Floor plan for wooden beams drawing. How to make a wooden floor between floors with your own hands

Wooden floors (Fig. 1) in most cases consist of load-bearing beams, a floor, inter-girder filling and a finishing layer of the ceiling. Sound or heat insulation is provided by a flooring, which is called a roll-up.

Beams are most often rectangular wooden beams. For rolling, it is advisable to use wooden shields. In order to save wood, plank rolls can be replaced by rolls of ribbed or hollow gypsum or lightweight concrete blocks. Such elements are somewhat heavier than wooden rolls, but they are non-flammable and do not rot.
To ensure better sound insulation from airborne sound transmission along the roll, a clay-sand grease with a thickness of 20-30 mm is made, on top of which slag or dry calcined sand 6-8 cm thick is poured. The filling of a porous material absorbs part of the sound waves.
The structure of a wooden floor includes a flooring of planed grooved boards, fastened with nails to logs, from plates or boards, which are laid across the beams every 500-700 mm.

Wooden floor beams

The load-bearing elements of the beams are wooden beams of rectangular cross-section 140-240 mm high and 50-160 mm thick, laid in 0.6; 0.8; 1 m. The cross-section of wooden floor beams depends on the load, filing (rolling) with backfill, and the plank floor laid along the logs as directly along the logs (Table 1.).

Table 1. Minimum cross-section of wooden floor beams of rectangular cross-section

The use of hardwoods as floor beams is not permissible, as they do not work well for bending. Therefore, as a material for the manufacture of wooden floor beams, conifers are used, cleaned of bark and antiseptic without fail. Most often, the ends of the beams are inserted into the nests specially left for this purpose in the brick walls directly during the masonry process ( rice. 2 a. or fig. 2 b.), or cut into the upper crown of log, cobbled and frame-shield walls.

The length of the supporting ends of the beam should be at least 15 cm. The beams are laid in a "beacon" way - first, the extreme beams are installed, and then the intermediate beams. The correct position of the extreme beams is checked with a level or spirit level, and the intermediate ones - with a rail and a template. The beams are leveled by placing tarred scraps of boards of different thicknesses under their ends. It is not recommended to add chips or hang up the ends of the beams.
As a rule, wooden floor beams are laid along a short span section, if possible parallel to each other and with the same distance between them. The ends of the beams, resting on the outer walls, are cut obliquely at an angle of 60 degrees, antiseptic, fired or wrapped in two layers of roofing tar paper or roofing material. When embedding wooden beams in the nests of brick walls, we recommend that the ends of the beams be treated with bitumen and dried to reduce the likelihood of moisture decay. The ends of the beams must be left open. When sealing wooden floor beams, space niches are filled around the beam with an effective insulation (mineral wool, polystyrene). With a brick wall thickness of up to 2 bricks, the gaps between the ends of the beams and the brick wall are poured with cement mortar. You can also, as an option, insulate the ends of the beams with wooden boxes, having previously resinified them. In thick walls (2.5 bricks or more), the ends of the beams are not covered, leaving ventilation openings. This protects the ends of the beams from moisture condensation. The diffusion of moisture in a wooden beam is shown in Fig. 3.

When the beams are supported on the inner walls, two layers of roofing roofing or roofing material are placed under their ends.
Every third beam embedded in the outer wall is secured with an anchor. Anchors are attached to the beams from the sides or bottom and embedded in the brickwork.
In the absence of a beam of a suitable section, you can use boards knocked together and placed on the edge, while the total cross section, in comparison with the whole beam, should not decrease.

In addition, instead of cobbled beams, you can use logs of the corresponding diameter, hewn from three sides, which is more economical (roundwood is much cheaper than sawn timber), but in this case the logs must be aged in a dry room for at least one year, like a log frame.
To enhance the load-bearing capacity of the floor, a cross-over installation of load-bearing beams can be used. When applying such a scheme, the floor rests on all walls of the building along the contour. The intersections of the beams are pulled together with clamps or wire twists. The cross-overlap scheme is used extremely rarely, since it is much easier to reduce the spacing of the load-bearing beams and make an ordinary overlap, but less lumber is consumed for the manufacture of a cross-overlap than for a traditional one, with the same bearing capacity of the floors.
Structural differences in floors are observed when they are insulated (Fig. 1). The interfloor overlap is not insulated, the attic (with a cold attic) is insulated with the device of the lower vapor barrier layer, and the basement is insulated with the device of the upper vapor barrier layer.

Roll forward

The next step in the construction of floors is the roll-over flooring. To attach it to the beams, cranial bars with a section of 5 x 5 cm are nailed, directly onto which the reel boards are laid. (Figure 4.)

The reel plates are tightly fitted to each other, removing all the gaps between the individual boards. Strive to ensure that the bottom surface of the roll is in the same plane with the floor beams. To do this, you need to select a quarter (rebate) in the roll-up boards. For the construction of a roll, it is not necessary to use full-fledged boards, they can be easily replaced with a slab. A filing made of boards with a thickness of 20-25 mm is fastened with nails driven in at an angle. As we have already noted, instead of rolling boards, you can use fiberboard, gypsum slag and other lightweight concrete slabs, which increases the fire resistance of the floors. The laid roll is covered with a layer of roofing tar paper or roofing material and an insulation material is covered or laid: as in the walls, here you can use mineral wool, sawdust, slag. When insulating floors, bulk heaters are not tamped, but they are backfilled to the heights of the beams. The type of insulation and its thickness are determined from the calculated outside air temperature, using the data in Table 2.

Table 2. Backfill thickness of the attic floor depending on the outside temperature

Lastly, the upper edge of the beams is covered with tar paper or roofing material, and logs are applied on top. Note that the lags are not a required overlap element. Laying logs is economically feasible if the beams are sparsely located.

We also draw your attention to what elements of the floors will be superfluous in the construction of basement and attic floors:
- there is no filing in the basement floor
- there is no log or clean floor in the attic floor

The basement floor can be designed in such a way that the run-up and insulation will be superfluous (of course, without prejudice to the performance), however, in this case, roofing felt over the entire floor area will be required, and the backfill will be gravel or compacted crushed stone (Fig 5.)

Chimney device (chimney)

In places of contact of wooden floors with smoke channels, they arrange cutting (Fig. 6.)

The distance from the edge of the smoke channel to the nearest wooden structure is taken at least 380 mm... Floor openings in the places of passage of chimneys are sheathed with non-combustible materials. In places of overlap in chimneys, they arrange cutting - thickening of the walls of the chimney. Within the groove, the thickness of the walls of the chimney increases to 1 brick, that is, up to 25 cm.But in this case, the floor beams should not touch the brickwork of the pipe and be at least 35 cm from the hot surface.This distance can be reduced to 30 cm by laying between the groove and the beam of felt or asbestos cardboard 3 mm thick soaked in clay solution. The end of the shortened beam, located opposite the groove, is supported on a transom suspended by clamps (Fig. 7.) to two adjacent beams.

Economical overlap

The overlap, consisting of wooden panels with one-sided and double-sided cladding, which takes vertical loads together with the frame of the panels, is considered economical. The cladding can perform its load-bearing function only if it is firmly connected to the edges of the boards of the backboard frame. The ribs and sheathing, which are firmly bonded to each other, have a high load-bearing capacity.

Particleboard and construction plywood proved to be excellent cladding. Boards are also suitable for this, but they, however, due to the large number of identically oriented joints, do not contribute to an increase in the load-bearing capacity of the floor.

Gypsum fiber boards or gypsum plasterboards cannot be considered as additional load-bearing elements. Sheets such as cement particle boards and joinery are also unable to bear the load. In addition, they are much more expensive than chipboard and plywood. In fig. 8 shows several options for the device of floors.

Rice. eight. .

Methods for calculating wooden floors

Previously, builders determined the bearing capacity of floors, guided by their experience. Often this let them down, especially when erecting buildings of complex configuration, which led to the collapse of buildings.
In our time, computer technology has come to the aid of builders, which, together with achievements in the field of materials science, provide high accuracy of calculation. In fig. 9, as an example, the results of calculating the floors shown in Fig. eight .

It can be seen that, despite the smaller thickness of the beams in the frame (by almost 40%), the shields can cover approximately the same spans as wooden beams. The maximum allowable width of the room and the width of the span in our case is about 6 m.

For one- and two-span structures, when the calculated values ​​are exceeded, additional supports are required under the ceiling, which significantly increases the cost of the structure.
For a single-span overlap, where the boards lie on the supports only with the ends of the stiffening ribs, the span width, which is slightly larger than the clear width of the room, should not exceed about 5 m.For a two-span overlap, the permissible span width and, accordingly, the room increases to 6 m.

In many projects offered by various firms, the depth of the house is determined by a two-span overlap. The width between the longitudinal walls of the house usually ranges from 9 ... 12 m, and a load-bearing wall is placed in its middle. When calculating floor structures, first of all, its own weight is determined. In the variant shown in Fig. nine , it is taken equal to 100 kg / sq. m., as it often happens. Additional load (weight of the inhabitants of the house and interior furnishings) take equal to 275 kg / sq.m.... Lightweight partitions installed on the floor are also taken into account without carrying out any static calculations. Such a load could be created, for example, in a situation where an overlap area of ​​20 sq. M. accommodate 73 people at a time. This simple example shows that the regulatory indicators are focused on the unconditional safety of the inhabitants of the house. When calculating wooden structures, a triple safety factor is usually provided, excluding the possibility of their collapse. In other words, a room with a total area of ​​20 sq. just unrealistic. However, this example suggests that the calculated load-bearing capacity of the floor is so high that you can safely put a fireplace, shelves, a tiled stove, a bed with a water mattress, an aquarium and much more on this floor.

Deflection limitation under standard load

However, even under a standard load, the floor bends, which can be felt even when walking on it. To avoid these unpleasant sensations, the deflection of the floor should be no more than 1/300... This means that with a span of 6 m, the ceiling can bend under the standard load (even if it occurs only in exceptional cases) no more than 2 cm.

The overlap, of course, can carry a load no more than that which is allowed by loaded walls, lintels and supports. In this regard, a developer who does not have the appropriate special knowledge, who intends to place heavy structures or objects on the ceiling, should seek advice from a specialist in static calculations of the stability of building structures.
The overlap gives the building additional rigidity. Wind loads acting on the building through the roof, gables and outer walls are transmitted through the ceiling to the entire structure of the building. To compensate for these loads, the upper floor covering is strengthened. When laying individual floor beams, sheathing slabs (usually made of chipboard) are positioned with mutual displacement of the seams and attached to the beams. When using ready-made floor elements, which is customary in the construction of prefabricated houses, they are firmly connected to each other, and at the edges - with a bearing support (walls, partitions).
If the size of the building on any of the facades exceeds 12.5 m, additional load-bearing partitions are required to give it the required rigidity. These walls must again be connected to the floor.

In contrast to the thermal insulation of the intermediate floor, which is of secondary importance, special attention is paid to its sound insulation. Structures with good strength, unfortunately, do not always meet the requirements for noise protection. Prefabricated house designers face a controversial problem: creating statically reliable connections on the one hand and, on the other, “soft” disconnected structures that provide optimal sound insulation.
Beams with rolling and filling with expanded clay or slag (Fig. 10 a, b) no longer meet the requirements either in terms of work technology, or in relation to sound insulation and a number of other problems.

The new standards were forced to include requirements to improve the protection against impact noise, even at the expense of the bearing capacity of structures. In order to jointly solve the problem of soundproofing, specialists from the field of prefabricated house construction and the production of gypsum and insulation boards sat down at the same table. As a result, new designs were created, which were soon included in the standards (Fig. 11).

Rice. eleven. Overlap options according to current standards with attenuation of airborne noise up to 52 ... 65 dB and shock - up to 7 ... 17 dB: 1 - grooved chipboard; 2 - wooden beams; 3 - gypsum plasterboards; 4 - fiber insulation board; 5 - fiber insulation mat or board; 6 - dry sand; 7 - lathing lathing, in which the distance between the rails along the axes is 400 mm and fastening with spring brackets; 7a - wood-based panels; 8 - connections with self-tapping screws or glue; 9 - sound-absorbing floor covering; 10 - logs with a section of 40x60 mm; 11 - gypsum plasterboards with a thickness of 12 - 18 mm or chipboard with a thickness of 10 ... 16 mm; 12 - concrete slabs laid on cold bitumen; 13 - sheathing made of grooved boards.

For the first time, the conversation turned to the use of so-called spring brackets, separating the beams and the lower floor cladding. (fig. 12)

Practice has shown that this innovation has led to a decrease in the noise level by about 14 dB - a result that deserves attention. To improve sound insulation, inside the floors of such a structure, it is necessary to place weighting agents, for example, sand, concrete slabs of various shapes and other materials that reduce the transmission of high-frequency sounds.
The disadvantages of sand filling are the likelihood of sand spilling through the seams and holes into the rooms below. However, this can be prevented, for example, by installing foil or special mats. These mats consist of two films welded together with sand between them.
Cement-based slabs can also be used instead of sand. The disadvantage of these solutions is that such fillers are heavy, which requires more durable beams to the detriment of the efficiency of structures.
It is hardly possible today to make a ceiling with open (that is, not sheathed at the bottom) wooden beams, which would provide reliable protection against noise. Unfortunately, new scientific studies have not yielded positive results. So the question of the perfection of the structures that protect against noise is still pending.

Climatic protection

The wooden structures of the outer wall, flat roof, overlapping of the attic (technical) floor or attic with inclined walls do not need special protection against climatic influences with a working roof. Protection of the interfloor wood is important only in "wet" rooms (as a rule, in the area of ​​showers, bathrooms, laundries and saunas). The ceiling does not need ventilation at all, therefore it should not be taken into account.
For all the non-ventilated floor structures presented in the article, including for open beams, the protection of wood with paint and varnish coatings or other finishes is quite sufficient. Special chemicals are not needed here.

Fire protection of floors

Fire protection standards impose special requirements on building materials and structures. All materials are divided into flammable and non-flammable. Structures made of materials of different properties are distinguished by their ability to hold back fire for some time (semi-fire-resistant) and completely prevent the spread of fire (fire-resistant). These characteristics are recorded in building codes.
In residential construction, in particular, in buildings where the floor of the upper floor is located more than 7 m from the ground level, the structures of the interfloor floors must have at least fire-retardant properties (the duration of fire resistance is at least 30 minutes under experimental conditions). For the manufacture of wooden structures, it is allowed to use solid wood and other wood materials of regular sizes and densities. However, in public buildings, wood is treated with fire-resistant solutions. Naturally, non-combustible materials can also be used, in particular, gypsum fiber and gypsum plasterboards.
Typical examples of slabs made of wood panels with fire insulation are shown in Fig. 12.

When designing floors on open wooden beams (Fig. 13), it is necessary to take into account the fact that these beams are exposed to fire not only from below, but also from the sides.
When determining the parameters of the resistance of structures made of solid wood (for example, coniferous), the rate of its burnout is taken equal to 0.8 mm / min.
When calculating floors on open wooden beams 24 cm high with a span of 5.80 or 5.85 m, the width of the beams is increased to 120 mm or more, so taking into account the fire resistance, they must be chosen with a cross section of 11x24 cm.
Based on the above, we can conclude that there are still enough questions regarding the reliability of sound insulation and fire safety of floors, and in the coming years they will have to be solved by joint efforts of scientists, designers, manufacturers of building materials, designers and builders.

Increasing the bearing capacity of floor beams

The load-bearing capacity of the floor beams can be increased if necessary. Increasing the cross-section of beams by attaching thick planks to them, the ends of which, like beams, must lie on supports - one of the most common ways to solve this problem.

Rice. fourteen. .

You can also use steel U-shaped channels, attaching them to the beam on the side with bolts. The advantage of this method is that it will be enough to open ("bare") the floor beams for fastening only on one side.
But, perhaps, the simplest, however, requiring serious labor costs, will be to strengthen the overlap by laying additional beams (between the existing ones), covering the span from support to support.
In most old houses, the cross-section of the floor beams is sufficient (and even with a margin) and they are laid with a small step, which indicates good construction.
The condition of the beams and floors must be checked in any case. Beams damaged by pests and moisture, and therefore weakened, should be strengthened.
With prolonged exposure to moisture due to leaks in the overhang zone, damage to the heads of the beams on the supports is not excluded. In this case, it is better to remove the damaged part of the beam to healthy wood, and reinforce and lengthen the remaining part with overlays made of thick enough boards that provide the required strength.

The clean floor and filing are elements of the interfloor overlap, but they belong to the category of finishing work. Therefore, we will talk about them in the next article.

Floor beams are the main load-bearing elements of the entire timber floor. The reliability of a wooden floor depends on the correct choice and selection of the size and number of beams. The main dimensions of wooden floor beams are their length and cross-section. You need to determine the length of the beam based on the width of the span that you will need to cover. The dimensions of the cross-section of the floor beams depend on the span length, the distance between the beams to be installed (installation step) and the expected load that will act on the floor beams. The article will tell you how you can independently calculate the number and size of beams.

Determination of the required number and size of floor beams.

The dimensions and number of wooden beams for the floor structure will be determined based on several components. First you need to measure the width of the span that will be covered. Then we determine the method of attaching the floor beams to the walls of the building, that is, how much the beams will go into the walls. After that, you need to calculate the loads that will act on the floor beams when the construction object is put into operation. And the final stage: using tables and special calculator programs, the desired section and step of the floor beams are selected.

Calculation of the length of the floor beams.

The dimensions of the span to be covered and the size of the embedding of the floor beams into the walls determines the length of the beams. The length is measured with a tape measure. The depth of embedment of the beam into the wall in each case should be determined individually, based on the material from which the walls are made. In brick or concrete walls, floor beams are installed in grooves with a depth of about 100 mm if the floor beam is made of plank and to a depth of 150 mm if the beam is made of timber. Special notches are cut in the wooden walls, the depth of which must be at least 70 mm. In the case of fastening floor beams to wooden walls using special metal fasteners, which are used as corners, brackets, clamps, the length of the beams is the same as the distance between the walls. In some cases, roof rafters are mounted on wooden floor beams, and then it is necessary to release the beams beyond the wall by 30-50 cm in order to form the light of the future roof.

Floor beams, depending on what material or wood they are made of, can overlap different sizes of spans. It should be borne in mind that the optimal span is 2.5-4 m. With a length of up to 6 m, a floor beam made of edged board or timber can be used. From 6 to 12 m, it is already necessary to use glued laminated timber floor beams, which can be rectangular or I-beams. In the case of using conventional floor beams, it is necessary to support them on intermediate supports, which are walls or columns. Instead of beams, if the span is more than 6 m, wooden trusses can be used.

To calculate the floor beams, use the online floor beam calculator.

Calculation of the load acting on the floor.

The self-weight load of all floor elements, including floor beams, stitching, inter-girder filling and the weight of the operating load, including the weight of furniture, other objects and devices in the room, the weight of people make up the total load acting on the floor beams on the floor itself. It is quite difficult to calculate this load, it is performed by specialists and is a cumbersome calculation performed by specialists in the process of designing a floor structure. However, using the simplified version below, you can perform these calculations yourself.

Wooden floor for the attic, if things or other materials are not stored in the attic, and the insulation is made of light materials, the constant load consists only of its own weight and is usually 50 kg / m 2.

According to SNiP 2.01.07-85, the operating load in this case will be 90 kg / m 2, including 70 kg / m 2 - the standard value for this type of attic is 1.3 - the safety factor.

Adding 50 kg / m 2 and 90 kg / m 2, we get the total design load for the above attic floor, which will be 140 kg / m 2, and after rounding 150 kg / m 2.

If the attic is planned to be used for storing things, for other purposes, when a large load will act on the floor, or heavy insulation and heavier filler and filler were used in the manufacture, the standard load value will increase to 150 kg / m 2, and, accordingly, the total rounded the load on the attic floor should be taken as 250 kg / m 2 (50 + 150x1.3 = 245 kg / m 2).
When the attic space is used for living as an attic, the total design load, taking into account the weight of floors, partitions, furniture, doors, increases to 300-350 kg / m 2. However, in this case, it is also necessary to take into account the weight of the interfloor wooden floors installed during the construction of the attic, and the temporary load during operation consists of a large number of furniture and people, the total load should be taken as 350 - 400 kg / cm 2.

Determination of the section and pitch of wooden floor beams.

Above, it was discussed how to determine the required length and calculate the total load. After that, you need to determine the required cross-section of the floor beams and the laying step, which are interconnected. A rectangular cross-section of a timber floor joist is best when the height to width ratio is 1.4: 1. Width floor beams in this case, it can be in the range from 40 to 200 mm, and the height from 100 to 300 mm. The height of the beams is chosen the same as the thickness of the insulation. If logs are used as floor beams, their diameter should be in the range from 110 to 300 mm.

The pitch of the wooden floor directly depends on what type and section the material of the floor beam is used and can be from 300 to 1200 mm, but most often the pitch of the wooden floor is chosen in the range from 600 to 1000 mm. When choosing the distance between the floor beams, you can also proceed from the size of the insulation slabs that will be laid in the interbeam space, or the ceiling filing sheets. In frame buildings, it is necessary to strive for the laying step to correspond to the step of the frame racks. Then the greatest reliability of the structure will be ensured due to its rigidity.

Using reference tables, you can fairly accurately do calculation of the dimensions of wooden floor beams or check the dimensions already selected. When carrying out calculations, it must be borne in mind that the relative deflection of attic floors should not exceed 1/200, and between floors - 1/350.

In construction, it is often required not so much to create a fairly strong support for structures, but to fasten the latter and make it more rigid. For this, a beam structure with a section in the shape of the letter "H" is often used. Such products are made of metal, wood and reinforced concrete. Wooden I-beam for floors is used in the construction of basement interfloor attic floors in wooden and brick houses. You can make it yourself.

What is an I-beam

An I-beam is a standard structural element resembling the letter "H" in cross-section. This unusual shape is the result of long engineering experiments aimed at obtaining a support beam that can withstand very high loads, but not as massive and expensive as an all-metal product.

An I-beam is 7 times stronger and 30 times stiffer than a solid square metal profile of the same size. But at the same time, much less metal is required for it. The same applies to timber structures. The photo shows an I-beam.

The optimal shape for a beam is a rectangular section. When laying, the long side is placed vertically, and the short side horizontally, since an increase in height is more important for increasing strength, rather than width. The shape of the I-beam is based on this observation. The wider elements in the lower and upper parts create sufficient support - the width, and the proper height is provided by the middle element, which can be made as thin as possible at a high height.

The production of a wooden I-beam is a rather complicated process, therefore such a product is rarely found on the market. At the same time, in private construction, a wooden I-beam is an excellent alternative to reinforced concrete structures, since it is much easier and easier to install.

Types of wooden I-beams

For the manufacture of an I-beam, a bar is used, and for a partition, OSB or plywood is used. The details of the product are glued together with a special adhesive solution for supporting structures. Depending on the nature of the material used, the following types of products are distinguished:

Besides the material, the custom characteristics of timber I-beams are provided by both dimensions and construction. According to these characteristics, the products are divided into several series:

• BDK series - glued wooden I-beams, used in the construction of short spans;
• BDKU - a reinforced structure for floors, a wider shelf is used here, the beam can withstand higher loads and is used on long spans;
• BDKSH are wooden I-beams of floor and rafter systems with very long spans, in the product the width of the shelf reaches 89 mm, which ensures the ability to withstand very high loads;
• SDKU is a reinforced rack, it is used not for floors, but for the construction of a wall frame;
• SDKSH - a rack with a wider flange, an I-beam structure is used for wall panels.

All options relate to structural materials, that is, they can be used for the construction of load-bearing structures. Most often, they are used in the construction of frame houses, where it is important not to increase the load on the walls and foundation.

Pros and cons of wood I-beams

The main advantage of the product is the combination of low weight with durability. This combination provides the advantages of using I-beams for slabs:

1. The weight of a wooden structure up to 6 m long is only 8 kg. Installation of such a beam does not require special equipment and does not take much time, and this reduces construction costs.
2. The light weight of the resulting slab does not create a large load on the foundation and walls, which also reduces costs.
3. The advantages include ease of transportation. Transportation of a wooden I-beam is much cheaper.
4. With the lightness of the material, it has high strength and is used for overlapping with purlins up to 6 to 12 m. There is no need to use intermediate elements.
5. The design of the I-beam allows you to use a wooden beam as a kind of niche when laying communications.
6. Wood has a low thermal conductivity, which excludes the creation of cold bridges and saves on heating the house.
7. I-beams made of wood retain their geometric shape and properties throughout their entire service life. But only if high-quality material was used for their manufacture.
8. There are wooden I-beams for floors in a very wide range, which allows you to expand the scope.

The disadvantages of the designs are as follows:

• there is a high risk of acquiring low-quality products, undried wood is deformed, "shrinks", which leads to distortions of the floor;
• wood is impregnated with fire retardants, but this does not make the material fire resistant.

Wooden I-beams are not recommended for use in cases where frequent lathing is required or when the frame structure needs to be reinforced with a large number of supporting elements. In this case, the savings in material cost will be negligible.

Characteristics of timber I-beams

The technical characteristics of the I-beam for floors are provided by the material of manufacture and shape. The combination of wood and particle board eliminates wood deficiencies such as shrinkage tendencies, but at the same time provides a strength that exceeds the stiffness and strength of a solid bar of the same size.

The design features of the products are as follows:

1. I-beam partitions are made of plywood. This material is resistant to moisture and temperature influences. In addition, it also provides a constant height of the beam, since in the manufacture of plywood its components are glued so that the fibers are perpendicular to each other. The baffle thickness varies from 24 to 27 mm.
2. The beam shelves are made of wood treated with antiseptic impregnations. This guarantees resistance to decay and fungi.
3. The partition is installed in the grooves made in the shelves. This fastening provides the mechanical strength of the base.
4. All parts are glued with water-resistant and heat-resistant glue. Timber I-beams are very durable as they are insensitive to high humidity or heat.
5. The finished timber beam is treated with a water-repellent paint to increase its resistance to water.

Important! The load capacity is determined by the thickness of the partition and the width of the shelf. This information is given in the description of the I-beam for slabs.

Dimensions of timber I-beams

The dimensions and weight of a wooden I-beam are regulated by GOST 30244-94 and 8486-86E, as well as some SNiP standards. The standardized indicators include the height of the product, the thickness and width of the shelf and the thickness of the partition;

• the height of the wooden I-beam varies from 117.6 to 1013 mm;
• the width of the shelf is in the range of 64-320 mm;
• wall thickness varies from 3.8 to 19.5 mm;
• the weight of the product ranges from 8.7 to 314.5 kg.

Important! According to GOST standards, when making an I-beam for overlap, you can use coniferous boards of at least 2 grade.

Calculation of the load on wooden I-beams

Determining the cross-section of an I-beam for a floor is approximately unacceptable. It is recommended to contact a specialist for calculations. You should not rely on ready-made documentation: it includes many corrections and updates that are not always available in the public domain.

It is allowed to calculate the dimensions yourself only when it comes to, for example, a wooden I-beam for formwork or overlapping a utility room, and a small area. In these cases, there is little risk of collapse and deformation.

• if we are talking about a non-residential attic, then the constant load is determined within 50 kg / sq. m, and operational - within 90 kg / sq., hence the total floor load is about 130 kg / sq. m, and taking into account the necessary margin of safety, it is increased to 150 kg / sq. m;
• if the attic will be often used, for example, as a workshop, then the operating load of the ceiling increases to 195 kg / sq. m, and the total reaches 245 kg / sq. m, taking into account the safety factor - up to 250 kg / sq. m;
• if the attic is converted into an attic, this implies a greater weight of the floor and partitions due to finishing, in addition, furniture appears in the living room, respectively, the total load increases to 300 kg / sq. m;
• if we are talking about an interfloor overlap, the load for it is considered the maximum - at least 420 kg / sq. m.

Then you should determine the length of the beam for the floor and the required frequency of location. As a rule, for an interfloor overlap or attic, the indicator is 50 cm.

Important! This definition is approximate, since the table does not take into account the characteristics of a particular building and the materials used.

How to make an I-beam with your own hands

Do-it-yourself wooden I-beams. Materials for production are quite affordable: softwood beams, plywood or OSB board with a thickness of 24-27 mm, as well as casein or polyurethane glue. From the tools you will need a circular saw, measuring tools, clamps and a channel. Ideally, a hydraulic press should be used, but if not, then the channel will replace it.

1. A dry timber is chosen, treated with an antiseptic. Mark the grooves with maximum accuracy.
   
   
2. A recess is made by marking with a saw or even on a milling machine. The width and depth of the groove is about 10%. The groove must be exactly on the center line.
   
   
3. Before assembling a wooden I-beam with your own hands from the boards, the edges of the slab or plywood are trimmed in order to ensure the most tight connection. The groove is coated with the selected glue. Then a partition is inserted into it and pressing is performed on a hydraulic press. Instead of the latter, you can use clamps and a channel. The product is held under a press until the glue is completely dry.
   
   

Important! The slightest distortions should be avoided. If the partition is not perfectly vertical, the strength properties of the I-beam will noticeably deteriorate.

Installation of an I-beam

Before installation, the product is treated with fire retardants and antiseptic. To install an I-beam in the ceilings of ancillary buildings, you do not need to have special skill. If it is planned to construct a wooden building of several floors, it is better to contact a specialist.

Installation of I-beams has some features:

• to insert the beam into the wall, holes need to be made in it - they are cut down in wooden or log walls, special niches for them are formed in brick or concrete walls during masonry;
• niches are lined with roofing material to provide waterproofing, when laying in a nest, the beam is coated with any water-repellent compound - bituminous mastic, for example;
• the supporting ends of the beams for floors must be at least 150 mm, this must be taken into account when calculating the length of the product;
• installation begins from the edge of one wall, only then the intermediate I-beams are fixed;
• it is important to achieve a horizontal surface for leveling I-beams; it is allowed to use wooden dies, which are placed in niches during installation;
• every third I-beam is fixed with anchors or spacers;
• free space in niches is insulated with mineral wool or filled with cement.

Ceiling beams after the construction of the roof are hemmed with plasterboard, clapboard, boards. The shape of the I-beam is very convenient for attaching insulation.

In order for an I-beam made of wood to perform its tasks with its own hands and serve for a long time, you need to follow the following recommendations:

• when making with your own hands, you cannot replace plywood or OSB with a board, this reduces its strength and increases the risk of deformation;
• before assembly, the material must be dried, the moisture content should not exceed 12%;
• when working inside the house, it is worth using water-based glue;
• if high humidity is expected in the room, the floor beams are left open;
• store products under a canopy or in a closed warehouse; it is impossible to leave wooden I-beams in the open, as wood absorbs moisture.

Small section I-beams are made at home. When erecting long floors, industrial products are required.

Conclusion

Wooden I-beam for slabs is a great alternative to a metal product. This option is much easier and easier to install, therefore it is often used in the construction of light frame buildings. In addition, small cross-section I-beams can be made by hand.

Before building a solid and reliable wooden floor, a number of calculations must be performed in order to determine the parameters of the structure. The main purpose of the calculation is to calculate the optimal ratio of the size of the cross-section of the beams and the distance between them in the floor structure.

Determination of the main parameters

The length is determined depending on the parameters of the building. It is equal to the width of the span to be covered. In turn, to calculate the section, the length of the span, the distance between the beams and the amount of load exerted on them are taken into account.

Before performing the calculations, the initial parameters of the structure are measured. You should also think about the design features in advance: the depth of immersion of the elements into the walls and the method of their fastening.

Length of timber beams

The width of the span is taken as the length of the beams of the wooden floor, which will overlap, taking into account the margin for deepening into the walls for fastening. The depth of immersion in the walls is determined taking into account the materials used to build the house and the type of lumber used to make the beams. For brick or block walls, the embedding depth of the elements will be 10 cm if a board is used and 15 cm if a timber is used. For the manufacture of floors in a wooden house, beams are installed in notches in the walls to a depth of at least 7 cm.

If special auxiliary fasteners (brackets, clamps, corners) are used to secure the beams, then the size of the span to be covered can be taken as the length of the beams. In this case, it is sufficient to measure the distance between the opposite walls on which the beams will be installed.

In some structures, the beams extend from the walls to the outside to form the roof slope. In this case, the legs of the roof truss system are attached directly to the floor beams. The outward release should be 30-50 cm.

The optimal span size suitable for overlapping with wooden beams is from 2.5 to 4 m.The maximum permissible span length, covered by an unedged board or timber, is 6 m. ... I-beams or rectangular beams can be made of it. It is possible to use a board or a regular beam only if intermediate supports are installed on which the beams will rest. Columns or internal walls can be installed as intermediate supports.

Floor load calculation

A wooden floor is loaded with its own weight, an operational load, which includes the weight of furniture, floor, household items and people walking on the floor. The operational load directly depends on the type of floor, which determines the characteristics of the load exerted on it.

As a rule, the calculation of the load on the floors is carried out at the design stage by specialists, but it can be done independently. First of all, the weight of the materials from which the floor is made is taken into account. For example, an attic floor insulated with a light material (for example, mineral wool), with a light filing, can withstand its own weight within the range of 50 kg / m². The service load is determined in accordance with the regulations. For an attic floor made of wooden basic materials and with light insulation and filing, the operating load in accordance with SNiP 2.01.07-85 is calculated in this way: 70 * 1.3 = 90 kg / m². 70 kg / m² in this calculation is the load in accordance with the standards, and 1.3 is the safety factor.

The total load is calculated by adding: 50 + 90 = 140 kg / m². For reliability, it is recommended to round up the figure slightly. In this case, the total load can be taken as 150 kg / m².

Image 1. Table for determining the minimum allowable section with a step of 0.5 m.

If the attic is planned to be used intensively, then it is required to increase the standard load value up to 150 in the calculation. In this case, the calculation will look like this: 50 + 150 * 1.3 = 245 kg / m². Rounding up - 250 kg / m². You should also carry out the calculation in this way if heavier materials are used: insulation, filing to fill the interbeam space.

If the attic will be equipped with an attic, then it is necessary to take into account the weight of the floor and furniture. In this case, the total load can be up to 400 kg / m².

Distance between beams and their section

After measuring the length (L) of the span and wooden beams, respectively, you can proceed to the main part of the calculations and calculate the pitch of the beams and their section (or diameter for round elements). These two quantities are interconnected, so the calculations for their determination are performed by the same mathematical operations.

The optimal sectional shape is considered to be rectangular.

Image 2. Table for determining the minimum allowable section at a step of 1 m.

In this case, the sides of the rectangle must relate to each other in a ratio of 1: 4: 1. The height must be greater than the width. The choice of the height of the elements often depends on the thickness of the insulation used. The height and width of rectangular elements can be in the range of 10-30 cm and 4-20 cm, respectively. If the overlap is made of logs, then the size of their diameter should fit into the interval of 11-30 cm.

The spacing between the elements can be 30 cm minimum and 1.2 m maximum. For the convenience of its installation, when calculating, they try to adjust the width of the sheets of the filing or insulation plates. If a frame building is cocked, then it is recommended to take a step equal to the distance between the frame posts.

To determine the minimum allowable section at a step of 0.5 m and 1 m, you can use the tables (images 1, 2).

Thus, the calculation and execution of the floor on wooden beams is a responsible task, on the effective solution of which the reliability of the whole house directly depends. These calculations are carried out in accordance with the existing approved regulations. In case of disputes or some doubts about the accuracy, it is always necessary to round up the obtained values.

This will avoid catastrophic consequences for the home. If home owners doubt their ability to calculate all the required values, then they need to seek professional help.

One of the most popular solutions for the construction of interfloor floors in private houses is the use of a supporting structure made of wooden beams. It must withstand the design loads without bending and, moreover, not collapsing. Before proceeding with the construction of the floor, we recommend using our online calculator and calculating the main parameters of the beam structure.