Overlapping a large span with wooden beams: Instruction + Photo and Video

Overlapping a large span with wooden beams: Instruction + Photo and Video Wooden floor beams for a large span. It is not uncommon to install wooden beams between floors. The main purpose is to evenly distribute the future load on the foundation and walls of the building.

In order for the structure to perform its functions, it is necessary to select the right materials, carry out calculations of the section and length.

General information

Types of floors

All wooden floors can be divided into several types according to purpose and types of material from which they are made.

By design, they are attic, interfloor, basement and basement. According to the type of material, beams are made of glued and solid wood. The span between floors must necessarily be reliable and durable, therefore, vapor barrier and soundproof fillers are placed between the floor and ceilings in the internal volume. The ceiling must be sewn with the required materials, and the floor must be laid on top.

An attic floor can be installed as a roof element, and then it will be part of the rafter system.

It can be set as an independent item. To retain heat, it is imperative to use layers with thermal insulation and vapor barrier. The overlap of the basement and basement must be very strong and capable of withstanding heavy loads. Such spans also insulate and lay layers of material for vapor barrier so that the cold does not in any case penetrate from the basement into the house.

Overlapping a large span with wooden beams: Instruction + Photo and Video Beams differ from each other in types, each of which has its own advantages and disadvantages.

In order to make solid beams, hardwood is used. Solid wood beams are a big disadvantage, since they have a length limit - no more than 5 meters. Glued timber beams perfectly combine aesthetics and high strength. Their use helps to significantly increase the maximum length, which can be up to 20 meters and is ideal for covering large spans. Considering that this material looks very beautiful, it is often not covered with a ceiling, and it is a design element.


There are several significant advantages, which include:

  • Easy to install.
  • Ability to bridge large spans.
  • Light weight.
  • Long service life.
  • High level of fire safety.

  • The material cannot be deformed.

Overlapping beams between floors is made with a material with a rectangular section, which is typical for a board or timber, or a round one is used, which is made of a log.

Requirements for floor beams

Installation of wooden beams can entail a number of special requirements that must be taken into account.

They consist of the following:

  1. Overlapping a large span with wooden beams: Instruction + Photo and Video Beam products are required must be made of coniferous wood, since they have a high margin of safety. At the same time, the moisture content of the wood should be no more than 14%, since otherwise the logs will have a large deflection under load.

  2. It is forbidden to use wood that has undergone diseases, fungi or has been damaged by insects to create floor beams.
  3. Before starting installation, the elements for creating beams should be treated with antiseptics.
  4. In order to prevent the floor or ceiling from sagging due to the load in the future, a building lift should be made. To do this, the ceiling of the lower floor must have a slight rise - this will not interfere with you, on the contrary, under load everything will level out and be in the right position.
  5. If you plan to lay beams at a high frequency, then instead of them, you can use boards that must be installed on the edges.

Calculation procedure

Before starting the installation of a wooden floor with beams, you should perform some calculations, thanks to which you will know the size and number of beams.

To do this, you will need:

  • Determine the length of the span on which the installation will be carried out.
  • Make calculations for the expected load that will be after installation.
  • With the specified data, calculations can be made for the cross-section of the beams and the installation pitch. To do this, use special online calculators or tables.

The length of the beams will be added from data such as the length of the span to cover and the stock of the beam to be installed in the wall itself. You can find out the span using any measuring devices, and the stock of beams that will be installed in the wall directly depends on the material from which the wall is made.

Important! If the building is brick, the stock of beams should be at least 10 cm for plank beams and at least 15 cm for beams made of planks. Wooden buildings must have special grooves, the depth of which must be at least 7 cm and even more for laying the beams. If the beams play the role of the basis for the roof, then they are made 5 cm longer than the span.

The most popular version of the span, which is covered with beams, is from 250 to 400 cm.But keep in mind that the largest allowable length of beams made of a board or timber cannot be more than 600 cm. if the span is longer than the permissible size, we advise you to make beams from glued laminated timber. In addition, a special wooden truss can be installed to cover the span of more than 600 cm. The load that goes on a wooden beam, in general, consists of the weight of the span parts (internal filling, beams, floor and ceiling sheathing) and the weight of temporary items (household appliances, furniture, people present in the room).

How to carry out the work


Exact calculations for the bearing capacity of beams, as a rule, are performed by special organizations with sufficient experience ... When performing calculations on your own , the following system is used :

  • Overlapping a large span with wooden beams: Instruction + Photo and Video Attic floor with filing, insulation in which mineral wool is, has a constant load of 50 kg / m 2 . According to SNiP standards, with such a load, the norm will be 70 kg / m 2 , if the safety factor is 1.

    3. So, it is easy to find out the total load - 1.3 * 70 + 50 = 130 kg / m 2 .

  • If you are making calculations for an attic room, then you should take into account the weight of the material from which the floor is made and the objects that are in this room. In this case, the load will be 350 kg / m 2 .

  • If wooden floor beams play the role of interfloor spans, then the load value will be equal to 400 kg / m 2.

Determination of the pitch and section of the beams

When the data on the length and load of the beams is known, the installation pitch and the section size / diameter can be found ...

Please note that the indicators are interconnected, and their can be calculated according to the established rules:

  1. The height and width of the beams must have a proportion of 1.

    4 :1. Please note that the width of the beams should be from 4 to 20 cm, and the height from 10 to 30 cm (this is based on insulation material). The logs for overlap must necessarily be with a diameter of 11 to 30 cm.

  2. The installation step must necessarily have a limit from 0.3 to 1.

    2 meters (taking into account the material for insulation and the material for filing). If the house is frame, then the step must be the same as between the frames.

  3. You can define the cross-section of beams made of wood using special tables or programs. When calculating the section, it should be taken into account that the maximum allowable bending of beams in the attic is 1 from 200, and for interfloor ones from 1 to 350.


The floor trusses made of wood look like two parallel bars or logs located under each other, which are interconnected by supports, and these, in turn, are in relation to the logs or bars vertically or under angle.

The main task of the trusses is to bridge long spans if it is impossible to install additional support legs. To make trusses, special developed tables and programs are used, which take into account the types of connections, installation step, overall dimensions and section of parts. Most often, farms are made according to an industrial method using high-precision equipment. At the same time, there is an option for making the farm yourself.

If you compare timber trusses and floor beams, you can identify all the advantages and disadvantages that trusses have.

The advantages include:

  • The ability to cover a large span without using additional support legs.
  • Low overall weight, so the load on the structural elements of the structure will also be small.
  • High strength and no sagging, resulting in a long service life for floor and hem material.
  • Easy to install on all bearing elements, regardless of the material of manufacture.
  • It is possible to change the width of the laying step.

  • Internal communication lines can be set.
  • Excellent sound insulation.
  • If the trusses were made beautifully, they don't even need to be sewn up and then they will play the role of a decorative element.

But in addition to the advantages, there are some disadvantages, namely:

  • Due to the design features, the thickness of the interfloor overlap increases greatly.
  • Large costs in terms of labor when making a farm with your own hands, special equipment is required.

  • Ready-made structures are quite expensive.

Choosing trusses or wooden beams is up to you.

( 3 marks, average 5 of 5 )