Thanks to its environmental cleanliness, aesthetics, naturalness, warmth and comfort in the home, wood floors have not lost popularity to this day. When choosing them, many questions arise - what should be the distance between the floor joists in wooden house, what material to choose, how to install correctly, etc. This article will answer all your questions.

Choosing timber for logs

1. Select material from coniferous wood, the price of which is low - spruce, pine or fir. If the room is damp, purchase larch slats. It is more expensive, but it almost does not rot from exposure to moisture.
2. To save money, you can purchase grade 2/3 lumber with a moisture content of 18/20%.
3. The beams must have a rectangular cross-section. At the same time, their height should be 1.5/2 times greater than their width. Having such a cross-section, the logs will operate optimally, withstanding high loads.
4. The dimensions of the beam must be selected based on the span, that is, the distance between the beams of the lower frame. The thickness of the insulation used is also important.

Below are the sections of the logs (with a step between them of 0.7 m) for different spans.

1. When the span width is of an intermediate value, you need to choose the closest option, taking into account the safety margin.
2. When purchasing timber, inspect it for defects. Before calculating floor joists, take into account their margin of 10/15%.

Pay attention! To protect wood from harmful insects, mold and fungi, it must be impregnated with an antiseptic. The underside of the beams must be treated twice, allowing the first layer to dry for 4/5 hours.

How to determine the pitch between joists

This value depends directly on the thickness of the floor covering.

Table you can use

When thick boards with good strength are used for flooring, logs can be installed relatively rarely. If the finishing coating is thin, the timber must be positioned frequently. Below is a table of distances between floor joists based on the thickness of the boards.

To more accurately determine the step between the lags, you will need to carry out calculations.

Calculation example

1. Let the length of the room be 11 m.
2. The width of the beam will be 0.15 m.
3. We will choose floorboards with a thickness of 25 mm (0.025 m) for flooring. Therefore, the gaps between the logs should be from 40 to 50 cm. Let’s average these figures to 45 centimeters, that is, 0.45 meters.
4. Let's denote the number of lags as x.
5. The width of all our logs will be equal to 0.15∙x.
6. The first beams will be installed at a distance of 30 mm (0.03 m) from the walls. Based on this, the step between the lags will be: x-1. The distance between all lags will be equal to 0.45∙(x-1).

To find out the distance between the floor joists, we create the equation:

length of the room = width of the beam + space between all the joists + distance from the walls.

1. We substitute the values: 11=0.15∙x+0.45∙(x-1)+0.06.
2. We solve the equation:

11=0.15∙x+0.45∙x-0.45+0.06;

11=0.6∙x-0.39;

1. The number of lags must be an integer; based on this, we round the value to 19.
2. The sum of all the gaps between the logs will be equal to 11-0.06-19∙0.15=8.09 meters.
3. We divide this figure by the number of distances - 8.0919-1=0.4494.
4. The result obtained: the exact distance between the floor joists should be 44.94 centimeters.

Frame installation

Floors with joists can be installed both on the floors of the house and on the ground base.

Installing joists on wooden floors

1. The logs must be fixed to the strapping beams. It should be taken into account that they are unlikely to have an absolutely even level. Therefore, it is best to attach the timber to the sidewalls of the beams.
2. IN in this case Determine the horizontalness of the lag using a control strip; pads do not need to be used.
3. Fix the logs with screws with a diameter of 6 mm. They should be 2/2.5 times longer than the width of the beam.
4. To prevent the lumber from cracking, drill holes in the joists and beams. In this case, use a drill that will have a diameter 2.5 mm smaller than the size of the screw.
5. When the beams are placed far from each other, you need to install double logs. First, lay the first row of joists on the beams, and on top of them, with smaller steps, another one.

Laying timber on the ground

1. First, level and compact the soil with your own hands. This work can be done using big log. Nail a board to it from below and, moving the tamper along the ground with a partner, compact it. The board should be at least 5 cm thick and slightly larger than the cross-section of the log.
2. Next, mark the support pillars for the joists. When the supports for the frame are the beams of the lower frame, marks can be left directly on the beams. If the support is a grillage covered with roofing felt, place marks on the waterproofing material.
3. The distance from the initial logs to the walls should be 3/20 cm.

Before installing the support posts, you need to make a foundation for them. It can be poured separately under each support or placed under a row of posts.

The dimensions of the foundation for the column are minimum 0.4×0.4 m, height 0.2 m, 5 cm of which should protrude from the soil.

The instructions for arranging the foundation are as follows.

1. Set aside 0.2 m from the log axis marked on the strapping beams in both directions.
2. Pull the string between the marks.
3. Perform a similar operation in a plane perpendicular to the joists to mark the corners of the posts located at the intersection points of the cords.
4. Drive stakes into the corners. Next, remove the cords.
5. When the foundation is laid under a row of supports, only the edges of the row are marked with cords.
6. In the marked areas, remove top layer soil. Compact them, pour in crushed stone and compact it.
7. Assemble the foundation formwork, which has a height of 0.1 m.
8. To waterproof concrete, place polyethylene film in the holes. If the soil is clay, then you don’t have to do this.
9. Reinforce the foundation with a frame welded from rebar, 0.8 cm in diameter. It should be laid slightly below the center of the future concrete layer.
10. Next, fill in the solution. Its composition should be the same as for the foundation of the house.
11. Allow the concrete to set for 2/3 days.
12. After this, lay the waterproofing. For this purpose, cut pieces of roofing felt according to the size of the supports, in other words, 40x40 cm. You can also make overlaps of 1 centimeter. Lay the insulation directly on the mortar; there is no need to coat it with bitumen.
13. Now you can start laying bricks. Two rows of them in height are enough, the top one should be oriented perpendicular to the length of the beam. To fasten the material, use sand-cement mortar, use brick grades not lower than m-100.
14. Lay waterproofing along the bricks.
15. Place soundproofing pads on top of it. To prevent them from moving, secure them.

First, lay the lighthouse logs, the first from the walls. Secure them at intervals of 2 meters from each other.

Pay attention! Check that the material is laid horizontally relative to the ground, as well as to each other. If the logs lie unevenly, the protruding areas can be removed with a plane, and pads can be installed under the sagging parts. It should be taken into account what maximum deviation is permissible - it should be one millimeter per 1 meter of timber.

Conclusion

The strength and reliability of the structure of all floors depends on the pitch of the joists, their cross-section and the wood used. Therefore, you need to take the choice of these parameters seriously. In the video presented in this article you will find additional information on this topic.

Many owners of summer cottages choose wooden floors when building houses. This is due to the fact that wood is environmentally friendly pure material, which has aesthetic appeal and natural naturalness. In most cases, the installation of a wooden floor requires the presence of logs - wooden beams laid on the main floor. During installation, it is very important to choose the correct distance between the floor joists.

Scheme of laying lags.

Purpose and methods of installation of logs

Logs (beams) perform several very important functions:

• increasing noise and thermal insulation of the base;
• creating a ventilated space under the floor in which utilities can be laid;
• correct redistribution of the load on the subfloor;
• creating a smooth and solid foundation for installation of finishing flooring.

Scheme for calculating the distance between lags.

In most cases, logs are made from wooden beams of coniferous and hardwood. Sometimes metal, reinforced concrete and polymer analogues are installed, but this is not economically viable. In the absence of wooden beams, logs can be constructed from several boards knocked together. In this case, they are laid on the ribs.

When choosing timber for making lags, you should be guided by the following recommendations:

1. Choose inexpensive wood (fir, pine or spruce). If the room in which the floor is installed will have high humidity (for example, a bathhouse), then you should use hardwood wood
2. To save your budget, you can choose building material of 2 or 3 grades with a humidity of 17-22%.
3. Beams must have rectangular section a certain size.
4. The dimensions of the beam should be selected based on the span, that is, on the distance between the beams of the lower junction.

How to choose the right lag section?

Scheme for installing a subfloor on joists.

The cross-section of timber for making logs is determined by 2 factors: the length of the span between the support points (columns, pads or cross beams) and the maximum load under which the floor will be during its operation (for a residential premises it is no more than 300 kg/m2).

The cross section of the beams should be rectangular shape with a width that is a multiple of 1.5 and a height of 2, that is, the aspect ratio in the section should be 1.5x2. When laying beams, the larger side should be vertical. This will allow you to achieve maximum structural rigidity with minimal volumes of wood and, accordingly, minimum costs. Table 1 shows the dependence of the beam cross-section on the span dimensions.

Table 1

Also, the cross-section of the beam will depend on the thickness and strength of the floor covering. When installing the floor, you should pay attention to the layer of thermal insulation material.

There should be a small gap between the finished floor and the insulation laid between the joists. natural ventilation air with a width of at least 2 mm.

This means that the timber must be purchased taking into account the size of the ventilation gap.

Options for joining logs.

Using columnar supports allows you to save on wood thickness. So, with a log length of 400 cm, just one support installed in the middle will allow you to reduce the cross-section from 180x100 to 110x60, which will ultimately have a significant impact on your budget.

Calculation of the distance between joists when installing the floor

The distance between the logs (step) is a very important parameter, on the basis of which calculations of the required amount of building material are made. When thick boards with good strength are used as the finishing floor, beams can be installed relatively rarely. If the flooring is carried out with thin elements, then the step must be reduced. Table 2 shows the dependence of the distance between the lags on the thickness finishing coating.

Table 2

The data shown in Table 2 is approximate. To more accurately calculate the pitch, we can give an example when it is necessary to find out what distance should be between the beams when constructing a floor in a room 9 m long. In this case, a beam with a cross-section of 180x100 mm is used, and boards 30 mm thick are used as the finishing coating.

Scheme of laying plywood on joists.

Since the thickness of the board is 30 mm, then, according to Table 2, the step should be 0.5 m. Total quantity beams will be designated as k. Therefore, the width of all joists will be equal to 100*k (mm). The first beams will be laid at a distance of 30 mm from the wall. Based on this, the step between them is k-1, and the distance between all elements is 0.5*(k-1).

To find out the pitch between the beams, you need to create an equation: length of the room = width of the beam + distance between all the joists + distance from the walls. The result is: 9 m = 100 mm*k+0.5*(k-1) m + 30 mm*2. Bringing all the values ​​into unified system calculus, you get: 9 = 0.1*k + 0.5*(k-1) + 0.03*2.

Solving this equation, you will see:

• 9 = 0.1*k + 0.5*k – 0.5 + 0.06;
• 9 + 0.5 – 0.06 = 0.1*k + 0.5*k;
• 9.44 = 0.6*k;
• k = 15.7 pcs.

The number of beams must be a whole number, so the resulting value should be rounded up. That is, to construct the floor it is necessary to prepare 16 lags. The sum of all the gaps between the logs will be equal to: 9 – 0.06 – 16 * 0.1 = 7.34 m. Dividing this value by the number of gaps, you get: 7.34 / 15 = 0.489 m. For the example given, it is necessary to install logs through every 0.489 m or 48.9 cm.

Floor insulation scheme with joists.

Follow these tips to ensure the resulting design is reliable:

1. The base on which the floor is to be installed must be thoroughly cleaned of debris and treated with a deep penetration primer.
2. All wooden elements should be treated with an antiseptic, which can increase the service life of the wooden structure.
3. The beams need to be laid along the window with gaps between the walls of 3-4 cm.
4. After installing the log, the surface is checked for horizontal evenness with a long level. If there are no gaps between the level and the beams, then all the work was done correctly.

The reliability of the entire structure depends on the cross-section of the logs and the step between them. Therefore, the choice of these parameters should be taken very seriously.

Wooden logs are one of the most popular building materials, used most often in individual construction, so it is important to maintain the correct distance between the logs of a private house.

Lags are wooden beam, serving as the basis for fastening subfloor elements (boards, plywood sheets, chipboard, etc.). As a rule, timber obtained from coniferous species wood (pine, spruce, fir, larch).

As a rule, before installing logs, they are additionally treated with antiseptic and fireproof impregnation.

The moisture content of the wood at the time of application of the logs should not exceed 18-20%. For the logs, choose a rectangular beam with a cross-sectional aspect ratio of 1.5-2. The shorter side of the beam section is installed in the direction of application of the static load.

If you do not have timber of the required cross-section, then it is permissible to use stacked logs from boards or timber of a smaller cross-section than the design one. In this case, a magnifying factor of 1.2 is applied. In order to ensure the evenness of the finished floor, it is necessary to install the base logs at a level.

Floor joists solve several problems:

LOG INSTALLATION OPTIONS

Most often, there are three options for installing logs as bases for flooring.

Base for subfloor

The joists can be used as a base for installing a subfloor and are mounted on an existing floor.

In this case, as a rule, the logs are fixed to concrete floors, or to earthen floor and their main function is to keep the rough and finishing floors from deformation and destruction.

Joists on poles

Logs can be installed on support pillars, mounted in the underground of the house. In this case, the logs transfer the load to these foundation elements. The task of the joists is to withstand the load acting on flooring and redistribute it to the support pillars.

Logs – interfloor covering

Logs can play the role of not only the basis for the floor, but also be an element interfloor covering and bear the static and dynamic load, redistributing it to other floor elements.

It is clear that the most insignificant requirements for the strength properties of the logs are imposed in the first case. The thickness of the timber for the logs is taken to be of the minimum cross-section. In this case, they are often guided by the thickness of the heat-insulating layer located between the joists rather than by calculating the strength.

The distance between the lags is selected based on the minimum sagging of the subfloor elements, be it boards or plywood. Recommended distance is 0.5-0.7 m. It is possible to create a box-shaped structure from logs by connecting them in perpendicular directions in the plane of the floor.

In the third option for using lags, an accurate calculation of the cross-section and distance between the lags is required. And in the second option, it is necessary to calculate the section of the beam, since the distance is determined by the gap between the support pillars.

There are several ways to correctly calculate these parameters: using construction tables, using special construction programs, or contacting a design specialist. Let's try to do this calculation ourselves.

CALCULATION OF LAYER PARAMETERS FOR FLOORS

For correct calculation, it is necessary to understand what other characteristics the strength of a given structure depends on and these are:

So, here's an example of a calculation.

You have chosen a board for rough flooring with a standard thickness of 2.4 cm, the width of your room is 3 m. The length is 11 m. Using two basic tables, the cross-section of the timber and the distance between the logs are selected. For a board thickness of 2.4 cm, the distance between the logs should be 40 cm. For a span width of 3 meters and design load 300kg/sq.m. We recommend timber with a cross section of 15*8cm.

Another feature of the calculation is that it is necessary to take into account the minimum distance between the supporting wall and the outer beam; from practice it is 3 cm. The number of lags is calculated using the formula:

DP=RL*(CHL-1)+TL*CHL+KB*2, Where

• DP– length of the room, for our example – 11m=1100cm.
• RL– distance between the logs (from the table) – 40 cm.
• TL– log thickness (from the table) – 15 cm.
• KB– distance from the outer joist to the wall – 3 cm.
• CL– number of lags – determined number.

Substituting the values ​​into the formula, we get:

1100=40*(CHL-1)+15*CHL+3*2

1100=55*CHL-CHL-34

CHL=1134/55=20.62 rounding to 21 pieces

Now let's calculate the distance between the lags:

1100=RL*(21-1)+15*21+3*2

1100-6-315=20*RL, RL=38.95 cm.

Using the above method, you can quickly calculate the distance between the joists and their number for the subfloor in a private house.

The distance between the joists for floorboards is a very important and often decisive value for long-term service wooden covering. If the step is too large, the laid boards will not be able to withstand the pressure pressing on them for a long time and the floor surface will quickly deform.

If you take too small a step, then wooden floor it will not bring any trouble, which cannot be said about your finances and the time spent on installing the floor: both the first and the second will be needed more than necessary. Therefore, when starting to install a wooden floor, first of all you need to correctly determine the distance between the joists.

What are lags

A joist is a beam or thick board laid strictly perpendicular to the boards being laid. The vast majority are wooden, although metal, reinforced concrete and polymer beams can also be used. But their cost is much higher than that of wooden ones, and attaching floor boards to them is much more difficult.

Using a log structure in floor installation allows you to solve several problems at once:

• arrangement of a flat and durable surface;
• additional sound insulation;
• ensuring air circulation in the underground;
• the possibility of using underground space for laying utilities;
• the possibility of installing additional thermal insulation;
• possibility of quick replacement individual elements structures in case of damage.

Typically, inexpensive pine, spruce or fir timber is used to construct logs. For arrangement in rooms with high humidity, for example, in a bathroom or toilet, it is better to take material from larch. Although it costs significantly more, this difference in price is more than compensated by the durability of its service.

For lags, material of the 2nd and even 3rd grade is suitable, the main thing is that the humidity in it does not exceed 18-20%. Special attention you need to pay attention to the cross-section of the timber - it should be rectangular. The optimal option is when the height of the beam is 1.5 times greater than its width.

It is these proportions that allow the laid beam to maintain maximum stability and provide maximum resistance to future loads.

What does the lag pitch depend on?

When determining the distance between the installed logs, it is important to consider 3 factors:

• their thickness;
• the thickness of the boards laid on them;
• external load that will affect the floor in the future.

In other words, with the same thickness of boards in a room where heavy furniture will be located, for example in the living room, the pitch of the lag for a floor made of boards should be 5-10 cm less than in the bedroom, and in the bedroom - the same amount less than in an empty corridor. This circumstance is often forgotten not only by inexperienced builders, but also by some construction reference books.

There is one thing golden rule, which must be followed strictly: the thinner it is batten, the smaller the step between the laid beams should be. If the thickness of the floor boards is 20 mm, the distance between two adjacent beams should not exceed 30 cm. If the thickness of the board is 25 mm, then the distance can be increased to 40 cm; when using boards of 30 mm - up to 50 cm, 40 mm - 60 cm, etc. If laying the floor boards on joists is carried out with a thickness of 50 mm, then the step can be taken in 1 m (all numbers in the example are indicated for empty rooms ).

Please note that in the recommendations for the pitch size of beams laid for joists, the cross-section of the beams themselves is not taken into account in any way. But, although when choosing the step size it is lowered, for the strength of the future floor this indicator is very great value. Even if all other parameters are met, if you lay the boards too far thin beams, then such a floor will not last long.

The cross-section of the beam used for installation of the joist structure depends mainly on the maximum span length, that is, on the maximum distance between two points of support. But it is always better to take material “with reserve”. If additional insulation of the floor is planned, then when choosing the cross-section of the beams, you must additionally take into account the thickness of the insulation.

With a span length of 2 m, the optimal beam section is 110x60 mm; with a length of 3 m -150X80 mm; at 4 m - 180X100 mm; at 5 m - 200X150 m, etc. When determining the length of the span, keep in mind that there is usually a significant difference between the width of the corridor and the width of the living room. But buy timber different sections Separately for the corridor and separately for the living room is impractical - the height of the floors in this case will be different.

Usually, material of the same size is taken, and if necessary, additional support points from brick columns are installed in the living room.

All parameters must be specified in mm

X- Floor width.

Y- Floor length.

S1— Lag width.

S2— Thickness of the logs.

S3— Distance between lags.

O1— Width of floorboards.

O2— Thickness of floorboards.

O3— Width of the subfloor board.

O4- Thickness of the board.

R— Distance between boards.

With the help online calculator and you can calculate:

• Volume of log materials;
• Calculation of floor joists: length, width and required quantity;
• Total floor area or square footage;
• Number of rows and volume of floor covering;
• Number of sheets of wood, laminate or parquet;
• Volume between joists for insulation;
• The amount of material for the subfloor.

Useful information

Wooden flooring is made in three tiers, as shown in the figure above. At the bottom there are load-bearing logs on which they will be laid rough boards, and on top there are finishing floorboards. Below we will describe the installation technology in detail.

DIY wooden floor

As a rule, this work is carried out after completion heating season. Since at this time, the boards will not absorb excess moisture. The weather should be dry and sunny. It is best to use unplaned boards for rough flooring. While milled and dried boards with longitudinal groove for ventilation. Boards with curved edges for groove connection. As a rule, each such board is pre-treated with a decorative and protective composition.

During the installation process, you must follow the requirements:

• All logs must have good stability;
• The logs are laid strictly horizontally (exception when the slope is provided for by the project);
• Ensure ventilation of the space under the floor;
• Wood moisture content should not be more than 12%.

Mark and prepare the floor surface

First of all, we mark out the room and designate the places that need to be planned in order to achieve a uniform level (taking into account the thickness of the seams and the height of the brick). To add incompressible soil, use fine crushed stone or sand with a layer thickness of up to 5 centimeters.

After this, compact the entire surface. In those places where the logs will be located, we fill in crushed stone and also compact it into the ground.

Installation of logs

As a log, you can use a wooden beam measuring 50x100 mm. According to your program results, we install the timber on an already compacted surface.

If you plan to increase this distance between the lags, then in this case you should use a larger section of the beam.

If the subfloor base has concrete floor or slabs, then we install the logs directly on the concrete. In this case, you can use a smaller cross-section of the beam, since the bending load is almost completely eliminated. The rough flooring will act as a retainer for the second tier, and therefore a section of 50x50 is sufficient.

The distance between the logs will depend on the thickness of the material being coated. For example, 60 centimeters - for a milling board, 40 centimeters - for covering OSB or plywood.

When the logs are installed, we move on to waterproofing the space underneath them using roofing felt or other modern material.

Rough layer

When the logs are laid, we begin to install the second level, namely “rough boards”. To do this, all end joints should be made directly in the middle of the joists. To fix the boards, we use wood screws of the required size. You can either press the rough boards against each other or nail them at short intervals. In our case, this interval is determined by the value R.

Nails should be driven towards each other at a slight angle for strong fixation.

If you are laying with milling boards, then it is not enough to press them together by hand. For this purpose, special stops and wedges or tightening devices are used.

To fix the finishing board we use nails or wood screws.

The caps of fasteners should not be higher than the surface of the board. To do this you need to go deeper by 2 millimeters. The recesses can be treated with a special putty before painting the floor.

If you use screws instead of nails, you will need to drill holes and subsequently countersink each recess.

During the installation process, a gap of 10-15 millimeters must be left between the wall and the end of the joist or the outer boards, which will subsequently be covered with a plinth. This gap will serve as a compensator during the process of thermal expansion or moisture swelling.

The flooring is ready, now it can be covered with stain or protective varnish.