Methodology and formulas for calculating wooden floor beams for strength and deflection- Review + Video

Methodology and formulas for calculating wooden floor beams for strength and deflection- Review + Video Wood is still very popular in the construction of houses, and it's not in vain. Wood has such unique qualities as strength, reliability, durability, environmental friendliness, and conifers, due to the presence of resins in the composition, enrich the air, disinfect it, and create a favorable indoor microclimate.

The material is used for arranging floors in residential buildings, and many people use either an online calculator or the services of professionals to correctly calculate a wooden beam. Calculations must be carried out without fail, this ensures a long service life.

For the construction of a wooden house, experts calculate the load on wooden beams.

In addition, in the construction industry there is the concept of determining the deflection of boards.

At any stage of building development, it is necessary to carry out mathematical calculations

Calculations are necessary for all the elements used, otherwise you will fail. Before starting the procurement of materials for construction, calculate the deflection of wooden beams. This will ensure the reliability of the future building, and you will be sure of the quality work.

Determination of the deflection and bearing capacity of floors is not an easy task, therefore it must be approached with all responsibility.

Calculations help determine how much material needs to be purchased, as well as what dimensions the beams should be.

Measure span

The first step is to measure the span that will be covered by timber beams. Also, do not forget to think over all the nuances of the ways of securing structural elements. In this situation, you need to determine how deep the fixing elements will be immersed in the walls. This will allow you to make an accurate calculation of the bearing capacity of a wooden beam.

The length of the wooden beams will give you the opportunity to accurately calculate the required parameters, including the deflection. These indicators are determined by the span length. Also, it is important to consider that the calculation is made with a certain margin.


Wooden beams entering the walls are calculated taking into account this parameter.

Consider the material

When calculating the strength of a wooden beam, you must take into account the material that is used for building. In brick houses, floor beams are installed in special nests, with a depth of 10 - 15 cm. For wooden houses there are other SNiP parameters. In this case, the depth of the nests should be 7 - 9 cm. The depth parameters of the nests determine the bearing capacity of the beams.

When using stirrups or brackets when installing slabs, the length of the beams must match the openings. In other owls, you must calculate the gap between the walls, resulting in the value of the bearing capacity.


When forming the roof slope, the beams must be removed from the walls by 30-50 cm.

The length of the edged board should be no more than 6 m.

Otherwise, this will reduce the bearing capacity and increase the deflection. Modern construction is distinguished by the fact that the spans in houses are sometimes marks of 10 - 12 m. Such dimensions provide for the use of glued beams (rectangular or I-beam). To increase the resistance indicators, the installation of supports is used. For example, columns or additional walls are often installed.

Also, to lengthen the span, truss installation technology is often used.

For the construction of low-rise buildings

Single-span floors are used: boards, logs, beams. Their length can be very diverse, but in any case it depends on the dimensions of the building.

Wooden beams take on the role of a supporting structure. Their cross-section should be 14 -25 cm, thickness 5.

5 cm - 15 cm. These sizes are the most commonly used in the construction of houses. In practice, a cross-overlapping scheme is often used. This makes it possible to strengthen the structure as much as possible without spending additional materials and time in work.

The optimal span length in the process of calculating wooden floor beams is 2.

5 - 4 m. The best section for floor beams is a height-to-width ratio of 1.5: 1.

In construction, there are certain formulas for calculating wooden beams and the necessary parameters that have been developed over the years of continuous practice.

Formulas for calculating wooden beams for bending

M / W.

= Rd

  • Methodology and formulas for calculating wooden floor beams for strength and deflection- Review + Video M - deflection moment, measured in kgf x m.
  • W - resistance level, measured in cm 3 .
  • M = (ql 2 ) / 8
  • The two variables in this formula help calculate the load on a timber beam.
  • q is the load that the beam can withstand.
  • l - floor beam length.


The result obtained from the methodology for calculating wooden beams and the degree of deflection is directly dependent on the material used and the processing method.


The importance of calculating wooden beams is so great that the strength of the entire further structure of the building depends on it. No matter how strong the timber you use for construction, during operation, it will still lose its original properties. Under the pressure and the applied load of the entire structure, the beams will begin to bend, and the more time passes, the worse.

Exceeding the indicators in 1/250 of the entire length of the floor board, increases the possibility of creating an emergency collapse situation. That is why, experts advise not to be negligent in calculating wooden floor beams in a residential building, and if you cannot calculate wooden beams yourself using a calculator, contact the professionals.


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