in the previous case.
We lay the insulation in small rectangles, cutting out the desired size with a clerical knife.
Important! When working with insulation, be sure to wear goggles and a mask.

A small digression.
There is another pretty good way to insulate the floor. Although it is used mainly for warming the floor of the second floor, it is also suitable for the first floor. Here, the insulation is placed in the space between the lags. In order for the insulation to hold, boards 80-100 cm long are nailed to the lags from below, you see, it’s not very convenient. Moreover, the boards should be tried to be nailed tightly to each other so that the insulation does not crumble over time and does not fall to the ground inside the foundation. However, in this case, you can lay the insulation in a thicker layer, and the floor will be better insulated as a result. With this method of insulation, the device of bars 50 by 50 mm will not be mandatory.

Construction technologies are constantly changing. Modern methods are often more effective, but not always cheap. In particular, one of the most affordable flooring technologies is a subfloor along logs. Yes, it is not perfect, but so far this is the cheapest way to make a floor. In any case, in those regions where the price of wood is still low.

In the construction of the floor, the rough flooring can perform two functions. The first is to serve as the basis for laying heat-, hydro-, sound-proof materials. The second function is to serve as a support for finishing flooring or floor screed under the floor covering. Moreover, insulating materials can also be used to improve performance.

One of the options for underfloor heating and tiles using

Is it possible to make a finishing floor without a draft? Basically, it is possible, but in this case it is more difficult to achieve the required characteristics. If the requirements are not too high (dacha, summer or guest house, technical building) and it is important to get only the necessary minimum, you can do without a subfloor.

If the requirements are high (for a residential or heated building), as a rule, a construction without a rough flooring requires more money. Why? For the subfloor, inexpensive materials are used. The main selection criterion is strength. They do not pay attention to the appearance and this allows the use of inexpensive materials. For example, unedged board (after appropriate processing), construction plywood, lean concrete slab. Other materials are laid on the rough base and claims to their strength are minimal. The main emphasis is on "protective" characteristics. After all, the load falls on the floor structure and rough flooring, and not on these materials. And they are usually relatively inexpensive.

All draft bases can be divided into two large groups: dry and wet. Wet include all types or. But this is not about them. We will talk about dry ones, and along the lags and beams.

To date, there are more modern technologies, but the subfloor on the logs remains the cheapest. This is a traditional version that has been modified to meet modern requirements for comfort and economy. But even with the changes, it is difficult to achieve those parameters that are considered the norm today. In particular, sound insulation, and thermal insulation cannot be ideal. You can only get closer to the norm. But the solution will not be the cheapest.

Ceilings on wooden beams

Beams in a floor structure are wooden or metal elements that rest on the foundation and serve to transfer the load. Since wood is still the cheapest tool for us, most often our beams are wooden. They are made from timber - solid, glued, or spliced ​​beams (from several boards) are used.

Beams can only rest on the foundation, they can have intermediate supports. In houses with a subfloor, piers serve as intermediate supports; in the absence of a subfloor, brick columns are folded or columns are made of reinforced concrete. Waterproofing is laid on these supports in two layers (roofing material or something like it, but not a film), and beams or logs are supported on the waterproofing.

Beams and logs - the difference

How are beams different from lag? In short, beams are load-bearing structures, but logs are not.

Beam - a linear element of load-bearing structures, based on both ends (unlike the console) and working mainly in bending. As a rule, the section of the beam is rectangular or square. In wooden houses, they are also made from hewn logs. The installation step of the beams and their cross section is considered during the development of the project. Logs are also prescribed, but they are not so critical, so their characteristics can be changed during the construction process.

The logs are not elements of the supporting structure and they are simply made of a thick board, which is often placed “standing up” - they are supported on a narrow part. With such an installation between the lags, it is convenient to lay the insulation - when choosing the installation step of the lag, the width of the insulation is also taken into account. The draft floor along the logs can also be with the location of the insulation on top. This type is called a floating floor, since the finish coating does not have direct contact with the base (in this case, with the rough flooring).

There are two important points. The first - when using mineral wool as a heater, it is necessary to measure the actual width of the roll or plates. It doesn't always match what is advertised. The second - the distance between the lags should be 3-4 cm less than the width of the insulation. Then it can be put in a thrust and it will be held due to the force of elasticity. This makes installation easier. But there is another advantage to this solution. Even if the insulation “bends” a little or dries out during operation, no gaps will appear between the cotton wool and the lag, as the material will straighten out.

When laying insulation, the main thing is not to leave gaps and minimize cold bridges

When using polystyrene foam, polystyrene foam, polyurethane foam as a heater, the step lag (and their cross section) is also better to select. But in this case, "compress" it will not work. The plates are cut into pieces of a slightly smaller width than the distance between the lags, and the gaps are filled with mounting foam.

Lag installation step

The installation step depends on the board from which the lags are made:

• for a board with a thickness of 40 mm, the distance between the centers of the support is 80-90 cm;
• 50 mm - distance 100-110 cm;
• board thickness 60 mm - 120-130 cm.

The draft floor is the basis for the finishing floor, so it must be leveled to the horizon. The smoother the base, the less problems when laying other materials. Therefore, already when installing the lag, their edge is brought out at the same level.

One of the possible options

If the step of the beams is small - up to 80 cm, the rough flooring can be laid immediately, without a log (board 40 mm). With a large step of the beams, logs are laid across, and the flooring of the subfloor is laid on them.

A couple of comments about the wide board. If the budget is limited, you can save money by making prefabricated logs. Two boards 25 mm thick cost less than one board of the same length 50 mm wide. We buy two boards, put them one to the other, connect them with nails or self-tapping screws (preferably nails). We put fasteners on both sides in a checkerboard pattern. They put the logs “on edge”, so that they even surpass the board in strength - there is less chance of a crack appearing along the wood layer. There is one more nuance that will help to avoid the "torsion" of the prefabricated log: we arrange the boards so that the annual rings are located towards each other.

Floor structures on wooden beams

When constructing a subfloor, a board is more often used. Basically, it serves only as a basis for laying insulation. The load from the insulation is small, so you can not knock down the flooring tightly, but leave a gap of up to 1 cm. But such a sparse laying is suitable for materials with sufficient density. When using bulk thermal insulation, you will have to make a continuous crate.

With a large length of beams or lags, intermediate jumpers are also made for a more stable geometry

Draft floor along the lags under the screed (floating floor)

Can be done if necessary. The only question is that the beams can withstand the load. This is calculated separately. How good is this design? The fact that:

• The usual "cold" floor can be made warm. You can even make it heated (if the beams withstand).
• On top of the concrete slab, you can lay tiles, lay sheet material and lay coatings that are demanding on the base - laminate, PVC tiles, linoleum.

By the same principle, you can make a rough floor on wooden logs without cement. As a top layer, you can lay plywood, OSB and other sheet materials that you consider suitable in two layers. On such a base, again, you can lay tiles and any other type of finish.

What lags and board to use? It is possible / necessary to select, since the thickness of the board depends on the installation step of the lag:

• the distance between the lags is 80 cm (permissible up to 100 cm, but not under a screed or tile, under lighter coatings) - board 40 mm;
• installation step lag 50-60 cm, board 30-35 mm;
• for boards less than 30 mm, support is required with a distance of 35-40 cm (depending on the specific thickness).

The draft floor in this case may not be solid, but with gaps. Under a concrete slab, it is best to take extruded polystyrene foam, high-density polyurethane foam as a heater. You can foam glass (foam glass), but it is very expensive. These materials normally withstand the weight of a monolithic screed. By the way, since it fits on an unstable foundation.

How to ensure long-term operation

With this design of the floor on wooden beams, it is important to protect the subfloor board from decay as best as possible. If the subfloor is below, care must be taken to ensure that it is ventilated (ventilated) and that the humidity in the subfloor is as low as possible. We need a blind area around the house (better insulated), as well as a drainage system.

As an additional measure, a film with sand is used. A dense PVC film is spread on the ground in two layers - the joints are glued with adhesive tape, brought to the foundation and fixed there. A layer of sand is poured on top of the film (at least 5 cm, but more is better). The film does not let in most of the moisture (if it is intact and the joints are well glued), and the sand absorbs the excess, and then slowly dries up. The same method is also used using any other draft floor along the logs.

Draft floor from OSB (OSB). You can remove the rough flooring from the board and lay the slab in two layers

As already mentioned, the subfloor board can be edged or unedged. A prerequisite is operating humidity. Few people will lay chamber drying, but the board must be dry - at least 6-9 months of drying. If the floor of the first floor is laid, the material must be treated with protective compounds. Humidity in the underground will be high, so the quality of processing should be good. It is better to process several times. Chemistry for wood today is more than enough. You can select properties. If folk remedies are needed, this is processed oil.

Ground floor above ventilated subfloor

The overlap of the first floor over an unheated underground is different in that it must be well insulated. If you are not going to do floor heating, you need to make sure that it is comfortable even with working products. To do this, it is better to make two layers of insulation and place them in different directions.

In this design, the rough flooring is only a support for the first layer of insulation, so taking a thick board here does not make sense. Usually they take 25 mm, process it and use it for filing. In the construction shown in the figure, a cranial bar is nailed to the bottom of the beams. Usually its cross section is 25 * 25 mm. A rough roll board is placed on the cranial bar. The segments are short - the length is equal to the step between the lags. Substandard length can be taken on this flooring, but there is less waste if the length is a multiple of the lag step.

Waterproofing is laid on the boards. Please note that if mineral wool is used as a heater, the material must be vapor-permeable. It should make it possible to remove moisture from the insulation. If the insulation is foam, polystyrene foam, foamed glass, they themselves do not conduct steam and this layer is generally irrelevant.

The thickness of the insulation should be such that its upper edge is 2-3 cm below the edge of the beam. This is necessary to ensure the ventilation gap. Wood changes humidity and it is necessary to give this opportunity, leaving a ventilation gap.

A cross frame is laid across the beams. These are lags. Their height depends on the required thickness of the insulation, and the installation step depends on what kind of flooring you plan on top. The dependence of the board thickness on the lag step is described above. But it can be not only a board, but also any sheet material.

Waterproofing flooring at a distance of 2-3 cm from the surface of the insulation

A vapor barrier is laid on top of the insulation. This time, the material should retain both vapor and liquid. In the case of using mineral wool, it is better to use a membrane with one-sided vapor permeability (for example, or Izover, other brands). It must be laid so that steam can escape from the heater. This solution is better, as it makes it possible to maintain normal humidity in the floor cake.

There are also options with one layer of insulation (pictured above). This method is convenient if, according to thermal engineering calculations, the thickness of the insulation is not too large.

What is the rough floor made of on the logs

The draft floor can be made from boards (edged or unedged without bark) and any sheet material, including drywall. Sheet materials include:

Now we are not talking about the environmental safety of the listed materials. Here everyone makes his own decision. The point is that any of these materials can be put on logs. These materials fulfill their role as foundations. The thickness of each material depends on the installation step of the beams or lag. Once you decide on a specific material, it will not be difficult to choose the thickness.

Everyone knows that it is not possible to fully live in an apartment or house without an equipped floor. It is simply necessary. Is it worth doing it in a wooden house - this question worries many. Their logic boils down to the fact that why spend money on an additional subfloor, it might be easier to just lay a finishing one right away. Everything is ambiguous here.

Of course, you can get by with a fair one, but in this case you will not be able to get a reliable and beautiful coating. But the main thing that the floor should stand out with is reliability, strength, a flat surface, as well as some other parameters that are extremely difficult to achieve without a subfloor. Changing the final floor every year, if there is no rough one, is an unaffordable luxury.

Photo: draft floor in a wooden house

Draft floor - what is it?

A subfloor is a special base for a finishing floor, which forms a flat horizontal plane for it. The subfloor provides distribution of the load that acts on the floor covering.

In a wooden house, the draft floor can be done in several ways:

• wooden on logs;
• plywood flooring;
• pouring concrete.

Wooden draft floor on logs

In a wooden house, the installation of a subfloor on logs is practically the same as its installation in monolithic or brick houses. The main difference is in the fastening of the lag.

General scheme of the device

lag mount

Floor logs should not be attached to a wooden wall, and you do not need to crash into it. It is advisable to fix the logs to the plinth or grillage of the foundation, retreating from the wall by a few centimeters. At the same time, the distance of the support, which falls on the foundation, must be observed at least 10 cm on either side of the log.

Legs are attached to the plinth

Before laying the logs on the foundation, you need to lay the lower harness, made of long thin boards, to which the logs will be attached using metal anchors (corners).

The lags should not be fixed rigidly to the harness - they only need to be fixed so that they do not travel while laying other layers of the subfloor. The created structure will have a few cm indent from each wall, where thin insulation can be installed.

Definitely need waterproofing

If the distance to the foundation is less than 10 cm, then it is better to crash into the walls, however, it will be necessary to initially lay the lags on the foundation, and then attach a log or beam to them. Measure the contour of the cutout and then cut out the necessary grooves in the wood with the dimensions necessary for the distance of the support (for subsequent expansion, the lag should be added about 2 cm).

Do not forget that the laying of beams and lags is carried out on the plinth or grillage only after laying the waterproofing layer.

Lags are attached to the foundation grillage

The standard step between the lags is 40-60 cm. However, its choice depends on the width of the insulation, as well as the direct load. The lag section is also selected from the current load. With a light section, choose 15 × 10 cm, with an average - 15 × 15 cm, with a heavy one - 15 × 20 cm.

If the beam has a small cross section, and the effect of the load is significant, then it must be placed at a distance of 30-40 cm - this is a fairly optimal option.

Installation of the subfloor on the logs

With the end of the laying of the log, the standard installation of the floor on the logs is carried out. It looks like this:

Between the insulation and the floorboard you need to leave a ventilation gap

Important! Boards, bars and logs should be treated with an antiseptic to prevent them from being exposed to various fungi and insects.

Subfloor plywood

A plywood floor will serve reliably for a long time. She has high strength. Plywood can even be used for final flooring, as if carefully sanded and varnished, it will look quite noble. However, it is more often used as a base for coating with laminate, parquet and linoleum.

Laying plywood on an old floor

Plywood can be laid:

1. On a cement base, but it is necessary to ensure the evenness and horizontalness of the base, or use adjusting racks.
2. Fastening on the logs. Here the difficulty is the exposure of the lags to ensure that the joints of the sheets hit them. Logs must be set so that their upper surface provides one horizontal plane. Engineering communications are hidden in the logs, insulation and sound insulation are laid.

Laying plywood on logs

Important! When laying plywood in one layer, it is necessary that its thickness be at least 15 mm, if in two layers, then you need to choose at least 9 mm for the layer.

All dust and debris must be removed from the subfloor before final laying of the plywood. It is also desirable to perform priming, that is, to process with a special primer.

Before installing the subfloor in a wooden house with your own hands, you need to familiarize yourself with all the design nuances. In what ways can they be laid, depending on the architectural characteristics of the buildings? What are the requirements for installation? Read more below.

Subfloor type	Technical features and brief characteristics
	They are more often used as bases for finishing coatings: glued board, piece natural parquet, various types of laminate, linoleum, soft coatings. The main requirement for such structures is an even and solid base that can withstand the maximum design loads. OSB boards, plywood, planed boards are used for manufacturing. To protect the structure from the harmful effects of moisture, traditional or modern materials are used. Such floors are recommended to be used during the construction of interfloor ceilings.
	The floors are installed under the logs on special cranial bars. Between the lags and the finished floor there is a space in which heaters can be laid. Small pieces and waste are used for manufacturing, which makes it possible to reduce financial losses.
	The most economical and reliable method of erecting rough floors. Taking into account the place of attachment, the bases can be insulated or under the finishing flooring. The distance between the bearing beams is selected depending on the operational characteristics of the finishing coating.

When choosing a specific option, it is necessary to take into account the purpose of the building, the number of storeys, the materials and technologies used.

General requirements for subfloors

Regardless of the type of structures, building codes and regulations require the following activities.

Fire protection. All fire-retardant materials are divided into two groups according to their resistance to fire. The first group is used for wooden houses with stove heating. In the implementation there is a wide range of solutions, impregnation is done with a pneumatic spray gun or paint brushes. A prerequisite is that the lumber must be dry. The number of layers is determined taking into account the purpose of the wood.

Protection against putrefactive processes and biological damage to wood. Work is recommended to be carried out with effective antiseptics, all of which reliably protect lumber from premature destruction due to high humidity. The disadvantage of such materials is the release of chemical compounds into the air. True, the concentration is considered safe for residents. For those who do not want to risk their health, there is a completely safe way to protect lumber - impregnation with natural technical oils.

Important. All impregnations and treatments must be carried out before laying the lumber, and not after. Another nuance - great attention should be paid to the ends, they are most susceptible to moisture. Fresh propyls and ends are subject to additional impregnation.

Mandatory presence of vents to ensure natural ventilation of wooden structures. No impregnation will save the wood if it is not constantly ventilated. The parameters of the vents are specified in SNiP 31-01-2003, the diameter and location of the holes depends on the area and height of the underground. The protection of the underground from the penetration of rodents, the openings are made of metal gratings, the geometry of the products is not regulated.

Practical advice. Be sure to check the effectiveness of natural ventilation, if it is not, then the subfloors will not last the expected amount of time. To check, you can use smoke or open fire. In the absence of visible air currents, measures should be taken immediately to improve the performance of natural ventilation.

Compliance with the requirements of building codes guarantees long-term and safe operation of floor coverings. For example, we will consider two methods for arranging subfloors.

Draft floors on load-bearing wooden beams

The beams are laid on the foundation tape or strapping beam. There is no fundamental difference between the two methods, it all depends on the chosen method of building a house. A prerequisite is that between wooden structures and concrete elements there must be reliable waterproofing, most often two layers of roofing material are used. This is the cheapest material that provides reliable waterproofing. In addition, the timber must be treated with any antiseptics.

The beam must lie strictly in one plane, the installation is done using a level. On both sides, round logs need to be cut with an ax.

In the absence of experience with an ax, it is better to purchase ready-made material. But keep in mind that in terms of strength it will be inferior to hewn round timber, and in terms of cost it will significantly exceed it. The draft floor is attached to the lower base of the bars, the flooring will be made of OSB. But if you wish, you can use any materials at hand, and not only wood.

Step 1. Unscrew the beam fasteners. The bars are screwed to the harness using metal corners and long self-tapping screws. The draft floor is installed only on pre-exposed beams, in connection with this, their dismantling is required.

Step 2 Carefully remove the beam from the seat and turn it face down.

Step 3 Attach the OSB strip to the bottom of the beam with self-tapping screws or ordinary nails. The width of the strip should be 10–15 cm greater than the width of the flat area of ​​the beam.

Important. The length of the screws should be ≈ 70% greater than the thickness of the plate, otherwise the fixation will not be reliable. This rule applies to all cases of fixing structures to each other.

While tightening the screws, press the drill with great force, the plate should not rise. Inexperienced builders do not press the self-tapping screws with sufficient force during screwing, the self-tapping screw rotates a little in the slab, due to this, a gap appears between it and the beam. This greatly worsens the parameters of the subfloor.

Using the same technology, attach sheets to all beams.

Step 4 Install all dismantled beams in place, secure them with metal squares and self-tapping screws. Check the position again, if necessary, adjust them with pads of different thicknesses. Never use lumber for underlays, they will definitely sag over time, which will disrupt the horizontal finish of the floor covering. For linings, use durable moisture-resistant building materials. Another important condition is that the dimensions must be equal to or greater than the areas of the beam, which will allow you to evenly distribute the load.

Step 5 Lay pieces of OSB in prepared places. During the preparation of sheets, there is no need to take accurate measurements, small gaps not only simplify the laying process, but also improve the natural ventilation of the subfloor. Thus, by the way, you can save lumber.

Practical advice. Never walk on the subfloor, it is not designed for such a large weight. During the laying of the last row, you should walk along the beams. If you wish, you can foam the joints of sheets and beams, but this operation is not considered mandatory. We have already mentioned that the tree must be ventilated. As for the increase in heat losses, it is insignificant.

Step 6 Lay a vapor barrier, never use an ordinary high-density polyethylene film for this purpose. The fact is that it does not let steam through, as a result, water will always accumulate in the heat insulator, it is in the insulation layer that the condensation point is located. High humidity significantly reduces the heat saving performance of mineral wool and has a very negative effect on wooden structures. Moisture must be constantly removed from the insulation layer, and only modern membranes can provide this.

Fix the vapor barrier to the beams with a stapler, the overlap of the layers is at least 10 cm, the joints should be carefully sealed with adhesive tape.

Step 7 Lay a layer of thermal insulation. For these purposes, you can use rolled and pressed mineral wool or. It is advisable to use mineral wool. Why?

1. Minvata does not burn. In connection with such characteristics of resistance to fire, it is also used as a fire barrier.
2. The material is completely safe. Mineral wool is made from basalt, which is natural glass of volcanic origin.
3. Basalt wool is not afraid of rodents, which is very important for wooden houses.

Pressed and rolled wool is produced in standard sizes, it is recommended to take them into account during the installation of beams. The width of the wool is 60 cm, the distance between the beams is recommended to be ≈ 55–58 cm. Due to such dimensions, the insulation is tightly attached to the structures, heat losses are reduced, and the microclimate in the room is improved. In addition, the sheets do not need to be cut, which speeds up work and reduces waste.

The thickness of the insulation is at least 10 cm. Make the second layer with an offset to cover the joints. If a wooden house is built in a cold climate zone, then the insulation layer must be at least 15 cm thick.

Step 8 Close the thermal insulation with a waterproof membrane. The technology of its laying is no different from the algorithm for installing a vapor barrier membrane.

Step 9 Nail slats about 2 cm thick to the beams, they will serve as a log.

Practical advice. Professional builders strongly do not recommend laying the floor directly on the beams. Due to the bars, ventilation of the finish coating is provided, and it is needed regardless of the type of floor.

Further work depends on the technology you have chosen and the materials of the floor finish.

The device of draft floors on logs

Such options are used in wooden buildings built using the most modern technologies. The floor will be made of glued moisture-resistant plywood 2 cm thick, the flooring method will be on logs.

Step 1. Measure 120 cm from one side of the floor, this is the length of standard sheets. If the plywood is studded, then measurements must be taken very carefully, otherwise the studs will not enter the groove along one line. The use of studded plywood eliminates the appearance of drafts, which is very important for high-quality laying of the final coating. For proper laying of sheets, use coated thread.

Using a nail with thread (left) and coated thread (right) for marking

If the house is very large and the length of the thread is not enough, then a rope should be used first. Drive nails into the extreme logs, taking into account the dimensions of the plywood, and pull the rope between them. Based on the length of the coated rope, drive one or more additional nails into the joists along the line of the stretched rope. Now the marks can be applied without fear, they will all be accurately located on the same line.

Step 2 Lay out the first row of plywood on logs, while first marking the extra width.

Important. The thickness of plywood is selected taking into account the distance between the lags and the maximum load on the floor. This means that the sheets can be not only two centimeters in thickness.

Step 3 Apply liquid nails to the logs. They have several advantages: they significantly speed up the construction process, the subfloor will never creak and guarantee sufficient fixation strength. In addition, liquid nails allow you to easily correct small errors. Glue should be applied in the middle of the lag. If the edge of the sheet lies in the middle of the log, then the glue, respectively, is applied only to a narrow section of the element.

Step 4 Turn over the plywood sheet and attach it with ordinary nails. According to the existing rules, the distance between them should be within ten centimeters along the perimeter of the building, and the length should be 6–7 cm. The distance between the hardware along the log is 15 cm, inside the building ≈30 cm.

Important. Plywood can expand from moisture, leave a gap of a few millimeters between the sheets. It is convenient to use nails as a template, insert them between the sheets, and remove them after fixing. There are situations when the edges of the sheet do not fall in the middle of the log. In these cases, the material must be carefully trimmed, taking into account the above requirements.

If the sheets fall on ventilation holes or other utilities, then measure their size and exact location, then, using a hand-held electric circular saw, cut off the excess.

Nails are much easier and faster to hammer with a pneumatic hammer. And how quickly to do it manually?

1. Put several nails in your left hand, they are all mixed up, hats and points are located on different sides.
2. With your right hand, grab the nails by the caps, carefully pull them out, turn them over to the desired position and put them with the rest. Now all the hats are on top.
3. Pry the nails one at a time with your thumb, grab them with your index and middle fingers and set them with a point on a sheet of plywood. Do not forget that you need to drive in nails at a slight angle to the plywood veneer, otherwise it may crack.
4. With the first light blow of the hammer, bait the nail, and with the second strong hammer it in until it stops.

You can be sure that after a few minutes of training, the speed of nailing will not differ from the machine, and the quality will not suffer.

Step 5 Cut the last sheet to size and fasten it to the logs.

The rows of joints should be staggered, for this the next one must start with half the sheet or the remaining segment. Docking tongue-and-groove plywood requires considerable effort. To do this, use a piece of the bar, apply it to the edge and connect the spike and groove with strong hammer blows. Apply blows alternately on each side, do not allow sheets to be skewed, remember about damper gaps.

Step 6 Mark the edges of the sheets protruding beyond the contour of the lag. It is better to use a coated thread, carefully cut off the excess along the line.

Important. Be very careful with electric woodworking tools. Injuries from them are complex, can cause disability. Tools must be serviceable and adjusted, and cutting devices must be sharp. Never remove factory guards.

Step 7 Proceed to sealing the opposite edge of the floor. The work will go faster if you do not take the dimensions of each sheet, but attach the whole ones. Then you should measure the width of the protruding pieces and transfer the lines to the front surface. Cut off the excess according to the marks with an electric saw.

For the final sheathing of the subfloor, most of the previously obtained segments can be used, due to this the estimated cost of a wooden house will decrease.

How to avoid mistakes during the construction of the subfloor

The main advice - do not try to simplify existing technologies on your own. Only an amateur thinks that he is smarter than everyone else and can do the work faster and cheaper. All rules were developed taking into account many years of building experience, each technological operation has its own specific purpose. An improperly laid subfloor causes deflections and squeaks.

1. Before starting work, check the position of the lag. The distance between the lags should not exceed 58 cm, this will allow you to tightly lay the insulation.

   

2. No need to save on the size of the beams. During the operation of the house, it becomes necessary to install heavy furniture, the likelihood of increasing loads should be foreseen in advance.

   

3. In the place of laying a brick oven, always reduce the distance between the logs or beams. During construction, use only healthy lumber without natural diseases and defects.
4. Boards for the manufacture of the subfloor must have low relative humidity. If the draft floor is laid before the construction of the roof of the house, then work should be done only in good weather. Waterlogged boards not only lose their original bearing characteristics faster, but also shrink in size during drying. As a result, the fastening is weakened, while walking the floor sags and creaks. It is very difficult to fix problems, often it is necessary to completely dismantle the coating.

   

5. If the draft floor is located between the floors of a wooden house, then the cranial bars should be stuffed along the beams. Stuffed across reduce the height of the premises.

   

6. When laying membrane vapor or waterproofing, carefully read the instructions. The material indicates which side it should be to the insulation. The fact is that steam can only go out in one direction, if the fabric is laid incorrectly, then there will be no positive effect. As a result, the subfloor will be constantly wet, and the effectiveness of thermal insulation will noticeably deteriorate.

   

7. Do not save on vapor barrier, cover the lags as well, attempts to cut the roll into small pieces always give a negative result. In terms of footage, the savings are scanty, and the negative consequences are noticeable.

   

8. Always leave a ventilation gap between the rough and finish flooring. At the same time, consider the location for the air outlet vents.

   

9. Practitioners recommend covering the soil under the floor of the first floor with plastic wrap or roofing material. Due to this, the amount of evaporated moisture decreases, the operating conditions of the building are significantly improved.
10. A warm draft floor is recommended to be done only under the living quarters of the first floor. There is nothing to save in unheated ones, an expensive complex cake is not needed.

The unconditional implementation of building codes ensures that during the operation of wooden houses there will be no unpleasant situations. Elimination of the consequences of violation of technology in all cases is much more expensive than compliance with the rules for the construction of subfloors.

The load from the building falls on its foundation. The structure that precedes the finishing coat and serves as the basis for the insulation is the “subfloor”. The temperature regime of your room depends on how it is installed. If cracks remain in it, then cold air will begin to flow from below, dampness and the smell of rot will appear in the house.

Description

When choosing a material for the load-bearing beams of the floor structure as a whole, consider the area of ​​\u200b\u200bthe room for which it will be intended. The larger it is, the thicker they are. This factor is explained by the fact that the finish coating and all the materials that are involved in the installation process must be evenly distributed on them.

How to make a draft floor in a wooden house

There are several options for its formation, but more often they use the "dry" method.

The draft floor is formed according to the following principles:

• According to the lags.
• "Prefabricated", using a dry screed.
• "Adjustable" (on plywood and chipboard).

"Prefabricated" subfloor

"Adjustable" subfloor

If the boards are laid on logs, then they are laid on the following base:

• Beams.
• Reinforced concrete slab.

The adjustable floor is formed on the following grounds:

• Logs.
• Plywood.

What do you need to know?

It is laid on the floor main floor, using less hard woods. These include coniferous varieties. These are the following types:

• Cutting board.
• croaker

In order to achieve the expected results from the installation done, you need to know the following:

• The basis of the entire floor structure is a beam, which is laid on a waterproofing layer (two layers of roofing material).
• A rolled protective material or 2 layers of high-density polyethylene is spread on it.
• Logs are attached to the timber, which serve as a frame for mounting. They are not brought to the walls, leaving a gap of up to 30 mm. This distance will be insurance against possible shrinkage of the soil (changes in temperature and groundwater levels in the soil) and natural fluctuations in the moisture content of the log during its operation.
• The artificially created free area between the wall must be filled with mineral wool.
• The whole tree must be treated with antiseptics and fire retardants. If ready-to-use materials are purchased, then the cuts made must be protected from moisture and bark beetles.

Do-it-yourself draft floor in a wooden house

For work, a board with a thickness of 15 to 20 mm is used. Properly prepared on milling machines, the source material will create grooves and shoulders on its side. This option will eliminate the work with a hammer and nails, which will speed up the assembly process and the tightness of the connection. The rigidity of the structure will not create a creak.

The thickness of the board for the subfloor affects the distance (step) between the lags. The larger it is, the wider this gap. For instance:

• With a board thickness of 40 mm, the step between the lags can reach one meter.
• With a thickness of 35 cm, the step between the lags should not exceed 850 cm.
• With a thickness of less than 35 cm, the step between the lags should not exceed 60 cm.

Of great importance is the correct location of the foundation pillars. They are located around the perimeter and in the central part of the building.

The thickness of the log is directly related to the step of placing the foundation pillars, since the main beam is attached to them.

The following ratios between the dimensions of the lag and the pitch of the foundation pillars, expressed in centimeters, should be observed:

• Logs 40 thick with a step no more than 900.
• Logs with a thickness of 50 at a step of 1100.
• Logs with a thickness of 60 at a step of 1300.

Subfloor installation using plywood

The sequence of work is as follows.

• Beams are placed on a layer of waterproofing.
• Roll material is laid on them, providing protection from moisture.
• The lags are fastening.
• They are lined with a plywood sheet 10 mm thick or moisture resistant boards (MDS, VAT).
• The seams of the connection are closed with construction tape or sealant is poured.
• Close the subfloor with a layer of vapor barrier.

For insulation from condensate from the side of the room, the following materials are used:

• cement mortar.
• Thick cellophane in 2 layers.
• Roll foamed polyethylene based on foil (lay foil to the room) and other materials.

An air barrier must remain between the vapor barrier and the floorboarding. Through the holes in the foundation (air), the subfloor must be ventilated.

Before applying, isolate pipes and meters with construction tape. Apply in layers using a brush, roller or rubber trowel. Pay special attention to hard-to-reach places. After the first layer, self-adhesive tape must be applied to all joints and joints. The second layer will close it. The composition should be partially applied to the wall (its lower part).

There are other materials for such work. Roll foil insulation can be used, which will simultaneously contribute to noise isolation and heat preservation in the room. They are overlapped with a metal part towards the room.

Video: Proper installation of the subfloor

Conclusion

This type of "dry subfloor" can serve as the basis for the formation of the main coating. In some cases, for laying a parquet board or laminate, the finished structure is covered with a layer of waterproof plasterboard.

Video: How to make a subfloor from plywood?