Wooden floor over 6 meters. Overlapping of large spans with wooden beams: glued beams, wooden trusses. wood flooring requirements

Installation of wooden beams in the ceilings of houses is not uncommon. Their main purpose is to evenly distribute the load on the walls and foundation of the building. In order for the beam structure to fulfill its functions, it is necessary to choose the right material for it, to calculate the length and section.

All beam ceilings made of wood are divided among themselves according to the purpose and type of material from which they are made. By appointment, they can be: interfloor, attic, basement and basement. According to the type of material, the beams can be made of solid wood or glued.

wooden floors in aerated concrete house

Interfloor span must be strong and reliable. Sound and vapor barrier fillers are placed in the internal volume between the ceiling and the floor. Ceiling is sewn up necessary material, the floor is laid on top.

The attic floor can be installed as an element of the roof, being part of it. roof structure. Can be installed as a separate independent element. In order to preserve heat, it is necessarily equipped with vapor and thermal insulation.

The ceiling of the basement and basement must be of great strength and withstand high loads. These spans are equipped with heat and vapor barrier to prevent the penetration of cold from the basement.

Beams differ in types, which have their own advantages and disadvantages.Wood is used to make solid beams hard rock. A significant disadvantage solid wood beams is a length limit that cannot exceed 5 meters.

Laminated timber beams combine high strength and aesthetics. Their use significantly increases the maximum length, which can be up to 20 meters. Given that glued floors look beautiful, they are often not covered with a ceiling and they serve as a design element.

They have several other significant advantages, which include:

• ability to cover large spans;
• ease of installation;
• small mass;
• long period of operation;
• high level of fire safety;
• are not subject to deformation.

The wooden parts of the floor beams may have rectangular section, which is typical for a bar or board, or round, made of logs.

Requirements for wooden beams

Installation of wooden beam floors entails a number of requirements that must be taken into account. They are as follows:

1. Beam products must be made of their conifers wood, which have a high margin of safety. At the same time, the moisture content of the wood should be no more than 14 percent, otherwise the logs under load will have a large deflection.
2. It is forbidden to use wood prone to fungal diseases or damaged by insects for the manufacture of beams.
3. Before installation, the beam elements must be treated with an antiseptic.
4. To prevent the ceiling or floor from sagging even under load, it is necessary to perform a construction lift. The ceiling of the lower floor will receive a slight rise in the center, which will become even when loaded.
5. If the bars are planned to be laid with great frequency, then boards can be used instead of them, which must be installed on the ribs.

The procedure for calculating wooden beams

Before carrying out the installation of a wooden floor, it is necessary to carry out calculations in which to determine the number and dimensions of the beams. For this you need:

• determine the length of the span on which they will be installed;
• calculate the possible load that they will carry after installation;
• having the indicated data, calculate the section of the beams and the step with which they will be installed. For this, special tables and programs are used.

Beam length consists of the length of the span that needs to be covered, and the stock of the beam, which will be built into the wall. The span can be determined using any measuring device. The stock of beams that will be mounted in the wall depends on the material from which the wall is made.

Important!

If the building is built of brick, then the margin for beams from the board should be at least 10 cm and at least 15 cm for beams made of timber. AT wooden buildings special grooves are made, with a depth of 7 cm or more, for laying beams. If the beams serve as the basis for the roof rafters, then they are made 4-6 cm longer than the span.

The most used span, which is covered by beams, is from 2.5 to 4 meters. The maximum length of beams made of timber or boards cannot exceed 6 meters. If the span length exceeds this dimension, it is recommended to install beams from glued beams. In addition, to cover spans that are more than 6 meters, you can install a wooden truss.

Load , which is carried by a wooden beam, consists of a mass of span details (beams, internal filling, ceiling and floor coverings) and the mass of temporary elements (furniture, Appliances people present in the room).

Accurate calculations of the bearing capacity of beams are usually carried out by specialized organizations. At self-fulfillment calculation, the following system is used:

• an attic floor with a lining, in which mineral wool is a heater, carries a constant own load of 50 kg per square meter. With such a load, according to SNiP standards, the standard load will be 70 kg per square meter with a safety factor of 1.3. Finding out the total load is not difficult: 1.3x70 + 50 \u003d 130 kilograms per square meter;
• if a heavier material than cotton wool is used as a heater, or thick boards were used as a filing, then the standard load will be 150 kg per square meter. And the total load will have a different value: 150x1.3 + 50 = 245 kg per square meter;
• if the calculation is for attic room, then the weight of the material from which the floor is laid and the objects in the attic are taken into account. The load in this case will be 350 kg per square meter;
• in the case when the beams perform the function of interfloor spans, the calculated load is 400 kg per square meter.

Calculation of wooden floor beams

Determination of the section and pitch of wooden beams

By calculating the load and length of the beams, you can determine their step and cross-sectional dimensions or diameter.

These indicators are interrelated and are calculated according to established rules:

1. The width and height of the beams should be in the ratio 1:1.,4. At the same time, the width of the beams should be in the range from 4 to 20 cm, and the height from 10 to 30 cm, taking into account the thickness insulation material. Logs for floors should have a diameter in the range from 11 to 30 cm.
2. The installation step should be in the range from 30 to 120 cm, taking into account the insulation and hemming materials, which will be in the inter-beam space. If the structure is frame, then the step should correspond to the distance between the frames.
3. The determination of the cross section of wooden beams is carried out according to the developed tables or using certain programs. When calculating sections, it must be taken into account that the maximum bending attic beams should not exceed 1/200, and interfloor 1/350.

The use of wooden trusses, advantages and disadvantages

Floor trusses made of wood look like two logs or bars parallel to each other, which are interconnected by supports located at an angle or vertically with respect to these logs or bars. The main task that trusses solve is to cover long spans if the installation of additional support posts is not possible.

For the manufacture of trusses, developed tables and programs are used, which take into account the type of connections, the installation step, the section of the structural details and its overall dimensions. Often, trusses are manufactured industrially using high-precision equipment. Along with this, you can make a farm with your own hands.

Comparing wooden beams and floor trusses, you can determine the advantages and disadvantages that trusses have. The benefits include:

• the ability to cover a span of considerable size without additional support posts;
• insignificant mass, which entails a small load on the load-bearing elements of the building;
• high strength and resistance to deflection, which entails long-term operation of hemming and floor materials;
• ease of installation on any load-bearing elements of the building, regardless of the material from which they are made;
• the ability to change the width of the truss laying step;
• possibility of installation of internal communication lines;
• excellent sound insulation;
• beautifully made trusses can be left unsewn and used as a decorative element.

In addition to the advantages, farms have some disadvantages, which include the following:

• at the expense design features, the thickness of interfloor ceilings increases significantly;
• significant labor costs in making a farm with your own hands, the need for special equipment;
• high price for the finished structure.

Wooden truss design

Among the many structural elements overlapping of a private house is one of the most responsible and difficult to design, install assemblies. It is here that inexperienced builders make, perhaps, the most dangerous mistakes, it is on the arrangement of this system that the most questions are asked.

1. Why choose a tree

In any building, the floor is a horizontal structure that acts as the basis for creating the floor. In addition, being tied with the load-bearing walls of the house, it provides the building with lateral stability, evenly distributing possible loads. Therefore, the highest requirements are placed on the reliability of this design.

Regardless of what material is used in the construction of a house, in the private sector, the most common is just wooden floors. They are often seen in various stone cottages, and it is quite obvious that in wooden construction(log, beam, frame and frame-panel technology) there is no alternative to such a solution. There are many objective reasons for this. Consider the advantages and disadvantages of wood floors.

In private low-rise construction ceilings are mounted in several versions:

• Finished concrete slab
• Monolithic reinforced concrete slab,
• Ready reinforced concrete beams,
• Beams and trusses from rolled metal products,
• Lumber cover.

pros

Or why hardwood floors are so popular.

• Small mass. Using a board or beam, we do not overload bearing walls and foundation. The weight of the floor is several times less than that of concrete or metal structures. Usually no technology is required.
• Minimum terms of performance of works. The minimum labor intensity among all options.
• Versatility. Suitable for any building, in any environment.
• Possibility of installation at sub-zero and very high temperatures.
• Absence of "wet" and dirty processes.
• The possibility of obtaining any level of heat-insulating and sound-proofing characteristics.
• Possibility of using cavities for laying engineering communications(electricity, heating, water supply, sewerage, low current ...).
• Relatively low price of prefabricated frame floor from lumber, both in terms of the cost of parts / components, and in terms of wages of the contractor.

Minuses

The disadvantages of a wooden overlapping system made of wood are rather arbitrary.

• The complexity of choosing the cross-section of materials and design solutions to ensure the calculated bearing capacity.
• The need to perform additional fire prevention measures, as well as provide protection from moisture and pests (antiseptic).
• The need to purchase soundproofing materials.
• Strict adherence to technology to avoid construction errors.

2. What material to use for assembly

Wooden floor - always consists of beams. That's just made they can be from a variety of lumber:

• Log rounded up to 30 cm in diameter.
• The beam is four-edged.
• Board large section(thickness from 50 mm, width up to 300 mm).
• Several boards of relatively small thickness, twisted with layers to each other.
• I-beams, top and lower belt which is made of edged planed board / bar, and the vertical wall is made of OSB-3, plywood or profiled metal (wooden-metal product).
• Closed boxes from sheet materials(plywood, OSB).
• SIP panel. In fact, these are separate sections in which the beams are already sheathed and have an insulator inside.
• Various truss designs, allowing you to cover large spans.

The simplest for installation, as well as the cheapest and most convenient for subsequent operations, are the options when the floor beams are made of edged lumber.

In view of the very high demands, imposed on the bearing capacity, durability and geometric deviations, as blanks it is necessary to consider lumber of the first grade. It is possible to use products that belong to the second grade according to GOST, which do not have critical geometric deviations, flaws and processing defects that can reduce the strength characteristics and service life of finished parts (through knots, graininess, oblique layers, deep extended cracks ...).

In these structures, the use of dead wood (dead wood, fallen wood, burnt wood) is excluded due to insufficient strength and multiple lesions by wood-destroying diseases and insects. It would also be a big mistake to buy a beam or a board “with air”, “with Armenian size”, “TU” - due to underestimated sections.

It should be an exceptionally healthy material from green spruce or pine, since the needles, due to their resinous content and the structure of the massif, endure bending loads and squeezing much better than most hardwood, and having a relatively low specific gravity.

Anyway edged lumber must be freed from the remnants of the bark and bast fibers, treated with an antiseptic and flame retardant. Dry planed sawn timber will show itself best here, but the material natural humidity(up to 20 percent) during normal processing is also actively (and most importantly - effectively) used, especially since the price of edged timber or boards of this type is noticeably lower.

3. How to choose the size of the beams and with what step to arrange them

The length of the beam is calculated in such a way that it overlaps the existing span and has a “margin” to provide support to the load-bearing walls (read below for specific figures for allowable spans and entry into the wall).

The cross section of the board / beam is determined depending on the design loads that will be exerted on the floor during the operation of the building. These loads are divided into:

• Permanent.
• Temporary.

Live loads in a residential building include the weight of people and animals that can move across the floor, moving objects. Constant loads include the mass of the construction lumber itself (beams, logs), floor filling (insulation / noise protection, insulating sheets), hemming (rolling), rough and finishing flooring, finishing floor covering, partitions, as well as built-in communications, furniture, equipment and household items...

Also, do not lose sight of the possibility of storing objects and materials, for example, when determining the bearing capacity of the floors of a non-residential cold attic, where unnecessary, rarely used things can be stored.

The sum of permanent and live loads is taken as a starting point, and a safety factor of 1.3 is usually applied to this. The exact figures (including the cross-section of lumber) should be determined by specialists in accordance with the provisions of SNiP 2.01.07-85 "Loads and Impacts", but practice shows that the load values ​​​​in private houses with wooden beams are approximately identical:

• For interfloor (including under a residential attic) and basement floors, the total load is about 350 - 400 kg / m2, where the share of the structure's own weight is about 100 kilograms.
• To cover an unloaded attic - about 130 - 150 kg / m2.
• To cover the loaded non-residential attic up to 250 kg/m2.

Obviously, unconditional security is paramount. Here it is taken into account good stock and the option is considered not so much of distributed loads on the entire floor (in such quantities they are practically unrealistic), but the possibility of a local load that can lead to deflections, which in turn caused:

• physiological discomfort of residents,
• destruction of components and materials,
• loss of aesthetic properties by the design.

By the way, certain deflection values ​​are allowed normative documents. For residential premises, they can be no more than 1/350 of the span length (that is, 10 mm at 3 meters or 20 mm at six meters), but provided that the above listed limiting requirements are not violated.

When choosing a section of lumber to create a beam, they are usually guided by the ratio of the width and thickness of the beam or board within 1 / 1.5 - 1/4. Specific figures will depend primarily on: loads and span lengths. At independent design you can use the data obtained on the basis of calculations using online calculators or public tables.

Optimal average cross-section of timber floor beams, mm

As you can see, to enlarge bearing capacity overlap - it is enough to choose lumber with a larger width or greater thickness. Including, it is possible to assemble a beam from two boards, but so that the resulting product has a cross section not less than the calculated one. It should also be noted that the load-bearing properties and stability of a wooden floor increase if logs or various kinds of draft floors are used over the beams (sheet flooring made of plywood / OSB or edged boards).

Another way to improve the power qualities of a wooden floor is to reduce the spacing of the beams. Engineers in their projects of private houses determine in different conditions the distance between the beams is from 300 mm to one and a half meters. AT frame construction the step of the beams is made dependent on the spacing of the racks so that there is a rack under the beam, and not just a run of horizontal strapping. Practice shows that the most appropriate in terms of practicality and cost of construction is a step of 600 or 1000 mm, since it is best suited for the subsequent installation of insulation and noise insulation by surprise ( insulating materials just have such a form factor of plates and rolls). This distance also creates the optimal distance between the support points for mounting the floor log, installed perpendicular to the beams. The dependence of the cross section on the pitch is clearly seen from the numbers in the table.

Possible cross-section of floor beams when changing the pitch (total load per square meter is about 400 kg)

4. How to properly install and secure beams

We decided on a step - from 60 centimeters to a meter will be the golden mean. As for the spans, it is best to limit yourself to 6 meters, ideally: four to five meters. Therefore, the designer always tries to "lay" the beams along the smaller side of the house / room. If the spans are too large (more than 6 meters), then they resort to installing load-bearing walls or supporting columns with crossbars inside the house. This approach allows the use of lumber of a smaller section and increase the spacing, thereby reducing the mass of the floor and its cost for the customer with the same (or better) load-bearing characteristics. Alternatively, trusses are created from lighter lumber using perforated metal fasteners, such as nail plates.

In any case, the beams are set strictly horizontally, parallel to each other, with the same pitch. On load-bearing walls and girders, a wooden beam must rest at least 10 centimeters. As a rule, use 2/3 of the thickness outer wall from the side of the room (so that the end of the beam does not go outside and remains protected from freezing). AT wooden walls make a cut, in stone - leave openings during masonry. At the point where the beams touch load-bearing structures it is necessary to lay insulating materials: damper elastic pads made of rubber / felt, several layers of roofing material as waterproofing, etc. Sometimes, firing of sections of the beam subsequently hidden or coating them with bituminous mastics / primers is used.

AT recent times Increasingly, to create a ceiling, special perforated brackets “beam holders / supports” are used, which allow you to mount the beam end-to-end with the wall. With the help of this type of brackets, nodes with transverse crossbars and beams truncated along the length are also assembled (opening for flight of stairs, chimney passage, etc.). The advantages of such a solution are obvious:

• The resulting T-connection is very reliable.
• The work is done quickly (you don’t have to make cuts, it’s much easier to set up a single plane).
• There are no cold bridges along the body of the beams, because the end is moving away from the street.
• It is possible to buy lumber of a shorter length, since it is not necessary to start a timber / board inside the wall.

In any case, it is very important to carefully antisepticize the end of the beam after fitting the lumber to size.

5. What insulation layers should be used inside wooden floors

To answer this question, first of all, it is necessary to divide the overlapping structures (in a year-round habitable house) into three separate types:

• ground floor,
• Interfloor,
• Attic.

In each case, the set of pie will be different.

Interfloor ceilings in the vast majority of cases separate the premises in which temperature regime similar or close in value (if there is room / floor / zone adjustment heating system). These also include the attic floor, which separates residential attic, since this room is heated, and the insulation is located inside roofing cake. For these reasons, thermal insulation is not needed here, but the issue of combating noise, air (voices, music ...) and shock (steps, furniture rearrangement ...) becomes very relevant. As sound insulation in the floor cavity, acoustic fibrous materials, created on the basis of mineral wool, as well as sheets of soundproof membranes are covered under the skin.

The basement design assumes that under the floor there is soil or a basement, a cellar, ground floor. Even if an operating room is equipped below, then this type of floor needs full insulation, which is characteristic of the building envelope of a particular climate zone and a specific building with its unique thermal balance. According to the norms, on average for the Moscow region, the thickness modern insulation With good performance thermal conductivity will be about 150-200 mm.

Similar requirements for thermal insulation apply to attic floor, above which there is no heated attic, because it will be the main barrier to heat loss through the roof of the building. By the way, due to the greater flow of heat through upper part at home, the thickness of the insulation here may be required more than in other places, for example, 200 mm instead of 150 or 250 mm instead of 200.

Apply foam, EPPS, mineral wool with a density of 35 kg / m3 in slabs or cut into roll mats (the one that is allowed for use in unloaded horizontal structures). Thermal insulation is laid between the beams, as a rule, in several layers, with dressing of the joints. The load from the insulation is transferred to the beam through a rough hemming (often it is attached to the beams by means of cranial bars).

Where a watt insulation / sound insulator works in structures, it should be protected from moisture. AT basement moisture can rise in the form of vapors from the ground or from the basement / cellar. AT interfloor ceilings and attic can get water vapor, which always saturates the air of residential premises in the process of human activities. In both cases, from below, under the insulation, you need to lay a building vapor barrier film, which can be ordinary or reinforced polyethylene. But, if thermal insulation is carried out using extruded polystyrene foam, which does not have any significant level of water absorption, then vapor barrier is not needed.

Top insulation and fibrous soundproofing materials protect with waterproof canvases, which can be membranes or non-perforated waterproofing.

A reliable hydrobarrier is especially relevant in rooms with high humidity: kitchen, laundry, bathroom ... In such places it is spread over the beams, always with an overlap of strips by 100-150 mm and sizing the seam. Cloths around the entire perimeter of the premises are necessarily brought to the wall - to a height of at least 50 mm above the finish coating.

Overlapping, which will be lined in the future tiles, it makes sense to supplement with a rough flooring made of waterproof sheet materials - various types cement-containing slabs, preferably grooved. On such a continuous flooring, it is possible to carry out additional coating waterproofing, perform a thin-layer alignment of the plane with a leveling compound or immediately lay the tiles.

You can choose another option - to collect from edged board continuous flooring, lay a hydro-barrier, pour a thin-layer screed (up to 30 mm), mount the tile.

There are also modern adhesive compositions(and elastic grouts), allowing tiling wooden bases, including movable and heated ones. Therefore, tiled floors are often sold here on moisture-resistant plywood or OSB.

Important! Taking into account the increasing loads (general or local - a large bath, a jacuzzi bowl, a floor-standing boiler ...), the calculation of the section and step of the beams under such premises must be performed individually.

If desired, the floors in the bathroom or in the kitchen wooden house can be completed with a heating cable or pipes for the water circuit of the heating system. They are mounted both in screeds and a layer of tile adhesive, and between lags in a deliberately created air gap. With any option chosen, the ceiling must be well insulated so as not to heat the ceiling of the room from below, preferably equipped with waterproofing with a reflective foil layer.