When building any house, special attention should be paid to the overlap of beams. The floor structure can consist of slabs and beams, which can be wooden, concrete or metal. The most important thing to consider is the method of supporting such supports on brick wall, since construction brick houses considered the most common. Supporting the beam on the beams and the wall in the designed building will be the most important element, since it is he who will determine the reliability of the structure and the safety of its operation.

What are the beams used for?

They are not only a support for flooring and interfloor passages, but also help to fasten all the parts of the structure together, giving them the necessary strength and reliability. In the manufacture of beams, a large number of different floors are used. But the main and most common types of load-bearing elements include metal, wood and reinforced concrete.

Wooden beams and its distinctive features

Beams for supporting beams and walls made of wood must comply with basic building codes, namely, be strong, rigid, and also comply with the rules fire safety. The calculation of such an element is carried out depending on the material used in construction.

The beam is an important part of any floor. Its main function is to separate the floors of the house, as well as to evenly distribute the load on the upper walls, roof of the house, communications, and furniture in the room.

The main advantages of support wooden beams:

• minimum labor intensity when installing the installation (when compared with metal and reinforced concrete structures);
• affordable cost of wood;
• opportunity self-installation without the use of expensive machinery and other construction equipment;
• attractive appearance;
• light weight;
• the possibility of replacing or restoring them.

Disadvantages of wooden structures

The main disadvantages of such bars include:

• high degree of ignition (to prevent sudden fire, the material must be treated with a special protective impregnation);
• compared to metal and reinforced concrete analogues, this structure is fragile;
• on wooden material the active spread of fungus and living organisms may begin, moisture can easily penetrate into it;
• wood is subject to deformation under conditions of regular temperature changes in the room.

What types of wooden floors are there?

Wooden ones can be divided according to their type of section, size and material used for their manufacture. Its length will directly depend on the distance between adjacent walls. To this value an additional 200-250 mm is added on each side.

All designs can be divided into the following types:

• rectangular;
• I-beam;
• square;
• oval or round.

The square section of the beam is considered optimal, since it is this that helps to achieve the most uniform distribution of the load throughout the structure. Builders also recommend choosing wooden floors with a rectangular cross-section. When mounting, their short side is placed horizontally, and the long side is placed vertically (for good strength it is important to increase the height of the structure).

Floor material and features

The overlap is the connection between the beam and the load-bearing structure. construction wall, which can be an attic, mansard or interfloor. Structurally, they are divided into two types: prefabricated (transverse flooring and longitudinal beam), and monolithic (supported on a slab).

When designing private structures, greater preference is given to floors with wooden beams. This design is considered quite durable and is well suited for the residential sector. Optimal size the support, depending on the purpose of its use and the applied loads, will vary:

• height - from 150 to 300 millimeters;
• width - from 100 to 250 millimeters.

In order to increase their service life, the supports are impregnated with a specialized antiseptic and also oiled.

In more complex structures, they resort to support on metal beams. For this construction companies create special strong steel supports. According to safety standards, when using beams of this type, their ends must rest on the brickwork through specialized distribution cushions.

Monolithic floors are created from reinforced concrete slabs. For this purpose, it is customary to use factory-made slabs made of reinforcement and concrete mass. In order to reduce the load on the finished structure, they are created hollow.

How is the beam sealed?

The reliability and quality of the ceiling will be largely determined by the method of embedding the beam into the wall. The sealing will determine the type of support on the brick wall - this stage of mounting the structure is the main one.

A wooden beam is mounted in the free space created in brickwork, up to 15 centimeters deep. The end ends are pre-treated: one end is beveled at an angle of 60 degrees, treated with a special antiseptic and resin, and wrapped with roofing felt or roofing felt. The processed ends of the beam are carefully installed in the brick wall with a gap of 3-5 centimeters from the rear wall of the niche. The resulting gap is filled with felt or mineral wool. Transverse edges are carefully sealed concrete mixture, bitumen or covered with roofing felt.

Leaning on a brick wall

When supporting a beam on a brick wall, it is important to pay special attention to the thickness of the structure. If the brick is more than 600 millimeters, the sealing method will be slightly different. This space in the masonry is created so that there is a free space of at least 10 centimeters between the end of the beam and the rear wall of the niche. The resulting gap helps to place thermal insulation material into it and allows you to create a special air gap.

The lower part of the gap is sealed with concrete, roofing felt or roofing felt in several layers. Using this technology, it is possible to create a laying cushion, which, in addition, additionally levels the surface of the masonry. The sides of the resulting recess are treated with roofing felt.

When creating a floor supported on a wall up to 500 millimeters thick (two bricks), the sealing method should be slightly different from the previous one. A wooden box with several walls is placed in the free space (its depth is no more than 250 millimeters). A tarred layer of felt is laid between the back wall of the niche and the box. The walls are carefully treated with an anti-flammable compound and resin.

At the bottom, the recess should be sealed with two layers of roofing felt or roofing felt. The side walls of the nest must be insulated with felt. The box is built into the free space so that it is pressed tightly against the felt. The floor beam is installed on the bottom of the box to a length of 15 centimeters.

If the wall thickness is less than the specified mark, then it is important to pay special attention to the total wall thickness that remains after creating a free compartment. If it is less than 50 millimeters, there is a risk of free passage of cold air into the room. If there is such a problem, it is important to consider additional insulation of the area where the beams are supported on the beams and the wall.

Mounting the beam

The installation of a support when creating a floor will directly depend on the further purposes of using the structure, the area and the load on it. More often wooden beam install along load-bearing walls at a distance from 600 to 1500 mm.

The sealing starts from the edges and then moves along the entire length of the wall. Builders recommend leaving at least 5 centimeters of free space between the outer beams and the wall itself.

Another quite important condition when supporting beams on a beam and a wall is to take into account the horizontal fastening of the support. In addition, all beams should be evenly positioned in relation to the floor. Deviation from horizontality and uneven level will lead to additional loads on the supporting area of ​​the brick wall, especially after installing additional cross beams.

Leaning on a column

It can be hinged or rigid. Builders advise doing it from above and transferring the main load to the center of the column profile. When the structure is fastened sideways, in addition to the compressive load, a moment from the action of this force additionally appears in the column. This provokes a significant increase in the load from the column.

When supporting a metal beam on a column from above, it is best to transfer the load to the rib. The rib size will be determined using the following formula: F/Ap is greater than or equal to RpYc.

• F in the presented formula is ground reaction beams;
• Ap - area of ​​bearing rib collapse;
• Rp is the design resistance of steel to end surface crushing.

In order for the entire load to transfer to the column through the rib, the rib protrusion should be maintained, as a rule, by 1.5-2 centimeters. Before installation, it is important to carefully plan the rib, which will help distribute the entire load evenly over its area.

Since the support unit for the floor beams is of a hinged type, only a few bolts on one side are sufficient for fastening. The diameter of the bolts is from 16 to 20 millimeters. They should not be tightened too much. The thickness of the support, as a rule, reaches 0-25 mm, the thickness of the rib - 8-12 mm.

If the structure has a roof angle, then the rib should be planed at the required angle and washers with a bevel should be used to mount the bolt.

Beam support standards

IN regulatory documents The minimum length for supporting a beam on a beam and a brick wall has been established - it reaches 9 centimeters. This value was determined by design engineers as a result of lengthy calculations and checks. The following factors influence the minimum support of a beam:

• span size and support length;
• the volume of load falling on the beam used;
• type of load - dynamic or static;
• the thickness of the brick wall on which the support rests;
• type of structure - private residential, industrial, etc.

It is important to take into account all the described factors when making calculations. The end of the beam should overlap the wall so that the resulting overlap does not exceed 12 centimeters.

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

Beams are most often wooden beams of rectangular cross-section. For roll-ups, it is advisable to use wooden shields. In order to save wood, plank beads can be replaced with beads made of ribbed or hollow gypsum or lightweight concrete blocks. Such elements are somewhat heavier than wooden planks, but they are non-flammable and do not rot.
To ensure better sound insulation from airborne sound transfer along the roll, a clay-sand lubricant 20-30 mm thick is made, on top of which slag or dry calcined sand 6-8 cm thick is poured. A backfill made of porous material absorbs part of the sound waves.
The wooden floor structure includes a flooring made of planed tongue-and-groove boards, nailed to the joists, plates or boards, which are laid across the beams at intervals of 500-700 mm.

Wooden floor beams

The load-bearing elements of beam floors are wooden beams of rectangular section with a height of 140-240 mm and a thickness of 50-160 mm, laid at intervals of 0.6; 0.8; 1 m. The cross-section of wooden floor beams depends on the load, the hemming (rolling) with backfill, and the plank floor laid over the joists as directly over the joists (Table 1.).

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

Width span, m	Distance between beams, m
	0,5				1
	1,5 (150)	2,5 (250)	3,5 (350)	4,5 (450)	1,5 (150)	2,5 (250)	3,5 (350)
2,0	5 x 8	5 x 10	5 x 11	5 x 12 (10 x 10)	10 x 10	10 x 10	10 x 11
2,5	5 x 10	5 x 12 (10 x 10)	5 x 13 (10 x 11)	5 x 15 (10 x 12)	10 x 10	10 x 12	10 x 13
3,0	5 x 12 (10 x 10)	5 x 14 (10 x 11)	5 x 16 (10 x 13)	5 x 18 (10 x 14)	10 x 12	10 x 14	10 x 15
3,5	5 x 14 (10 x 11)	5 x 16 (10 x 13)	5 x 18 (10 x 15)	10 x 16	10 x 14	10 x 16	10 x 18 (15 x 16)
4,0	5 x 16 (10 x 13)	5 x 18 (10 x 15)	10 x 17 (15 x 15)	10 x 18 (15 x 16)	10 x 16	10 x 19	10 x 21 (15 x 19)
4,5	5 x 18 (10 x 14)	10 x 17 (15 x 15)	10 x 19 (15 x 17)	10 x 20 (15 x 18)	10 x 18	10 x 21	10 x 23 (15 x 21)
5,0	10 x 16	10 x 19 (15 x 16)	10 x 21 (15 x 18)	10 x 23 (15 x 20)	10 x 20	10 x 23	10 x 26 (15 x 23)

The use of hardwood as floor beams is not permissible, as they do not bend well. Therefore, coniferous wood, cleared of bark and antiseptic, is used as a material for the manufacture of wooden floor beams. Most often, the ends of the beams are inserted into sockets specially left for this purpose in brick walls directly during the laying process ( rice. 2 a. or rice 2 b.

), or are cut into the upper crown of log, cobblestone and frame-panel walls.
The length of the supporting ends of the beam must be at least 15 cm. The beams are laid using the “beacon” method - first the outer beams are installed, and then the intermediate ones. The correct position of the outer beams is checked with a level or spirit level, and the intermediate beams with a lath and a template. The beams are leveled by placing tarred scraps of boards of different thicknesses under their ends. It is not recommended to place wood chips or trim the ends of beams. Wooden floor beams are usually laid along a short section of the span, as parallel to each other as possible 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, burned or wrapped in two layers of roofing felt or roofing felt. When embedding wooden beams into nests of brick walls, we recommend treating the ends of the beams with bitumen and drying them to reduce the likelihood of rotting from moisture. The ends of the beams must be left open. Spatial niches when sealing wooden floor beams are filled around the beam with effective insulation ( mineral wool , Styrofoam). When the thickness of brick walls is up to 2 bricks, the gaps between the ends of the beams and the brick wall are filled cement mortar

. You can also, as an option, insulate the ends of the beams with wooden boxes, having previously tarred them. In thick walls (2.5 bricks or more), the ends of the beams are not covered, leaving ventilation holes. This protects the ends of the beams from moisture condensation. The diffusion of moisture in a wooden beam is shown in Fig. 3. When supporting beams on interior walls
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.
If there is no timber of a suitable cross-section, you can use boards knocked together and placed on edge, and the total cross-section, compared to the whole beam, should not decrease.

In addition, instead of block beams, you can use logs of the appropriate diameter, hewn on three sides, which is more economical ( round wood much cheaper than lumber), but in this case the logs must be kept in a dry room for at least one year, like a log house.
To enhance the load-bearing capacity of the floor, a cross pattern for installing load-bearing beams can be used. When using this scheme, the ceiling rests on all the walls of the building along the contour. The intersection nodes of the beams are tightened with clamps or twisted wires. The cross floor scheme is used extremely rarely, since it is much easier to reduce the pitch of the load-bearing beams and make an ordinary floor, but the production of a cross floor requires less lumber than a traditional one, with the same load-bearing capacity of the floors.
Structural differences in floors are observed when they are insulated (Fig. 1.). The interfloor ceiling is not insulated, the attic floor (with a cold attic) is insulated with the installation of a lower vapor barrier layer, and the basement floor is insulated with the installation of an upper vapor barrier layer.

Roll up

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

The knurling plates are tightly fitted to each other, eliminating all the gaps between the individual boards. Strive to ensure that the bottom surface of the knurl is in the same plane as the floor beams. To do this, you need to select a quarter (rebate) in the knurling boards. To build a ramp, it is not necessary to use full-fledged boards; they can be replaced with a slab. A lining of boards 20-25 mm thick is secured with nails driven in at an angle. As we have already noted, instead of rolling boards, you can use fiberboard, gypsum slag and others easily concrete plates, which increases the fire resistance of the floors. The laid bevel is covered with a layer of roofing felt or roofing felt and insulation is filled in or laid: as in the walls, mineral wool, sawdust, and slag can be used here. When insulating floors, loose insulation materials are not compacted, but are backfilled to the height of the beams. The type of insulation and its thickness are determined from the calculated outside temperature air, using the data in Table 2.

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

Material	Volumetric weight, kg/m³	Backfill thickness (mm) at outside air temperature, °C
		-15	-20	-25
Wood sawdust	250	50	50	60
Wood shavings	300	60	70	80
Agloporite	800	100	120	140
Boiler slag	1000	130	160	190

Lastly, the upper edge of the beams is covered with roofing felt or roofing felt, and logs are placed on top. Note that lags are not mandatory element ceilings Laying lags is economically justified if the beams have a sparse arrangement.

We also draw your attention to which floor elements will be superfluous when constructing basement and attic floors:
- V basement floor no filing
- there are no joists or clean floor in the attic floor

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

Chimney (chimney) device

In places where the wooden floors come into contact with the smoke ducts, cutting is carried out (Fig. 6.)

The distance from the edge of the smoke duct to the nearest wooden structure is taken to be at least 380 mm. Floor openings where chimneys pass through are sheathed with fireproof materials. In areas of overlap in chimneys, cutting is done - thickening the walls of the pipe. Within the cutting, the thickness of the walls of the chimney increases to 1 brick, that is, up to 25 cm. But even in this case, the floor beams should not touch the brickwork of the chimney 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 3 mm thick felt or asbestos cardboard soaked in a clay solution. The end of the shortened beam, located opposite the groove, is supported by a crossbar suspended on clamps (Fig. 7.) to two adjacent beams.

Economical covering

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

Chipboard and construction plywood performed well as cladding. Boards are also suitable for this, but they, however, large quantity identically oriented seams do not contribute to increasing the load-bearing capacity of the floor.

Gypsum fiber or plasterboard boards cannot be considered as additional load-bearing elements. Sheet materials such as cement particle boards and joinery boards 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 installation of floors.

Rice. 8. .

Methods for calculating wooden floors

Previously, master builders determined the load-bearing capacity of floors based on their experience. This often failed them, especially when constructing buildings with complex configurations, which led to the collapse of buildings.
Nowadays, computer technology has come to the aid of builders, providing, together with advances in the field of materials science, high calculation accuracy. In Fig. 9, as an example, gives the results of calculating the floors shown in Fig. 8 .

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

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

In many projects offered by various companies, the depth of the house is determined by a two-span floor. 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, their own weight is determined first of all. In the version shown in Fig. 9 , it is taken equal to 100 kg/sq.m., as most often happens. Additional load (weight of the inhabitants of the house and interior furnishings) taken equal to 275 kg/sq.m.. Light partitions installed on the ceiling without any static calculations are also taken into account. Such a load could be created, for example, in a situation where on a floor area of ​​20 sq.m. accommodate 73 people at a time. On this simple example it is clear that the regulatory indicators are focused on the unconditional safety of the inhabitants of the house. When calculating wooden structures usually provide a triple safety margin, eliminating the likelihood of their collapse. In other words, in a room with a total area of ​​20 sq.m., that is, dimensions 5.90 x 3.40 m (see the permissible width of the floor span indicated in Fig. 9), 220 people could be accommodated, which, of course, simply unrealistic. However, this example suggests that the calculated load-bearing capacity of the floor is so high that on this floor you can safely install a fireplace, shelves, a tiled stove, a bed with a water mattress, an aquarium and much more.

Limitation of deflection under standard load

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

The ceiling, naturally, can bear a load no more than that allowed by loaded walls, lintels and supports. In this regard, a developer who does not have the appropriate special knowledge and 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 ceiling gives the building additional rigidity. Wind loads acting on the building through the roof, gables and external walls are transmitted through the ceiling to the entire building structure. To compensate for these loads, the upper cladding of the floor is strengthened. When laying individual floor beams, sheathing slabs (usually made of chipboard) are placed with mutually offset seams and attached to the beams. When using ready-made floor elements, which is common in the construction of prefabricated houses, they are firmly connected to each other, and at the edges - to the load-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 ceiling.

Unlike the thermal insulation of the interfloor ceiling, which is of secondary importance, its sound insulation is given special attention. Structures with good strength, unfortunately, do not always meet the requirements for noise protection. Designers working in the construction of prefabricated houses have to solve a contradictory problem: creating statically reliable connections on the one hand, and on the other, “soft” disconnected structures that provide optimal sound insulation.
Beams rolled up and filled with expanded clay or slag (Fig. 10 a, b) no longer meet the requirements either from the point of view of work technology or in terms of sound insulation and a number of other problems.

The new standards were forced to include requirements to improve protection against impact noise, even to the detriment of the load-bearing capacity of structures. To jointly solve the problem of sound insulation, experts from the field of construction of prefabricated houses and the production of gypsum and insulating boards sat down at one table. As a result, new designs were created, which were soon included in the standards (Fig. 11).

Rice. eleven. Flooring options according to current standards with attenuation of airborne noise up to 52...65 dB and shock noise - up to 7...17 dB: 1 - tongue-and-groove chipboards; 2 - wooden beams; 3 - plasterboards; 4 - fiber insulating board; 5 - fibrous insulating mat or board; 6 - dry sand; 7 - slatted sheathing, in which the distance between the slats along the axes is 400 mm and fastened with spring brackets; 7a - wood boards; 8 - connections with screws or glue; 9 - sound-absorbing floor covering; 10 - logs with a section of 40x60 mm; 11 - plasterboard boards 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 tongue-and-groove boards.

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

Practice has shown that this innovation has led to a reduction in noise levels by approximately 14 dB - a result that deserves attention. To improve sound insulation, weighting agents, such as sand, concrete slabs of various shapes and other materials that reduce the transmission of high-frequency sounds, must be placed inside ceilings of this design.
The disadvantages of filling with sand are the likelihood of it spilling through seams and holes into the rooms below. But this can be prevented, for example, by laying film or special mats. These mats consist of two films welded together, with sand between them.
Instead of sand, you can also use slabs based on a cement binder. The disadvantage of these solutions is that such fillers are heavy, which requires stronger beams to the detriment of the efficiency of structures.
Make a floor with open (that is, not sheathed underneath) wooden beams that would provide reliable protection from noise is hardly possible today. Unfortunately, new scientific studies have not yielded positive results. So the question of the perfection of noise-protecting structures is awaiting its solution.

Climate protection

In special protection from climatic influences, wooden structures of the external wall, flat roof, there is no need to cover the attic (technical) floor or attic with sloping walls if the roof is in good working order. Protection of interfloor wood is important only in “wet” rooms (as a rule, in the shower area, bathrooms, laundries and baths). The ceiling does not need ventilation at all, so it should not be taken into account.
For all non-ventilated floor structures presented in the article, including open beams, wood protection is quite sufficient paint coatings or other finishing. Special chemicals not needed here.

Fire protection for floors

Fire protection standards impose special requirements on building materials and structures. All materials are divided into flammable and non-flammable. Structures made from materials with different properties are distinguished between those that can hold fire for some time (semi-fire-resistant) and those that 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 interfloor structures must have at least fire-retardant properties (fire resistance duration is at least 30 minutes per experimental conditions). For the manufacture of wooden structures it is allowed to use solid wood and others wood materials normal sizes and density. However, in public buildings The wood is treated with solutions that make it fire resistant. Naturally, non-combustible materials can also be used, in particular, gypsum fiber and plasterboard boards.
Typical examples of floors made of wooden panels with fire insulation are shown in Fig. 12.

When designing floors on open wooden beams (Fig. 13), it is also 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 durability parameters of structures made of solid wood (for example, coniferous), its burnout rate is taken to be 0.8 mm/min.
When calculating floors using open wooden beams 24 cm high with a span width of 5.80 or 5.85 m, the width of the beams is increased to 120 mm or more, so taking into account 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 resolved through the joint efforts of scientists, designers, and manufacturers building materials, designers and builders.

Increasing the load-bearing capacity of floor beams

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

Rice. 14. .

You can also use U-shaped steel channels, attaching them to the side of the beam with bolts. The advantage of this method is that the floor beams will only need to be opened (“exposed”) for fastening on only one side.
But perhaps the simplest, but requiring serious labor costs, would be to strengthen the floor by laying additional beams (between existing ones) spanning 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 in small increments, which indicates good construction.
The condition of the beams and ceilings 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 area, damage to the ends of the beams on the supports is possible. In this case, it is better to remove the damaged part of the beam to healthy wood, and strengthen and lengthen the remaining part with overlays made of sufficiently thick boards that provide the required strength.

The clean floor and lining are elements of the interfloor covering, but belong to the category finishing works. Therefore, we will talk about them in the next article.

6.2.1 The floor frame consists of purlins (main beams), floor beams (secondary beams), frame beams (beams built into load-bearing walls and located between the wall frame frame frames or on the foundation wall).

Purlins with a two-span design rest at one end on wall frame or foundation wall, others - on a column (in the basement), on a wooden stand or on a load-bearing internal wall. It is possible to use continuous purlins (for two or more spans between supports).

Floor beams rest on purlins (from above or on the side - on cranial bars or shelves) or on internal walls. The outer beams are attached to the strapping beams, through which the load is transferred to the wall frame. When supporting floor beams on internal walls, purlins are not provided.

The rigidity of the beam floor is ensured by filing the ceiling and installing a subfloor from rigid sheet or slab materials, as well as by fastening the beams with rigid connections.

Beams and purlins divide the internal space of the floor into closed cells and act as fireproof diaphragms.

6.2.2 It is envisaged to use beams made of solid lumber and purlins of a composite section made of nailed boards. In ceilings supported by foundation walls, in houses no more than two floors high, they can also be used. steel purlins.

6.2.3 Steel purlins must be made from rolled steel of I-section, corresponding technical requirements GOST 27772.

The minimum cross-sectional dimensions and maximum spans of I-steel purlins must be determined on the basis of calculations. Also, based on calculations, it should be established minimum dimensions sections and maximum spans of beams, the design of which differs from that established in this Code of Practice (for example, beams of a combined I-section with lumber flanges and a fiberboard wall).

6.2.6 Wooden purlins of composite section

6.2.6.1 Wooden purlins of a composite section must be made of individual wooden elements (boards) with a thickness of at least 38 mm, installed on edge and nailed in accordance with. Connections of elements of purlins (individual boards) should not coincide with connections in adjacent elements (arranged “staggered”). In this case, in one section of the run, connections of no more than half of the elements are allowed.

"Figure 6-1 - Composite timber purlins"

6.2.6.2 The end-to-end connection of multi-section purlins must be located above the support. It is allowed to use continuous purlins (for 2 or more spans). Elements of such purlins (individual boards) must be butt-joined at a distance of a quarter of the span from the support + -150 mm in accordance with. Purlin elements connected within a quarter span of one support must be continuous over the adjacent support.

"Figure 6-2 - Joints of boards in continuous purlins of a composite section"

6.2.6.3 Within any span, there should not be more than one butt connection in any element of the purlin of a composite section.

6.2.7 Steel purlins

6.2.7.2 Steel purlins must be pre-primed with anti-corrosion compounds.

6.2.8 Supporting purlins and floor beams

6.2.8.1 When supporting purlins and floor beams on masonry, the supporting platforms under the purlins and beams must be of sufficient size to support the transmitted load. The length of the support area for purlins on masonry or concrete must be at least 89 mm, for floor beams - at least 38 mm. The length of the support area for purlins and beams nailed at the ends to the framing beams on the wooden elements of the wall frame must be at least 38 mm.

6.2.8.2 The ends of the purlins and beams of the lower floor (floor above the basement) must either be embedded in a concrete or stone foundation wall in accordance with, or attached to the lower trim beams installed on a support board laid on the foundation wall (). The second option is provided in cases where the calculation of the wind load leads to the conclusion that it is necessary to anchor the house frame to the foundation. Other options are possible for securing the frame elements of the lower floor to the foundation walls (see examples on).

6.2.8.3 Elements wooden frame Floors resting on concrete or masonry are recommended to be made from lumber treated with antiseptics. It is permissible to use lumber that has not been treated with antiseptics, provided that the requirements for sealing the ends of all purlins and beams, the bottom of which is located above ground level, are observed. In cases where the bottom of purlins and beams made of lumber not treated with antiseptics is at or below ground level, at their ends, embedded in masonry or concrete, unfilled air gaps of at least 10 mm wide should be left, and the supporting surface of the beams and purlins must be separated from concrete or masonry waterproofing material(). In all cases of using lumber that has not been treated with antiseptics, the outer surfaces of concrete or masonry walls must be insulated from moisture penetration.

6.2.8.4 The lower support board with a cross-section of at least 38 x 88 mm must be laid on the foundation wall level per layer mortar or onto a sealing gasket made of sealing material. The support board must be attached to the foundation wall with steel anchor bolts with a diameter of at least 12 mm in accordance with GOST 1759.0. Anchor bolts should be placed with a step determined by calculation, but not more than 2.4 m, fixed to the lower frame frame using nuts and washers and embedded in the foundation to a depth of at least 100 mm ().

6.2.8.5 Beams and purlins of interfloor floors rest on the top frame frames of load-bearing walls. The strapping beams are nailed to their ends so that the outer edge of the strapping beam is in the same plane with the outer side of the wall frame (see example on).

6.2.8.6 The support of floor beams on the purlins can be carried out either on the top of the purlins (), or by attaching them to the side faces of the purlins. The first of these options is used mainly in ceilings above the basement, when the ends of the purlins are embedded in a stone or concrete foundation wall. In this case, the joints of the floor beams are overlapped. For interfloor and attic floors, the second option for supporting beams is preferable.

6.2.8.7 When attaching beams to the side surface of wooden purlins, the description is carried out either on metal corner plates or on wooden support bars nailed to the side surface of the purlins. Options for attaching beams to the side surface of the purlins are indicated on.

6.2.8.8 When attaching wooden beams to steel purlins, they must rest on the bottom flange of the purlin or on a backing block with a cross-section of at least 38 x 38 mm, attached to the wall of the purlin with bolts with a diameter of 6 mm in increments of 600 mm ().

The beams must be connected above the purlin using a connecting bar with a cross-section of at least 38 x 38 mm and a length of at least 600 mm to describe the subfloor above the purlin. A gap of at least 10 mm should be left between this block and the upper surface of the purlin (in case of shrinkage of wooden beams).

6.2.8.9 Floor beams supported by steel purlins must be kept from twisting and warping by driving nails at each end of the beam at an angle, bent behind the flange of the purlin, or by installing a continuous strapping of boards along the bottom of the beams at the supports, or by creating a system of vertical cross braces between beams in accordance with.

6.2.9 Connections between beams

In other cases, either horizontal connections or vertical connections must be installed between the floor beams, or simultaneously horizontal connections at the supports and vertical connections in the span of the beams. Methods for fastening beams are indicated on.

6.2.9.2 Requirements for spans and cross-sectional dimensions of beams for the case when the ceiling lining is not provided are specified in Appendix B, and when the ceiling lining is provided on a wooden sheathing made of boards - in Appendix B. It is compiled taking into account the fact that the sheathing is made of boards with a section no less than 19x89 mm with a pitch of no more than 600 mm (along the axes) or a cross-section of no less than 19x64 mm with a pitch of no more than 400 mm (along the axes), and the filing is made of the materials specified in.

1. have a cross-section of at least 19 x 64 mm and be nailed to the bottom of the beams;
2. be located at a distance of no more than 2100 mm from each beam support and from other rows of ties;
3. nail the ends to the outer beams in a row or to the support boards along the top of the foundation walls.

6.2.9.5 When used simultaneously for fastening horizontal and horizontal beams vertical connections(the most reliable option) this bracing should include connections along , located near the supports, and along, located in the span of the beams.

6.2.10 Cantilever floor beams

6.2.10.1 In cases where the cantilever part of the floor beams bearing the load from the roof does not exceed 400 mm, when the cantilever overhang is up to 600 mm inclusive, the cross-section of the beams must be at least 38 x 235 mm; when the cantilever overhang is more than 600 mm, the cross-section of the beams must be determined by calculation.

6.2.10.2 The cross-section of beams, the cantilever parts of which carry loads not only from the roof, but also from other floors, must be determined by calculation.

6.2.10.3 Cantilever beams perpendicular to the floor beams must be inserted into the ceiling at a distance of at least six console lengths and nailed to the internal double floor beam ().

6.2.11 Construction of openings in the ceiling

6.2.11.1 If there is an opening in the ceiling with a length (perpendicular to the floor beams) of more than 1.2 m, the beams limiting the opening in this direction must be double. For an opening length of more than 3.2 m, the required cross-section of these beams must be determined by calculation (.

Table 6-1

Construction detail	Minimum length of nails, mm	Minimum number of nails or maximum distance between nails
Floor beam to the top frame of the wall frame - with an oblique nail	80	2 2
Horizontal connections to the bottom of the floor beams	60	Two at each end
Vertical cross braces between beams - to beams	60	300 mm
Double beam (framed by openings, at the end cantilever beams)	80	Two per floor beam
Floor beam to purlin	80	Two at each end
Butt connection of floor beams	80
Shortened beam at the opening in the ceiling to the beam limiting the opening (at the end)	80 or 100	5 3
Beam limiting the opening in the floor to the adjacent main floor beam (at the end)	80 or 100	5 3

The ends of the beams into the walls are sealed in the following sequence. Ends of beams of interfloor and attic floors wooden buildings they turn it on frying pan in the upper crowns for the entire thickness of the wall. In stone buildings, beams are placed on the walls or placed in specially placed sockets. In earthen walls, beams are placed on frames.

In interfloor ceilings there are zones where conditions are created for the formation of condensation. Usually these are the places where the ceilings adjoin the outer walls, where freezing and blowing of the structures are possible. To prevent these phenomena, the joints of floors with external walls must be made taking into account sufficient thermal protection and air tightness.

Rice. 1. Diffusion of water vapor in a wooden floor beam.

When resting a wooden beam on a stone wall, it is necessary to protect the joint cavity from the penetration of moist air from the premises. This necessity is caused by the fact that upon penetration warm air, the water vapor it contains upon contact with cold stone walls condensation will condense at the joint and moisten the end of the beam embedded in the wall socket. Therefore, the ends of the beams resting on the wall should be antiseptic, and their surface should be covered with 2 layers of roofing material.

The ends of the beams cannot be pasted over.

Rice. 2. Supporting wooden beams on stone walls:
a - one beam;
b - two beams;
1 - sealing with mortar; 2 - two layers of roofing felt; 3 - anchor; 4 - antiseptic part of the beam; 5 - nail; 6 - steel plate 50x6 mm; 7 - two layers of roofing material.

The beams rest on the wall to a depth of 1215 cm. However, the nests are made 18 cm deep. Thanks to a gap of 3 cm, the wooden beam does not come into contact with the masonry, and water vapor through its unlined end exits out through the masonry.

The size of the nests should be 23 cm larger than the cross-section of the beam. After installing the beam, they are sealed with mortar, thereby protecting the joint from internal air penetrating into it and becoming damp.

To ensure rigidity, the beams are reinforced one after another. To do this, a steel anchor is installed in the masonry. Its end should not reach the outer surface of the wall by 12 cm (to avoid the formation of cold bridges), the other end should protrude into the room by 20 cm. The anchor is attached to a wooden beam using a steel plate with a section of 50x6 mm and nails Ø56 mm.

Sometimes open sealing of the ends of the floor beams is performed, but this is only possible indoors normal humidity(no more than 60%) with good ventilation of the ceiling (with slotted skirting boards) and sufficient thermal insulation capacity of the rear wall of the nest. With a brick wall, the wall thickness of the nest must be at least 46 cm. With a smaller thickness, it is necessary to insulate the nest, while ensuring middle lane Russia heat transfer resistance 0.57 m 2 °C/W.

Rice. 3. Open embedding of the ends of the beam into a wall 0.51m thick;
1 - beam; 2 - insulation; 3 - wooden board; 4 - wooden box; 5 - gasket made of roofing felt in 12 layers.

With a wall thickness of 2 bricks (0.51 m), the support of a wooden beam on the wall is solved in the following way. A nest 25 cm deep (1 brick) is made in the wall. A layer of heat-insulating material - antiseptic or mineral felt - is placed near the vertical wall of the nest. 2 layers of roofing material are laid on the lower surface of the nest, and then a wooden box made of antiseptic wood is installed in the nest, pressing mineral felt against it. The floor beam is supported on the bottom surface of the box to a depth of 15 cm so that an air gap is formed between its surfaces and the beam. One option for this unit is to install a wooden box that has 3 vertical sides and 1 horizontal upper surface, but without a lower horizontal one. In this case, the antiseptic end of the beam will rest in the socket on 23 layers of roofing material. There will be wooden boards on the sides, top and end of the beam.

Rice. 4. Embedding the ends of the beam into a wall with a thickness of 0.64 m or more:
1 - beam; 2 - floor; 3 - lags; 4 - the end of the beam wrapped in 2 layers of roofing material; 5 - board 25 mm thick; 6 - roofing felt; 7 - insulation (construction felt in 1 layer); 8 - roofing material in 12 layers.

When the wall thickness is 2½ bricks or more, the beam is supported in a socket 25 cm deep. In the lower part it is covered with bitumen, on which 2 layers of roofing felt are laid, the upper and side surfaces are also covered with roofing felt. Then, near the back surface of the nest, a thermal insulation layer of mineral felt is placed, which is pressed against the wall wooden board 25 mm thick. The floor beam is placed in the nest so that an air gap of about 4 cm thick remains between it and the walls.

The most important element in the construction of any house is the floor. The design of the floor can be based on the use of beams and slabs, which, in turn, can be wooden, metal, or concrete. Of particular interest is the specifics of installing floors on, since the construction of brick houses is very common. The support of a beam on a brick wall or, accordingly, the support of a slab on a brick wall is the most important factor in the reliability and safety of the entire floor.

The choice of support design depends on the material, embedment depth, and fastening (anchoring) in the wall.

The main characteristic feature of supporting a structure on a brick wall is the possibility of fairly free deformation of the ends of the beam when it deflects. Safety and reliability of the structure can only be achieved by ensuring the correct connection of the beam with the wall, eliminating dangerous stresses in the material even when exposed to extreme temperature conditions. When choosing a support design, the material, embedment depth, and fastening (anchoring) in the wall are fully taken into account.

Floor material and design

Table for calculating the cross-section of floor beams.

In general, the floor is a load-bearing building construction, subdivided by purpose: interfloor, attic, attic. Structurally, the floor can be divided into two types: prefabricated (longitudinal beam and transverse flooring) and monolithic (slab).

In the construction of private houses, prefabricated floors using wooden beams are most widely used. This material is made from durable deciduous and coniferous wood. The size of a standard specimen, depending on the purpose of the floor and loads, ranges from:

• height - 150-300 mm;
• width - 100-250 mm.

To increase durability, the timber is impregnated with an antiseptic and oiled.

Reinforced load-bearing structures are sometimes made using metal beams. Standard steel beams are available for these purposes. Safety standards state that if such beams are used, their ends must rest on the brickwork through distribution pads.

Monolithic floors are made of reinforced concrete slabs. Factory slabs are used, consisting of reinforcement and concrete mass with standard sizes. To reduce weight, the slabs are usually made hollow.

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Beam sealing methods

Scheme for embedding the ends of wooden beams in the attic floor into a wall 2 bricks thick.

The reliability and safety of the ceiling is largely determined by the correct embedding of the beam into the wall. The embedding determines the nature of the support on the brick wall, and this stage of construction is the most important.

The wooden beam is installed in a niche made in brickwork, up to 150 mm deep. The end ends undergo certain processing: the end is hewn at an angle of about 60º, impregnated with antiseptic and resin, and wrapped in roofing felt or roofing felt. The wrapped ends are laid in a brick wall with a gap of 30-50 mm from the back wall of the niche. The gap is filled with thermal insulation (mineral wool, felt, etc.). The laid ends are usually coated (sealed) with a concrete solution, bitumen or covered with a layer of roofing felt.

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A thick brick wall and a beam resting on it

In the case where the thickness of the brick wall exceeds 600 mm (2.5 bricks), a slightly different sealing method is recommended. The nest in the brickwork is made in such a way that there is a distance of at least 100 mm between the end of the beam and the rear wall of the niche. The total depth of the niche is selected taking into account the fact that the beam must rest on the wall at a length of at least 150 mm. The gap left allows you to lay it in thermal insulation material and provide an air gap.

The lower part of the socket is reinforced with concrete mortar, a bitumen layer and two layers of roofing felt or roofing felt. In this way, a laying cushion is created, which at the same time levels the surface of the masonry. The niche in its upper and side parts is covered with roofing felt.

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Supporting a beam when reducing wall thickness

Scheme for embedding the ends of a beam into a wall with a thickness of 0.64 m or more.

When performing overlapping on brick walls with a thickness of about 500 mm (2 bricks), the sealing method should be changed. A wooden box (box) with 2-3 walls is installed in a niche up to 250 mm deep, left in the brickwork. Tarred felt is placed between the back wall of the niche and the box. The walls of the box are treated with an antiseptic and impregnated with resin.

The lower part of the niche is leveled with two layers of roofing felt or roofing felt. The side walls of the nest are insulated with felt. The box is installed in a niche so that it presses the felt. The floor beam rests on the bottom of the box at a length of at least 150 mm.

With a reduced thickness of the brick wall, you should control the thickness of the wall remaining after the formation of the niche. When the wall thickness is less than 50 mm, there is a danger of cold penetration, and, therefore, it is necessary to provide additional insulation in the area where the beam rests on the brick wall.

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Installation and fastening of beams

The process of installing beams in the manufacture of floors depends on the purpose of the floor, its area and loads. Typically, wooden beams are distributed along load-bearing brick walls at a distance of 600 to 1500 cm from each other. The sealing of beams begins with the outer ones and is evenly distributed along the length of the wall. It is recommended to provide a gap of at least 5 cm between the end beam and the edge of the wall.

Scheme of laying floors and subsequent fixation.

An important element of floor installation is checking that the beams are fastened horizontally and that all beams are at the same level relative to the floor. Horizontal deviation or uneven level will cause additional load in the area of ​​support on the brick wall, especially after further laying of the transverse floor boards.

You can increase the reliability and rigidity of support on a brick wall by using additional fasteners. Most Applications found steel anchors. The anchor is strengthened so that there is a distance of at least 15 mm between the outer surface of the wall and its end. The anchor and the floor beam are fastened with nails and a metal plate measuring at least 6x50 mm.

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Floor installation

After completing the installation and sealing of the beams, the transverse flooring is installed. To make the flooring, boards 25-45 mm thick and thick plywood are used. The flooring is installed on top of layers of thermal insulation. When making interfloor ceilings, a noise-insulating layer is also laid. Installation of the flooring is carried out on top of bars (joists), which are fastened across the load-bearing beams.

When making a floor, you must use a standard tool. The following set of tools is recommended.

For processing and fastening wooden elements:

• hacksaw;
• axe;
• hammer;
• Bulgarian;
• drill;
• hammer drill (for working with bricks).

To take measurements and measurements:

• roulette;
• ruler;
• level.