Table of floor spans frame house helps to choose the correct section of floor joists, which means avoiding problems with sagging floors, creaking and vibration when walking. Our homegrown approach - taking larger beams - is not economically justified. The board is cheaper than timber, especially large sections. Most often, the length of floor spans is within 3.5-4.5 meters and, by observing the correct section and pitch, a reliable floor can be installed.
Let me remind you that floor joists are installed with a certain pitch, a multiple of the long side of the rough sheathing slab, namely 305 mm, 407 mm, 488 mm and 610 mm for osb boards/ plywood measuring 2240 x 1220 mm.
For pitch 305 mm (12" OC)
For pitch 407 mm (16" OC)
For pitch 488 mm (19.2" OC)
For pitch 610 mm (24" OC)
Where did the data in these tables come from?
How to work with tables correctly and what is residential and non-residential load?
Living space is everything that is located and moves around the floor space: people, objects. Non-residential load is weight building elements. For example, the weight of floor joists and subfloor slabs.
Depends on what will be located on top: a double bed or a regular chair. Finish coating The floor could be a light laminate, or it could be a heated floor screed with tiles.
Typically for residential premises the total load is in the range of 200-250 kg per sq.m. If you plan to install cast iron bath, then look at its weight and add a lot of water and your loved one in it.
What type of wood are these values taken for?
Since our markets do not have a system for quality and accurate determination of the grade of lumber, the tables indicate the values for ordinary spruce and grade II pine according to the North American classification.
The actual cross-sectional dimensions of the boards in American tables are smaller than European ones, what should I do?
This is true. If Americans say that the board is 2" x 6", then it is not 50.8 mm x 152.4 mm. In fact it is 38.1 mm x 139.7 mm. The cross-section of the board is reduced as a result of drying and planing. Our sawmills, lumberyards and markets are also not furniture stores. Sellers claim that the board has a cross-section of 50 mm x 150 mm, but in fact it can be 40-50 mm x 135-150 mm.
Wooden floor beams provide not only the strength of the horizontal structure. The purpose of the ceiling is to provide rigidity to the entire building. It is for this reason that special attention should be paid to the selection of load-bearing elements and their installation.
Pros and cons of wooden floors
To install the ceiling yourself, you need to prepare. The floor in the house must rest on a strong 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 can be highlighted wooden floor:
- attractive appearance, the ability to make a wooden floor without additional measures;
- light weight, reduced load on walls and foundations, savings on construction;
- possibility of carrying out repairs during operation;
- speed of installation, execution of work without additional machines and mechanisms.
But it is also worth highlighting the disadvantages:
- flammability of wood, the need for special impregnation with fire retardants;
- lower strength compared to reinforced concrete or metal elements;
- shrinkage and deformation due to changes in temperature and humidity;
- susceptibility to rot, mildew and mold at high humidity, it is necessary to treat with antiseptics at the construction stage and periodically during the service life.
Requirements for wooden floors
Wooden floor beams must meet the following requirements:
- correspondence of section dimensions to load, span and pitch, this requires calculation of beams;
- good strength and rigidity;
- Fire safety;
- no serious wood defects or damage.
To work you need to prepare quality material There are also certain requirements for the material from which the beams are made. It is recommended to choose wood coniferous species. It contains a lot of resin, so it is better resistant to various microorganisms. The best material those trees that grew in harsh conditions are considered. Their trunk density is higher. For this reason, it is worth purchasing pine or spruce that grew in the northern regions of the country.
You also need to pay attention to the preparation time. The best period is considered to be at the end of winter. At this time, the tree is in a dormant state, there is less juice in it, and therefore the moisture content of the material will be less.
What types of wooden floors are there?
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 (first floor floor);
- interfloor covering;
- attic floor.
The thickness of the supporting beam for the attic is from 10 to 20 cm The normalized payload, which is taken into account in the calculation of wooden floor beams, depends on the type. There will also be a difference in the thickness of the insulation and its necessity.
Between 5 and 15 cm of mineral wool, polystyrene foam or extruded polystyrene foam is usually laid between the beams above the basement. 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 depend on the climatic region of construction.
Place between the basement beams mineral wool Sometimes they prefer to make the basement floor not from wood, but from metal and reinforced concrete. In this case, as load-bearing beams an I-beam or channel is used, and the concrete is poured into formwork made of corrugated sheets. This option will be more reliable if there is a risk of flooding. It will also better resist moisture from the basement.
What types of beams are there?
There are several criteria by which wooden floor beams are classified: 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, you need to provide 200-250 mm.
Based on material, elements are divided into the following types:
- from solid timber or boards;
- from laminated veneer lumber.
Made from laminated veneer lumber bent beams The latter are significantly more expensive. But such the material is suitable for covering large spans. A regular beam can work at distances of 4-6 m, while a laminated 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 ones. A significant disadvantage of such a material will be the presence of non-natural components (glue).
The cross-section of beams can be of the following types:
- square;
- rectangular;
- I-beam
The latter has widened 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 making such an element is not easy. For this reason, I-beams are not often used in construction.
The most commonly used timber rectangular shape The best option will become a rectangle. In this case, the long side is located vertically, and the short side is horizontal. This is due to the fact that increasing height has a better effect on strength than increasing width. Installing a beam from a board flat is practically useless.
The most unfavorable of the presented ones can be considered a square section. It is least adjusted to the diagram of forces in the element.
You can also use logs for roofing. But this option did not gain popularity. The section from the board is much more profitable and easier to install, therefore it is used much more often.
Calculations
Calculation of the cross-section will allow you to have no doubt about the strength and rigidity of the structure. In this case it is determined maximum length, which 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 the load-bearing walls);
- the distance between the beams (their pitch);
To calculate, you need to know the distance between the beams, the width of the span and the load on the structure The load consists of two values: permanent and temporary. The permanent includes the mass of the beams themselves (preliminary for now), insulation, ceiling lining, rough and finished floor. The temporary load is the mass of people and furniture. According to regulatory documents for residential premises, it is taken to be 150 kg/m2. For the attic you can take less, but it is recommended to use the same one. 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 using the following formulas:
- Mmax = (q*l2)/8;
- Wreq = Mmax/130.
In these formulas, q is the load per square meter. m of flooring, which includes the mass of structures and 150 kg of useful value. In this case, these values must be multiplied by the distance between the beams. This is due to the fact that the calculations require a load per linear meter, and initially the value was calculated per square meter. l2 - the distance between the load-bearing walls on which the purlin rests, taken in a square.
Knowing Wrequirement, you can select the section of the floor. W = b*h2/6. Knowing W, you can easily create an equation with one unknown. Here it is enough just to set one geometric characteristic b (section width) or h (its height).
More often 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.
By calculation in this case, the required height of the element is found. But there are cases when you need to fit into a certain ceiling pie so as not to reduce the height of the premises. In this case, the height of the section is added to the equation as a known quantity, 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 pins. In this case, when tightening the nuts, be sure to use wider washers. They prevent the metal from pressing into the softer wood. It is imperative to provide insulation between wood and steel fasteners. For this, you can use a material such as TECHNOELAST brand EPP.
Wooden blocks must be waterproofed before installation Before use wooden elements they are treated with an antiseptic composition. This is necessary to prevent mold and rot. It is also recommended to treat with fire retardants, which will increase fire safety. When resting the purlins on a wall made of brick or concrete, their ends are wrapped with technoelast, linocrom, waterproofing or roofing felt.
Installation of wooden beams in the floors 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 a beam structure to fulfill its functions, it is necessary to select the correct material for it and calculate the length and cross-section.
All wooden beams are divided among themselves according to their purpose and the type of material from which they are made. According to their purpose, they can be: interfloor, attic, basement and basement. Depending on the type of material, beams can be made of solid wood or laminated wood.
wooden floors in aerated concrete house
The interfloor span must be strong and reliable. Sound and vapor barrier fillers are placed in the internal volume between the ceiling and floor. The ceiling part 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 truss structure. Can be installed as a separate independent element. In order to preserve heat, it must be equipped with steam and thermal insulation.
The ceiling of the basement and ground floor must be of great strength and withstand high loads. These spans are equipped with heat and vapor barriers to prevent the penetration of cold from the basement.
Beams differ in types, which have their own advantages and disadvantages.Hardwood is used to make solid beams. A significant disadvantage of solid wooden beams is the length limitation, which cannot exceed 5 meters.
Beams made of laminated wood combine high strength and aesthetics. Their use significantly increases the maximum length, which can be up to 20 meters. Considering that glued floors look beautiful, they are often not covered with a ceiling and serve as a design element.
They have several more significant advantages, which include:
- ability to cover large spans;
- ease of installation;
- small weight;
- long period of operation;
- high level of fire safety;
- cannot be deformed.
The wooden parts of the floor beams can have a rectangular cross-section, which is typical for timber or boards, or round, made from logs.
Requirements for wooden floor beams
Installation of wooden beam floors entails a number of requirements that must be taken into account. They are as follows:
- Beam products must be made from coniferous wood, which has 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 prohibited to use wood that is susceptible to fungal diseases or damaged by insects to make beams.
- Before installation, beam elements must be treated with an antiseptic.
- To ensure that the ceiling or floor does not sag 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 under load.
- If the beams are planned to be laid with great frequency, then instead of them you can use boards that need to be installed on the ribs.
The procedure for calculating wooden beams
Before installing a wooden floor, it is necessary to carry out calculations in which to determine the number and dimensions of beams. To do this you need:
- determine the length of the span on which they will be installed;
- calculate the possible load they will bear after installation;
- Having the specified data, calculate the cross-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 that will be mounted into the wall. The span can be determined using any measuring device. The supply 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 made from boards should be at least 10 cm and at least 15 cm for beams made from timber. IN 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 with beams, ranges 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 size, then it is recommended to install beams made of laminated veneer lumber. In addition, to cover spans longer than 6 meters, you can install a wooden truss.
Load carried by a wooden beam consists of a mass of span parts (beams, internal filling, ceiling and floor coverings) and a mass of temporary elements (furniture, Appliances, people present in the room).
Accurate calculations of the load-bearing capacity of beams are usually carried out by specialized organizations. At independent execution The following system is used for calculation:
- an attic floor with a lining, in which the insulation is mineral wool, carries a constant self-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=130 kilograms per square meter;
- if a heavier material than cotton wool is used as insulation, or thick boards were used as lining, 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 attic room, then the weight of the material from which the floor is laid and the objects located in the attic is taken into account. The load in this case will be 350 kg per square meter;
- in the case where the beams serve as 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 pitch and cross-sectional dimensions or diameter.
These indicators are interrelated and are calculated according to established rules:
- The width and height of the beams should be in proportion 1:1.,4. In this case, 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 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 lining materials that will be in the space between the beams. If the structure is frame, then the step should correspond to the distance between the frames.
- The cross-section of wooden beams is determined using developed tables or using certain programs. When calculating sections, it is necessary to take into account that the maximum bending attic beams should not exceed 1/200, and between floors 1/350.
Application of wooden trusses, advantages and disadvantages
Floor trusses made of wood look like two parallel logs or bars located above each other, which are connected to each other by supports located at an angle or vertically in relation to these logs or bars. The main task that trusses solve is covering long spans if the installation of additional support posts is impossible.
For the manufacture of trusses, developed tables and programs are used, which take into account the type of connections, installation pitch, cross-section of structural parts 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.
By comparing wooden beams and floor trusses, you can determine the advantages and disadvantages that the trusses have. The advantages include:
- the ability to cover a span of significant size without additional support posts;
- insignificant mass, which entails a small load on load-bearing elements building;
- high strength and resistance to deflection, which entails long-term operation hemming and flooring 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 installing internal communication lines;
- excellent sound insulation;
- beautifully made trusses can be left unsewn and used as a decorative element.
In addition to advantages, farms have some disadvantages, which include the following:
- due to design features, the thickness of interfloor ceilings increases significantly;
- significant labor costs when making a farm with your own hands, the need for special equipment;
- high price for a finished structure.
Wood truss design
Among the many structural elements In a private house, the ceiling is one of the most important and difficult components to design and install. This is where inexperienced builders make, perhaps, the most dangerous mistakes; it is about the arrangement of this system that the most questions are asked.
1. Why choose a tree
In any building, the ceiling is a horizontal structure that serves as the basis for creating the floor. In addition, being connected to the load-bearing walls of the house, it provides lateral stability to the structure, evenly distributing possible loads. Therefore, the highest demands are placed on the reliability of this design.
Regardless of what material is used to build a house, in the private sector greatest distribution We just got wooden floors. They can often be seen in various stone cottages, and it is quite obvious that in wood construction(logs, beams, frame and frame-panel technology) there is no alternative to such a solution. There are many objective reasons for this. Let's look at the advantages and disadvantages of wood floors.
In private low-rise construction, floors are installed in several options:
- Ready reinforced concrete slab,
- Monolithic reinforced concrete slab,
- Ready-made reinforced concrete beams,
- Beams and trusses made of rolled metal,
- Flooring made of lumber.
pros
Or why wooden floors are so popular.
- Small mass. By using boards or timber, we do not overload load-bearing walls and foundations. The weight of the ceiling is several times less than that of concrete or metal structures. Usually no technology is required.
- Minimum deadlines for completing work. Minimum labor intensity among all options.
- Versatility. Suitable for any building, in any environment.
- Possibility of installation at sub-zero and very high temperatures.
- No “wet” or dirty processes.
- Possibility of obtaining any level of thermal insulation and sound insulation characteristics.
- Possibility of using cavities for gaskets engineering communications(power grid, heating, water supply, sewerage, low current...).
- The relatively low price of a prefabricated frame floor made of lumber, both in terms of the cost of parts/components and the contractor’s wages.
Minuses
The disadvantages of a wooden ceiling system made of wood are quite conventional.
- The difficulty of choosing the cross-section of materials and design solutions to ensure the calculated load-bearing capacity.
- The need to carry out additional fire prevention measures, as well as provide protection from moisture and pests (antiseptic treatment).
- The need to purchase soundproofing materials.
- Strict adherence to technology to avoid construction errors.
2. What material to use for assembly
Wooden flooring always consists of beams. But they can be made from a variety of lumber:
- Rounded log up to 30 cm in diameter.
- The beam is four-edged.
- Large section board (thickness from 50 mm, width up to 300 mm).
- Several boards of relatively small thickness, twisted face to face.
- I-beams, the upper and lower chords of which are made of edged planed boards/bars, and vertical wall- from OSB-3, plywood or profiled metal (wood-metal product).
- Closed boxes made of sheet materials(plywood, OSB).
- SIP panel. In essence, these are separate sections in which the beams are already sheathed and have an insulator inside.
- Various truss designs, allowing to cover large spans.
The easiest options for installation, as well as the cheapest and most convenient for subsequent operations, are those where the floor beams are made of edged lumber.
Due to the very high requirements for load-bearing capacity, durability and geometric deviations, first-grade lumber must be considered as blanks. It is possible to use products classified as second grade according to GOST, which do not have critical geometric deviations, defects and processing defects that can reduce the strength characteristics and service life of finished parts (through knots, twists, cross-layers, deep extended cracks...).
In these structures, the use of dead wood (dead wood, dead wood, burnt wood) is excluded due to insufficient strength and multiple damage to wood-destroying diseases and insects. It would also be a big mistake to buy a timber or board “with air”, “with Armenian size”, “TU” - due to the underestimated sections.
It should be exclusively healthy stuff from green spruce or pine, since needles, due to their resin content and the structure of the massif, withstand bending loads and compression much better than most hardwood, and having a relatively low specific gravity.
Anyway edged lumber must be freed from remnants of bark and bast fibers, treated with an antiseptic and fire retardant. Dry planed lumber will perform best here, but the material natural humidity(up to 20 percent) during normal processing are also actively (and most importantly - effectively) used, especially since the price edged timber or boards of this type are noticeably lower.
3. How to choose the size of beams and at what step to arrange them
The length of the beam is calculated in such a way that it covers the existing span and has a “margin” to provide support on load-bearing walls (read below for specific figures for permissible spans and wall penetration).
The cross-section of the board/beam is determined depending on the design loads that will be exerted on the floor during the operation of the building. These loads are divided into:
- Permanent.
- Temporary.
Temporary loads in a residential building include the weight of people and animals that can move along the floor, moving objects. Constant loads include the mass of the lumber of the structure itself (beams, joists), floor filling (insulation/noise insulation, insulating sheets), hemming (rolling), rough and finishing flooring, finishing flooring, partitions, as well as built-in communications, furniture, equipment and household items...
Also, you should not lose sight of the possibility of storing objects and materials, for example, when determining the load-bearing capacity of the floors of a non-residential cold attic, where unnecessary, rarely used things can be stored.
As starting point the sum of permanent and temporary loads is taken, and a safety factor of 1.3 is usually applied to it. Exact numbers(including the cross-section of lumber) should be determined by specialists in accordance with the provisions of SNiP 2.01.07-85 “Loads and impacts”, but practice shows that the load values in private houses with wooden beams are approximately identical:
- For interfloor (including under a residential attic) and basement floors, the total load is about 350 - 400 kg/m2, where the share of the structure’s own weight is about 100 kilograms.
- For covering an unloaded attic - about 130 - 150 kg/m2.
- For covering a loaded non-residential attic up to 250 kg/m2.
It is obvious that unconditional safety is of paramount importance. Here a good margin is taken into account and the option is considered not so much of distributed loads on the entire floor (in such quantities they are practically unrealistic), but rather the possibility of a local load that can lead to deflections, which in turn caused:
- physiological discomfort of residents,
- destruction of components and materials,
- loss of aesthetic properties of the structure.
By the way, certain deflection values are allowed regulatory documents. For residential premises, they can be no more than 1/350 of the span length (that is, 10 mm at 3 meters or 20 mm at six meters), but provided that the above limiting requirements are not violated.
When choosing the cross-section of lumber to create a beam, they are usually guided by the ratio of the width and thickness of the beam or board in the range of 1/1.5 - 1/4. Specific figures will depend, first of all, on: loads and span lengths. At independent design You can use data obtained from calculations using online calculators or publicly available tables.
Optimal average cross-section of wooden floor beams, mm
As we can see, to enlarge load-bearing capacity ceilings - it is enough to choose lumber with a larger width or greater thickness. It is also possible to assemble a beam from two boards, but in such a way that the resulting product has a cross-section no less than the calculated one. It should also be noted that the load-bearing properties and stability of a wooden floor increase if logs or various types of subfloors (sheet flooring made of plywood/OSB or edged boards) are used on top of the beams.
Another way to improve the strength properties of a wooden floor is to reduce the spacing of the beams. Engineers in their projects of private houses determine different conditions the distance between the beams is from 300 mm to one and a half meters. IN frame construction The pitch of the beams is made dependent on the spacing of the posts, so that there is a post under the beam, and not just a horizontal frame run. Practice shows that the most appropriate from the point of view of practicality and cost of construction is a step of 600 or 1000 mm, since it is best suited for the subsequent installation of insulation and noise insulation by surprise (insulating materials have just such a form factor of plates and rolls). This distance also creates the optimal distance between the support points for installing floor joists installed perpendicular to the beams. The dependence of the cross section on the pitch is clearly visible from the numbers in the table.
Possible cross-section of floor beams when changing the pitch (total load per square meter is about 400 kg)
4. How to properly install and secure beams
We have decided on the step - from 60 centimeters to a meter will be the golden mean. As for spans, it is best to limit yourself to 6 meters, ideally: four to five meters. Therefore, the designer always tries to “lay” the beams along the smaller side of the house/room. If the spans are too large (more than 6 meters), then they resort to installing load-bearing walls or support columns with crossbars inside the house. This approach makes it possible to use lumber of a smaller cross-section and increase the spacing, thereby reducing the weight of the floor and its cost for the customer with the same (or better) load-bearing characteristics. As an option, trusses are created from lighter lumber using metal perforated fasteners, for example, nail plates.
In any case, the beams are placed strictly horizontally, parallel to each other, maintaining the same pitch. The wooden beam must rest on load-bearing walls and purlins by at least 10 centimeters. As a rule, use 2/3 thickness outer wall from the side of the room (so that the end of the beam does not go out onto the street and remains protected from freezing). IN wooden walls they make a cut, in stone ones they leave openings during laying. In places where the beams of supporting structures touch, it is necessary to lay insulating materials: damping elastic pads made of rubber/felt, several layers of roofing felt as waterproofing, etc. Sometimes they use firing of sections of the beam that are subsequently hidden or coating them with bitumen mastics/primers.
IN Lately Increasingly, special perforated brackets “beam holders/supports” are being used to create floors, which allow the beam to be mounted end-to-end with the wall. With help of this type brackets are also assembled assemblies with transverse crossbars and beams truncated in length (opening for flight of stairs, chimney passage, etc.). The advantages of this solution are obvious:
- The resulting T-shaped connection is very reliable.
- The work is done quickly (there is no need to make cuts, it is much easier to set a single plane).
- No cold bridges are formed along the body of the beams, because the end is moving away from the street.
- It is possible to buy lumber of shorter length, since there is no need to insert the timber/board inside the wall.
In any case, it is very important, after adjusting the lumber to size, to thoroughly antisepticize the end of the beam.
5. What insulating layers should be used inside wooden floors
To answer this question, first of all, it is necessary to divide the overlapping structures (in a year-round habitable house) into three separate types:
- Basement ceiling,
- Interfloor,
- Attic.
In each specific case, the set of pie will be different.
Interfloor ceilings in the vast majority of cases separate rooms in which temperature regime similar or close in value (if there is room/floor/zone adjustment heating system). These also include the attic floor, which separates residential attic, since this room is heated, and the insulation is located inside roofing pie. For these reasons, thermal insulation is not needed here, but the issue of combating noise, airborne (voices, music...) and shock (steps, rearranging furniture...) becomes very relevant. As sound insulation, acoustic fibrous materials based on mineral wool are laid in the ceiling cavity, and sheets of sound-proofing membranes are also laid under the sheathing.
The basement design assumes that under the ceiling there is soil or a basement, cellar, ground floor. Even if the room below is equipped for use, this type of floor requires full insulation, characteristic of the enclosing structures of a particular climate zone and a specific building with its unique thermal balance. According to the standards, on average for the Moscow region the thickness of modern insulation is good performance thermal conductivity will be about 150-200 mm.
Similar thermal insulation requirements apply to the attic floor, which does not have a heated attic above it, because it will be the main barrier to heat loss through the roof of the building. By the way, due to the greater heat flow through top part at home, the thickness of the insulation here may be required more than in other places, for example, 200 mm instead of 150 or 250 mm instead of 200.
They use polystyrene foam, EPS, mineral wool with a density of 35 kg/m3 in slabs or cut into mats from a roll (the one that is allowed for use in non-load-bearing horizontal structures is suitable). Thermal insulation is laid between the beams, usually in several layers, with the joints bandaged. The load from the insulation is transferred to the beam through the rough hemming (often it is attached to the beams using cranial bars).
Where wadding insulation/sound insulation is used in structures, it should be protected from moisture. In the basement, moisture can rise in the form of evaporation from the ground or from the basement/cellar. IN interfloor ceilings and attics, water vapor can enter, which always saturates the air in residential premises during human daily activities. In both cases, underneath the insulation you need to lay a construction vapor barrier film, which can be ordinary or reinforced polyethylene. But, if thermal insulation is performed using extruded polystyrene foam, which does not have any significant level of water absorption, then a vapor barrier will not be needed.
Insulation and fiber on top soundproofing materials protected with waterproof sheets, which can be membranes or non-perforated waterproofing.
A reliable water barrier is especially relevant in rooms with high humidity: kitchen, laundry room, bathroom... In such places it is spread on top of the beams, always with the strips overlapping by 100-150 mm and gluing the seam. The canvases along the entire perimeter of the premises must be placed on the wall - to a height of at least 50 mm above the finishing coating.
The ceiling, which will later be lined tiles, it makes sense to supplement with rough flooring made of waterproof sheet materials - various types cement-containing slabs, preferably tongue-and-groove. On such a continuous flooring, you can carry out additional coating waterproofing, perform thin-layer leveling of the plane with leveling compound, or lay tiles immediately.
You can choose another option - collect from edged boards continuous flooring, lay a hydraulic barrier, pour a thin-layer screed (up to 30 mm), install tiles.
There are also modern adhesive compositions(and elastic grouts) allowing tiling wooden bases, including movable and heated ones. Therefore, tiled floors are often sold here on moisture-resistant plywood or OSB.
Important! Taking into account the increasing loads (general or local - a large bathtub, a Jacuzzi bowl, a floor-standing boiler...), the calculation of the cross-section and pitch of beams under such rooms must be performed individually.
If desired, floors in the bathroom or kitchen wooden house can be equipped with a heating cable or pipes of the water circuit of the heating system. They are mounted both in screeds and a layer of tile adhesive, and between joists in a deliberately created air gap. With any chosen option, the ceiling must be well insulated so as not to heat the ceiling of the room from below, preferably equipped with waterproofing with a reflective foil layer.
appointed after fulfilling a number of requirements. Thus, the removal of the side elements of the formwork, which do not bear the load from the weight of the structure, is allowed only after the concrete has achieved strength that ensures the safety of the surface and edges of the corners.
More stringent requirements are imposed on the removal of load-bearing formwork of reinforced concrete structures, which can be removed only after the concrete reaches the design strength value:
- load-bearing structural elements with a span of up to 2 m – 50%;
- load-bearing structures of beams, crossbars, purlins, slabs and vaults 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%.
Standard conditions for concrete hardening 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 40-50% strength, and at 5ºC - only 30-35%. If hardened at a temperature of 30-35ºC, concrete will gain 45% strength within 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 time frame for concrete to achieve a given strength is established by the construction laboratory based on the results of testing control samples or using non-destructive testing methods. At sites with a total volume of work less than 50 m3, receiving ready-mix 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 concrete mixture without making test samples at the installation site. However, this instruction does not apply to critical paired and thin-walled structures: beams, columns, floor slabs, as well as monolithic joints of prefabricated structures.
Of course, when constructing suburban residential buildings, concrete strength measurements are usually not taken, since most construction companies There are simply no construction laboratories working in the private housing construction sector. Therefore, in this case, you will have to rely on the laboratory data of the concrete mix manufacturer. Additionally, you can conduct your own concrete strength testing. 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 to concrete surface: control and subject. Based on the height of the ball’s rebound, it will be possible, I’ll make a reservation right away - with a big stretch, to determine whether the strength of the concrete has reached the required value.
Full design load in stripped form reinforced concrete structure can be allowed only after the concrete has acquired its design strength.
A metal floor beam in the form of an I-beam has a number of undeniable advantages. So a metal I-beam can cover large spans with a significant load. In addition, the metal steel beam is absolutely non-flammable and resistant to biological influences. However, a metal beam when exposed to aggressive environment may corrode, so a protective coating must be applied to it.
In most cases in private housing construction, a metal beam has hinged supports - its ends are not rigidly fixed, for example, since in a frame steel structure. The load on the floor with steel I-beams, taking into account its own weight, should be calculated without a screed of 350 kg/m2 and 500 kg/m2 with a screed.
It is recommended to make the step between I-beams equal to 1000 mm, however, in order to save money, you can increase the step between the metal beams to 1200 mm.
The table below shows the choice of the number of an I-beam metal beam for different pitches and lengths of purlins.
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Span3 m |
Span4 m |
Span6 m |
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I-beam number at step |
I-beam number at step |
I-beam number at step |
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As can be seen from the table, with a total load of 500 kg/m2 and a span length of 6 m, you should have chosen an I-beam of a higher number and chosen a smaller beam installation step.
Added: 05/26/2012 08:21
Discussion of the issue on the forum:
We poured the ceiling between the first and second floors along I-beam No. 12, span 6 meters with an outlet 1 meter from load-bearing wall first floor. The distance between the I-beams is 2 meters, from below between them a mesh of cell 20 is connected from reinforcement No. 12, on top of mesh 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?
