overlap between. The device of modern wooden floors of houses. Do-it-yourself installation of interfloor ceilings

An example of an attic floor on wooden beams

Overlapping on wooden beams is a load-bearing structure that separates adjacent rooms: floors, attic, underground. During its construction, factors such as bearing capacity, sound and heat insulation, seismic resistance and heat resistance are taken into account. This structure is regularly exposed to stress and atmospheric influences, therefore, it must meet the criteria for strength and wear resistance. According to the purpose of the overlap, they are classified into basement, interfloor and attic.

Design work includes the planning of the supporting structure, as well as the calculation and selection of materials. For various floors, bars of the appropriate type are used. Most often, wooden beams are typed according to external characteristics: cross section, composition and bearing capacity:

• board- a simple structural material used in the construction of the crate and subfloor;
• I-beam- structural material with a section in the form of the letter H. I-beam allows you to reduce the total weight of the structure without loss in bearing capacity;
• LVL-beam- a beam of glued veneer, made by gluing peeled softwood: pine, spruce, larch. Differs in high rates of durability at horizontal loading. They are used in the construction of rafter legs, beams of interfloor ceilings, as well as ridge beams;
• combined beam- glued laminated timber, which includes veneer from several types of wood;
• four-edged beam- quadrangular lumber, having 4 processed sides, is most popular in the construction of floors of any type;
• double edge beam(carriage) - lumber that has 2 processed sides opposite to each other. Despite the relatively low strength indicators, the carriage is often used in the construction of interfloor ceilings;
• rounded log- milled lumber from a single piece of wood, characterized by the highest load-bearing capacity. Maximum load per 1 sq. m. beams of this type is 500 kg. However, due to their rounded shape, rounded logs are more often used in the construction of attic, rather than interfloor floors.

When harvesting beams, preference is given to coniferous species due to their increased strength and resistance to putrefactive processes. An analogue of spruce, larch and pine can also be acacia, oak or maple. These types of wood are characterized by low moisture content (from 12% to 14%). Over the years, the strength of beam ceilings increases due to the evaporation of moisture from their surface. After 5 years of shrinkage, the strength of the timber approaches the strength indicators of metal beams.

Horizontal supporting structures are of several types:

• interfloor overlapping on wooden beams;
• attic floor;
• basement cover.

After the type and material of the beams are determined, the builders proceed to the calculation of the potential section. The choice of bars with one or another section directly depends on such indicators as:

Tab. 1 - Cross section of beams at a step of 0.5 meters

Tab. 2 - Cross-section of beams at a step of 1 meter.

The calculation of the number of beams for the floor is made according to the following formula:

KB \u003d DP / W, where:

• KB - the number of beams of the established section;
• DP - span length;
• W - step.

The total number of beams depends on the number of spans.

Floor covering technology on wooden beams

The maximum bearing load on the floor in residential premises is about 400 kg per 1 m 2. Based on this value, bars of the corresponding section are purchased.

In outbuildings, baths, garages and other non-residential premises, the load varies from 100 to 300 kg. on m 2. Based on these indicators, beams with a smaller section are selected (see Tables 1 and 2).

It is worth noting that each beam should have an allowance of 30 cm to the main length. This is necessary for mounting the beam into the wall. So, for example, for spans of 3 meters, beams with a length of 3.3 meters are used.

The technology of mounting beams has a number of features, among which are the following:

• The step depends on the type of building. In wooden buildings, the bars are laid parallel to each other at a distance of 1 meter, in frame houses - at a distance of 50 - 60 cm;
• The height of the beam should not be less than 1/24 of its length. Smaller indicators reduce the strength of the structure;
• The optimal width of the beam is equal to its height, or half the height.
• The distance from the nearest beams to the furnace must exceed 30 cm.

Basement ceilings are mounted according to the "pie" principle. The supporting structure consists of the following layers:

1. draft floor;
2. waterproofing;
3. insulation;
4. bearing beams;
5. lags;
6. floor boards.

Wooden beam floor construction

Floor arrangement technologies differ only in the type of fastening of the beams. When installing floor beams, hinged and recessed fastening methods are used. In the first case, metal canopies are mounted on opposite walls at an equal distance from each other - timber supports. After all the supports are placed, the floor beams snap into them. This type of fastener is suitable for premises with a strip foundation, brickwork, as well as in aerated concrete structures. The canopy will provide the beam with maximum fixation in the groove.

With recessed mounting methods, a hole for beams is cut at the base of the walls. Before mounting the beam, this recess is laid with tow. In this case, the ends of the beams can be processed as a lock. So, for example, a spike and a hole are often ground down to a trapezoidal shape and fastened according to the dovetail principle.

This method is considered the most complex and effective.

Basement installation technology consists of several stages:

1. Marking and construction of nests. With the help of a building level and a measuring tape along the first beam (ordering) from the foundation, the step of the beams is set. After that, nests are drilled at the marks, or nests are cut through with a cross section of 5-6 cm more than the beam and a depth of 10 to 15 cm. The nests are laid with a heater.
2. Beam installation. Logs are mounted in recesses. The first and last beam fit snugly against the adjacent wall. The gaps between the nest and the beams are caulked with tow or other insulation. If necessary, fixing canopies are attached to the bars and the wall. In cases where it is impossible to drill nests, ceilings are installed only on sheds (brickwork), or fastened with side rails (wooden walls).
3. Floor screed. Boards are laid on the beams. The end of the first board is pressed tightly against the adjacent wall. Nails are driven in at an angle of 45 degrees. The end of the second board is pressed against the end of the first and attached to the beams using the same technology. Depending on the length of the span, 1 board can take from 4 to 10 nails. For floors in residential premises, a five-board and nails No. 12 are optimal.

After installation of the basement floor, facing material is laid on the subfloor: fiberboard, laminate, linoleum and others.

The device of interfloor ceilings on wooden beams

The overlapping of the second floor on wooden beams is carried out according to the same technology as the installation of basement structures. The main difference between interfloor flooring and outdoor flooring is the presence of a double subfloor. At the same time, the lower draft floor is the ceiling of the 1st floor and is made of boards with a smaller section.

The construction of attic and interfloor ceilings is carried out according to the following technology:

1. Bearing beams are installed in the landing nests.
2. From below, with the help of a construction stapler, a windproof film is attached.
3. A draft floor is attached below.
4. A heater is lined in the niches between the beams. It can be mineral wool, expanded polystyrene, or ecowool based on split paper.
5. Boards are laid on top of the insulation and a screed of the upper subfloor is carried out.

Ways to reinforce wooden floor beams

Conventionally, beam reinforcement technologies can be divided into several types:

• restoration;
• reconstruction.

Restoration . This category includes such methods as reinforcement with wooden overlays, metal plates, carbon fiber wrapping, prosthetics. Let's consider each of the options in more detail.

Wooden lining

Damaged beams (rotten, brittle, potentially weak) can be reinforced with wooden overlays. To do this, the beam itself is cleaned with sandpaper or a planer and treated with an antifungal drug. On both sides lay out a beam with a smaller section. The structure is pulled together with cords and stitched through bolts.

metal plates

The bearing capacity of broken logs is restored using metal prostheses according to the technology described above. The hardware is applied to the cleaned and processed beam and tightened onto a series of through bolts.

Carbon fiber wrap

Carbon fiber glued to damaged timber.

The technology for restoring floors using carbon fiber is simple and easy. To do this, the damaged area is glued with several layers of carbon material.

Prosthetics

Prosthetics are used to increase the strength and wear resistance of the joints between the beam and the wall. This is where the effects of corrosion and wear most often appear due to the maximum pressure. Preventive measures are taken at the stage of initial installation of the structure. Metal linings are sewn with bolts to the bar spike. The reinforced structure is installed in the socket. An analogue of the overlays is a metal prosthesis. It is drilled into the body of the beam and installed in a small hole in the wall.

• installation of supports (columns, vertical beams);
• installation of additional beams.

Installation of supports

With insufficient bearing capacity of the beam, it is often reinforced with vertical supports. Installation of the pile allows you to redistribute the pressure from the beam to the support. This technology is most popular for repair work in attics and under the floor.

Additional beams

With a meter step, you can increase the bearing capacity of wooden floor beams with the help of additional bars. To do this, the floor is completely dismantled and the beam is installed in increments of 50 cm.

Video instruction

When erecting a wooden floor on beams, each of the stages of work is important: from calculations to commissioning. The videos below demonstrate the technology for designing and erecting roof structures.

1. Calculation of materials for wooden floors.

2. Construction of the basement on wooden beams

3. Erection of floor slabs on wooden beams.

4. The construction of the attic floor.

5. Ways to strengthen wooden logs.

6. Installation of the subfloor of the ceilings.

Insulation of the interfloor ceiling on wooden beams is a crucial part of the work: it is required to create a barrier to the cold and reliable sound insulation of the premises, while preventing the possible formation of drafts and mold on the ceilings.

Thermal insulation is required for a bridging between a cold basement and ground floor living quarters or between living quarters and an unheated attic. Floors between living spaces need soundproofing, and therefore the approach to solving problems will be different.

How to insulate the interfloor overlap to eliminate drafts, dampness and mold? From the point of view of building thermal physics, the insulation of an interfloor ceiling along wooden beams will be competent when the thermal insulation is located on the side of cold air.

The correct arrangement of layers in the floor structure repeats the principle of facade insulation: a vapor barrier is placed on the side of cold air inlet, then a heater, another vapor barrier, then a slab or other supporting structure. The arrangement of the layers must ensure the release of water vapor to the outside.

But when it comes to specifically wooden structures in a private house, constructive difficulties arise.

When insulating the attic floor, there are two of them: thermal insulation, sound insulation and waterproofing of the structure are required at the same time. In addition, it will be necessary to walk on the floor for periodic inspection and repairs of the roof. The "pie" of the interfloor overlap in this case will look like this:

1. A layer of material that can withstand occasional traffic.
2. Vapor permeable waterproofing.
3. Insulation.
4. Vapor barrier.
5. Basic structure.
6. Room ceiling.

Insulation of wooden floors above a cold basement requires the layers to be arranged in the reverse order:

1. Clean floor.
2. Vapor barrier.
3. Insulation.
4. Vapor barrier.
5. Basic structure.

ATTENTION: In the absence of a basement and the presence of a ventilated underground under the house, which often happens when laying pile foundations, the insulation from below must be protected with a moisture-windproof membrane.

In order to fulfill all these conditions, a competent choice of materials is necessary.

Material selection

Insulation of floors on wooden beams can be performed by any of the types of heat-insulating materials:

1. Bulk (slag, expanded clay gravel).
2. Monolithic laying (lightweight concrete - expanded clay concrete, aerated concrete, etc., foam).
3. Slab (slabs and mats from various materials of mineral and synthetic origin - from porous concrete "Velit", mineral wool, foam glass, expanded polystyrene).
4. Film.

In order to choose a heater, it is necessary to analyze their heat-insulating properties, volumetric weight and the supporting structure of the building itself.

As a rule, bulk and monolithic heaters with high thermal conductivity have an impressive weight and, in order to ensure the required heat transfer resistance of external enclosing structures, a thickness of, for example, expanded clay concrete backfill of 0.5 m will be required with a minimum volumetric weight of the material of 200 kg / m3, which is wooden beams may not endure. These heaters are more often chosen for interfloor ceilings on concrete slabs in brick houses.

The materials that are most in demand for insulation are mineral wool boards (from stone, basalt or glass wool) and expanded polystyrene. These materials have excellent characteristics:

• thermal conductivity indicators from 0.33 to 0.42 W / (m × K);
• low volumetric weight – from 10 kg/m3;
• low water absorption;
• high vapor permeability;
• compression density from 70 kPa.

These indicators indicate the following:

• insulation of interfloor ceilings along wooden beams will not require a thick layer of heat-insulating material;
• load-bearing structures will not be overloaded;
• the insulation, in the presence of proper vapor and waterproofing, will not accumulate moisture, which means it will last a long time and will
• maintain comfortable conditions in the house;
• during the repair will not collapse from the severity of the person.

No less important for the durability of the structure is the choice of vapor barrier materials. A significant number of them are offered in the construction markets. Before buying, you need to find out how this material works, and in the case of multilayer membranes, which side it should be adjacent to the insulation.

IMPORTANT: Polyethylene films, due to their short service life, brittleness and inelasticity, are unsuitable for use as vapor and waterproofing when insulating floors in a wooden house.

We warm the attic floor on wooden beams

Insulation of the attic floor on wooden beams can be done in several ways. The choice depends on the distance between the beams and financial capabilities.

First way

The floor plan using mineral wool boards is as follows:

Work algorithm:

1. Preparation of beams - impregnation with flame retardant and fungicide, if necessary, reinforcement.
2. Attach a layer of vapor barrier to the lower edge of the beams with a crate.
3. Lay a layer of soft insulation between the beams - mineral wool mats.
4. Lay the second layer of insulation on the upper edge of the floor beams - rigid mineral wool boards with a laminated surface that can withstand limited walking.
5. Fuse a layer of waterproofing welded roofing material (Technoelast, Krovlyaelast, Bikrost, etc.) onto the slabs using a building hair dryer.
6. Attach a hemmed ceiling along the crate (drywall, OSB, chipboard, lining, etc.).

Second way

Work algorithm:

1. Beam preparation.
2. Using the crate, we attach the vapor barrier to the beams.
3. We lay the first layer of thermal insulation.
4. We mount wooden logs along the beams.
5. Between the lags we lay the second layer of heat-insulating material.
6. We mount the flooring from moisture-resistant chipboard, OSB or other material.

When laying the insulation plate, fix the foam on the mounting glue or glue. According to the second method, mineral wool boards can be replaced with polystyrene foam or foam plastic.

We insulate the ceiling of the first floor

Insulation of the floor in this case can also be done in several ways, the choice depends on the design features of the house. If there is a ventilated space under the ceiling, insulation can be performed according to the attic principle by changing the alternation of layers.

First way

Insulation of the floor of the first floor along the logs, with a cold underground, is as follows:

Work algorithm:

1. Beam preparation.
2. We fasten the cranial bar along the lower edge.
3. We fasten the black floor (boards, plywood, OSB, DSP, etc.) to the cranial bars with nails.
4. We lay a moisture-windproof membrane on top, attaching it to the beams through the counter rails.
5. We put a heater in the interbeam space.
6. Laying a clean floor.

Second way

The insulation of the floor above the cold basement differs from the previous method in small nuances, respectively, the algorithm for performing work does not change.

IMPORTANT: Before performing work, the tree must be protected from decay with antiseptic impregnations and fire retardants to make it fire resistant.

Conclusion

Properly executed floor insulation between floors on wooden beams is guaranteed to ensure the comfort of housing, eliminate drafts and the formation of fungus and mold. All work will not be difficult for any homeowner who knows how to use a drill and a building level.

The overlap between floors is necessary to protect the levels of the building from each other. Today, there are many ways to accomplish this task. It should be noted that the cost may vary depending on the material. Some of the most popular devices are made of wood and metal. Which cover to choose is up to you. In our article, we will consider the features of beam ceilings, and the basic rules for their creation.

Features of the choice of material

The wooden floor is mounted with a width of not more than 8 meters. For load-bearing elements, a beam type of timber is selected, having sections from 5 by 15 to 14 by 24 cm. It is worth noting that a debarked log with an appropriate diameter indicator can be used. The step between the beams reaches from 1 to 6 meters.

In the production of the material, only coniferous wood is used. The level of strength of such a log is much higher than other types of wood. Before using the timber, it is necessary to dry it thoroughly in the air. Tapping the material with a hammer should produce a ringing sound. The length of the beam is tightly supported in the masonry nests of brick or log house, at the optimal size. In addition to floor covering on wooden beams, you can choose the following products:

• To complete the task, you can use the cranial types of bars measuring 5 by 5 cm. Such elements are mounted to the lower surface of the beams on both sides, and then the ceiling of the first floor is hemmed to the upper level.
• The floor board of the second floor is used. For such purposes, unplaned wood can also be used.
• Ideal for construction work and planed tongue-and-groove type of board.
• Warming agents. For wood, you can use a mineral plate, special rolls, as the fibrous structure will enhance fire protection. Plus, this method will improve sound insulation.
• Waterproofing film, which is used to insulate and protect the material from moisture.
• A special antiseptic, bituminous mastic or ruberoid scraps are also suitable.

Attention! The material you choose can create various decorative solutions, especially when used for this purpose.

Cover device

How to strengthen wooden floor beams? We will talk about this later in our article. It is worth noting that the surface between the levels of the building must be strengthened. For this, processing should take place to increase thermal, sound and thermal insulation, as well as ensure that all standards are met for the optimal bearing capacity of the elements.

You can make ceilings between the floors of a wooden building on your own and in about one day. Plus, for such buildings there is no need to lay a powerful foundation. The span can be 5 or 6 meters long. Also, one should not forget about significant shortcomings, for example, such as:

• The design has a high level of fire risk;
• The material may rot;
• In addition, the device must be strengthened, since the bearing capacity of the elements has poor adhesion.

Attention! The low strength of the material does not allow it to withstand, and therefore, for beams less than 5 meters long, reinforcement is needed. If this indicator is 5, 6 and higher, then it can be mounted without additional fasteners.

Types and classification of floors

The ceiling for the first floor should be waterproofed. You need to install it in such a way that there is a layer for ventilation. This method will preserve the integrity of the structure for a long period. For the 2nd level, it is not necessary to perform additional insulation - this will make it possible to evenly maintain the temperature inside the building. In this situation, it is sufficient to isolate the structure from noise exposure. To date, there are several types of overlap:

• Structures with metal beams or wooden trusses;
• Use wood as the main material.

The first type was used until the 2nd half of the 19th century. It is worth noting that they were used only if the span was large. This method can be observed in the structures of the old type of buildings, for example, stalinok. The 2nd type of overlap is used in the construction of stone and brick buildings. It should be noted that the material is used even during the overhaul.

For laying floors between floors, a dry type of wood is most often used. It should be noted that to obtain such material, the logs are dried for 1 - 2 years.

Attention! The best result is obtained when drying for a period of 3 years.

Most often, experts advise opting for coniferous types of wood, as they have the best strength indicator. By the way, pine logs are best resistant to negative environmental factors. The span and amount of material is calculated taking into account certain construction tricky skills. Next, we will look at the main ways to increase the ability to withstand the load:

• If the beams are laid side by side, then the sum of the load capacity of the adjacent elements is combined. So, if one log can withstand 6 hundred kilograms, then two can withstand a pressure of 1200.
• Strengthening the strength of structural parts four times is carried out by laying beams one on top of the other.
• Beams are calculated using this technology: the cross-sectional value is usually more than 4 parts of the length. Thus, if the thickness is 6 meters, then the length should be 24 cm.

Please note that optimally selected beams will help extend the life of the structure, as well as increase its stability.

Basics of installation work

One of the main components of the design of a wooden beam ceiling is the selected material. So, it is recommended to use deciduous or coniferous wood. The overlap is created from beams, rolls and floors and heaters. In the case of creating a building in the form of a rectangle, it is better to use masonry parallel to the smallest wall.

To avoid the occurrence of deflections of beam elements, it is necessary to maintain a certain structure between them. It is worth noting that in order to complete this task, the section of the parts and the length that the span has should be taken into account.

Attention! With a thickness of 3 cm, the distance must be kept at a distance of 50 cm. By the way, this value does not depend on the section of the beams.

Before proceeding with the installation work, the material should be treated with antiseptic agents. We lay the ends of the beams on the wall, wrap them with roofing felts. It should be noted that the ends of the elements must be left free. When performing this work, we observe a gap of 3 cm.

Attention! You have free space left, so you can seal it with mounting foam.

Next, we attach the beams to the structure with anchor bolts. We attach the cranial bars, 5 by 5 cm in size, to the side part, which will ensure a rolling. After using screws, we fasten the boards to the building. We definitely need these actions if we plan to do the ceiling on our own.

After fixing the roll, we proceed to the insulation, which will protect the building from the penetration of noise, and for the basement and basement will also create thermal insulation. For such purposes in modern construction, mineral wool, which circulates air well.

Attention! For insulation, you can use foam, sawdust, wood shavings and expanded clay.

So we got acquainted with the features of the overlap, and how to install them.

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

They made a wooden floor in a log house, and the floor is shaking, bending, the effect of a “trampoline” 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 the 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 bar 6000x150x200mm, laid every 80 cm. The logs are laid on an I-beam, which rests on a pole 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, it is necessary to understand what kind of load a wooden log of one or another section can withstand. And then think over, having determined the load for the floor beam, what kind of rough and finish flooring will need to be done; what will the ceiling be hemmed with; whether the floor will be a full-fledged living space or a non-residential attic above the garage.

Leo060147 FORUMHOUSE User

1. The load from the own weight of all structural elements of the floor. 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. is taken into account. 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 operational load, it is necessary to think through everything - up to what furniture is planned to be installed, and whether there is a possibility of installing a sports simulator in the future, which also weighs far more than 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 of the attic floor, the total load is taken at the rate 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 the construction of 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 of the ceiling.

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 the minimum load requirements 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.

According to the type of cross section, a 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.

To do 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. With a dovetail cutter, I chose a groove in the middle of the board with a depth of 12 mm and a width of 14 mm - so that a trapezoid with an extension downwards was obtained. 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.

During the construction of any private house, it is always necessary to produce various types of floors. These can be interfloor or attic structures, but in any case, their installation must be approached responsibly, and the most suitable materials must be chosen for this.

We can say that these structures are the same integral element of any home as walls, foundations or roofs.

Types of floors used in private construction

Depending on the type of buildings and the planned costs for their manufacture, the following can be used:

• reinforced concrete;
• foam concrete blocks and monolithic reinforced concrete beams;
• I-beam rails and wooden draft flooring;
• wooden joists.

Calculation of the section of wooden beams

During the construction of most private houses, developers make the floor of the second floor from a bar. This is a relatively inexpensive, but at the same time quite reliable material that has been used for such purposes for several centuries. The only necessary condition is the correct calculation of the cross section of such cross members installed in the span as a lag.

In order to more accurately determine the cross-section of a beam for overlapping, special formulas are used, which, among other things, take into account the resistance of the wood used and its moisture content. These parameters are defined in SNiP II-25-80, with which any developer or private master must be familiarized without fail.

You can also find the necessary formulas and tables there, with the help of which the parameters of the beams for specific interfloor structures are determined.

When calculating wooden floors, it is also necessary to take into account the span width, the distance between the beams, and the shape of their section. When calculating each crossbeam to be laid, it must be remembered that the value of its deflection under load should not exceed 1/250 of the span length.

Since it is quite difficult for a technically untrained person to correctly calculate the lag parameters using formulas and tables, special calculators can be used to independently select beams. In such a program, it is enough to enter a few basic quantities, and as a result, you can choose the correct dimensions of the bearing lag.

Calculation of the beam section

As an example, using one of these calculators, we will try to calculate which beam to use to cover 5 meters.

For data entry we need to know:

• the material from which the crossbar is made (only coniferous trees are recommended);
• span length;
• beam width;
• beam height;
• type of material (log or timber).

In order to make the correct calculations, we substitute the span width equal to 5 m to the input values, and set the beam type to the beam type. We will select the height and width empirically in the parameters “bar dimensions for floor beams”. Be sure to take into account such values ​​as the load per kg / m, and the step between the crossbars.

For interfloor structures, the load value should not be less than 300 kg / m, since it is necessary to take into account not only the weight of furniture and people, but also the weight of the materials themselves from which the floor is made. This includes floor beams, rough and finishing floors and, of course, insulation and soundproofing.

Advice. For non-residential attic structures, a load value of 200 kg / m will be quite sufficient.

Possible options

In almost all bases that sell lumber, floor beams are sold mainly in several sizes. As a rule, these are beams from 100x100 mm to 100x250 mm, and from 150x150 mm to 150x250 mm. In order not to waste time and money on searching for logs with non-standard sizes, the price of which can be much higher than the standard ones, we substitute into the program those parameters that are commercially available.

To do this, you must first find out on the basis of lumber what sizes they sell. Thus, we obtain that for interfloor structures the minimum size of the beam should be approximately 100x250 mm, and for attic structures 100x200 mm will be quite enough, with a step between them equal to 60 cm.

If you do not trust software calculators and want to independently calculate the size of the floor beam, then you will have to use the formulas and tables given in the relevant technical documentation. Or you can use the general rule, which says that the height of each log should be 1/24 of the length of the opening, and its width is 5/7 of the height of the crossbar.

Installation of interfloor and ceiling ceilings on wooden logs

Interfloor ceilings in a house made of timber begin to be mounted by laying a log. To do this, a prepared beam is placed on the walls, which is pre-wrapped with roofing material. This will protect the wood from moisture penetration, and as a result, from decay.

The extreme beams should be laid no closer than 5 cm from the wall, and the distance between adjacent crossbars should not exceed the previously calculated values, which in our case are 60 cm.

An important condition is that the logs must be laid over the entire thickness of the walls, having maximum support and stability. The gaps between the lags on the wall are laid with bricks or building blocks, after which the draft floor is stuffed from the top of the edged boards 150x25 mm.

Ceiling ceilings made of timber are almost completely identical to interfloor ones, with the only difference being that the thickness of the beams can be less, and the step between them is several centimeters larger.

prefabricated timber

Let's say you need logs of 150x250 mm in size, but there are no such sizes on sale, but there are always plenty of boards with dimensions of 50x250 mm at any lumber base. In order to get a beam of the desired size, it is enough to buy 3 of these boards and fasten them together.

As fasteners, it is better to use not nails, but wood screws, because over time the wood dries out, and the nails do not hold the boards together so firmly.

As the instructions for self-manufacturing prefabricated logs advise, if you use them for basement or basement floors, then before tightening with self-tapping screws, it is worth treating each board with an antiseptic.

This will prevent the appearance of wood pests and significantly increase the life of the entire floor. If you use prefabricated timber for interfloor ceilings, then no pre-treatment of the boards is required.

The admissibility of using this type of lag is obvious and not questioned. This material is also environmentally friendly, like conventional timber, since no adhesives are used during assembly.

Attention!
The load-bearing capacity of prefabricated timber is even higher than that of solid lumber, while the cost is somewhat lower.
From the foregoing, it becomes clear that in some cases the use of prefabricated elements is even more preferable than solid ones.

Glued laminated timber

This type of lumber is an acceptable alternative if the desired solid logs cannot be found, or their price is high enough for you, and it is not possible to make a prefabricated structure yourself.

Beams for floors in a wooden house made of glued beams are distinguished by good strength and resistance to loads, but they also have some disadvantages.

1. In view of the fact that adhesives are used in their manufacture, such material can no longer be called environmentally friendly.
2. In their manufacture, a fairly large percentage of low-quality lumber is used. Significant shrinkage is possible after several years of operation, which means that a laminated veneer lumber floor may "lead" over time.
3. And the main disadvantage of glued beams is their limited service life, which is determined by the manufacturer at 20 years.