How many floorboards do you need? Laying floorboards with your own hands

Wooden structural materials, combining high strength, environmental friendliness and ease of installation, are widely used in modern low-rise construction for the construction of roofs, floors and power frame floor. Correctly calculated distance between the floor joists and interfloor beams is the key to strength and durability not only of the individual structural element, but also the entire structure as a whole.

What are floor joists?

Floor joists, made of wooden beams of a certain, precisely calculated cross-section, are power elements that absorb static loads from furniture and equipment installed on the floor and dynamic loads that arise when people move indoors. Floors on wooden logs ah have some features that make it possible to level out minor shortcomings of building structures:

• Uniform distribution of load on underlying building structures;
• Increasing the overall strength of the floor or ceiling;
• Improving sound insulation properties with the formation of an additional heat-insulating layer;
• Possibility of laying utilities while ensuring relatively high maintainability;
• Low complexity of installation, providing a flat surface for installing floors made of sheet or roll materials and flooring from natural wood valuable species.

Joists are made mainly from coniferous species wood, the resin content of which provides protection from moisture and a long service life. To install logs in difficult-to-use rooms, hardwood with high moisture resistance or larch products with a high content of natural resins are used.

Why is it necessary to calculate the distance between lags?

Like any other construction materials, wooden crafts have certain indicators of strength, wear resistance, service life and, of course, prices. When installing wooden floors along joists or interfloor beam floors You can also use thick logs laid at close distances from each other, obtaining the highest structural strength and spending a fairly significant amount. But use required quantity logs or beams having a cross-section corresponding to the expected load will allow obtaining the necessary structural strength at significantly lower costs.

IN panel house when the logs are laid on the surface reinforced concrete slab ceilings, their cross-section is chosen to be the minimum required for fastening floorboards or chipboards. Another thing is application wooden structures V frame structure, when the logs serve not only as the basis for the future floor, but also serve as a strength element of the frame connected to the wall supports.

Main calculation criteria

• Thickness of the floorboard or board materials OSB, chipboard;
• Number of support points or distance between walls;

Having even such minimal data, you can correctly calculate the required cross-section of a wooden beam for making lags and the maximum step between lags.

Beam section

The cross-section of the wooden beam for installing the logs is selected depending on the distance between the supports and the required load-bearing capacity of the floor. When calculating the required cross-section of the joist, you should take the maximum load on the floor to be no more than 300 kg per m2.

A square or square beam is used as a log rectangular section, the wider side of which is located vertically. This way, the maximum rigidity of the log is obtained at minimum consumption wood, which reduces unproductive costs for flooring. In construction practice, the ratio of the beam width to its height is 1.5-2, which is optimal from the point of view of strength and cost. When using a standard 5 cm thick edged board as a log, its height with a gap between supports of 2 m should be from 10 to 15 cm. Standard sizes The log depending on the span is presented in the table:

Sometimes it is difficult for an individual developer to find standard timber, suitable for manufacturing logs of the required cross-section. The way out of this situation is quite simple. To ensure the required load-bearing capacity of the floor, you can install several standard boards 5-6 cm thick, increasing the height of the resulting beam by 1-2 cm relative to the standard one. Such a “layer cake”, even in the absence of fastening the boards together, completely replaces a solid beam of the required size. Similar results can be achieved if the boards are placed at regular intervals along the entire length of the supporting surface of the foundation.

The only thing to consider is frame house This method of load distribution is quite difficult to apply due to the connection of the joists to the racks wall structures, openings and distribution of insulation. In a frame house, floor joists are used as interfloor beams, so the minimum required cross-section must be increased taking into account the load from ceiling structures and insulation.

Step between joists

When making wooden floors, it is clearly visible how the distance between the joists, called the step, depends on the thickness, and the type of materials used. The thicker the board used as flooring, the greater the distance between the joists. More clearly about which step you need to choose when using different thicknesses boards, the table below shows.

As a rough draft flooring V modern construction very often slab construction materials are used instead of boards, which accordingly changes the calculation method. Chipboard (chipboard), cement bonded particle board(DSP), oriented strand board (OSB) and gypsum fiber boards (GFP) are successfully used as a base for coverings made of rolled materials or ceramic tiles laid over wooden joists. In some cases, chipboard may be additionally coated with cement-based or gypsum-based materials. Considering the greater bending rigidity of chipboard and lower strength than boards, you should choose a pitch between lags of no more than 40 cm, and when using thicker chipboard (20-22 mm), increase the pitch between lags to a maximum of 60 cm.

When calculating the step between lags for a specific room, you can use the average table values, and if the distance between the last lags is smaller, then the strength of the floor in this place will only increase.

Consequences of errors in calculation

What happens if you choose the wrong section of the lag and the step between them? When installing floors concrete base the most important parameter will be the pitch between the lags, on which the behavior of the finishing coating depends. Chipboard board, fixed on logs installed with a larger gap than allowed, may sag or break, ceramic tile- crack, and the board - bend. In any case, the floors will require redoing.

More unpleasant consequences occur from errors in calculating the required number of logs used as interfloor coverings. If a larger number of joists or a larger cross-section is used than indicated in erroneous calculations, the strength of the entire structure is significantly reduced, which can lead to irreversible deformations and complete destruction of the floors.

Calculation methods

To calculate the size of the timber and the number of elements required for installing a wooden floor on joists with rough coverings made of boards or chipboards, you can:

• Contact the design organization that professional level will calculate how many elements there should be for a covering made of boards or chipboards, and what size of timber should be used during construction;
• Use special average tables yourself, choosing which value is closer to the required one, leaning towards the larger side if there is no exact match between the real and tabulated sizes;
• Use computer programs and online calculators into which you enter enough a large number of parameters, and the program will accurately determine required dimensions timber and the distance through which it must be installed.

Beams in a house usually belong to rafter system or overlap, and to get reliable design, the operation of which can be carried out without any fear, it is necessary to use a beam calculator.

What is the beam calculator based on?

When the walls have already been brought under the second floor or under the roof, it is necessary to make, in the second case smoothly turning into rafter legs. In this case, the materials must be selected so that the load on the brick or log walls did not exceed the permissible limit, and the strength of the structure was at the proper level. Therefore, if you are going to use wood, you need to choose the right beams from it, make calculations to find out required thickness and of sufficient length.

Subsidence or partial destruction of the ceiling may be caused by different reasons, for example, too large a pitch between the joists, deflection of the cross members, too small cross-sectional area or defects in the structure. To eliminate possible excesses, you should find out the expected load on the floor, be it basement or interfloor, and then use a beam calculator, taking into account their own weight. The latter can change in concrete lintels, the weight of which depends on the density of the reinforcement; for wood and metal, with a certain geometry, the weight is constant. The exception is damp wood, which is not used in construction work without pre-drying.

On beam systems in floors and rafter structures load is exerted by forces acting on section bending, torsion, and deflection along the length. For rafters, it is also necessary to provide for snow and wind loads, which also create certain forces applied to the beams. You also need to accurately determine the required step between the jumpers, since too many crossbars will lead to excess weight of the floor (or roof), and too little, as mentioned above, will weaken the structure.

You may also be interested in an article about calculating the amount of unedged and edged boards in a cube:

How to calculate the load on a floor beam

The distance between the walls is called a span, and there are two of them in the room, and one span will necessarily be smaller than the other if the shape of the room is not square. Interfloor lintels or attic floor should be laid along a shorter span, the optimal length of which is from 3 to 4 meters. Longer distances may require beams non-standard sizes, which will lead to some instability of the flooring. The best solution in this case would be to use metal crossbars.

Regarding the cross-section of a wooden beam, there is a certain standard that requires that the sides of the beam have a ratio of 7:5, that is, the height is divided into 7 parts, and 5 of them must make up the width of the profile. In this case, deformation of the section is excluded, but if you deviate from the above indicators, then if the width exceeds the height, you will get a deflection, or, if the opposite discrepancy occurs, a bend to the side. To prevent this from happening due to the excessive length of the beam, you need to know how to calculate the load on the beam. In particular, permissible deflection calculated from the ratio to the length of the jumper as 1:200, that is, it should be 2 centimeters by 4 meters.

To prevent the beam from sagging under the weight of logs and flooring, as well as interior items, you can grind it from below a few centimeters, giving it the shape of an arch; in this case, its height should have an appropriate margin.

Now let's turn to the formulas. The same deflection mentioned earlier is calculated as follows: f nor = L/200, where L is the span length, and 200 is the permissible distance in centimeters for each unit of beam subsidence. For reinforced concrete beam, distributed load q which is usually equated to 400 kg/m 2, the calculation of the limiting bending moment is performed using the formula M max = (q · L 2)/8. In this case, the amount of reinforcement and its weight is determined according to the following table:

Cross-sectional areas and mass of reinforcing bars

Diameter, mm	Cross-sectional area, cm 2, with the number of rods									Weight 1 linear meter, kg	Diameter, mm
Wire and rod reinforcement
Seven-wire ropes class K-7

The load on any beam made of a sufficiently homogeneous material is calculated using a number of formulas. To begin with, the moment of resistance W ≥ M/R is calculated. Here M is the maximum bending moment of the applied load, and R– calculated resistance, which is taken from reference books depending on the material used. Since most often beams have rectangular shape, the moment of resistance can be calculated differently: W z = b h 2 /6, where b is the width of the beam, and h– height.

What else should you know about beam loads?

The ceiling, as a rule, is at the same time the floor of the next floor and the ceiling of the previous one. This means that it needs to be made in such a way that there is no risk of combining the upper and lower rooms by simply overloading the furniture. This probability especially arises when the step between the beams is too large and logs are abandoned (plank floors are laid directly on the timber laid in the spans). In this case, the distance between the crossbars directly depends on the thickness of the boards, for example, if it is 28 millimeters, then the length of the board should not be more than 50 centimeters. If there are lags, the minimum gap between the beams can reach 1 meter.

It is also necessary to take into account the mass used for the floor. For example, if mineral wool mats are laid, then square meter the basement floor will weigh from 90 to 120 kilograms, depending on the thickness of the thermal insulation. Sawdust concrete will double the mass of the same area. The use of expanded clay will make the flooring even heavier, since the load per square meter will be 3 times greater than when laying mineral wool. Next, we should not forget about the payload, which for interfloor ceilings is 150 kilograms per square meter minimum. In the attic it is enough to take permissible load 75 kilograms per square.

A wooden house and bathhouse is the dream of many city residents. Each of those who had to build a log house from wood with their own hands knows very well the purpose of logs and beams. This bearing structures buildings, so you need to select the material for them, as well as their quantity, very carefully. It is recommended to make floor joists from dry, first-class material treated with antiseptic and fire retardant compounds. The most common way to install them is by mounting them on beams cut into the walls during construction.

Calculations of floor joists are made taking into account the basic parameters; the joists must be 1.5-2 times higher than the height of the flooring, otherwise the nails will not be able to firmly hold the floor boards.

They are installed taking into account the fact that insulation material is usually placed between them. This can be expanded clay, polystyrene foam, but most often mineral wool is used, pressed into slabs 50-60 cm wide. Logs are mounted at the same distance from each other. creeps on them wooden floor, which at correct installation will last for several decades. Logs can be made of bars, beams, boards. They serve to redistribute loads from the floor, and also act as a fastener that combines all components and parts into a solid system.

Benefits of using lag

Floors on joists have a certain degree of functionality. In the space between them you can lay pipes, wires, and heat-insulating materials.

The bars are relatively inexpensive. Installation is available to everyone.

These floor supports can withstand a load of 5 tons per square meter.

Figure 1. Mounting diagram wooden beams.

When repairing a floor, it is often enough to repair the joist. There is no need to re-floor the floor.

The design has no large mass. The load on the floor is much less than with a cement screed.

A space filled with mineral wool will keep the house warm and protect it from excess noise.

The bars allow you to bring the floor plane to any height.

Once the structures are in place, they do not require any additional work. You can immediately lay the floor covering.

Disadvantages of flooring on joists:

The room loses several centimeters of height.

High labor intensity. It is necessary to carefully mark and align all structural elements.

Calculation of some lag parameters

Calculation of floor lags is carried out taking into account the main parameters. The floor joists should be 1.5-2 times higher than the height of the flooring, otherwise the nail will not be able to firmly hold the floor boards. If the thickness of the floorboard is 50 mm, then the height of the bars should be about 100 mm. If the subfloor is made of plywood or other sheet material, having a thickness of 20 mm, the bars can be significantly lower, 30-40 mm.

The material for making wooden logs should be coniferous. The humidity of the workpieces should not exceed 20%. The cross-section of the bars is chosen to be rectangular. They can be cut from boards 50-60 mm thick. Stacked finished goods across the light coming from the windows. The laying step is from 40 to 70 cm. Knowing the laying step and the dimensions of the room, it is not difficult to calculate the required number of elements. Everything before installation wooden elements are treated twice with an antiseptic composition. The antiseptic can be replaced with ordinary hot bitumen.

Figure 2. Adjusting sleeves. Used to level floors on joists.

In practice, very often the height of the logs is selected taking into account the thickness of the insulation layer. Typically used as floor insulation mineral wool, produced in slabs whose thickness is 50 mm. The floor joists should be the same height. If you decide to install thermal insulation double layer, then the bars are needed with a height of 100 mm. The distance between them depends on the thickness of the subfloor material. The thinner the rough flooring, the more often logs are installed. With a plywood thickness of 12 mm, which can be used as a substrate for finishing flooring, the gap between the bars is 30 cm.

Most often, the subfloor is made from tongue-and-groove boards. The boards should be spruce, pine or fir. They are not suitable for finished floors, since the wood is very soft, even marks from thin heels remain on it. A laminate or other finishing coating must be laid on top. The thickness of the boards with a normal lag pitch of 50 cm is recommended to be at least 35 mm. In most cases, the calculation of the pitch of the bars is made taking into account the thickness of the floor material:

Figure 3. Fasteners. Used for fastening wooden structures.

Board thickness (mm) – lag pitch (mm):

• 20 – 300;
• 24 – 400;
• 30 – 500;
• 35 – 600;
• 40 – 700;
• 45 – 800;
• 50 – 1000.

To make these parts, not only wood is used, but also reinforced concrete, various polymers and metals. Reinforced concrete products differ high strength. They can be used when building a house outside the city. Other materials can be used when repairing floors.

If the base of the floor is wooden beams, the logs can be installed by attaching them to the side using self-tapping screws (Fig. 1). The size of the fasteners should exceed the thickness of the bar by 2.5 times with a diameter of 6 mm. The positive aspect of this method is that when adjusting the height of individual joists, the use of additional adjusting pads is not required.

In construction, special wooden or plastic products having holes into which small plastic adjusting bushings are inserted. They help quickly level the surface formed by the lags. Such products are installed very quickly and do not require the use of pads (Fig. 2).

Figure 4. Scheme of installing a floor on joists.

Before installation, wooden elements must be protected from various microorganisms and wood-boring pests by treating the material with a disinfectant and then with a water-repellent composition.

In rooms with low ceilings It is better to use other floor installation methods. When performing the calculation, we must not forget that the bars reduce the size of the room in height by 10 cm or more.

Floorboards or sheets of subflooring should be attached to each joist.

Ends structural elements should not touch the walls of the building. There should be a gap of at least 5 cm between them.

Instead of a certain section of a wooden beam, you can use boards connected in pairs to each other and reaching the size of the desired beam in diameter. Some big sizes are not prohibited. The boards are installed on edge.

TO concrete base logs can be fixed with special galvanized metal corners, which are fixed to the base using dowels and screws. Instead of corners, U-shaped devices are often used (Fig. 3).

If necessary, the bars from which the logs are made are joined to each other to achieve the required length. There must be a strong support under the joint. This support is often brick pillar. Under its construction, you need to dig a hole about 10 cm deep. It is covered with sand and watered abundantly with water. The sand cushion is covered with a layer of polyethylene on top. They put it on him cement-sand mortar and lay out a column of red brick.

You can lay out the columns in rows and attach the logs to them (Fig. 4). The size of the columns is 25x25 cm. Calculating the number of bricks is not difficult.

The design of the floor on joists allows you to immediately install rough and finishing flooring.

Logs can be made from various materials. Most often, their production goes wooden block or board. And materials for finishing there are a lot. Their choice depends only on the preferences of the owners and the contents of their wallet. A paper plan of the rooms with exactly indicated dimensions will help you calculate the materials for making floor joists. It is better to do all calculations before starting the main installation work.

All parameters must be specified in mm

X - Floor width.

Y - Floor length.

S1 - Lag width.

S2 - Lag thickness.

S3 - Distance between joists.

O1 - Width of floorboards.

O2 - Thickness of floorboards.

O3 - Width of the subfloor board.

O4 - Board thickness.

R - Distance between boards.

With help online calculator You will be able to 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.

Helpful 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 for the final finishing layer, milled and dried boards with longitudinal grooves for ventilation are used. Boards with a curved edge for a 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.

Wooden flooring is the simplest in terms of installation and inexpensive way to separate adjacent rooms of the house by height. The main elements of a wooden floor are beams (beams or boards) with boards sewn end-to-end on them.

If you decide to use this type floors in your home or compare its cost with another type, for example, with reinforced concrete, then the calculator below will help you with this. With its help, you can calculate the number of boards for the floor, as well as find out their cost.

The calculator calculates the number of boards for two types of floors:

• Type 1 - simple rectangular ceiling with or without opening;

• Type 2 - overlap of any shape.

Calculator Instructions for the calculator

The calculator has 3 fields: drawing, input data and result.

Drawing

This field displays a picture corresponding to the selected type of structure.

Initial data

Before calculating, you must fill in the fields in this field.

First you need to choose how many sides of the skin you want to immediately take into account in the calculation. Because wooden floors They may have only one covering of boards that serve as the floor for the upper floor, or they may have two. And the lower cladding in this case is the ceiling for the lower floor. This is usually done for aesthetic reasons or if they want to place insulation between these two skins.

Type 1

The length (L) and width (K) of the room are the dimensions of the room or the dimensions of the ceiling. Indicated from the inner edges of the walls (see figure).

The area of ​​the openings (S) is the sum of all openings that fall within the area of ​​the calculated overlap.

The length (A), width (B) and height (F) of the board are the dimensions of the board, where A and B determine the covering area, and F is the thickness of the floor.

Price for 1 m3 or 1 m2 - depending on how this lumber is sold, in that column you indicate the amount. For example, 1 m3 of boards costs 5,000 rubles, then you indicate this figure opposite the column “Price per 1 m3”.

Type 2

The fundamental difference between type 1 and type 2 is that the area of ​​the room is immediately indicated here, and not the lengths of the sides, as in the previous case.

In addition, in the calculation of type 2 floors, the “Stock” column appears, with which you can adjust the number of boards. Its appearance is due to the fact that when covering polygonal (complex) floors, a lot of scraps appear that are unsuitable for further use. Here it is advisable to indicate 5-10%.

Result

Floor area - the area of ​​the room minus the openings.

The total number of boards is the required integer number of boards required for the flooring arrangement (cladding on one or both sides).

Boards in 1 m3 - the number of boards of a given section (BxF) in one cube. The length of the board (A) does not play any role in this case.

The volume and area of ​​the boards is the required number of boards, expressed in cubic and square meters.

Cost per 1 m3 or 1 m2 - depending on what you indicated the price in, here you get the total cost of the boards.