Wooden floor beams provide not only the strength of the horizontal structure. The ceiling is designed to give rigidity to the entire building. For this reason, the choice of load-bearing elements and their installation should be given special attention.
Pros and cons of wood flooring
To install the floor with your own hands, you need to prepare. The floor in the house must be supported by a solid and rigid structure. Before starting work, you will have to study the requirements for the elements, the features of their calculation and the types of sections.
The following advantages of wood flooring can be distinguished:
- attractive appearance, the ability to make a wooden floor without additional measures;
- light weight, reducing the load on the walls and foundations, saving on construction;
- the possibility of carrying out repairs during operation;
- installation speed, work without additional machines and mechanisms.
But it is also worth highlighting the disadvantages:
- flammability of wood, the need for special impregnation with flame retardants;
- lower strength in comparison with reinforced concrete or metal elements;
- shrinkage and deformation under extremes of temperature and humidity;
- susceptibility to decay, fungus and mold at high humidity, it is necessary to perform antiseptic treatment at the construction stage and periodically during the service life.
Wood flooring requirements
Wooden floor beams must meet the following requirements:
- correspondence of section sizes to load, span and step;
- good strength and rigidity;
- Fire safety;
- absence of serious wood defects and damage.
There are also certain requirements for the material from which the beams are made. It is recommended to choose coniferous wood. It contains a lot of resin, therefore it is better resistant to various microorganisms. The best material are those trees that have grown in harsh conditions. Their trunk density is higher. For this reason, it is worth buying pine or spruce, which grew in the northern regions of the country.
You also need to pay attention to the harvesting time. The best is considered the period at the end of winter. At this time, the tree is in a sleeping state, there are fewer juices in it, therefore, the moisture content of the material will be less.
What are wooden floors
Wooden beams are used for almost all levels of the house. The beam frame must be provided for the following types of construction:
- basement or basement (floor of the first floor);
- interfloor overlap;
- attic floor.
The standardized payload depends on the type, which is taken into account in the calculation of wooden floor beams. Also, the difference will be in the thickness of the insulation and its necessity.
Between the beams above the basement, from 5 to 15 cm of mineral wool, foam or extruded polystyrene foam is usually laid. In interfloor structures, it will be enough to provide a couple of centimeters for sound insulation. The cold attic requires the most material. Here, the thickness can be from 10 to 20 cm. The exact values depend on the climatic region of construction.
Sometimes they prefer to make the basement not of wood, but of metal and reinforced concrete. In this case, an I-beam or channel is used as load-bearing beams, and concrete is poured into the formwork from the profiled sheet. This option will be more reliable with the likelihood of flooding. He will also better resist damp from the basement.
What are the beams
There are several signs by which the classification of wooden beams of floors is carried out: by size, material, type of section. The length of the floor beams depends on the distance between the walls. To this value, you need to add a margin on the support from two sides.. Optimally need to provide for 200-250 mm.
According to the material, the elements are divided into the following types:
- from a solid bar or board;
- from glued beams.
The latter are significantly more expensive. But such material is suitable for covering large spans. An ordinary beam can work on 4-6 m, while glued beam copes well with distances of 6-9 m. Glued beam practically does not shrink, is fireproof and resistant to moisture. You can make not only linear elements, but also bent. A significant drawback of such a material will be the presence of unnatural components (glue).
The cross section of the beams can be of the following types:
- square;
- rectangular;
- I-beam.
The latter has broadened elements at the top and bottom. In the middle of the section, it is reduced to the maximum possible size. This option allows you to rationally use wood and reduce its consumption. But to make such an element is not easy. For this reason, the I-beam is not so often used in construction.
The best option is a rectangle. In this case, the long side is vertical, and the short side is horizontal. This is because increasing the height has a better effect on strength than width. Installing a beam from a board flat is almost useless.
The most disadvantageous of the presented can be considered a square section. It is least adapted to the plot of the forces in the element.
You can also use logs to overlap. But this option has not gained popularity. A section from a board is much more profitable and more convenient to install, so it is used much more often.
Calculations
The calculation of the cross section will allow you to doubt the strength and rigidity of the structure. In this case, the maximum length that is allowed for any section is determined. To perform the calculation, you need the following data:
- the length of the wooden joist (more precisely, the distance between the supporting walls);
- the distance between the beams (their step);
- load on the structure.
The load consists of two values: permanent and temporary. Constant includes the mass of the beams themselves (still preliminary), insulation, ceiling filing, rough and clean floor. Temporary load is a mass of people and furniture. According to regulatory documents for residential premises, it is taken equal to 150 kg / m2. For the attic, you can take less, but recommended - the same. This will not only provide a certain margin of safety, but will also make it possible in the future to convert your attic into an attic without reconstruction of load-bearing elements.
The beam frame should be calculated by the following formulas:
- Mmax = (q * l2) / 8;
- Wreq = Mmax / 130.
In these formulas, q is the load per square meter. m of flooring, which includes a mass of structures and 150 kg of useful value. Moreover, these values must be multiplied by the distance between the beams. This is because for calculations you need to load per linear meter, and initially the value is calculated per square meter. l2 is the distance between the bearing walls on which the run, taken in the square, is based.
Knowing Wreb, you can choose the cross section of the overlap. W = b * h2 / 6. Knowing W, one can easily make an equation with one unknown. Here it is enough to set only one geometric characteristic b (section width) or h (its height).
Most often, a wooden beam already has a known width. It is more convenient to make it from a board 50 or 100 mm wide. You can also consider a variant with a composite section. It is made of several boards 50 mm thick.
Calculation in this case, find the required height of the element. But there are such cases that you need to fit into a certain overlap cake, so as not to reduce the height of the rooms. In this case, the height of the section is added to the equation as a known quantity, and the width is found. But the smaller the height, the more uneconomical the skeleton will be.
To tighten two or three boards together, it is convenient to use metal studs. In this case, when tightening the nuts, wider washers must be used. They prevent the metal from being pressed into a softer tree. Between a tree and steel fixtures it is necessary to provide isolation. For this, you can use a material such as TEKHNOELAST EPP brand.
Before using wooden elements, they are treated with an antiseptic composition. This is to prevent mold and rot. It is also recommended to perform flame retardant treatment that will increase fire safety. When the runs are supported on a wall of brick or concrete, their ends are wrapped with technoelast, linocrom, hydroisol or roofing material.