Floors are structures that simultaneously perform load-bearing and enclosing functions. In civil buildings with walls made of small-sized elements, beam or slab floors can be used as a load-bearing part. The composition of the enclosing part is determined by the design of the load-bearing part and the purpose of the ceiling.

Floors on wooden beams used in buildings up to four floors high. Beams are most often made of rectangular cross-section from solid or laminated wood. To support the inter-beam filling, cranial bars are nailed to the beams on one or both sides. The nomenclature of beams with cranial bars is shown in Figure 3.1, b. Skull bars with a cross section of 40x50 mm are nailed to the beams with nails ø-4.5 mm, ℓ=125 mm in increments of 300 mm.

The support of the beams on the walls must be at least 180 mm. The ends of the beams in an area of ​​50-75 cm from the end are antiseptic, and when resting on external walls or internal walls of damp rooms, they are coated with resin or bitumen and wrapped with roofing felt. The ends of the beams are left open to remove moisture from the beams during operation of the floor. When supporting beams on internal and external layered walls with a load-bearing layer thickness of less than 510 mm, a closed seal is performed (Fig. 3.1, e and f). Beams are fastened in external walls using anchors embedded in the wall masonry and connected to the beam with nails. On the internal walls, two opposing beams are connected by metal plates.

Between the beams, along the cranial bars, a roll of wooden panels up to 2 m long is laid (Fig. 3.1, c, d), slabs or gypsum slabs. Clay grease with a thickness of 20-30 mm is placed on the roll-up shields or a layer of rolled waterproofing is laid. In interfloor ceilings, a layer of sound insulation made of slag or calcined sand 50-60 mm thick is laid on clay lubricant or roofing felt, and in attic ceilings - a layer of thermal insulation made of the same materials 200-260 mm thick. Mineral wool boards and other non-flammable materials can also be used as sound insulation and insulation. thermal insulation materials. The floor in such floors is laid on joists or directly on beams with a beam pitch of 0.6 m.

Floor structures on wooden beams are shown in Figures 3.2 and 3.3.

Figure 3.1a shows a fragment of the floor plan on wooden beams with the roll of their wooden panels.

Figure 3.1. Floors on wooden beams with cranial bars

a – fragment of the floor plan; b – nomenclature of wooden beams; c – rolling boards supported through overhead strips; d – the same with continuous support on the cranial bars; d – supporting the beam on the outer wall; e – support of beams on interior wall premises with normal humidity;

1 – load-bearing brick layer; 2 – antiseptic ends of beams (including the end); 3 – wrapping the ends with roofing felt (excluding the ends); 4 – blind sealing with cement-sand mortar; 5 – steel L-shaped anchor 50x5 mm; 6 – two layers of roofing felt; 7 – strip steel anchor

Rice. 3.2. Floor structures on wooden beams with cranial bars

a – interfloor with a ramp of slabs; b – interfloor with a ramp made of wooden panels; c – attic with boards; d – interfloor with suspended ceiling;

1 – wooden beam; 2 – roll from slabs; 3 – roll made of wooden panels;

4 – clay lubricant; 5 – roofing felt; 6 – glass backfill; 7 – effective insulation;

8 – roofing felt bag; 9 – logs; 10 – finished floor boards; 11 – walking boards

Rice. 3.3. Ceilings on laminated timber beams with suspended ceilings

1 – glued wooden beam; 2 – spring bracket; 3 – cross-section 25x50 mm; 4 – plasterboards; 5 – mineral wool slabs; 6 – particle boards; 7 – felt pad; 8 – logs 40x60 mm; 9 - parquet boards

Reinforced concrete beams the floors are laid in increments of 0.6 - 1.1 m (Fig. 3.4). Beam embedment depth in stone wall- 180-200 mm. The ends of the beams from the outside are insulated (Fig. 3.5). Inter-beam filling liners are laid along the beams (Fig. 3.6). Options for installing interfloor and attic floors according to reinforced concrete beams are shown in Fig. 3.7.

Floors on metal beams have a similar design solution (Fig. 3.8).

When supporting beams on walls made of gas silicate, cellular concrete or expanded clay concrete blocks, the installation of monolithic or prefabricated monolithic (Fig. 1.3) reinforced belts should be provided.

Rice. 3.4. Fragment of the floor plan using reinforced concrete beams

Rice. 3.5. Connections between precast reinforced concrete beams and walls

a – leaning on the outer wall; b – leaning on the inner wall; c – abutment to a self-supporting wall

1 – reinforced concrete beam; 2 – steel anchor; 3 – insulation; 4 - cement-sand mortar

Rice. 3.6. Inter-beam filler inserts

a – gypsum or gypsum concrete; b – lightweight concrete double-hollow; c - reinforced concrete top slab; d – expanded clay concrete liner of continuous section; d – reinforced concrete trough section; e – reinforced concrete vaulted

Rice. 3.7. Floors on reinforced concrete beams

a, b – interfloor; c – attic

Rice. 3.8. Interfloor ceiling on steel beams

Floors in the form hollow core slab decking are shown in Figure 3.9. The most commonly used slabs with round voids are 220 mm thick for spans of 2.4-7.2 m (with gradations of 0.3 m), 300 and 360 mm for spans of 9 and 12 m, respectively. The slabs work only in the longitudinal direction, and, therefore, must rest on load-bearing walls made of brick or ceramic stones with short sides of at least 90 mm. Support on walls made of cellular concrete - 120-150 mm. To strengthen the supporting sections, it is planned to reduce the size of the voids at one end, and at the other end, resting on the outer wall, to plug them with concrete liners. The joint operation of the floors is ensured by connecting the panels with steel welded connections.

Recently, slabs with vertical voids, produced by the method of formless molding, have become widely used (Fig. 3.9).

In buildings with walls made of small-sized elements, it is also possible to use floor slabs made of cellular concrete. The design of such an overlap is shown in Figure 3.10.

Figure 3.11 shows examples constructive solutions floors on hollow-core floorings.

In buildings without basements, the floors of the first floor can be made on joists or on the ground (Fig. 3.12).

In recent years, during the construction of low-rise buildings, all greater application get prefabricated monolithic beams(frequently ribbed) floor structures (Fig. 3.13 – 3.15). Such floors are used for spans up to 7.8 m.

Rice. 3.9. Hollow-core floor slabs

a – main dimensions; b – options for joining the slab to the wall;

d) – fragment of the floor plan

Rice. 3.10. Floor slabs made of cellular concrete

a – the main dimensions of the slabs; b – supporting cellular concrete slabs on the wall; c – connecting the plates to each other; d – floor plan

Figure 3.11. Floors on interfloor slabs

Figure 3.12. Floors of the first floor of buildings without basements (waterproofing is not shown)

Rice. 3.13. Prefabricated monolithic floors(section across the beams)

Rice. 3.14. Prefabricated monolithic floors (supporting beams on the wall)

Fig.3.15. Fragment of the prefabricated monolithic floor plan

When building any house Special attention should be applied 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 how to support such supports on a 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 supporting 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 wood 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

A ceiling is the connection of a beam with a load-bearing building wall, which can be an attic, attic or between floors. 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, 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.

The wooden beam is mounted in the free space created in the 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. Most often, wooden beams are installed along load-bearing walls at a distance of 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.

One more is enough an important condition When supporting beams on a beam and a wall, the horizontal fastening of the support is taken into account. 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 force 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 rectangular 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.
In design wooden floor includes 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. When sealing wooden floor beams, spatial niches are filled around the beam with effective insulation (mineral wool, polystyrene foam). When the brick walls are up to 2 bricks thick, the gaps between the ends of the beams and the brick wall are filled with 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 internal walls, two layers of roofing felt or roofing felt 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.
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 or laid: as in the walls, here you can use mineral wool, sawdust, slag. 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 limits, 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 brickwork pipes and be at least 35 cm from the hot surface. This distance can be reduced to 30 cm by laying felt or asbestos cardboard 3 mm thick between the groove and the beam, 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 accuracy of calculations. 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, a triple safety margin is usually provided, eliminating the possibility 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 against climatic influences wooden structures outer 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 and varnish coatings or other finishing. Special chemicals not needed here.

Fire protection for floors

Standards impose special requirements on building materials and structures fire protection. 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 the filing are elements of the interfloor covering, but belong to the category finishing works. Therefore, we will talk about them in the next article.

Floors, as you know, can be slabs or beams. The first option, of course, is very reliable, but it requires considerable investment, including hiring lifting equipment.

When constructing a one- or two-story private house, including a brick one, such strength is not required at all. In addition, this is an extra load on the walls and foundation, so low-rise construction Mostly they use beam floors.

For those who build a house with their own hands, a logical question arises: “How is a wooden beam supported on a brick wall?” We will understand this topic using the video in this article.

Wooden beams and requirements for them

In principle, beam floors can also be different: reinforced concrete, metal, or wood. The first two options are not inferior in technical specifications slab floors, but they are quite complex to execute and therefore are practically not used in private construction. But wooden beams are a completely different matter!

So:

• Despite its apparent simplicity, there are also a lot of nuances that must be observed. First of all, you should choose the right lumber. Most often, hard coniferous wood is used for this purpose: larch, pine, spruce, cedar. The price doesn’t matter here - it’s just that coniferous beams work best in bending.

• There are, of course, advocates of deciduous wood who claim that aspen and birch cope well with this task. But building codes recommend that all load-bearing wooden structures - and not just floor beams - be made from softwood lumber. Hard hardwood, suitable only for connecting parts (dowels, dowels, etc.).
• It is possible, and even preferable, to use planed timber rather than glued timber for flooring. It must be well dried and treated with a fire-retardant compound before installation. In heated buildings, solid beams must be installed without intersecting walls and partitions, and the floor structure, as such, must guarantee good ventilation.

• Blind (monolithic) embedding of beams into walls is not allowed - they are placed in nests, and always on shock-absorbing pads made of deciduous wood. The ends of beams mounted using metal fasteners must be protected with a moisture-proof layer, since when condensation forms, metal corrosion can lead to wood corrosion.

But before we start installation work, load-bearing elements of the floor need to be calculated. Therefore, further you will be offered instructions for selecting the section of beams and determining the step of their installation.

Dimensions of beams and methods of their installation

So, you need to determine how many beams you need to install, and what cross-sectional size they should be. First of all, it is necessary to measure the span of the floors, and, having determined the depth of their installation in the walls, calculate the operating loads.

So:

• The length of the beams depends on the method of their fastening. If the ends are laid in the wall, then their length can be obtained by adding the span and twice the depth of the beam (at two ends). In block and brick houses, the depth of the nests for laying beams is at least 10-15 cm, which depends on their size.

• If the beams will be attached to the walls using metal clamps or consoles, then their length corresponds to the distance between parallel walls. A lot here depends on where exactly the ceiling is installed: above the basement, between floors, or in the attic. Sometimes, when arranging attic floors, the beams are extended outside, beyond the walls, by mounting rafter legs to them.
• This is one of the ways to form a roof overhang. In another option, the roof beams can be mounted directly to the mauerlat beam - which is what we see in the photo below. Naturally, the length of beams with the same span will be different in such situations, and when calculating the constituent elements of the floor, all these nuances must be taken into account.

Note! The maximum length of beams made of timber or edged boards is 6 m. If you need to cover a larger span, it is better to give preference to metal I-beams, or instead of beams you will have to use wooden trusses. But in general, for a wooden floor, six meters is too much - the most best option– span within 3-4m.

Loads

The load that the ceiling absorbs consists of two components: the dead weight of the structure, and the operational load (people, furniture, equipment). It can be calculated using a simplified scheme.

For example, the dead weight of an attic floor with light mineral wool insulation is traditionally 50 kg/m2.

So:

• According to the standards, the operational load for a non-residential attic in which things are not stored is no more than 70 kg/m2. It is multiplied by the safety factor, taken as 1.3, and summed with the constant load. After all the manipulations, the result is 130 kg/m2. This figure needs to be rounded up - that is, to 150 kg/m2.

• But to insulate the attic, heavier material can be used, for example, expanded clay - and naturally, its weight must also be taken into account. The picture changes dramatically if the attic turns into residential attic. In this case, the standard operating load is no longer 70, but 150 kg/m2.
• Here you also need to add the weight of what is being installed in the lower room. suspended ceiling, and the utilities installed in it - and this is at least another 15-25 kg. You should take into account both the weight of the floor covering and the weight of zoning partitions, if any will be erected in the upper room.

All additional loads must be added to the standard load, but the self-weight of the floor and the safety factor are assumed to be the same. The loads are calculated in a similar way, using the same formula mentioned above.

The ideal option is if the basement and interfloor ceilings are designed for 400 kg/m2 - then it can easily withstand massive furniture, a piano, and an influx of guests.

Sections

After you have calculated the length of the beams and the loads they bear, you can begin selecting the section. It is most convenient to use a rectangular beam for this purpose - the optimal aspect ratio is 1.35:1.

Since slab insulation is installed in the ceiling structure, you need to be guided by its thickness, plus a small ventilation gap.

• The step between the beams must again be correlated with the size of the insulating boards, only now with their width. But to be more precise, it’s more likely the other way around: the insulation is selected to match the ceiling structure. The distance between the beams and their cross-section can be selected using this table, which we present below.

This is a simplified selection method, so don’t forget that insurance never gets in the way. Therefore, it is always better to increase the margin and round all values ​​up.

The step between the beams is determined in such a way that the outermost beam is not close to the walls or mauerlat, and there is a distance of at least 20 cm between them.

Installation nuances

We have already said that installation of beams can be done in two ways: by laying them in specially provided nests in the masonry, and by fastening them with clamps or other metal devices.

So:

• Let's consider the first method. To do this, the ends of the ceiling beams need to be cut at an angle of 60 degrees, and treated with bitumen mastic or any other hydrophobic compound, and then also wrapped roll material: glassine or roofing felt.

• Before installing the beam, a piece of foam plastic or other insulation is placed near the rear wall of the mounting socket - there must be a wooden spacer under the beam. The ceiling beam is placed in the nests so that there is still a few millimeters of gap between its end and the back wall of the nest.
• A very convenient way to mount floor beams on a metal console, and the diagram above shows its support unit. And also, please note that for reliability, crossbars are mounted between the beams, connected to them using metal corners.

It turns out to be a kind of frame, which is hemmed from below with a board or plasterboard. Then, from the side of the upper room, the “filling” is laid in it: vapor barrier and insulation, after which rigid sheet material is mounted on top of the beams: OSP boards, fiberboard, plywood, chipboard. Further settling in flooring the top floor - but that's a completely different topic.

Methods for supporting floor beams on foundation walls are divided into two: general types depending on whether they are used in a platform frame or in a frame with through posts. The platform frame is most widespread. When constructing a platform frame, two types of nodes for supporting beams on foundation walls are used: supported by strapping and embedded in concrete

Harness support unit

This unit is applicable to walls made of both monolithic concrete, and from

small concrete blocks It consists of a wooden strapping beam reinforced with anchors to the wall (Figure 34), on which the floor beams and the final main beam rest. The strapping beam is usually located at the top of the wall. In this case, its bottom should be at a height of at least 150 mm (6 in. ) from the planning ground level If it is necessary to lower the floor level of the first floor, the width of the top of the wall can be reduced to 90 mm (3 1/2 dm) In this case, depending on exterior finishing walls, two wall support units are used. If the wall decoration consists of outer skin or plaster, the wall frame is placed on a separate frame anchored at the top of the wall, and the floor beams rest on another frame located below on a shelf formed in concrete (Fig. 35) If the finishing

walls are made of finishing bricks, the brick is laid on the raised part of the foundation wall, and the wooden load-bearing frame rests on top of the floor beams (Figure 36) The top of the wall of reduced thickness should not exceed 350 mm (14 dm)

Supporting beams embedded in concrete

This method is only used with monolithic basement foundation walls. Structural beams, secondary beams and end beams are assembled before placing concrete. Temporary ceiling frame

it is secured on the inner panel of the formwork and leveled with wedges. Between the floor beams, on the line of the inner surface of the wall, blocking boards are installed for formwork during concreting (Fig. 37). End beams and end floor beams serve as external formwork. The ends of the beams, if they are at or below the level of the layout, are treated with an antiseptic. After this, concrete is laid, so that at least two-thirds of the height of the beams is in concrete. This creates a completely acceptable anchorage for the beams.

Other methods of performing floors

One of the principles of a healthy home, namely the efficient use of resources, can be applied when making floors if you use factory-made products. Products such as prefabricated components replace lumber, and custom sheathing panels can replace plywood.

Publicly available products that replace floor beams made of

boards are wooden I-beams and floor trusses.

In addition to the fact that systems made from these elements provide a more rigid and less squeaky floor, they also make it easier to carry out

wiring of ventilation ducts and pipelines.

On average, for the production of floors from I-beams and trusses require 20% less material than conventional flooring of dimensional lumber, and taking into account the possibility of increasing the distances between support elements, material savings increase even more.

Because the spans of these products are much greater than those of conventional lumber, prefabricated floor systems can cover large areas without the need for internal load-bearing walls. This makes the layout of the house more flexible and further reduces the material consumption and labor intensity of construction.

Instead of plywood for sheathing beam floor you can use wafer panels or oriented

Fiber board. Waffle boards are made from briquetted waste lumber, which is glued and pressed into one whole. Oriented fiber boards are similar to wafer panels, but they are made with fibers that are aligned and oriented in opposite directions for greater strength.

When using factory-made products, it is very important to strictly follow the factory instructions.

ceilings in the walls. The blocking boards between the beams are removed along with the formwork after the concrete has gained strength. The same method is applicable when finishing the facade facing bricks(Fig. 38).

BEAM COVER

Floor beams are selected for strength and rigidity. Strength requirements depend on the load the beams must bear. Rigidity, in turn, should

permissible spans of beams for different varieties and wood species depending on different loading conditions. Allowable spans in these tables are given between the inside edges of the support planes and are based on lumber planed to standard Canadian dimensions.

Options include using laminated plywood boards, parallel chord trusses, or I-beams in place of measuring boards. Information about the permitted spans for these prefabricated products can be obtained from the manufacturers.

Where strapping is used,

floor beams are installed after leveling the frame on the bed of mortar and attaching it to foundation wall by using anchor bolts. As mentioned above, if the floor beams are embedded in the upper part concrete walls, they must be installed before laying concrete. Beams are installed and secured in accordance with the drawings.

The spacing between beams is usually 400 mm (16 in.), although for higher loads or limited space, reduced height beams can be spaced 300 mm (12 in.) apart. On the other hand, if

The thickness of the slab is not a limitation; installing taller joists at 600 mm (24 in) intervals may be more advantageous. (Note: Joist distances given in millimeters are nominal and should not be used as panel products are manufactured using Imperial measurement).

If the beam board has a slight curvature in the plane, it should be installed with the curved side up. Once the decking and finished floor are installed, the curvature of the beam is usually leveled out.

The end beam is nailed to the floor beams from the ends (Fig. 39) or from the sides (Fig. 35). With a platform frame, each

the beam, including the beam parallel to the wall, is attached to the frame with nails from the sides (Fig. 39). The internal supporting ends of the beams are attached to the main beam from above (Fig. 31) or end-to-end (Fig. 32).

If the load-bearing wall is parallel to the floor beams, it must rest on a load-bearing main beam or on a load-bearing basement wall.

According to floor plans It often turns out that the load-bearing wall is located perpendicular to the floor beams, but at some distance from the line of beam supports. Such a load-bearing internal wall, perpendicular to the floor beams, can be located no more than 900 mm (36 in.) from the beam supports, unless it carries the following

ceilings If one or two floors rest on it, the distance from the supports should not exceed 600 mm (24 dm) or the beams on which it rests should be designed for such concentrated loads.

Non-load-bearing partitions parallel to the floor beams must rest on the beam or on spacers between the beams. Such spacers are made from 38 x 89 (2 x 4 in.) mm bars and are located at a distance of no more than 1.2 meters (4 ft) from one another.

Around large openings, such as for a staircase or fireplace, the side joists are assembled from doubled boards if they are supported by end support beams longer than 800 mm (32 in). For lengths greater than 1.2 meters (4 ft), the support beams should also be assembled from double planks. Around very large openings, the cross-sections of support beams greater than 3.2 m (10 ft 6 in) in length and side beams supporting support beams greater than 2.0 m (6 ft 6 in) in length should be calculated by generally accepted engineering methods.

A typical detail for assembling nailed beams around the frame of the openings is shown in Fig. 40.

Metal support hangers are often used to support long end beams on side beams and to attach long floor beams to the end beams.

To prevent rotation out of plane, floor beams are secured by installing vertical ties, blocking between beams, overlays or ceiling finishing panels at the bottom of the beams. If finishing panels not installed, beam ties should be located at mid-span and at distances of no more than 2.1 meters (6 ft 10 in).

Vertical fastening connections in spans are provided

using the following methods: installing vertical crosses from bars 19 x 64 mm (1 x 3 dm) or 38 x 38 mm (2x2 dm) or installing blocking boards 38 mm thick (2 dm) to the entire height of the beams with fastening on nails along the entire length under beams of continuous overlays 19 x 64 mm (1 x 3 dm). These trims are not needed if ceiling trim panels are installed.

Beam quality

The span tables for floor beams take vibration conditions into account. When developing the tables, it was taken into account that some floor structures are more “springy” than others. Therefore, with additional vertical links and blocking, as well as with an increased thickness of the base under the floors, increased beam spans are allowed. Alternatively, you can use prefabricated products such as laminated plywood beams, parallel chord trusses or I-beams.

PREPARATION UNDER FLOORS

Preparation for floors is done by paneling made of plywood, parallel-strip wood, wafer boards, and by paneling with boards no more than 184 mm (8 in.) wide, quartered or tongue-and-groove. The minimum thicknesses of plywood, parallel-strip wood, wafer boards and boards are given in Table 17.

Plywood is often used as preparation for a wooden ship's floor or in combination with an underlay for a resilient or wood floor. ceramic tiles. When preparation is made along with the spacer, the side edges of the panels should be supported by blocking with 38 x 38 mm (2 x 2 in) blocks between

floor beams. There is no need to support if the edges of the panels are connected by tongue and groove.

The plywood panels are installed so that the surface fibers are directed perpendicular to the floor beams, and the edges on the short sides are attached to the beams staggered with nails every 150 mm (6 in) at the edges and every 300 mm (12 in) on intermediate supports. In cases where panels form a floor preparation in combination with a gasket, threaded nails are used to prevent “popping out” or approved brackets are used (Table 18 gives the dimensions of fasteners for attaching sheathing and preparations).

The rigidity of the floor can be significantly increased and its squeakiness can be reduced if plywood preparation panels are installed over the beams using elastomeric adhesive. At the same time, glued plywood and beams work together as a strengthened frame and deformations between adjacent beams are reduced.

Wafer panels, like panels made of parallel strip wood, can also be used as preparation for floors, and when vinyl floors a gasket is laid over them. The panels are installed staggered and fastened with nails in the same way as plywood.

All plywood, parallel strip timber and waferboard panels used for preparations and subfloors must be of the external type, i.e. made with waterproof adhesives.

No spacer is required if the preparation panels are supported at the edges.

For preparation of boards or plank sheathing, boards with a thickness of 19 mm (1 dm) are used; with distances between beams of 400 mm (16 dm), boards up to 17 mm thick (11/16 dm) can be used. Boards

should be positioned so that their ends rest on the beams. The ends of the boards are usually spaced apart. The boards are laid perpendicular to the beams, but can be placed diagonally at an angle of 45°. If the plank flooring is laid at right angles to the joists, the finished slab flooring is laid perpendicular to the decking. This rule does not apply if there is a gasket underneath the finished floor. With diagonal flooring, the plate floor can be laid parallel or perpendicular to the floor beams. The deck boards are secured with 51 mm (2 in) long nails at each support. For elastic, clean floors, a layer of rolled material is placed on the plank flooring.

FRAME

Related information.