The main condition for any construction is the simplicity and reliability of the design, but in order to achieve this, it is necessary to produce correct calculations strength of the material. Since for the construction wooden houses, attic or attic space used wooden frame its choice must be approached with all responsibility, because the durability, reliability and stability of the built house will directly depend on what load the beam can withstand (100x100, 50x50, 150x150, etc.).

For the correct calculation of the load withstood by the beam, special programs or formulas can be used, but in this case, additional loads will have to be introduced into the calculations, which directly affect the strength of the structure. In order to calculate the load on the beam correctly, you will have to indicate the snow and wind effects that are present directly in the building region, as well as the characteristics of the materials used (thermal isover, beam, etc.).

In this article, we will consider what kind of load a beam with a size of 50x50, 100x100, 150x150 can withstand. various designs, such as a log house, wooden floor and the truss system, and as an example, we will analyze the latter, because this is the most responsible and difficult work.

In the photo you can see the varieties of timber, which differ not only in shape, but also in the load capacity.

What will be discussed:

How does the cross-section of a log house affect its reliability?

When creating a roof, a prerequisite for its reliability is the cross section of the timber used and the type of wood, which affects durability.

Performing the calculation with your own hands, you will need to take into account such indicators as:

• what is the mass of all roofing building materials;
• the weight of the attic or attic finish;
• for truss supports and beams, the calculated value is taken into account;
• the thermal and sedimentary effects of nature are taken into account.

In addition, you will need to specify:

• distance between beams;
• the length of the gap between the rafter supports;
• the principle of fastening the rafters and the configuration of its truss;
• the severity of precipitation and the effect of winds on the structure;
• other factors that may affect the reliability of the design.

All these calculations can be done manually using special formulas. But it will be simpler both in terms of time and quality to calculate the load of the beam using special programs, and even better when these calculations are performed by a professional.

What requirements must the beam meet?

In order for the entire rafter system to be strong and reliable, the quality of building materials will have to be approached with all responsibility. For example, there should be no defects on the beam (cracks, knots, etc.), and its moisture content should not exceed 20%. In addition, a log house of any size (50x50, 100x100, 150x150, etc.) must be processed protective equipment from shashel and other insects, rotting and fire.

Also, when choosing a material, you will have to take into account that additional loads may be applied to the timber, such as:

• Continuous load beam. These include directly the weight of the entire truss system, which includes: facing and roofing materials, heaters, etc. The data obtained for each material are summarized.
• Short-term loads can be of several types: especially rare, short-term and long-term effects. The first type includes incidents that happen very rarely (earthquakes, floods, etc.). Wind and snow impacts, the movement of people repairing the roof, etc. are short-lived. All other impacts that occur within a certain period of time are long-term loads.

We determine the wind and snow load on the beam

To determine what load the beam can withstand (100x100, 150x150.50x50, etc.) under wind and snow exposure, you can use certain tables.

To determine the snow effect on rafters of different sections, the formula S \u003d Sg * µ is used.

• Sg - is the calculated weight of snow lying on the ground, which affects 1 m².

Important! This value cannot be compared with the roof load.

• µ is the value of the load on the roof surface, which varies from horizontal to sloping. This coefficient can be various meanings, it all depends on the slope of the roof.

With a surface slope of up to 25 degrees, µ takes on the value 1.

When the slope of the roof is in the range of 25-60 degrees, µ is 0.7.

With a slope of 60 degrees or more, the coefficient µ is not taken into account because it practically does not affect the truss system.

In addition to the snow load, before the construction of the truss system, the wind load on the wooden beam is calculated 50 by 50, 100x100, etc. If these indicators are not taken into account, as a result, everything can end in failure. Table values ​​and the formula W=Wo*k are used for the calculation.

Wo - is a tabular value of the wind load for each individual region.

k is the wind pressure, which has different meanings as altitude changes. These indicators are also tabular.

The table of beam loads shown in the photo when exposed to the elements is easy to use, you just need to remember that the 1st column shows the values ​​\u200b\u200bfor the steppe, desert regions, rivers, lakes, forest-steppe, tundra, seashores and reservoirs. The next column contains data related to urban areas and areas with 10 meter obstacles.

Important! In calculations, it is desirable to use information on the direction of wind movement, because this can make an important correction to the results.

By what rules is the desired cross section of the beam calculated?

Several parameters influence the selection of the log section for the truss system:

• what is the length of the rafter construction;
• the distance between each subsequent beam;
• the results of load calculations for the corresponding area.

Today, for each specific area, there are special tables with data already entered on the load values ​​\u200b\u200bfor truss systems. An example is the Moscow region:

• in order to install a Mauerlat, you can use a bar with a section of at least 100x100, 150x100 and 150x150;
• timber 200x100 can be used for diagonal valleys and rafter supports (legs);
• runs can be created from wood 100x100, 150x100 or 200x100;
• a log house 150x50 will be the best solution for tightening;
• it is best to use a log house 150x150 or 100x100 as racks;
• a 150x50 rafter is suitable for a cornice, struts or filly;
• crossbars are best installed from rafters 150x100 or 200x100;
• As a sheathing or frontal, you can use a board of at least 22x100.

The above data are optimal, that is, less than this value, the material cannot be used. Also, all dimensions are in millimeters.

Summarize

To create a reliable and durable wooden structure, you need to carefully calculate all possible loads, after which you only need to purchase timber. If you have doubts about the correctness of the calculations, it is best to use the services of a professional or use a special program that will calculate the allowable load on the timber (150x150, 100x100, etc.).

The beams in the house usually refer to the truss system or ceiling, and in order to get robust design which can be operated without any concern, it is necessary to use beam calculator.

What is the beam calculator based on

When the walls are already brought under the second floor or under the roof, it is necessary to do, in the second case, smoothly turning into rafter legs. In this case, the materials must be selected so that the load on the brick or log walls did not exceed the allowable, and the strength of the structure was at the proper level. Therefore, if you are going to use wood, you need to choose the right beams from it, make calculations to find out desired thickness and of sufficient length.

Sagging or partial destruction of the ceiling can be different reasons eg too large joist spacing, deflection of cross members, too small cross-sectional area or defects in the structure. To exclude possible excesses, you should find out the estimated load on the floor, whether it is basement or interfloor, after which we use the beam calculator, taking into account their own mass. The latter may change concrete lintels, the weight of which depends on the density of reinforcement, for wood and metal with a certain geometry, the mass is constant. An exception is damp wood, which is not used in construction work without pre-drying.

On beam systems in floors and roof structures exert a load of forces acting on the bending of the section, on torsion, on deflection along the length. For rafters, it is also necessary to provide snow and wind load, which also create certain forces applied to the beams. You also need to accurately determine the required step between the jumpers, since too a large number of crossbars will lead to excess mass of the floor (or roof), and too little, as mentioned above, will weaken the structure.

You may also be interested in the article on calculating the amount of unedged and edged board cubed:

How to calculate the load on the floor beam

The distance between the walls is called a span, and there are two of them in a room, and one span will necessarily be smaller than the other if the shape of the room is not square. Lintels of an interfloor or attic floor should be laid along a shorter span, optimal length which is from 3 to 4 meters. At greater distance beams may be required custom sizes, which will lead to some fluctuation of the flooring. The best way out in this case would be to use metal crossbars.

As for the cross section of a wooden beam, there is a certain standard that requires that the sides of the beam be in a ratio of 7: 5, that is, the height is divided into 7 parts, and 5 of them should make up the width of the profile. In this case, the deformation of the section is excluded, but if you deviate from the above indicators, then with a width exceeding the height, you will get a deflection, or, in case of a reverse discrepancy, a bend to the side. To prevent this from happening due to the excessive length of the beam, you need to know how to calculate the load on the beam. In particular, the allowable deflection is calculated from the ratio to the length of the jumper, as 1:200, that is, it should be 2 centimeters by 4 meters.

So that the beam does not sag under the weight of the lags and flooring, as well as interior items, you can carve it from the bottom by several centimeters, giving it the shape of an arch, in which case its height should have an appropriate margin.

Now let's turn to the formulas. The same deflection, which was mentioned earlier, is calculated as follows: fnorm \u003d L / 200, where L- the span length, and 200 - the allowable distance in centimeters for each unit of subsidence of the timber. For reinforced concrete beam, distributed load q to which 400 kg / m 2 is usually equated, the calculation of the limiting bending moment is performed according to the formula M max \u003d (q · L 2) / 8. In this case, the number of reinforcement and its weight is determined according to the following table:

Cross-sectional areas and masses of reinforcing bars

The load on any beam of sufficiently homogeneous material is calculated using a number of formulas. To begin with, the moment of resistance W ≥ M / R is calculated. Here M is the maximum bending moment of the applied load, and R- design resistance, which is taken from reference books, depending on the material used. Since most beams have rectangular shape, the moment of resistance can be calculated differently: W z \u003d b h 2 / 6, where b is the width of the beam, and h- height.

What else you should know about beam loads

The ceiling, as a rule, is at the same time the floor of the next floor and the ceiling of the previous one. So, you need to make it so that there is no risk of combining the upper and lower rooms by simply overloading the furniture. This is especially likely to occur when big step between the beams and the rejection of lags (plank floors are laid directly on the timber laid in the spans). In this case, the distance between the crossbars directly depends on the thickness of the boards, for example, if it is 28 millimeters, then the length of the board should not be more than 50 centimeters. In the presence of lags, the minimum gap between the beams can reach 1 meter.

You should also take into account the mass used for the floor. For example, if mats are laid from mineral wool, then square meter basement floor will weigh from 90 to 120 kilograms, depending on the thickness of the thermal insulation. Sawdust concrete will double the mass of the same area. The use of expanded clay will make the floor even harder, since the load per square meter will be 3 times more than when laying mineral wool. Next, we should not forget about the payload, which for floors is 150 kilograms per square meter minimum. In the attic enough to take permissible load 75 kilograms per square.

Today, a variety of materials are used for construction, but wooden beams are most often in demand. They are used for the construction of the truss system, for the organization of floors of attics, basements and between floors. Exactly wooden structures used in the construction of the floor on the logs. This material is durable, able to withstand numerous loads, environmentally friendly and relatively low cost. If a wooden beam is used, it is necessary to first carry out calculations regarding their length. If there is no experience, then it is better to entrust the work to specialists.

Loads on wooden structures

If floor beams are used, it should be taken into account what load will be in general. This takes into account:

• own weight of a wooden beam;
• weight from inter-beam filling, i.e. insulation, waterproofing and other things;
• sheathing.

The calculation is carried out taking into account what kind of insulation is used, what step of the beams is taken (the amount of material depends on this). The issue of insulation should be taken seriously. Cold attic will lead to an increase in heating costs, this is approximately 15% additional costs . To insulate the attic, you can purchase fiberglass or basalt slabs. They are relatively lightweight and install quickly.

The weight from furniture, equipment and people is taken into account. Usually the value is taken as an average of 50 kg / m² for hemming and inter-beam filler. The operational load according to SNiP 2.01.07-85 for overlapping in this case will be equal to:

70 * 1.3 = 90 kg / m², while

"70" is the standard, and 1.3 is the so-called safety factor.

The total value is:

50 + 90 = 130 kg/m².

The value should be rounded to big side, it turns out the number 150. If heavy material is purchased for insulation, then general meaning will be different. It will be 245 or 250 kg / m².

50 + 1.3 * 150, where 150 kg / m² is the standard value.

If the attic is used as living space, then the calculated load level rises to 350 kg / m².

This should not be forgotten, otherwise the design will not turn out as strong as it is necessary. For ordinary interfloor, a standard value of 350-400 kg / m² is used.

Cross section and other parameters

To measure the cross section of timber beams, data such as:

Table 1. Choice of section of truss systems.

• product length for the overlapping device - L;
• product height - h;
• beam width - s.

For construction work, it is recommended to use products rectangular section, while the height and width should be in a ratio of 1.4: 1. Optimal Height should be 100-300 mm, and the width - 40-200 mm (depending on the purpose of laying the material). When choosing a height, it is necessary to focus on what kind of heat insulator will be bought, since after laying it should go flush with the surface, not form cavities and gaps after sewing.

If logs are used for work, then it is best to take the diameter equal to 110-300 mm - this is the most optimal size. When installing a ceiling from wooden beams attention should be paid to what the laying step will be. It can be equal to 30-120 cm, it all depends on the features of the future structure and the expected loads. Often the step is chosen based on what the insulation will be. For building a house frame technology it must be equal to the pitch of the racks used. For example, if the vertical racks of the walls are mounted in increments of 60 cm, then the distance between the lags is made equal to 60 cm.

How is the data calculated? There are specially developed standards, according to which any calculation is carried out. Using them, it must be remembered that the deflection for an interfloor ceiling can be 1/350, and for an attic - 1/200 of the length of the product.

Table 2 attic floors depending on the span at a load of 400 kg per 1 m2.

For example, when a calculation is carried out taking into account the beam section, the following steps and span lengths are observed:

• section of a wooden beam 75 * 100 mm, step - 60 cm, span - 200 cm;
• 75*150 mm, step - 100 cm, span - 200 cm;
• 75*200 mm, span - 200 cm, etc.

Such data are used when an interfloor floor is being constructed with a planned load of 400 kg / m². If it is at the level of 150-350 kg / m² for the attic (less often interfloor) floor, then you need to take the following data:

• load 150 kg/m², span 300 cm, beam section 50*140 mm;
• 200 kg / m², span - 300 cm, beam section 50 * 160 mm, etc.

These data are shown in table 1.

If logs will be used for the construction of the floor, then the data indicated in table 2 (with a weight of 400 kg / m²) are used for the calculation. When using the given data for calculation, it must be remembered that the products should be taken whole, without defects, including cracks, rot, falling knots.

When using wooden beams for construction, utmost attention should be paid to calculations. This concerns the calculation of the section and the step of the overlap, corresponding to its length of the span. It is necessary to immediately carry out all the calculations, do not forget that for the attic, basement and interfloor structures loads will be completely different.

Publication date: 03/03/2018 00:00

What loads can the beam withstand?

Beam and logs have long been used in Russia for the construction of houses. wooden buildings have a number of advantages:

• Ease of construction.
• High construction speed;
• Low cost.
• Unique microclimate. Wooden house“breathes”, the air in it is much lighter and more pleasant;
• Excellent operational characteristics;
• A wooden house holds heat well. He's warmer brick buildings 6 times, and buildings made of foam concrete 1.5 times;
• Various types and sizes of this lumber allow you to realize a wide variety of projects and design ideas.

This kind building material represents a log of rectangular section. It is considered the cheapest lumber and at the same time very convenient for construction.

A beam is made from saw logs, conifers.

• Double-edged - processed (cut off at the log) only two opposite sides, while the other two are left rounded.
• Three-edged. There are three sides cut off.
• Four-edged - cut 4-sides.

Dimensions:

The standard length of the beam is 6 meters. Glued laminated timber is a prefabricated structure, so here the length can reach 18 meters.

Section dimensions

• Thickness from 100 to 250 mm. The section step size is 25 mm, that is, the thickness is 100, 125.
• Width from 100 mm to 275 mm.

The choice of cross-section of the beam must be approached with particular care. After all, the safety of the building will depend on what load this building material can withstand.

For the correct calculation of the load, there are special formulas and programs.

1. Permanent. These are the loads on the beam that the entire structure of the building exerts, the weight of the insulation, finishing materials and roofs.

2. Temporary. These loads can be short-term, rare and long-term. These include soil movements and erosion, wind and snow loads, and the weight of people during construction work. Snow loads different, they depend on the region of construction of the structure. In the north, the snow cover is greater, so the load on the timber will be higher.

In order for the calculation of the load to be correct in the formula (it can be found on the Internet), both types of loads, the characteristics of the building material, its quality, and humidity must be entered. Especially carefully you need to calculate the load on the timber during the construction of the rafters.

What load can a beam 150x150 withstand A bar with a section of 15 by 15 cm is widely used in the construction of buildings. It is used for the manufacture of supports, formwork and for the construction of walls, as it can withstand heavy loads. But the size of 15 by 15 is better to use for building houses in the southern regions, in the north you need additional insulation walls, since this lumber stores heat only at an air temperature of -15 degrees. But if you use a glued beam of this size, then in terms of its heat-saving properties it will be equal to a beam with a section of 25 by 20 cm.

What load can a beam 100 by 100 mm withstand

This beam is no longer so reliable, it can withstand less load, so its main application - manufacturing rafters and ceilings between floors. It is also necessary in the construction of stairs, the manufacture of props, arches, the design of attics, the ceiling of the house. You can also make a frame of a panel one-story house out of it.

What load can a beam 50 by 50 mm withstand

A beam of 50x50 mm is in great demand. You can’t do without this size when, the way it is auxiliary material. Of course, it is not suitable for building walls, since it can withstand a small load, but for building battens for exterior finish walls, frames, partitions, this size is needed. A wall frame is made from a 50 by 50 timber, onto which drywall is then attached. Here you can use a wide variety of fasteners from nails to staples or wire.

One of the most popular solutions for arranging interfloor floors in private homes is to use load-bearing structure from wooden beams. It must withstand the design loads without bending and, moreover, without collapsing. Before proceeding with the construction of the ceiling, we recommend using our online calculator and calculating the main parameters of the beam structure.