Floor beam span 6 m. Wooden floors. What insulating layers should be used inside wooden floors
The possibility of unsupported overlapping of large areas greatly expands the 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 block a distance of 3-4 meters with a “tree”, then which beams to use on a span of 5 m or more is already a difficult question.
Wooden floor beams - dimensions and loads
Made a wood floor log house, and the floor is shaking, bending, the “trampoline” effect has appeared; we want to make wooden floor beams of 7 meters; you need to block the room with a length of 6.8 meters 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 a free layout - such questions are often asked by members of the forum.
Maxinova FORUMHOUSE user
My house is about 10x10 meters. I “threw” wooden logs onto the ceiling, their length is 5 meters, the section is 200x50. The distance between the lags is 60 cm. During the operation of the floor, it turned out that when children run in one room and you stand in another, there is quite a strong vibration on the floor.
And this case is far from the only one.
elena555 FORUMHOUSE user
I can’t figure out which beams for interfloor ceilings are needed. My house is 12x12 meters, 2-storey. The first floor is made of aerated concrete, the second floor is attic, wooden, covered with a beam 6000x150x200mm, laid every 80 cm. 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 kind of load it can withstand wooden log one section or another. And then think over, having determined the load for the floor beam, what rough and top coat gender; what will the ceiling be hemmed with; whether the floor will be a full-fledged living space or non-residential attic above the garage.
Leo060147 FORUMHOUSE user
- The load from the own weight of all structural elements of the floor. This includes the weight of beams, insulation, fasteners, flooring, ceiling, etc.
- 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 with the arrival of guests, noisy celebrations, rearrangement of furniture, 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 - up to what furniture is planned to be installed, and whether there is a possibility of installation in the future sports simulator, which also weighs far from one kilogram.
For the load acting on wooden beams of a long floor, the following values \u200b\u200bare taken (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 - this is the load from the floor's own weight, and 100 kg / sq.m - the standard load.
If it is planned to store things, materials and other household items in the attic, then the load is assumed to be 250 kg / sq.m.
- For interfloor floors and ceilings attic floor the total load is taken from the calculation of 350-400 kg / sq.m.
Overlapping boards 200 by 50 and other running sizes
These are the beams on a span of 4 meters that are allowed by the regulations.
Most often in construction wooden floors boards and timber of the so-called running sizes are used: 50x150, 50x200, 100x150, etc. Such beams satisfy the standards ( after calculation), if it is planned to block the opening no more than four meters.
For overlapping with a length of 6 meters or more, 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 running sizes.
You should remember the rule: the strength and rigidity of the floor to a greater extent depend 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 "end-to-end", but with a margin of strength and allowable deflection. This ensures normal and safe operation overlap.
50x200 - overlap for an opening of 4 and 5 meters.
To calculate the load that the overlap will withstand, you must have the appropriate knowledge. In order not to delve into the strength of materials formulas (and this is definitely redundant when building a garage), it is enough for an ordinary developer to use online calculators for calculating wooden single-span beams.
Leo060147 FORUMHOUSE user
A self-builder is most often not a professional designer. All he wants to know is which beams need to be installed 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 necessary values, it is enough to enter the dimensions of the lag and the length of the span, which they must cover.
Also, to simplify the task, you can use ready-made tables presented by the gurus of our forum with the nickname Roracotta.
Roracotta FORUMHOUSE user
I spent several evenings to make tables that even a novice builder will understand:
Table 1. It presents data that meet minimum requirements on the load for the floors of the second floor - 147kg / sq.m.
Note: since the tables are based on American standards, and the dimensions of lumber overseas are somewhat different from the sections adopted in our country, the column highlighted in yellow should be used in the calculations.
Table 2. Here are the data on the average load for the floors of the first and second floors - 293 kg / sq.m.
Table 3. Here are 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 length of the span, first of all, it is necessary to increase the height of the log, and not its width.
Leo060147 FORUMHOUSE user
You can change the stiffness and strength of the lag upwards by increasing its height and making “shelves”. That is, a wooden I-beam is being made.
Independent production of a wooden glued beam
One solution for long span spans is the use of timber beams in the spans. Consider a span of 6 meters - which beams can withstand a large load.
By type cross section long beam can be:
- rectangular;
- I-beam;
- box-shaped.
There is no consensus among self-builders which section is better. If you do not take into account purchased products (prefabricated I-beams), then the simplicity of manufacturing in the "field conditions" comes first, without the use of expensive equipment and tooling.
Just Grandpa FORUMHOUSE user
If you look at the cross section of any metal I-beam, you can see that from 85% to 90% of the mass of the metal is concentrated in the "shelves". The bonding wall accounts for no more than 10-15% of the metal. This is done on the basis of calculation.
What board to use for beams
According to the strength of materials: the larger the section of the “shelves” and the further they are spaced from each other in height, the greater the load the I-beam will withstand. For a self-builder, the optimal technology for manufacturing an I-beam is a simple box-shaped design, where the upper and lower "shelves" are made of a board laid flat. (50x150mm, and the side walls are 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 (only not black, they do not cut) and must be glued.
If you install such an I-beam on a six-meter span in increments of 60 cm, then it will withstand a large load. Additionally, an I-beam for a ceiling of 6 meters can be laid with a heater.
Also, using a similar principle, you can connect two long boards, assembling them into a “package”, and then put them on top of each other on an edge (take boards at 150x50 or 200x50), as a result, the cross section of the beam will be 300x100 or 400x100 mm. The boards are planted on glue and pulled together with studs or planted on capercaillie / 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 independently make a glued I-beam to block a span of 8 meters.
For this, the forum member purchased OSB sheets 12 mm thick, cut them lengthwise into five equal parts. Then I bought a board 150x50 mm, 8 meters long. Fresa " dovetail"I chose a groove 12 mm deep and 14 mm wide in the middle of the board - so that I get a trapezoid with an extension downwards. OSB in grooves Taras174 glued with the help of polyester resin (epoxy), having previously “shooted” a strip of fiberglass 5 mm wide to the end of the plate with a stapler. This, according to the forum member, would strengthen the design. To speed up drying, the glued area was heated with a heater.
Taras174 FORUMHOUSE user
On the first beam, I trained "filled my hand." The second one was done in 1 business day. At a cost, taking into account all materials, I include a solid board of 8 meters, the cost of a beam is 2000 rubles. for 1 piece
Despite the positive experience, such a "squatter" did not escape several criticisms made by our experts. Namely.
01.10.2010, 11:47
calculation:
1) beam 200 * 200 * 6000 through 0.5M = 22 tr (deflection 20 mm)
2) I-beam 20B c / o 1.2m = 27 tr. (deflection 20 mm)
By weight 1) -90 kg timber, 2) - 120 kg beam
In theory, the solutions are very similar. Interested in practice, which is better?
Green Cat
01.10.2010, 11:55
Bar.
You should not do any iron at all bearing structures for in case of fire, wood holds out to the last, but iron is cracked and ready.
01.10.2010, 15:55
The temperature at which the deformation of the I-beam will go is incompatible with life. Especially if from below it will all be sheathed with drywall.
If you still decide to make wood, then I advise 200x60x6000 in increments of 600 mm.
01.10.2010, 16:55
"hryas and ready" - but it won't matter anyway)))
It can deform in one place and fly to another, where there are still conditions for life ... :) but in general you are right.
+Wood itself will sustain combustion, but iron will not...
Green Cat
01.10.2010, 17:41
The temperature at which the deformation of the I-beam will go is incompatible with life.
Not properly.
It's one thing when it's on its own, and another thing when it's under load.
Until recently, it was generally forbidden to use meth as rafters. profile, now I'm doing it with might and main.
I advise 200x60x6000 with a step of 600 mm
It will be too small, too small - we look at the caculator.
01.10.2010, 20:32
In my room, the span turned out to be 5.7 meters, the overlap between the 1st and 2nd floors. I chose an I-beam 20B after 1.3 meters, it seems that according to the calculation, the I-beam was stronger than wood. It is worth considering that a tree can be found 6.5 meters long, and the length of an I-beam is 11.7 meters or 12 meters (to cover a span of 6 meters, you need at least 15 cm per side). It would have been better to lay the plates, but I did not succeed. The difference between a tree and an I-beam was somewhere around 10-12%. When laying the walls, I installed 3 cm foam plastic between the cutout in the gas block and the I-beam.
As for the fire, you need to protect yourself.
02.10.2010, 00:47
And I put a 5.8 meter reinforced concrete slab on a 6 m span and don’t think about anything else. Doesn't burn, doesn't melt, doesn't bend...
02.10.2010, 09:00
Thanks to everyone, I still lean towards an I-beam, since it is stronger, I want to put internal walls of 100 cm foam block on the ceiling. (although it was probably possible to put 2 beams under the wall)
then wawan001 span 6M is along the axes of the walls, that is, there will be 15 cm on each side of the support.
then the Cat, I suppose if you fill up a non-combustible insulation ala expanded clay, then there will be nothing to burn there at all (a foam block house).
And another question, if you overlap with an I-beam, is it possible to use a wooden, say, 50-ku fixed to the side walls instead of the extreme beams ??
02.10.2010, 18:30
There is another option.
02.10.2010, 19:12
There is another option.
You make a carrier beam (albeit from an I-beam), on which you lay simple wooden floor beams. It will come out much cheaper.
I-beams will need one or two, but powerful. The price will still come out cheaper.
I did it myself
02.10.2010, 20:01
dengt, this idea came to my mind from the point of view of the manufacturability of the device in the future of the floors, if the wooden floors are installed inside the I-beam, and on top to make a counter-lattice (beams according to the calculation). The distance from the edge of the beam to the I-beam is 40 cm - reliably. Indeed, according to calculations on the extreme beams, the load is less than 2 times than on the neighboring one, you can put a 150x200 beam or take 2 pieces of 50x200 boards and install pieces of the board of the same size 1.5 meters long between them, and 50 I think is flimsy, although if the wall can pull and it will be fine. If you are sure about the fasteners, then probably yes.
04.10.2010, 05:57
I blocked the span with a 5 m beam 150 * 150 folded in half and tied with studs, i.e. it turned out a beam 150 * 300. It turned out pretty tough, but I would still make it out of concrete if I had the opportunity :(
05.10.2010, 09:32
[
i did it myself
span 11 by 6, divided into three parts by two I-beams and laid wooden beams, and in order not to increase the thickness of the ceiling, he laid them inside the brand. I pre-welded the corners to the brand and fastened the beams to the bolts.
As I understand it, I-beams were 6 meters long?
here already a minimum of 25B2 is needed, this is a 5 cm thicker overlay, it seems not fatal.
As for fixing the side beams to the walls, I am worried that all the other beams will sag and the outer ones will not, then the slab will sag with a “bubble”? what will it come to?
05.10.2010, 10:11
I-beam 6-gauge 20B1 - two pieces across the length, it turned out 3 zones, two with the support of beams of one side on the wall, and the second on an I-beam, and one zone with beams sandwiched between the I-beams. I did not notice any deflection, an I-beam does not go at such a length.
06.10.2010, 13:06
06.10.2010, 13:47
depending on how to load, if according to the theory 400 kg / m, then in your case 20B1 will bend by 77 mm
I wonder how you calculated it?
Installation of wooden beams in the ceilings of houses is not uncommon. Their main purpose is to evenly distribute the load on the walls and foundation of the building. In order for the beam structure to fulfill its functions, it is necessary to choose the right material for it, to calculate the length and section.
All beam ceilings made of wood are divided among themselves according to the purpose and type of material from which they are made. By appointment, they can be: interfloor, attic, basement and basement. According to the type of material, the beams can be made of solid wood or glued.
wooden floors in aerated concrete house
Interfloor span must be strong and reliable. Sound and vapor barrier fillers are placed in the internal volume between the ceiling and the floor. Ceiling is sewn up necessary material, the floor is laid on top.
The attic floor can be installed as an element of the roof, being part of it. roof structure. Can be installed as a separate independent element. In order to preserve heat, it is necessarily equipped with vapor and thermal insulation.
basement cover and ground floor must be of high strength and withstand high loads. These spans are equipped with heat and vapor barrier to prevent the penetration of cold from the basement.
Beams differ in types, which have their own advantages and disadvantages.For the manufacture of solid beams, hardwood is used. A significant disadvantage of solid wooden beams is the length limit, which cannot exceed 5 meters.
Laminated timber beams combine high strength and aesthetics. Their use significantly increases the maximum length, which can be up to 20 meters. Given that glued floors look beautiful, they are often not covered with a ceiling and they serve as a design element.
They have several other significant advantages, which include:
- ability to cover large spans;
- ease of installation;
- small mass;
- long period of operation;
- high level of fire safety;
- are not subject to deformation.
The wooden parts of the floor beams may have rectangular section, which is typical for a bar or board, or round, made of logs.
Requirements for wooden beams
The installation of wooden beam ceilings entails a number of requirements that must be taken into account. They are as follows:
- Beam products must be made of coniferous wood, which have a high margin of safety. At the same time, the moisture content of the wood should be no more than 14 percent, otherwise the logs under load will have a large deflection.
- It is forbidden to use wood prone to fungal diseases or damaged by insects for the manufacture of beams.
- Before installation, the beam elements must be treated with an antiseptic.
- To prevent the ceiling or floor from sagging even under load, it is necessary to perform a construction lift. The ceiling of the lower floor will receive a slight rise in the center, which will become even when loaded.
- If the bars are planned to be laid with great frequency, then boards can be used instead of them, which must be installed on the ribs.
The procedure for calculating wooden beams
Before carrying out the installation of a wooden floor, it is necessary to carry out calculations in which to determine the number and dimensions of the beams. For this you need:
- determine the length of the span on which they will be installed;
- calculate possible load, which they will carry after installation;
- having the indicated data, calculate the section of the beams and the step with which they will be installed. For this, special tables and programs are used.
Beam length consists of the length of the span that needs to be covered, and the stock of the beam, which will be built into the wall. The span can be determined using any measuring device. The stock of beams that will be mounted in the wall depends on the material from which the wall is made.
Important!
If the building is built of brick, then the margin for beams from the board should be at least 10 cm and at least 15 cm for beams made of timber. AT wooden buildings special grooves are made, with a depth of 7 cm or more, for laying beams. If the beams serve as the basis for the roof rafters, then they are made 4-6 cm longer than the span.
The most used span, which is covered by beams, is from 2.5 to 4 meters. The maximum length of beams made of timber or boards cannot exceed 6 meters. If the span length exceeds this dimension, it is recommended to install beams from glued beams. In addition, to cover spans that are more than 6 meters, you can install a wooden truss.
Load , which carries wooden beam, consists of a mass of span details (beams, internal filling, ceiling and floor cladding) and a mass of temporary elements (furniture, household appliances, people present in the room).
Accurate calculations of the bearing capacity of beams are usually carried out by specialized organizations. When performing the calculation independently, the following system is used:
- an attic floor with a lining, in which mineral wool is a heater, carries a constant own load of 50 kg per square meter. With such a load, according to SNiP standards, the standard load will be 70 kg per square meter with a safety factor of 1.3. Finding out the total load is not difficult: 1.3x70 + 50 \u003d 130 kilograms per square meter;
- if a heavier material than cotton wool is used as a heater, or thick boards were used as a filing, then the standard load will be 150 kg per square meter. And the total load will have a different value: 150x1.3 + 50 = 245 kg per square meter;
- if the calculation is carried out for the attic room, then the weight of the material from which the floor is laid and the objects in the attic are taken into account. The load in this case will be 350 kg per square meter;
- in the case when the beams perform the function of interfloor spans, the calculated load is 400 kg per square meter.
Calculation of wooden floor beams
Determination of the section and pitch of wooden beams
By calculating the load and length of the beams, you can determine their step and cross-sectional dimensions or diameter.
These indicators are interconnected and calculated according to the established rules:
- The width and height of the beams should be in the ratio 1:1.,4. At the same time, the width of the beams should be in the range from 4 to 20 cm, and the height from 10 to 30 cm, taking into account the thickness of the insulation material. Logs for floors should have a diameter in the range from 11 to 30 cm.
- The installation step should be in the range from 30 to 120 cm, taking into account the insulation and hemming materials, which will be in the inter-beam space. If the structure is frame, then the step should correspond to the distance between the frames.
- The determination of the section of wooden beams is carried out according to the developed tables or using certain programs. When calculating the sections, it must be taken into account that the maximum bending of the attic beams should not exceed 1/200, and interfloor 1/350.
The use of wooden trusses, advantages and disadvantages
Floor trusses made of wood look like two logs or bars parallel to each other, which are interconnected by supports located at an angle or vertically with respect to these logs or bars. The main task that trusses solve is to cover long spans if the installation of additional support posts is not possible.
For the manufacture of trusses, developed tables and programs are used, which take into account the type of connections, the installation step, the section of the structural details and its overall dimensions. Often, trusses are manufactured industrially using high-precision equipment. Along with this, you can make a farm with your own hands.
Comparing wooden beams and floor trusses, you can determine the advantages and disadvantages that trusses have. The benefits include:
- the ability to cover a span of considerable size without additional support posts;
- insignificant mass, which entails a small load on the load-bearing elements of the building;
- high strength and resistance to deflection, which entails long-term operation of hemming and floor materials;
- ease of installation on any load-bearing elements of the building, regardless of the material from which they are made;
- the ability to change the width of the truss laying step;
- possibility of installation of internal communication lines;
- excellent sound insulation;
- beautifully made trusses can be left unsewn and used as a decorative element.
In addition to the advantages, farms have some disadvantages, which include the following:
- at the expense design features, the thickness of interfloor ceilings increases significantly;
- significant labor costs in making a farm with your own hands, the need for special equipment;
- high price for the finished structure.
Wooden truss design
appointed after meeting a number of requirements. Thus, the removal of side formwork elements that do not bear the load from the weight of the structures is allowed only after the concrete has reached strength, ensuring the safety of the surface and edges of the corners.
More stringent requirements are imposed on the removal of the bearing formwork of reinforced concrete structures, which is allowed to be removed only after the concrete reaches the strength value from the design one:
- load-bearing structural elements with a span of up to 2 m - 50%;
- load-bearing structures of beams, crossbars, girders, slabs and arches with a span of 2-6 m - at least 70%;
- load-bearing structures with a span of more than 6 m - at least 80%;
- load-bearing structures reinforced with load-bearing welded frames - at least 25%.
The standard conditions for hardening concrete are: temperature 20±5ºC and air humidity above
90%. It should be borne in mind that in practice, as a rule, real conditions do not correspond to standard standards, and the concrete hardening process either slows down or accelerates. For example, at a temperature of 10ºC after 7 days, concrete will gain strength of 40-50%, and at 5ºC - only 30-35%. In the case of hardening at a temperature of 30-35ºC, concrete will gain 45% strength after 3 days. At negative temperatures, concrete without special additives does not gain strength at all. Therefore, the decision to strip the formwork and load the structure should be made after testing the concrete for strength.
The terms for concrete to achieve a given strength are established by the construction laboratory based on the results of testing control samples or non-destructive testing methods. At facilities with a total volume of work less than 50 m 3, receiving ready-mixed concrete from factories or installations located at a distance of no more than 20 km, it is allowed to assess the strength of concrete according to the laboratory of the manufacturer of the concrete mix without making control samples at the place of laying. However, this instruction does not apply to critical paired and thin-walled structures: beams, columns, floor slabs, as well as to monolithic joints of prefabricated structures.
Of course, during the construction of suburban residential buildings, concrete strength measurements are usually not performed, since most construction companies operating in the private housing sector simply do not have construction laboratories. Therefore, in this case, you will have to focus on the data of the laboratory of the manufacturer of the concrete mix. Additionally, you can conduct your own test of concrete for strength. To do this, you need to take a metal ball with a diameter of at least 20 mm and throw it from the same height onto a concrete surface: control and test. According to the height of the rebound of the ball, it will be possible, I will immediately make a reservation - with a big stretch, to determine whether the strength of the concrete has reached the required value.
The full design load in the stripped reinforced concrete structure can be allowed only after the concrete has acquired design strength.
Metal floor beam in the form of an I-profile - has a number of undeniable advantages. So metallic I-beam it is possible to block large spans with a significant load. In addition, metal steel beam absolutely nonflammable and resistant to biological influences. However, a metal beam, when exposed to an aggressive environment can corrode, so a protective coating is required.
In most cases, in private housing construction, a metal beam has hinged supports - its ends are not rigidly fixed, for example, as in a steel frame structure. The load on the ceiling with steel I-beams, taking into account their own weight, should be calculated without a screed of 350 kg / m 2 and 500 kg / m 2 with a screed.
The step between the I-beams is recommended to be 1000 mm, however, in order to save money, you can increase the step between the metal beams up to 1200 mm.
The table below shows the choice of the number of the I-beam metal beam when different pitch and run lengths.
|
Span3 m |
span4 m |
Span6 m |
|||||||
|
No. I-beam at step |
No. I-beam at step |
No. I-beam at step |
|||||||
As can be seen from the table, with a total load of 500 kg / m 2 and a span of 6 m, you should have chosen an I-beam of a higher number, and choose a smaller beam installation step.
Added: 05/26/2012 08:21
Forum discussion:
We poured the ceiling between the first and second floors along the I-beam No. 12, a span of 6 meters with a release of 1 meter from the load-bearing wall of the first floor. The distance between the I-beams is 2 meters, from the bottom between them from the reinforcement No. 12 a grid cell 20 is connected from above the grid No. 5 cell 10 cm. Question: after how many days can the formwork be removed and after how many days can the walls be laid, including at the outlet?
Wooden floor beams provide not only the strength of the horizontal structure. Overlapping is designed to give rigidity to the entire building. It is for this reason that the choice of load-bearing elements and their installation should be given special attention.
Pros and cons of wood flooring
To install the ceiling with your own hands, you need to prepare. The floor in the house should be based on 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 walls and foundations, saving on construction;
- the possibility of carrying out repairs during operation;
- speed of installation, performance of work without additional machines and mechanisms.
But it is also worth highlighting the disadvantages:
- combustibility of wood, the need for special impregnation flame retardants;
- lower strength compared to reinforced concrete or metal elements;
- shrinkage and deformation during temperature and humidity changes;
- susceptibility to decay, fungus and mold high humidity, it is necessary to carry out 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 the cross-sectional dimensions to the load, span and step, this requires the calculation of beams;
- good strength and rigidity;
- Fire safety;
- absence of serious defects of wood and damages.
For work it is necessary to prepare quality material There are also certain requirements for the material from which the beams are made. It is recommended to choose softwood. It contains a lot of resin, so it better resists various microorganisms. best material those trees that have grown in harsh conditions are considered. Their stem 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 preparation time. The best period is at the end of winter. At this time, the tree is in a dormant state, there is less juice in it, therefore, the moisture content of the material will be less.
What are wooden floors
Wooden floor 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 (floor of the first floor);
- interfloor overlap;
- attic cover.
The thickness of the supporting beam for the attic is from 10 to 20 cm The normalized 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 need.
Between the beams above the basement, usually 5 to 15 cm of mineral wool, polystyrene foam or extruded polystyrene foam are laid. In interfloor structures, it will be enough to provide a couple of centimeters for sound insulation. A cold attic requires the most material. Here the thickness can be from 10 to 20 cm. The exact values \u200b\u200bdepend on the climatic area of \u200b\u200bconstruction.
Between the beams of the basement are laid mineral wool Sometimes the basement ceiling is preferred not to be made 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 a profiled sheet. This option will be more reliable with the likelihood of flooding. It will also better resist dampness from the basement.
What are the beams
There are several signs by which the classification of wooden floor beams 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 for support on both sides. Optimally, it is necessary 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 timber.
Bent beams are made from glued beams The latter are significantly more expensive. But on the other hand, such material is suitable for covering large spans. A regular beam can work at 4-6 m, while a glued beam copes well with distances of 6-9 m. Glued laminated timber practically does not shrink, is fireproof and resistant to moisture. It is possible to produce not only linear elements, but also bent. A significant drawback of such a material will be the presence of non-natural components (glue).
The beam section 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.
Most often, a rectangular bar is used. The best option becomes a rectangle. In this case, the long side is located vertically, and the short side is horizontal. This is due to the fact that an increase in height has a better effect on strength than width. Installing a beam from a board flat is almost useless.
The most unfavorable of the presented can be considered a square section. It is the least fitted to the diagram of forces in the element.
You can also use logs to cover. But this option has not gained popularity. The cross section of the board is much more profitable and easier to install, so it is used much more often.
Calculations
The calculation of the section will allow you to have no doubt about the strength and rigidity of the structure. This determines the maximum length that is allowed for any section. To perform the calculation, you need the following data:
- the length of the wooden floor beam (more precisely, the distance between bearing walls);
- the distance between the beams (their step);
For the calculation, you need to know the distance between the beams, the span width and the load on the structure The load consists of two values: permanent and temporary. The constant includes the mass of the beams themselves (so far preliminary), insulation, ceiling filing, rough and clean floor. A temporary load is a mass of people and furniture. By regulatory documents for residential premises, it is taken equal to 150 kg / m2. For the attic, you can take less, but it is 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 reconstructing the load-bearing elements.
The beam frame should be calculated according to the following formulas:
- Mmax = (q*l2)/8;
- Wreq = Мmax/130.
In these formulas, q is the load per sq. m of overlap, which includes a mass of structures and 150 kg useful value. In this case, these values \u200b\u200bmust be multiplied by the distance between the beams. This is due to the fact that the calculations require loading on running meter, and initially the value is calculated per square. l2 - the distance between the bearing walls on which the run rests, taken in a square.
Knowing Wreq, you can choose the overlap section. W = b*h2/6. Knowing W, one can easily write an equation with one unknown. Here it is enough to specify one geometric characteristic b (width of the section) 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 the option with a composite section. It is made from several boards 50 mm thick.
Calculation in this case find the required height of the element. But there are cases when you need to fit into a certain floor pie so as not to reduce the height of the premises. In this case, as a known value, the height of the section is added to the equation, and the width is found. But the lower the height, the more uneconomical the floor frame 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 metal from being pressed into more soft wood. It is imperative to provide insulation between wood and steel fasteners. To do this, you can use a material such as TECHNOELAST brand EPP.
wooden bars Must be waterproofed prior to installation Before using wooden elements, they are treated with an antiseptic composition. This is necessary to prevent mold and decay. It is also recommended to perform treatment with flame retardants, which will increase fire safety. When the runs are supported on a brick or concrete wall, their ends are wrapped with technoelast, linocrom, hydroisol or roofing material.