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How long can a 150 x 150 beam withstand? What loads can the beam withstand? What is needed to make the correct calculation

One of the most popular solutions for the device interfloor ceilings in private houses is the use of a load-bearing structure made of wooden beams. It must withstand the design loads without bending and, especially, without collapsing. Before you start constructing the floor, we recommend using our online calculator and calculating the main parameters beam structure.

Floor beams or ceiling joists are load-bearing structure at home, so before you start installing floor joists yourself log house at home or in a bathhouse, we strongly recommend that you take special care approach the choice of material And calculate correctly floor construction.

For the manufacture of floor joists, it is best to use dry, first-grade material impregnated with a fire-bioprotective composition.

Beams are most often embedded:

How to ensure the strength of floors and convenient installation

Having previously marked the places where the beams will be inserted, cuts are made in the log and tight beams are inserted into them at a distance of about 600 mm from each other. This distance between the beams provides the necessary strength of the floors. Most types of insulation are produced exactly 600 mm wide, which ensures convenient installation of heat and noise insulation. With this method of installing logs, there is no need to attach them additionally to the wall.

Floor joists can also be mounted after the frame has been assembled, securing them to the wall using special brackets and screws. On construction market available nowa huge variety of fastening devices. But more correct and reliable installation method - first!

Questions arising during the construction process

During construction log house, log bathhouse Questions naturally arise: What section should I embed the floor beams (floor, ceiling)? What load can wooden joists (beams) withstand? Which maximum length beams is possible for what section of board, beam, log?

Based on the table below, it is easy to calculate the cross-section of the log, depending on its length. The data is given for standard spans with a width of 2 to 6 meters, with a frequency of lags every 600 mm (distance between lags 600 mm) Design load 300 kg per 1 sq. meter. The table shows the breaking loads for these logs in kg per square meter.

Simply put, the numbers on a colored background are the load in kilograms per 1 m2, at which the ceiling will simply break. But in order to prevent the floor from “springing”, there is also an indicator of the bending of the beam. Blue background - the floor will not “spring”, yellow - maximum permissible, and red background the floor will sag under a load of 300 kg more permissible norm.

Table for calculating the destructive load (kg/m2) on the joists (beams) of the floors of a log house.

Blue are highlighted in the table values ​​with safety margin

Yellow the values ​​are highlighted in the table maximum permissible by beam deflection for these conditions

In red values ​​are highlighted unacceptable for deflection(more than twice the permissible norm) of beams for these conditions.

Note: additional rigidity can also be given to the beam by splicing two or more boards in thickness.

Date of publication: 03/03/2018 00:00

What loads will the beam withstand?

Timber and logs have long been used in Rus' to build houses. Wooden buildings have whole line advantages:

• Ease of building construction.
• High speed of construction;
• Low cost.
• Unique microclimate. Wooden house“breathes”, the air in it is much lighter and more pleasant;
• Excellent performance characteristics;
• A wooden house holds heat well. It'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 is a log rectangular section. It is considered the cheapest lumber and at the same time very convenient for construction.

The timber is made from saw logs and coniferous trees.

• Double-edged - only two are processed (cut off from the log) opposite sides, and the other two are left rounded.
• Three-edged. Three sides are cut off here.
• Four-edged - 4 sides cut off.

Dimensions:

The standard length of the timber is 6 meters. Glued laminated timber is a prefabricated structure, so the length here 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 beam cross-section must be approached with special care. After all, the safety of the building will depend on the load this building material can withstand.

To correctly calculate the load, there are special formulas and programs.

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

2. Temporary. These loads can be short-term, infrequent or long-term. This includes ground movements and erosion, wind, snow loads, the weight of people when construction work. Snow loads different, they depend on the region of construction of the building. In the north there is more snow cover, so the load on the timber will be higher.

In order for the calculation of the load to be correct, both types of loads, the characteristics of the building material, its quality, and humidity must be entered into the formula (it can be found on the Internet). Particular care must be taken to calculate the load on the timber when erecting rafters.

What load can a 150x150 beam withstand? Beam 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 15 by 15 is better used for building houses in the southern regions; in the north you will need additional insulation walls, since this lumber stores heat only at an air temperature of -15 degrees. But if you use glued laminated timber of this size, then in terms of its heat-saving properties it will be equal to a timber with a cross-section of 25 by 20 cm.

What load can a 100 by 100 mm beam 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 when constructing stairs, making supports, arches, decorating attics, and the ceiling of a house. You can also make the frame of a panel one-story house from it.

What load can a 50 by 50 mm beam withstand?

50x50 mm timber is in great demand. You can’t do without this size, as it is auxiliary material. It, of course, is not suitable for erecting walls, since it can withstand a small load, but for erecting sheathing for exterior finishing walls, frames, partitions, this size is required. A wall frame is made from 50 by 50 timber, onto which drywall is then attached. Here you can use the most various fastenings from nails to staples or wire.

Beams in a house usually belong to rafter system or overlap, and to get reliable design, the operation of which can be carried out without any fear, must be used beam calculator.

What is the beam calculator based on?

When the walls have already been brought under the second floor or under the roof, it is necessary to make, 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 does not exceed the permissible value, and the strength of the structure is at the proper level. Therefore, if you are going to use wood, you need to choose the right beams from it and make calculations to determine the required thickness and sufficient length.

The subsidence or partial destruction of the ceiling can be caused by various reasons, for example, too large a step between the lags, deflection of the cross members, too small area their cross sections or defects in the structure. To eliminate possible excesses, you should find out the expected load on the floor, be it basement or interfloor, and then use a beam calculator, taking into account their own weight. The latter can change in concrete lintels, the weight of which depends on the density of the reinforcement; for wood and metal, with a certain geometry, the weight is constant. The exception is damp wood, which is not used in construction work without first drying it.

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

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

How to calculate the load on a floor beam

The distance between the walls is called a span, and there are two of them in the room, and one span will necessarily be smaller than the other if the shape of the room is not square. Interfloor lintels or attic floor should be laid along a shorter span, the optimal length of which is from 3 to 4 meters. Longer distances may require beams non-standard sizes, which will lead to some instability of the flooring. The best solution in this case would be to use metal crossbars.

Regarding the section 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 must make up the width of the profile. In this case, deformation of the section is excluded, but if you deviate from the above indicators, then if the width exceeds the height, you will get a deflection, or, if the opposite discrepancy occurs, 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 permissible deflection is calculated from the ratio to the length of the lintel as 1:200, that is, it should be 2 centimeters per 4 meters.

To prevent the beam from sagging under the weight of logs and flooring, as well as interior items, you can grind it from below a few centimeters, giving it the shape of an arch; in this case, its height should have an appropriate margin.

Now let's turn to the formulas. The same deflection mentioned earlier is calculated as follows: f nor = L/200, where L is the span length, and 200 is the permissible distance in centimeters for each unit of beam subsidence. For reinforced concrete beam, distributed load q which is usually equated to 400 kg/m 2, the calculation of the limiting bending moment is performed using the formula M max = (q · L 2)/8. In this case, the amount of reinforcement and its weight is determined according to the following table:

Cross-sectional areas and mass of reinforcing bars

The load on any beam made of a 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– calculated resistance, which is taken from reference books depending on the material used. Since most often beams have rectangular shape, the moment of resistance can be calculated differently: W z = b h 2 /6, where b is the width of the beam, and h– height.

What else should you 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. This means that it needs to be made in such a way that there is no risk of combining the upper and lower rooms by simply overloading the furniture. This probability especially arises when the step between the beams is too large and logs are abandoned (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. If there are lags, the minimum gap between the beams can reach 1 meter.

It is also necessary to 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 flooring even heavier, since the load per square meter will be 3 times greater than when laying mineral wool. Further, we should not forget about the payload, which for interfloor floors is at least 150 kilograms per square meter. In the attic, it is enough to accept a permissible load of 75 kilograms per square.

Possibility of unsupported ceiling large areas significantly expands architectural possibilities when designing a house. A positive solution to the beam issue allows you to “play” with the volume of rooms, install panoramic windows, build large halls. But if it is not difficult to cover a distance of 3-4 meters with “wood”, then which beams to use on a span of 5 m or more is already a difficult question.

Wooden floor beams - dimensions and loads

We made a wooden floor in a timber house, and the floor shook, sagged, and a “trampoline” effect appeared; we want to make wooden floor beams 7 meters long; you need to cover a room 6.8 meters long so as not to rest the logs on intermediate supports; what should be the floor beam for a span of 6 meters, a house made of timber; what to do if you want to make an open plan - such questions are often asked by forum users.

Maxinova User FORUMHOUSE

My house is about 10x10 meters. I “threw” wooden logs onto the ceiling, their length is 5 meters, cross-section is 200x50. The distance between the joists is 60 cm. During the operation of the floor, it turned out that when children run around in one room and you stand in another, there is quite a strong vibration along the floor.

And such a case is far from the only one.

Elena555 User FORUMHOUSE

I can’t figure out what kind of beams are needed for the interfloor floors. I have a house 12x12 meters, 2 floors. The first floor is made of aerated concrete, the second floor is an attic, wooden, covered with timber 6000x150x200mm, laid every 80 cm. The logs are laid on an I-beam, which rests on a pillar installed in the middle of the first floor. When I walk on the second floor, I feel shaking.

Beams for long spans must withstand heavy loads, therefore, in order to build a strong and reliable wooden floor with a large span, they must be carefully calculated. First of all, you need to understand what load it can withstand. wooden joist one section or another. And then think about, having determined the load for the floor beam, what rough and finishing floor coverings will need to be made; what the ceiling will be hemmed with; will the floor be a full-fledged living space or uninhabited attic above the garage.

Leo060147 User FORUMHOUSE

1. Load from everyone's own weight structural elements ceilings This includes the weight of beams, insulation, fasteners, flooring, ceiling, etc.
2. Operating load. The operating load can be permanent or temporary.

When calculating the operating load, the mass of people, furniture, household appliances etc. The load temporarily increases when guests arrive, noisy celebrations, or furniture is rearranged if it is moved away from the walls to the center of the room.

Therefore, when calculating the operating load, it is necessary to think through everything - right down to what kind of furniture you plan to install, and whether there is a possibility in the future of installing a sports exercise machine, which also weighs more than one kilogram.

The following values ​​are taken for the load acting on long wooden floor beams (for attic and interfloor floors):

• Attic floor – 150 kg/sq.m. Where (according to SNiP 2.01.07-85), taking into account the safety factor, 50 kg/sq.m is the load from the floor’s own weight, and 100 kg/sq.m is the standard load.

If you plan to store things, materials and other household items in the attic, then the load is assumed to be 250 kg/sq.m.

• For interfloor slabs and slabs attic floor the total load is taken at the rate of 350-400 kg/sq.m.

Flooring with boards 200 by 50 and other common sizes

These are the types of beams on a span of 4 meters that are allowed by the standards.

Most often, in the construction of wooden floors, boards and timber of the so-called running sizes are used: 50x150, 50x200, 100x150, etc. Such beams meet the standards ( after calculation), if you plan to cover the opening no more than four meters.

For floors 6 or more meters long, the dimensions 50x150, 50x200, 100x150 are no longer suitable.

Wooden beam over 6 meters: subtleties

A beam for a span of 6 meters or more should not be made of timber and boards of standard sizes.

You should remember the rule: the strength and rigidity of the floor depend to a greater extent on the height of the beam and to a lesser extent on its width.

A distributed and concentrated load acts on the floor beam. Therefore, wooden beams for large spans are not designed “butt-to-tail”, but with a margin of strength and permissible deflection. This ensures normal and safe operation ceilings

50x200 - overlap for openings of 4 and 5 meters.

To calculate the load that the ceiling will withstand, you must have the appropriate knowledge. In order not to delve into the strength of strength formulas (and when building a garage this is definitely redundant), an ordinary developer just needs to use online calculators for calculating wooden single-span beams.

Leo060147 User FORUMHOUSE

A self-builder is most often not a professional designer. All he wants to know is what beams need to be mounted in the ceiling so that it meets the basic requirements for strength and reliability. This is what online calculators allow you to calculate.

These calculators are easy to use. To make calculations of the required values, it is enough to enter the dimensions of the logs and the length of the span that they must cover.

Also, to simplify the task, you can use ready-made tables presented by the guru of our forum with the nickname Roracotta.

Roracotta User FORUMHOUSE

I spent several evenings to make tables that would be understandable even to a novice builder:

Table 1. It presents data that meets the minimum load requirements for the floors of the second floor - 147 kg/sq.m.

Note: since the tables are based on American standards, and the sizes of lumber overseas are somewhat different from the sections accepted in our country, you need to use the column highlighted in yellow in the calculations.

Table 2. Here is data on the average load for the floors of the first and second floors - 293 kg/sq.m.

Table 3. Here is the data for the calculated increased load of 365 kg/sq.m.

How to calculate the distance between I-beams

If you carefully read the tables presented above, it becomes clear that with an increase in the span length, first of all, it is necessary to increase the height of the log, and not its width.

Leo060147 User FORUMHOUSE

You can change the rigidity and strength of the lag upward by increasing its height and making “shelves”. That is, a wooden I-beam is made.

Self-production of laminated wood beams

One of the solutions for covering long spans is the use of wooden beam. Let's consider a span of 6 meters - which beams can withstand a larger load.

According to the type of cross section, a long beam can be:

• rectangular;
• I-beam;
• box-shaped

None among self-builders consensus, which section is better. If we do not take into account purchased products (factory-made I-beams), then the ease of production in “field conditions”, without the use of expensive equipment and accessories, comes first.

Just Grandfather User FORUMHOUSE

If you look at a cross section of any metal I-beam, you can see that from 85% to 90% of the metal mass is concentrated in the “shelves”. The connecting wall contains no more than 10-15% of the metal. This is done based on calculation.

Which board to use for beams

According to the strength of strength: the larger the cross-section of the “shelves” and the farther they are spaced apart in height, the greater the loads the I-beam will withstand. For the self-builder optimal technology The manufacture of an I-beam is a simple box-shaped structure, where the upper and lower “shelves” are made of boards laid flat. (50x150mm, and side walls made of plywood with a thickness of 8-12 mm and a height of 350 to 400 mm (determined by calculation), etc.).

Plywood is nailed to the shelves or screwed with self-tapping screws (not black ones, they do not work for cutting) and must be placed on glue.

If you install such an I-beam on a six-meter span with a step of 60 cm, then it will withstand a large load. Additionally, an I-beam for a 6-meter ceiling can be lined with insulation.

Also, using a similar principle, you can connect two long boards, collecting them in a “package”, and then put them on top of each other on an edge (take boards 150x50 or 200x50), as a result, the cross-section of the beam will be 300x100 or 400x100 mm. The boards are placed on glue and tied together with pins or placed on wood grouse/dowels. You can also screw or nail plywood to the side surfaces of such a beam, having previously lubricated it with glue.

Also interesting is the experience of a forum member under the nickname Taras174, who decided to make his own glued I-beam to cover a span of 8 meters.

To do this, the forum member purchased 12 mm thick OSB sheets and cut them lengthwise into five equal parts. Then I bought a board 150x50 mm, 8 meters long. Using a dovetail cutter, I used a dovetail cutter to select a groove 12 mm deep and 14 mm wide in the middle of the board, so as to create a trapezoid with a downward expansion. OSB in grooves Taras174 glued with polyester resin(epoxy), having previously “shot” a strip of fiberglass 5 mm wide to the end of the slab with a stapler. This, according to the forum member, would strengthen the structure. To speed up drying, the glued area was heated with a heater.

Taras174 User FORUMHOUSE

On the first beam I practiced “pushing my hand.” The second one was done in 1 working day. In terms of cost, taking into account all materials, I include a solid board of 8 meters, the cost of the beam is 2000 rubles. for 1 piece

Despite the positive experience, such “squatter construction” did not escape several critical remarks expressed by our experts. Namely.