How to calculate the floor beam. Calculation of wooden floor beams: online calculator, calculation principles

During the construction of private residential buildings, outbuildings and other buildings, it is important to correctly calculate the parameters of each structural element. One of the key elements of any wood structure is the floor.

About floor materials

Properly selected material, choice of length, section and installation scheme determines its durability and the loads that it can withstand. The selection and calculation of wooden beams for floors between floors is one of the most important decisions in private construction. Because wood is environmentally friendly pure material and strong enough.

The only supposed minus of wood when compared with concrete is its combustibility, the indicator of which, if necessary, can be reduced if the wood is treated with special compounds.

It is generally accepted that concrete is refractory, although this is not entirely true: it cracks at temperatures above 250 and crumbles at temperatures of 550 degrees, that is, it is completely destroyed in a fire. Therefore, wood is a good alternative to concrete.

But, in order to calculate how much wood is needed for construction, so that there is no excess of it, so that the maximum load bearing capacity this wooden beam, often use a calculator to automatically calculate the parameters of the overlap. The calculator for calculating wood floor beams will help you quickly and fairly accurately determine the safety margin indicators when using different materials and, accordingly, choose one of them. The best materials, cross-sectional parameters, design features, high-quality floor beams allow you to optimally distribute the load without exceeding the permissible one, as well as walls made of brick or made of other material.

What determines the strength of the coating?

The main parameters that affect the quality of the overlap depend on the properties of the material, technical parameters and operating conditions.

Properties of wood materials:

• Type of tree. Pine, spruce, larch are considered popular species for use in residential construction. Sometimes oak, birch, aspen, as well as combined materials are used.
• Sort. Three types of wood are determined, which are numbered 1 (the best), 2 and 3. The grade is determined by the maximum number of knots on the wood, the bending of beams, including healthy and rotten ones, the number, depth and length of cracks, and other wood defects. Detailed requirements for wood are determined by standards, norms, rules (SNiP II-25-80, SP 64.13330.2011 and others).

Each material has its own strength and deflection characteristics, which depend on the technical parameters described below. Some breeds are lighter, others more resistant to moisture.

For example, softwoods have better resistance to moisture. The first type of wood is different best quality, lack of flaws, but it is correspondingly more expensive.

Technical indicators:

• Beam type. Defines types such as rectangular beams, round logs, beams,. glued from boards or LVL veneer.
• Span length. Typically, a beam span for private residential buildings is no more than 6 meters. It is important to remember that this indicator is different from the length of the beam itself, which must also capture the supporting sections on the walls or other supports.
• Beam height and width. For a beam, another rectangular beam, these indicators may be the same or different. The greater their height, the greater the rigidity and the less they flex. In the case of logs, the diameter or average diameter of the log is taken into account. When choosing these parameters, the features and ease of manufacture, transportation, and installation of beams are also taken into account.
• Beam step. This is the distance between two adjacent beams in the floor. The closer the beams, the higher their consumption of beams, the strength of the overlap, but the deflection and maximum load decrease.
and concentrated load, which are defined by standards and depend on the type of premises, the number of residents or employees, the type and amount of furniture or equipment in them, and other features of their use.
• Cover type. This refers to interfloor floors with increased requirements for relative deflection, which is 1/250; attic floors, the requirements for which are lower - 1/200; coatings and floorings, the relative deflection of which is 1/150.

The last 3 points are also defined as the operating conditions of the wooden floor, which depend directly on the features of the construction.

Result and calculation example

How the wooden beam calculator works and how the load is calculated are the main questions to be answered here.

The 2 main indicators that determine the quality of the floor are the distributed load on the floor itself, as well as the concentrated load on the crossbars, if they are used. The quality of the crossbar also depends on the method of fixing it.

The online calculator automatically shows how large the reserve of distributed load and deflection at the floor will be. Or vice versa, it will indicate an overload.

Calculation example

For example, the following input parameters are used: pine timber, single-span for interfloor overlapping, length 6 meters, has square section 120 by 120 millimeters. They will be located in increments of 40 centimeters with a load on the beam, which is 60 kilograms per square meter.

The moment of inertia of the section will be 1728 cm⁴, and such beams weigh 43 kilograms each.
As a result, the calculated deflection of such an overlap will be 23 millimeters (or 1/261 of the relative deflection). It will have a deflection margin of 1.04 times and collapse under a load of 845 kilograms.

For the corresponding crossbar with a concentrated load of 90 kg, the calculated deflection will be 23 millimeters, and the deflection margin will be 1.04 times. The design will not withstand loads over 422 kilograms.
Consequently, building experts will recommend not to use a floor between floors with such indicators, since the deflection margin is too small.

The optimal deflection index is from 1.5 to 3, respectively. The higher this indicator, the higher the wood consumption, but the lower the deflection margin, the less stable the building as a whole and its elements in particular will turn out.

Benefits of a calculator

Using the calculator, the builder can independently select the necessary parameters, selecting each of the available or desirable options and calculating more profitable materials and type of beams.

When building any private house, you always have to make different kinds floors. These can be interfloor or attic structures, but in any case, their installation must be approached responsibly, and the most suitable materials must be chosen for this.

We can say that these structures are the same integral element of any home as walls, foundations or roofs.

Types of floors used in private construction

Depending on the type of buildings and the planned costs for their manufacture, the following can be used:

• reinforced concrete;
• foam concrete blocks and monolithic reinforced concrete beams;
• I-beam rails and wooden draft flooring;
• wooden joists.

Calculation of the section of wooden beams

During the construction of most private houses, developers make the floor of the second floor from a bar. It is relatively inexpensive, but still sufficient reliable material, which has been used for such purposes for several centuries. Only necessary condition is an correct calculation sections of such crossbars installed in the span as a log.

In order to more accurately determine the cross-section of a beam for overlapping, special formulas are used, which, among other things, take into account the resistance of the wood used and its moisture content. These parameters are defined in SNiP II-25-80, with which any developer or private master must be familiarized without fail.

There you can also find necessary formulas and tables that determine the parameters of beams for specific interfloor structures.

When calculating wooden floors, it is also necessary to take into account the span width, the distance between the beams, and the shape of their section. When calculating each cross member to be laid, it must be remembered that the value of its deflection under load should not exceed 1/250 of the span length.

Since it is quite difficult for a technically untrained person to correctly calculate the lag parameters using formulas and tables, special calculators can be used to independently select beams. In such a program, it is enough to enter several basic quantities, and as a result, you can choose correct dimensions bearing lag.

Calculation of the beam section

As an example, using one of these calculators, we will try to calculate which beam to use to cover 5 meters.

For data entry we need to know:

• the material from which the crossbar is made (only coniferous trees are recommended);
• span length;
• beam width;
• beam height;
• type of material (log or timber).

To do correct calculations, we substitute the span width equal to 5 m to the input values, and set the beam type as the beam type. We will select the height and width empirically in the parameters “bar dimensions for floor beams”. Be sure to take into account such values ​​as the load per kg / m, and the step between the crossbars.

For interfloor structures, the load value should not be less than 300 kg / m, since it is necessary to take into account not only the weight of furniture and people, but also the weight of the materials themselves from which the floor is made. This includes floor beams, rough and finishing floors and, of course, insulation and sound insulation.

Advice. For non-residential attic structures, a load value of 200 kg / m will be quite sufficient.

Possible options

In almost all bases that sell lumber, floor beams are sold mainly in several sizes. As a rule, these are beams from 100x100 mm to 100x250 mm, and from 150x150 mm to 150x250 mm. In order not to waste too much time and money searching for a lag with non-standard sizes, the price of which can be much higher than the standard ones, we substitute into the program those parameters that are commercially available.

To do this, you must first find out on the basis of lumber what sizes they sell. Thus, we obtain that for interfloor structures minimum size the beam should be approximately 100x250 mm, and for the attic, 100x200 mm will be enough, with a step between them equal to 60 cm.

If you do not trust software calculators and want to independently calculate the size of the floor beam, then you will have to use the formulas and tables given in the relevant technical documentation. Or you can use general rule, which states that the height of each lag should be equal to 1/24 of the length of the opening, and its width is equal to 5/7 of the height of the crossbar.

Installation of interfloor and ceiling ceilings on wooden logs

Interfloor ceilings in a house made of timber begin to be mounted by laying a log. To do this, a prepared beam is placed on the walls, which is pre-wrapped with roofing material. This will protect the wood from moisture penetration, and as a result, from decay.

The extreme beams should be laid no closer than 5 cm from the wall, and the distance between adjacent crossbars should not exceed the previously calculated values, which in our case are 60 cm.

An important condition is that the logs must be laid over the entire thickness of the walls, having maximum support and stability. The gaps between the lags on the wall are laid with bricks or building blocks, after which a draft floor is stuffed from above edged boards 150x25 mm.

Ceiling ceilings made of timber are almost completely identical to interfloor ones, with the only difference being that the thickness of the beams can be less, and the step between them is several centimeters larger.

prefabricated timber

Let's say you need logs of 150x250 mm in size, but there are no such sizes on sale, but there are always plenty of boards with dimensions of 50x250 mm at any lumber base. To get a beam right size, it is enough to buy 3 of these boards and fasten them together.

As fasteners, it is better to use not nails, but wood screws, because over time the wood dries out, and the nails do not hold the boards together so firmly.

As the instructions for self-manufacturing prefabricated logs, if you use them for basement or basement floors, then before tightening with self-tapping screws, it is worth treating each board with an antiseptic.

This will prevent the appearance of wood pests and significantly increase the life of the entire floor. If you use prefabricated timber for floors, then no pre-treatment boards are not required.

The admissibility of using this type of lag is obvious and not questioned. This material is also environmentally friendly ordinary timber because no adhesives are used during assembly.

Attention!
The load-bearing capacity of prefabricated timber is even higher than that of solid lumber, while the cost is somewhat lower.
From the foregoing, it becomes clear that in some cases the use of prefabricated elements is even more preferable than solid ones.

Glued laminated timber

This type of lumber is an acceptable alternative if the desired solid logs cannot be found, or their price is high enough for you, and it is not possible to make a prefabricated structure yourself.

Floor beams in wooden house from glued beams are distinguished by good strength and resistance to stress, but they also have some disadvantages.

1. In view of the fact that adhesives are used in their manufacture, such material can no longer be called environmentally friendly.
2. In their manufacture, a fairly large percentage of low-quality lumber is used. Significant shrinkage is possible after several years of operation, which means that a laminated veneer lumber floor may "lead" over time.
3. And the most main disadvantage glued beams is their limited service life, which is determined by the manufacturer at 20 years.

Calculation of logs for roofs, floors, coverings of wooden structures.

To calculate, you need to know the snow load in the region. Snow load for Udmurtia 320 kg/m.

The most advanced wooden floor beam calculator...

Manual calculation of floor beams

The main load-bearing structures of a wooden floor are beams. They perceive the load of their own weight, filling, as well as operational loads, transferring them to runs or poles.

Beams (logs), usually made of pine, spruce, larch, for interfloor and attic floors must be dry (permissible humidity is not more than 14%; with proper storage wood acquires such moisture in a year). The drier the beam, the stronger it is and the less it sags from the load.

Beams should not have defects that affect their strength characteristics ( big number knots, slanting, curl, etc.). Beams are subject to mandatory antiseptic and fire impregnation.

If the floor beams of the first floor rest on columns set quite often, then the beams of interfloor and attic floors rest on the walls only at their ends and rarely when supports are placed under them. So that the interfloor beams do not sag, they should be carefully calculated and laid at a distance of 1 m from each other, or even closer.

The most durable beam in bending is a beam with an aspect ratio of 7: 5, i.e., the height of the beam should be equal to seven of some measures, and the width should be only five of the same measures. round log withstands a greater load than a beam hewn out of it, however, it is less bending strong.

Typically, beams sag from the pressure on them from the weight of the backfill, floor, furniture, people, etc. The deflection mainly depends on the height of the beam, not on its width. If, for example, two identical beams are fastened with bolts and dowels, then such a beam will withstand a load already twice as large as both of these beams laid side by side. Therefore, it is more profitable to increase the height of the beam than its width. However, there is a limit to reducing the width. If the beam is too thin, it may bend to the side.

Let us assume that the deflection of the beams floors it is considered no more than 1/300 of the length of the overlapped span, attic - no more than 1/250. If the attic is covered with a span of 9 m (900 cm), then the deflection should not be more than 3.5 cm (900:250 = 3.5 cm). Visually, it is almost imperceptible, but the deflection is still there.

Any overlap, even under load, will be completely even if the so-called building rise is pre-cut out in the beams being laid. In this case, the bottom side of each beam is shaped into a smooth curve with a rise in the middle (Fig. 1).

Rice. 1 Structural lifting beam (dimensions in cm)

At first, the ceiling with such beams will be slightly raised in the middle, but gradually it will level out from the load and become almost horizontal. For the same purpose, logs bent to one side can be used for beams, respectively hemming them.

The thickness of beams for interfloor and attic floors should be at least 1/24 of its length. For example, a beam with a length of 6 m (600 cm) is installed. This means that its thickness should be: 600:24 \u003d 25 cm. If it is necessary to carve out a rectangular beam with an aspect ratio of 7:5, they take a log with a diameter of 30 cm.

The beam can be replaced by two boards with a total cross section equal to the beam. Such boards are usually knocked down with nails, staggering them every 20 cm.

With more frequent laying, instead of logs (beams), you can use ordinary thick boards placed on edge.

Let's consider such an example. To span a 5 m long span with a load of 1259 kg, two beams of a rectangular section 200X140 mm are required, laid every 1000 mm. However, they can be replaced with three boards with a section of 200X70 mm, placed every 500 mm, or four boards with a section of 200X50 mm, laid every 330 mm (Fig. 2).

Rice. 2 Arrangement of block and plank beams

The fact is that a board with a section of 200X70 mm can withstand a load of 650 kg, a section of 200X50 mm - 420 kg. In sum, they will withstand the expected load.

To select the cross section of round or rectangular beams for a load of 400 kg per 1 m2 of floor, you can use the data in the table or the above calculations.

Permissible sections of beams of interfloor and attic floors, depending on the span at a load of 400 kg

Span (m)	Distance between beams (m)	Log diameter (cm)	Section of bars (height to width, cm)
2	1	13	12×8
	0,6	11	10×7
2,5	1	15	14x10
	0,6	13	12×8
3	1	17	16x11
	0,6	14	14×9
3,5	1	19	18×12
	0,6	16	15x10
4	1	21	20×12
	0,6	17	16×12
4,5	1	22	22×14
	0,6	19	18×12
5	1	24	22×16
	0,6	20	18×14
5,5	1	25	24×16
	0,6	21	20×14
6	1	27	25×18
	0,6	23	22×14
6,5	1	29	25×20
	0,6	25	23x15
7	1	31	27×20
	0,6	27	26x15
7,5	1	33	30×27
	0,6	29	28×16

The ends of the beams of interfloor and attic floors wooden buildings they are cut with a frying pan into the upper crowns for the entire thickness of the wall.

To select beams, you can also use the table developed by I. Stoyanov.

Selection of wooden floor beams

Loads, kg/rm	Cross-section of beams with span length, m
	3,0	3,5	4,0	4,5	5,0	5,5	6,0
150	5×14	5×16	6×18	8×18	8×20	10×20	10×22
200	5×16	5×18	7x18	7×20	10×20	12×22	14×22
250	6×16	6×18	7×20	10×20	12×20	14×22	16×22
350	7×16	7x18	8×20	10×22	12×22	16×22	20×00

The loads on the floors are made up of their own mass and temporary loads that arise during the operation of the house. The own weight of interfloor wooden floors depends on the design of the floor, the insulation used and is usually 220-230 kg / m2, attic - depending on the weight of the insulation - 250-300 kg / m2. Temporary loads on the attic floor are taken as 100 kg / m2, on the interfloor - 200 kg / m2. In order to determine the total load per square meter of flooring during the operation of the house, the temporary and own loads are added up and their sum is the desired value.

The most economical in terms of wood consumption are beams with a thickness of 5 and a height of 15-18 cm with a distance between them of 40-60 cm and mineral wool insulation.

Here is a table for calculating a cold attic.

Maximum beam spans attic floor. Unused attic.

Despite the variety of materials used to make floors in houses, wood remains the most popular for small residential buildings with two or three floors. This is due to their special properties:

• wooden floors are lightweight compared to their counterparts made of reinforced concrete, and even more so monolithic, while maintaining good performance;
• it's easy to handle, so installation work installation is carried out without the use of special equipment, which is impossible for other materials;
• the design feature of wooden floors allows the use of any insulating materials;
• finished wood floors are the best foundation for finishing the ceiling or floor;
• wood is still the most environmentally friendly and safe material.

The only drawback of its use can be considered a limitation in the permissible load, which reduces the scope of their application.

Types of floors in the house

Depending on layout, availability basement, conducted heating and the number of floors, the following wooden floors in the house can be used:

• basement or basement;
• interfloor or attic;
• attic.

Each overlap, depending on the type of room, the planned temperature and humidity levels, performs its function. To do this, during installation, the necessary insulation is laid, which prevents the passage of sound, moisture and heat and allows you to reliably separate the rooms in the house.

Floor structure

The device of wooden floors depends on their functional purpose, but they all have a very similar structure. Their main component, which serves as the basis for other elements, are wooden beams fixed to load-bearing structures at home, that is, against the walls. All future load during the operation of the house will fall on them. Therefore, the calculation of wooden floor beams takes important place at the preparatory stage.

For the manufacture of beams, a wooden beam is used from conifers trees that almost do not sag over time, unlike deciduous ones.

A rough or auxiliary floor is fixed on the installed beams. For this, plywood, OSB or chipboard sheets are used, on top of which, after completion of work, top coat, floor or ceiling. The space formed between the subfloor and the ceiling is filled with different insulators, depending on the parameters of the room.

Floor options for different rooms

Depending on the type of room, wooden floors may have different structure. There are three options in total:

• for basement ceilings, where the temperature difference and high humidity are characteristic, the use of a vapor barrier, an increased layer of thermal insulation and a special reflective film or foil is required;
• for interfloor floors, which are characterized by a simpler structure, due to a uniform temperature regime and a stable level of humidity, sound insulation is required;
• for attic floors, if they are not heated, the same filling is used as for basement floors, with the difference that the location of the insulators occurs in the reverse order due to the direction of the cold.

More about the building different floors will be written below.

Types of structures

Wooden floors in the house, depending on the size of the opening, may have different design, which must withstand the specified loads and provide for the placement of technological elements, including those that give rigidity, as well as various mounting hardware.

Today, wooden floors are built with three main types of structures:

• using beams, the oldest of all types, in which the reliability of the structure is ensured by beams from an array of square or rectangular shape laid in increments of 60 cm to 1.0 m;
• with the help of ribs, in which rigidity is created by a board up to 7 cm thick and at least 20 cm wide, laid on the rib in increments of not more than 60 cm;
• beam-ribbed, used for spans up to 15 m and consisting of beams and perpendicularly installed ribs attached to them.

Below are indicators of each type of structure.

Thus, the type of floor structure is determined for each opening individually.

Methods for attaching a beam to a wall

For creating robust design all beams must be firmly fixed in the load-bearing walls. This can be done in several ways. Some have been used, like the wooden floors themselves, for several centuries, others have become possible relatively recently.

First way - traditional . It is applied for brick houses or built from timber. Beams are placed inside the wall in a specially made niche to a depth of 10 to 15 cm, subject to several rules:

• the recommended depth is 2/3 of the thickness of the bearing wall;
• the part of the beam that is in contact with the walls of the niche is covered with roofing material in two layers;
• the end parts are cut at an angle of approximately 60 ° for air access to the tree;
• the distance between the beam and the walls of the niche is at least 5.5 cm;
• the beam rests on a wooden substrate treated with an antiseptic;
• empty space is sealed with insulation;
• the sides are covered with cement mortar;
• every fifth (more often) beam is additionally fixed to the wall with an anchor.

If this mounting method is used for wooden houses, the depth of the niche is no more than 7 cm with the obligatory laying of insulation between the wall and the beam. This reduces the likelihood of a squeak.

Second way consists in the use of special metal fasteners:

• corners;
• clamps;
• brackets.

The selected fasteners are fixed to the wall and to the beam using self-tapping screws or dowels. Sometimes metal mount can be used to reinforce the structure.

This method allows you to install wooden beams faster and easier. At the same time, the traditional version is still the most reliable.

Making calculations

Having decided on the type of construction, it is necessary to prepare a calculation of the wooden floor, first of all required amount beams, taking into account desired section and order of location. Precisely made calculations will help to avoid unpleasant surprises during operation.

The length of the beam is calculated based on the size of the opening and the selected method of fastening. For traditional way the total length includes the width of the opening and the length of the parts placed in the niche. If fasteners are used, the length of the beam is equal to the width of the opening.

The distance between the beams, or pitch, is usually greater than 60 cm and less than 1 m, but can be placed more often. The quantity is calculated by dividing the length of the opening by the selected step with the obligatory displacement of the outer beams from the wall by at least 5 cm.

Calculation features

The cross section of the beam depends on three parameters:

• opening width;
• distances between beams;
• planned load.

The average load is usually considered to be about 400 kg per square meter (its own weight is about 200 kg and permissible load 200 kg). For non-residential premises this value can be two times less.

The cross section is directly related to the width of the opening. The wider it is, the larger the value should be. Here, the rule for the ratio of the size of the opening and the height of the beam, equal to 1/25, is used. For example, for an opening 5 m wide, a beam 200 cm high is needed. The most commonly used section is 5-16 cm wide and 14-24 cm long in a rectangular shape.

Today, it is possible to calculate wooden floor beams using calculators that are freely available on the network or ready-made tables.

Table for calculating sections in centimeters for a load of 400 kg per square meter

Opening, m / step, m

After completing the calculations, you can begin to install wooden floors.

Features of the installation of the basement

The installation of a basement can be done using any of the three types of structures described.

When installing on beams, it is used additional element- cranial bar - 50 x 50 cm in size. It is fixed from below to the beam at the same level, and the auxiliary coating is attached to it. Next, a layer of thermal insulation (polystyrene, expanded polystyrene, cotton wool) with a thickness of at least 10 cm is laid, which is covered with a vapor barrier, preferably in rolls.

With a distance between the beams of more than 60 cm, logs are first installed, to which the second is attached rough coating(plywood, OSB or chipboard). From above, you can lay the finishing floor covering.

For installation along the ribs, cranial bars are not used. The draft ceiling (plywood or OSB) is sewn directly to the ribs in increments of no more than 15 cm. The thermal insulation fits tightly between the ribs. Next, the vapor barrier and subfloor are laid.

The installation of a beam-ribbed floor is carried out in a similar way.

Features of the installation of interfloor overlapping

When installed wooden floor between floors, the main task is to ensure good sound insulation. Same temperature regime and the absence of moisture make it possible not to use a vapor barrier. In other words, if the budget is strictly limited, you can deviate from some mandatory rules.

When installing the ceiling of the second floor on beams, as a rule, logs are always additionally used, to which a subfloor made of plywood or chipboard is attached. In addition, the use of a cranial bar is recommended.

The wooden floor between floors differs from all others in the use of a rubber or cork substrate up to 5 mm thick, placed twice:

• between beams and lags;
• between the subfloor and the finish coat.

For mounting the ceiling on the ribs, the crate is not used. Another feature is the execution of the lathing for the ceiling of the first floor made of wood, since the metal profile can make noise during operation.

Features of installing an attic floor

As mentioned earlier, a wooden attic floor is very similar to a basement. The difference is in the movement of cold air, which moves from top to bottom in the attic, and vice versa in the basement.

That is why one serious mistake is most often made. Instead of placing a vapor barrier under the insulation, it is placed on top, as on the basement.

For additional security, waterproofing in rolls can be placed on top of the thermal insulation, which protects against direct moisture penetration through the roof.

Operation and prevention

Properly selected, well processed and correctly laid beams can serve for a long time. But this does not exclude the need for periodic preventive maintenance and verification. If there is a suspicion of damage to any structural element, it is recommended to replace or strengthen it in a timely manner.

Wooden floor beams provide not only strength horizontal design. Overlapping is designed to give rigidity to the entire building. It is for this reason that the choice of load-bearing elements and their installation should be given special attention.

Pros and cons of wood flooring

To install the ceiling with your own hands, you need to prepare. The floor in the house should be based on a solid and rigid structure. Before starting work, you will have to study the requirements for the elements, the features of their calculation and the types of sections.

The following advantages of wood flooring can be distinguished:

• attractive appearance, the ability to make a wooden floor without additional measures;
• light weight, reducing the load on walls and foundations, saving on construction;
• the possibility of carrying out repairs during operation;
• installation speed, performance of work without additional machines and mechanisms.

Wooden beams do not weigh down the structure and are quickly mounted

But it is also worth highlighting the disadvantages:

• combustibility of wood, the need for special impregnation flame retardants;
• lower strength compared to reinforced concrete or metal elements;
• shrinkage and deformation during temperature and humidity changes;
• susceptibility to decay, fungus and mold high humidity, it is necessary to carry out treatment with antiseptics at the construction stage and periodically during the service life.

wood flooring requirements

Wooden floor beams must meet the following requirements:

• correspondence of the cross-sectional dimensions to the load, span and step, this requires the calculation of beams;
• good strength and rigidity;
• Fire safety;
• absence of serious defects of wood and damages.

For work it is necessary to prepare quality material

There are also certain requirements for the material from which the beams are made. It is recommended to choose softwood. It contains a lot of resin, so it better resists various microorganisms. best material those trees that have grown in harsh conditions are considered. Their stem density is higher. For this reason, it is worth buying pine or spruce, which grew in the northern regions of the country.

You also need to pay attention to the preparation time. The best period is at the end of winter. At this time, the tree is in a dormant state, there is less juice in it, therefore, the moisture content of the material will be less.

What are wooden floors

Wooden floor beams are used for almost all levels of the house. The beam frame must be provided for the following types of construction:

• basement or basement floor (floor of the first floor);
• interfloor overlap;
• attic cover.

Thickness load-bearing beam for the attic is from 10 to 20 cm

The normalized payload depends on the type, which is taken into account in the calculation of wooden floor beams.. Also, the difference will be in the thickness of the insulation and its need.

Between the beams above the basement, usually 5 to 15 cm of mineral wool, polystyrene foam or extruded polystyrene foam are laid. In interfloor structures, it will be enough to provide a couple of centimeters for sound insulation. A cold attic requires the most material. Here the thickness can be from 10 to 20 cm. Exact values depend on the climatic region of construction.

Between the beams of the basement are laid mineral wool

Sometimes the basement ceiling is preferred not to be made of wood, but of metal and reinforced concrete. In this case, as bearing beams use an I-beam or channel, and concrete is poured into the formwork from a profiled sheet. This option will be more reliable with the likelihood of flooding. It will also better resist dampness from the basement.

What are the beams

There are several signs by which the classification of wooden floor beams is carried out: by size, material, type of section. The length of the floor beams depends on the distance between the walls. To this value you need to add a margin for support on both sides. Optimally, it is necessary to provide for 200-250 mm.

According to the material, the elements are divided into the following types:

• from solid timber or boards;
• from glued timber.

Bent beams are made from glued beams

The latter are significantly more expensive. But on the other hand, such material is suitable for covering large spans. A regular beam can work at 4-6 m, while a glued beam copes well with distances of 6-9 m. Glued laminated timber practically does not shrink, is fireproof and resistant to moisture. It is possible to produce not only linear elements, but also bent. A significant disadvantage such material will be the presence of non-natural components (adhesive).

The beam section can be of the following types:

• square;
• rectangular;
• I-beam.

The latter has broadened elements at the top and bottom. In the middle of the section, it is reduced to the maximum possible sizes. This option allows you to rationally use wood and reduce its consumption. But to make such an element is not easy. For this reason, the I-beam is not so often used in construction.

Most often, a rectangular bar is used.

The best option becomes a rectangle. In this case, the long side is located vertically, and the short side is horizontal. This is due to the fact that an increase in height has a better effect on strength than width. Installing a beam from a board flat is almost useless.

The most unfavorable of the presented can be considered a square section. It is the least fitted to the diagram of forces in the element.

You can also use logs to cover. But this option has not gained popularity. The cross section of the board is much more profitable and easier to install, so it is used much more often.

Calculations

The calculation of the section will allow you to have no doubt about the strength and rigidity of the structure. At the same time, it is determined maximum length, which is allowed for any section. To perform the calculation, you need the following data:

• the length of the wooden floor beam (more precisely, the distance between bearing walls);
• the distance between the beams (their step);

For the calculation, you need to know the distance between the beams, the span width and the load on the structure

The load consists of two values: permanent and temporary. The constant includes the mass of the beams themselves (so far preliminary), insulation, ceiling filing, rough and clean floor. A temporary load is a mass of people and furniture. By regulatory documents for residential premises, it is taken equal to 150 kg / m2. For the attic, you can take less, but it is recommended - the same. This will not only provide a certain margin of safety, but will also make it possible in the future to convert your attic into an attic without reconstructing the load-bearing elements.

The beam frame should be calculated according to the following formulas:

• Mmax = (q*l2)/8;
• Wreq = Мmax/130.

In these formulas, q is the load per sq. m of overlap, which includes a mass of structures and 150 kg useful value. In this case, these values ​​\u200b\u200bmust be multiplied by the distance between the beams. This is due to the fact that the calculations require loading on running meter, and initially the value is calculated per square. l2 - the distance between the bearing walls on which the run rests, taken in a square.

Knowing Wreq, you can choose the overlap section. W = b*h2/6. Knowing W, one can easily write an equation with one unknown. Here it is enough to specify one geometric characteristic b (width of the section) or h (its height).

Most often, a wooden beam already has a known width. It is more convenient to make it from a board 50 or 100 mm wide. You can also consider the option with a composite section. It is made from several boards 50 mm thick.

Calculation in this case find the required height of the element. But there are cases when you need to fit into a certain floor pie so as not to reduce the height of the premises. In this case, as a known value, the height of the section is added to the equation, and the width is found. But the lower the height, the more uneconomical the floor frame will be.

To tighten two or three boards together, it is convenient to use metal studs. In this case, when tightening the nuts, wider washers must be used. They prevent the metal from being pressed into the softer wood. It is imperative to provide insulation between wood and steel fasteners. To do this, you can use a material such as TECHNOELAST brand EPP.

wooden blocks Must be waterproofed prior to installation

Before use wooden elements they are treated with an antiseptic composition. This is necessary to prevent mold and decay. It is also recommended to perform treatment with flame retardants, which will increase fire safety. When the runs are supported on a brick or concrete wall, their ends are wrapped with technoelast, linocrom, hydroisol or roofing material.