Floor joists, use and contraindications. How to make floors on joists in an apartment? Wooden floors on joists installed on floor beams

A wooden floor on joists makes it possible to avoid without the use of reinforced concrete floors or other concrete foundations, the cost of construction of which is quite high.

Effective ventilation of wood on joists in a private house - a necessary and mandatory condition for the reliability and durability of the structure.

Wooden floor on posts along joists

The figure shows a design option for a wooden floor on joists in a private house with an underground space.

The space under the floor is formed by the fact that the logs are laid on fairly high columns of brick or concrete blocks. This design allows you to raise the floor level of the first floor with a minimum volume of backfilling the basement space with soil.

Here the basement and basement space under the floor are outside, outside the thermal envelope of the house, and will be cold.

To ventilate the underground space, vents are made in opposite external walls, above ground level - through holes covered with a metal mesh to protect against rodents. The same openings should be in the internal load-bearing walls.

Air movement under the floor occurs mainly due to wind pressure.

In winter, there is a danger of soil freezing in the underground space, which can lead to heaving soils causing the floor to move relative to the walls.

To prevent freezing, it is recommended to close the vents for the winter and insulate the base.
However, deterioration of ventilation as a result of closing the vents leads to the accumulation of moisture in the insulation and wooden parts - reducing the thermal resistance and durability of these elements.

It must be said that such a device for underground space has been used in private construction for a long time. The design was not originally designed for the use of effective floor insulation.

In houses with weak floor insulation in winter, part of the heat from the room penetrated into the underground space and warmed it, preventing freezing, but increasing heat loss.

Modern floor insulation practically blocks the flow of heat into the subfloor from the premises.Freezing of the subfloor can only be prevented by saving ground heat.

Given modern requirements for energy saving, a cold underground ventilated through vents is not the best option. It is still used rather by inertia.

Scheme of effective underground ventilation in the basement of a private house through an exhaust duct

To ventilate the subfloor of a private house or cottage, it is beneficial to use effective ventilation through an exhaust duct. This ventilation scheme is the only correct option for a house with an insulated base or basement.

How to make a wooden floor on posts

In old books and construction regulations you can find floor designs on posts using NOT effective heat-waterproofing materials.

Modern floors on joists in a private house do this

The support columns are laid out from ceramic bricks or concrete blocks. The distance between adjacent columns along the log (span) is recommended to be no more than 2 m. The base of the column can be a layer of compacted crushed stone with a thickness of 50-100 mm, spilled with bitumen mastic. Or, instead of mastic, a waterproofing film is used.

The top of the columns is leveled to one level with a solution. If the solution thickness is more than 3 cm. The masonry mesh is embedded in the solution. The top of the posts is covered with a sheet of waterproofing material.

Wooden beams are laid on the waterproofing layer. The distance between adjacent joist beams (lag pitch) is determined by their cross-section, as well as the load-bearing capacity and rigidity of the overlying floor layers - sheathing, subfloor, finishing coating. Typically, a step convenient for laying standard mineral wool insulation slabs between joists is taken, about 600 mm.

For the above-mentioned lag pitch and span between the columns, taking into account the thickness of the insulation and sheathing, with normal floor loads, the lag cross-section is sufficiently 100-150x50 mm. A galvanized steel mesh is attached to the bottom of the logs lying on the posts. Instead of a mesh, you can nail boards or slats with a thickness of at least 20 mm.

A windproof, highly vapor-permeable film is laid on top of the mesh (boards) and logs.

This film prevents makes it difficult to carry away insulation particles by air flow (dust formation), but does not prevent the evaporation of moisture from the insulation and wooden parts.

A sheet of windproof, vapor-permeable film is laid on top, across the joists, and lowered on both sides of each joist until it touches the steel mesh so that a tray is formed between the joists. The film is stapled to each side of all joists.

Mineral wool insulation is laid in the formed channel between the joists on the windproof film. You can do without a windproof film if you use special insulation boards with a compacted windproof layer for the bottom layer.

How to determine the thickness of floor insulation

The thickness of the floor insulation is selected according to calculation, providing standard heat transfer resistance R = 4-5 m 2 o K/W. If the base is not insulated, then the thickness of the floor insulation is determined from the condition that the temperature of the space under the floor is equal to the temperature of the outside air. The recommended thickness of mineral wool insulation in this case is no less than 150-200 mm.

For a house with an insulated foundation and plinth, the thickness of the floor insulation can be reduced so that the sum of the heat transfer resistance of the plinth + floor is no less than the standard (see above).

How to calculate the thickness of floor (floor) thermal insulation

A sheathing of bars with a thickness of at least 50 mm is laid across the joists. Another layer of insulation is placed between the sheathing bars. This two-layer insulation design ensures that the insulation covers the cold bridges through the joists. The distance between the sheathing bars is chosen in the range of 300-600 mm., a multiple of the width of the subfloor covering slabs.

This two-layer construction of the floor base (joists + sheathing bars) allows you to conveniently place both insulation boards and floor covering slabs (CBF, plywood, etc.).

The insulation with the lathing on top is covered with a vapor barrier film. The joints of the film panels are sealed. The junctions of the film to the walls are connected to the waterproofing of the walls and the same is sealed.

It is recommended to select the thickness of the sheathing bars at 25-30 mm. greater than the thickness of the top layer of insulation. This will allow, by lowering the film on both sides of each sheathing bar, to create a ventilated gap between the vapor barrier film and the floor covering.

Vapor and thermal insulation with penofol

Instead of the top layer of insulation and vapor barrier film, it is more profitable to lay penofol - a foamed polymer covered with aluminum foil, 10 mm thick. mm. (also available under other trade names).

Penofol must be laid with the aluminized side up, towards the ventilated gap, across the sheathing bars and lowered on both sides of each bar. After this, penofol is nailed to each side of all the bars with a stapler so that a gap of 3-4 is formed between the aluminized surface and the floor slabs cm.. The joints of the penofol panels are sealed with aluminized adhesive tape. A layer of penofol will provide heat transfer resistance equivalent to a layer of mineral wool with a thickness of 40 mm., and the necessary vapor impermeability.

Subfloor boards are attached to the sheathing bars on top of a vapor-proof film or penofol. Instead of boards, slabs are more often used: cement-bonded particleboard (thickness > 22 mm.), plywood (> 18 mm.), etc. Sheets and slabs are placed with the long side on the sheathing bars. Spacers are secured under the short side between the sheathing bars. All edges of the laid sheet must be supported - a block or spacer.

The use of polystyrene foam and polystyrene foam boards as insulation is not recommended. Such slabs serve as a barrier to moisture, which is always contained in the wood of the floor. By preventing moisture from escaping from the wood, foam insulation shortens the service life of the wooden floor parts. In addition, mineral wool insulation, due to its better elasticity, adheres more tightly to the joists than polystyrene foam.

To protect the underground space from ground moisture, it is advisable to cover the entire surface of the soil with a waterproofing film (and not just under the posts, as in the figure). The joints of the covering panels are sealed. The junction of the film to the walls must be connected to the waterproofing of the walls and also sealed. The floor posts lie directly on the film.

As a result, we obtain a ventilated underground space, limited by sealed shells - on top (vapor barrier) and below (waterproofing).

Such an underground space protects the house not only from moisture and cold, but also from penetration into living spaces.

Floor with joists on intermediate walls

In modern floor designs, joists are located at a short distance from each other, which makes it possible to use lumber of a smaller cross-section, and therefore cost, and also to conveniently place insulation boards.

Instead of brick columns, it can be advantageous to rest the logs on intermediate walls laid across the logs at intervals of about 2 m. Bricks or blocks in the wall are laid using the honeycomb masonry method, half a brick thick, leaving increased gaps of 1/4 brick in the vertical joints for ventilation of the underground space. If the wall has a height of more than 0.4 m., then no less than every 2 m. length of the wall, lay out pilasters - brick-thick columns to increase the stability of the wall.

If the lag step is no more than 600 mm. and span less than 2 m., then the cross-section of the wooden log is enough to be 100x50 mm.

Wooden floor on the ground on joists

Another option for a wooden floor along joists in a private house is shown in the following figure:

Here, unlike the first option, the floor level is raised to the required height by filling the base with compacted soil.

Ventilation of the floor is carried out due to the movement of air under the influence of the draft of the ventilation duct.

Warm air is taken from the room and enters the space between the joists through the ventilation holes in the baseboards and the gap between the subfloor covering and the wall. Next, the air enters the ventilation duct.

To ensure ventilation of the underground space, baseboards with holes are used or baseboards are installed with a gap between them and the walls.

In order for the air to move more or less evenly under the entire surface of the floor, the gap for air passage is made of different widths - the farther from the ventilation duct, the wider the gap (2 cm.). Near the ventilation duct, no holes are made in the baseboards or gaps between the wall and the floor covering (or the gap is sealed with tape).

It is important to understand that in this ventilation option, unlike the first, the underground space is located inside the heat-protective shell of the house and must be warm. The outer shell of the subfloor must have a heat transfer resistance no less than the wall of the house. Otherwise, the flow of warm air from the room may lead to condensation on the subfloor parts.

Make the layer of bulk soil thicker than 600 mm. Not recommended. Pour the soil and carefully compact it in layers no more than 200 thick. mm. It is still not possible to compact the fill soil to the state of natural soil. Therefore, the soil will settle over time. A thick layer of fill soil can cause the floor to settle too much and unevenly.

The waterproofing film is laid on a leveling layer of sand with a thickness of at least 30 mm. The joints of the film panels are sealed. The junctions of the film to the walls must be connected to the waterproofing of the wall and also sealed.

Thermal insulation is laid on top of the waterproofing.

In this option, it is better to use polymer insulation boards - polystyrene foam (expanded polystyrene). The thickness of the insulation is 50-100 mm., since the ground temperature under the house is always positive.

If the walls and basement of the house are not insulated, then along the external walls a width of at least 800 mm. a thicker layer of insulation should be laid, 150 - 200 mm.

In a house with multi-layer external walls with insulation on the outside, to eliminate the cold bridge bypassing the insulation of the walls and floor, the outside must be insulated(see picture in the first part of the article).

The floor joists rest on low pads made of brick or concrete blocks.

If extruded polystyrene foam boards (XPS, penoplex, etc.) are used as thermal insulation, then the logs can be laid on pads cut from these boards.

A gap of 3-5 should be provided between the thermal insulation and the wooden floor joists. cm. for free air movement.

According to building regulations, there is one restriction on flooring. Since the space under the floor is ventilated through a natural ventilation exhaust duct, it is prohibited to make the final floor covering from combustible materials: boards, parquet boards and panels, etc. Or a non-combustible base should be provided under them, for example a prefabricated screed made of plasterboard, gypsum fiber sheets or a subfloor made of cement bonded particle boards.

In this option, the joists and other floor elements are in better humidity conditions than in the first case.

In this design, the ventilation duct serves to ventilate not only the subfloor, but also the rooms of the house. About what needs to be done to save heat emitted by the ventilation system,

Floors, soils and foundations

Ground floors are not connected to the foundation and rest directly on the ground under the house. If it is heaving, then the floor can “go on a spree” under the influence of forces in winter and spring. To prevent this from happening, the heaving soil under the house must be made not to heave. The easiest way to do this is the underground part

The design of pile foundations on bored (including TISE) and screw piles involves the installation of a cold base. Insulating the soil under a house with such foundations is a rather problematic and expensive task. Floors on the ground in a house on a pile foundation can only be recommended for non-heaving or slightly heaving soils on the site.

When building a house on heaving soils, it is necessary to have an underground part of the foundation to a depth of 0.5 - 1 m.

Z Knowledge of how to make a wooden floor using joists is very useful information that will sooner or later come in handy or is already necessary. Laying a wooden floor with your own hands will provide significant savings, whether you are planning a new construction or a major renovation. If you don’t have the desire or time to do the work yourself, you will be able to effectively supervise the work.

The main elements of a wooden floor by joists

Let's look at the main elements of wooden floors laid on joists. This system is used both for the construction of bases with subsequent finishing coating, and for finishing floors.

The main elements of wooden floors by joists:

1. Brick columns (arranged when the floor is laid on the ground using joists)
2. Lags. Representing smooth wooden beams of rectangular cross-section;
3. Coating. Boards or artificial sheet materials (OSB, chipboard, plywood).
4. Plinth or fillet are elements of the junction of the floor covering and the wall of the room.

For rough floors, unplaned (often unedged) boards and pressed slabs from waste wood are used. Finish floors are made from high-quality, well-dried, often milled boards that have a curved edge for tongue-and-groove joints and a longitudinal groove for ventilation. Often, such boards are pre-treated with protective and decorative compounds.

Basic requirements for the correct installation of a wooden floor using joists

Laying a wooden floor along joists with your own hands requires strict adherence to the following basic requirements:

1. The logs are installed strictly horizontally (except in rare cases when the slope is provided for by the project)
2. The logs must be stable.
3. The moisture content of the wood used should not exceed 12%.
4. Ventilation of the underground space must be ensured.

If you install a wooden floor with your own hands on the first floors of rooms where the base is soil, the logs are usually laid on brick columns measuring 250x250 in plan, made of ceramic (required!) bricks with cement mortar.

Wood moisture determination

The moisture content of wood is the most important factor when installing a floor using joists. If the wood is damp and not sufficiently dried, the joists and the boards themselves will soon dry out and may change shape, which will ruin the entire floor.

Before starting masonry, you need to build a small foundation for the columns.

We dig square holes, 30*30 cm wide, 30-40 cm deep, level the walls of the holes and compact the base with crushed stone. To do this, on the “patch” where they will stand, we scatter crushed stone in a layer approximately 1.5-2 times the size of the largest pieces. Using a tamper, we “drive” the crushed stone into the ground.

We make formwork from boards so that our foundation protrudes above the ground level by about 10 cm. Fill it → not lower than grade 200 (the link tells about preparing concrete with your own hands). Let it dry for at least a week, then lay roofing felt waterproofing on top of the foundation. We begin laying bricks.

The foundation formwork for our columns must be aligned in one plane, for this we use a laser plane builder, or → (the link explains what a hydraulic level is and how to use it), so that all the columns are on the same level. If for the first time you have deviations of about 1 cm, it’s not a big deal, the main thing is to align the pillars. You can adjust the level using masonry mortar, making its layer smaller or larger when laying brick columns.

Installing logs yourself

For logs laid on columns (pedestals), we use 50x100 mm timber. At the same time, we leave the distances between the centers of the columns (bollards) per meter or so. As the distance between the columns increases, the section of the log also increases.

When making a wooden floor using joists with your own hands on concrete floor slabs, we lay the joists directly on the concrete. For logs laid on a solid base, you can use timber of a much smaller cross-section, because they will not experience bending load. In fact, in this case, logs are needed for precise alignment and for nailing the boards. The size of the bars 40x50 or 50x50 will be quite enough.

Without exaggeration, we can say that this flooring option has been tested for centuries. The technology of laying wooden floors on logs has been used for several centuries with minor changes. This is the most environmentally friendly solution for flooring, but at the same time, this coating has a number of disadvantages and important nuances that you need to know before starting work.

Currently, the main area of ​​application for wooden floors is the construction of small private houses. Especially often, floors on logs are installed in wooden houses and log houses, in which the floors between floors are made of beams.

Much less often, wooden floors are laid in city apartments with reinforced concrete floors. However, the technology is still used, especially in cases where pouring a full leveling screed is impossible for some reason.

Sometimes plank flooring is a finishing coating and part of the designer’s idea when creating a renovation concept. In this case, beautiful wood species such as oak, larch or pine are chosen for the flooring. The boards are thoroughly polished, impregnated with an antiseptic and covered with varnish or wax. The result is a very beautiful and durable coating that pleases the eye with the natural texture of wood.

Wooden floors can be used even when arranging wet rooms, such as baths and bathrooms. However, this is done infrequently, as it requires careful selection of wood, reliable waterproofing and impregnation of the boards with very expensive solutions that prevent moisture absorption.

Features of laying wooden floors on joists

The main feature of this type of floor, which must be taken into account, is that wood can absorb moisture from the environment, deform due to temperature changes, and is also susceptible to rotting. Therefore, when laying a wooden floor, it is extremely important to take care of reliable vapor barrier and impregnate the joists and boards with an antiseptic.

The joists must be attached to the base and the floor boards to the joists as securely as possible; it is necessary to prevent the formation of cracks, voids and “sagging” of the boards and joists. When laying the finishing boards, be sure to use expansion wedges that will press the boards together as tightly as possible.

Wood screws provide maximum security of fastening. The length of the screw must exceed the thickness of the board being fixed by at least 2.5 times. To prevent the board from splitting when you screw in the screw, you must first drill a hole in it with a diameter 2-3 mm smaller than the diameter of the screw.

If the boards are planned as a finishing coating, then care should be taken to hide the heads of the screws or nails. To do this, use either a special putty or small plugs made of the same type of wood as the entire floor. But the best option is to screw the screw into the chamfer of the board at an angle to the joist. The disadvantage of this option is that it is more labor intensive.

You should also make sure that all the finishing boards are from the same batch, because the color of the wood depends on the growing conditions, and the shade of different batches may differ.

What are the consequences of mistakes when laying a wooden floor on joists?

The biggest mistake you can make when laying a wooden floor is insufficient vapor barrier. It is usually made of dense polyethylene or foam foam, which will also provide additional sound insulation. If this step is neglected or the insulation coating is damaged, the floor will very soon begin to rot and mold will appear on it. This will not only significantly shorten the life of the floor, but can also negatively affect people’s health.

The second most common mistake is using wood that is not dry enough. The humidity of boards and joists should be no more than 15%. It is important to remember that in wet weather, even initially dry boards very quickly absorb moisture from the air. If there are prolonged rains outside the window, then it is better to refuse to lay the floor on these days. If you lay a floor with wet planks, they will begin to warp as they dry. This will lead to creaking, the appearance of cracks and differences in height between adjacent boards, which, in turn, will affect the finishing coating.

An insufficiently precise level when laying joists will lead to creaking of the floor and gradual loosening of the boards. This will greatly reduce the service life of the coating and will require periodic repairs.

Another common mistake is insufficient distance from the end board to the wall; it should be at least 10 mm. This distance is necessary to compensate for the thermal expansion of wood. If it is neglected, then with seasonal temperature changes the floor will experience very serious internal loads, which will lead to cracking of some boards and the appearance of creaks.

Advantages and disadvantages of wooden floors on joists

The advantages of this coating

Disadvantages of wooden floors on joists

Step-by-step instructions for laying a wooden floor on joists

Below are step-by-step instructions for installing wood flooring. The installation of such a floor in a private house with a soil foundation is somewhat more complicated than in a house with a reinforced concrete foundation, but in general the stages of work are the same in both cases.

Laying logs on the ground base

If you are laying a wooden floor directly above the soil, then it must be cleared of turf and plant roots and a layer at least 20 cm thick must be removed. After which the soil is covered with fine crushed stone and thoroughly compacted.

On this basis, brick columns with a cross-section of 250 x 250 mm and a height of at least two layers of brick are built. The tops of all columns should be at the same level, this will prevent sagging of the joists and floor boards.

If beams 100 x 50 mm and up to 3 meters long are used as logs, then two columns at the edges of the logs are sufficient. The distance between the logs, and therefore between adjacent columns, should be 600 mm. If the length of the log is more than 3 meters, then one is strengthened with an additional column in the middle.

The top of the column is lined with a rigid waterproofing material, for example, dense polyethylene film. Wooden spacers or wedges are installed on top of it, which are necessary for the final horizontal adjustment of the joists.

After this, you can begin laying the joists. Initially, the two outermost logs are laid level. A fishing line is stretched between them, along which all other logs are set. Adjustment is carried out using spacers or wedges. The lags are fastened to the posts using anchor bolts.

In this case, the procedure is much simpler; it is enough to cover the floor with waterproofing, for example, made of polyethylene, and logs are laid on top of it at a distance of 400-600 mm on wooden control pads. First, the two outer logs are laid level, after which a fishing line is stretched between them, along which the height of all other logs is adjusted.

Adjustment is carried out by adding or, conversely, removing adjusting shims.

Currently, the use of adjustable logs is sometimes practiced. These logs have drilled and threaded holes into which a special pin is screwed and secured to the concrete base using dowels. Rotating the pin adjusts the height of the log.

After all the logs are aligned to the same level, the protruding parts of the studs are cut off using a grinder. This method greatly simplifies the horizontal alignment of the logs, but is not used very widely due to the noticeable increase in the cost of the structure.

Adjustable lags with clamps

It is important to remember that there must be a distance of at least 10 mm between the edges of the joist and the wall. It is necessary to compensate for the thermal expansion of wood.

Preparing for flooring

Before you begin laying the boards, you need to lay a layer of thermal insulation between the joists. This can be mineral wool or polystyrene. At the same stage, wires in plastic corrugation can be laid between the logs, if necessary. The standard width of insulation sheets is most often 600 mm, which makes it easy to lay it between the joists.

After all the necessary communications and insulation have been laid, you can begin laying the rough or finished floor.

Laying rough wood flooring

If laminate, carpet or linoleum is intended to be used as a finishing coating, then, as a rule, a rough covering of uncut boards, plywood or fiberboard is laid on the logs.

Sheets of plywood or fiberboard are laid on the joists and secured with nails or screws. You should not skimp on fastening points; screws should be screwed into each joist at intervals of no more than 30 cm. The head of the screw or nail should be recessed into the slab by 1-2 mm. It is important to leave a distance of at least 10 mm between the wall and the coating. This gap will also provide ventilation of the space under the floor. 2-3 weeks after completion of work, it can be covered with a plinth.

When laying a subfloor made of boards, you need to start work from the far corner of the room and move towards the entrance. The length of the boards is selected so that their joint is in the middle of the log. The boards are laid as closely as possible to each other and fixed with screws. To prevent the board from splitting when screwing in a screw, you must first drill a hole for it with a drill bit with a diameter slightly smaller than the diameter of the screw. Using a drill of a slightly larger diameter, you need to make a small recess into which the screw head will hide.

Laying finished wood flooring

A folded board or a board made of laminated veneer lumber is usually used as a final finishing coating. These boards must be soaked in a protective antiseptic solution. There are some nuances in laying such boards. Since this floor will no longer be covered with anything, it is extremely important to avoid the slightest gaps between the boards, and it is also important to hide the screw heads so that they do not spoil the appearance of the floor.

Laying folded boards is carried out according to the same principle as laying boards for a subfloor, with the only difference being that two adjacent boards are pressed against each other as tightly as possible. To do this, a bracket is driven into the joist at a distance of 4-6 cm from the board, between which and the edge of the board a wedge is installed, pressing the board. When the pressure on the board is maximum, it is fixed with screws, after which the wedge and bracket are removed. The operation must be repeated for each row of boards, this will prevent the formation of cracks. The board is attached to the joist using a screw, which is screwed into the chamfer at an angle, this allows you to hide its head and improve the appearance of the floor. You can also use special decorative nails for the floor, driving them in strictly at equal distances, but this is a compromise option; the absence of visible fastening looks much better.

Comparative characteristics of floorboards

Batten. Prices

In a house with external multilayer walls with insulation on the outside, a cold bridge is formed through the base and load-bearing part of the wall, bypassing the insulation of the wall and floor.

Floor board. Name, material, size	Price, rub./m2
Floorboard Pine K1-2 (25x90) 1.8m	250
Floorboard Pine K1-2 (25x90) 1.0m	250
Floorboard Pine K1-2 (28x130) 1.8m	290
Floorboard Pine K1-2 (28x130) 2.0m	480
Floorboard Pine K1-2 (28x130) 6.0m	480
Floorboard Pine K1-2 (32x100) 5.4m	570
Floorboard Pine K1-2 (32x130) 5.85m	570
Floorboard Larch K2-3 (27x90) 5.4m	460
Floorboard Larch K2-3 (27x90) 5.1m	460
Floorboard Larch K2-3 (27x90) 4.8m	460
Floorboard Larch K1-2 (27x130) 3.0m	560
Floorboard Larch K1-2 (27x110) 3.0m	560
Heat-treated pine LUNAWOOD (Finland). Floor board (tongue and groove) 26x92	195 rub. /linear m
Europol (pine, 32 mm)	grade 0 (Extra) 970.56 rub/m2; grade 1 (Prima) 676.80 rub/m2; grade 2 (B) 460.00 rub/m2; grade 3 (C) 384.00 rub/m2; grade N/K (D) 301.76 rub/m2.

Video - Laying a wooden floor on joists

Many homeowners choose wood flooring based on its environmental appeal. Man has lived in harmony with trees for thousands of years, and during this time a kind of symbiosis has even arisen between them.

The installation of a wooden floor in the vast majority of cases requires the presence of logs - special wooden beams laid on the main floor. Then the finishing floor covering is laid on the joists. Modern materials and technologies have only added to the popularity of this method of arranging the floor in a home.

So, constructing a wooden floor involves two main options: the use of a concrete screed, the so-called “wet” technology, and the “” construction, when the wooden floor is installed on logs, and the floor is screeded using dry slabs. The design of the adjustable floor system stands somewhat apart.

The advantage of the “dry” field construction system is its relative simplicity and high speed of installation.

Installation of dry floors on joists

Wooden logs - beams - are installed on the base - that is, on the floor. The distance between them is determined based on the characteristics of the coating that you plan to place on the joists. So, if you want to use plywood, then you need to reduce the step between the joists, but when using durable wooden boards as floorboards, the distance between the joists can be increased. After covering them with plywood or boards, a finishing coating can be laid on top.

On logs it can be laid on almost any base. Let's consider the design of such a floor on various surfaces.

Wooden floor on joists on a ground surface

Installation of a wooden floor on a reinforced concrete floor

1. As a base for joists on concrete, pieces of fiberboard impregnated with an antiseptic compound are used.
2. The distance between the logs should be about 60 centimeters. If you plan to use ceramic tiles as the finishing layer, then the logs should be placed 30 centimeters from each other.
3. Attach the joists to the ceiling using self-tapping screws and dowels. When fixing the joists, check their position relative to the horizon using a building level.

Wooden floor construction on floor beams

Despite the fact that the ceiling in the form of wooden beams looks like logs, they can be used as a basis for a subfloor only if the distance between them does not exceed 30 centimeters. Otherwise, you will have to install the joists themselves on the floor beams, leveling them horizontally, and only then install the subfloor on the joists.

Adjustable floor system

You can level the floor horizontally not only using a traditional screed, but also using an adjustable floor system. The adjustable floor can be installed either on joists or directly on the ceiling using adjustable bolts. An adjustable floor system is usually installed in rooms where the overall weight of the floor is critical, for example, in light suburban buildings. In addition, an adjustable floor system can create dramatic large differences in surface level, for example to visually divide a room.

Unlike the traditional method, here wooden logs are not mounted directly on the ceiling, but are installed on adjustable screw supports. Using a special wrench, the stand bolts are rotated in their bushings, raising or lowering part of the floor. Otherwise, the algorithm for constructing such a floor is identical to the traditional one.

Wooden plywood floor on adjustable posts

An adjustable wooden floor made of thick plywood is installed not on logs, but on many adjustable bolt posts, by turning which you can quickly achieve a perfectly horizontal surface.

It turns out to be a kind of floor on many legs. The covering is usually 120mm plywood in the form of square sheets with a side of 1.5 meters. It is mounted in two layers, so that the joints of the sheets are not on top of each other. The layer is fastened with self-tapping screws, and then the finishing floor covering is installed.

Algorithm for constructing a concrete floor on joists in rooms with high loads

In some cases, it becomes necessary to create a wooden floor on joists in rooms with high loads, for example, in garages. In principle, the procedure for constructing such a floor is identical to installation on a soil or concrete base, the difference is that not brick columns, but a concrete base are used as the base of the logs.

1. Dry thoroughly and coat the joists with an antiseptic solution.
2. Place a layer of waterproofing on the concrete base under the joists.
3. Install beacon logs, the distance between which should be 2 meters. Every 50 centimeters, fix them to the surface with dowels, controlling the horizontal surface using a building level.
4. Between the beacon logs, place intermediate log bars in steps of 40 centimeters.
5. Insulate the resulting gaps using expanded clay or mineral wool.
6. Mount the floorboards on the joists using self-tapping screws. The floor boards should be directed perpendicular to the joists and laid without gaps.

Video - wooden floor on joists

Small tricks for installing a wooden floor on joists

1. For a better aesthetic perception of a wooden floor on joists, lay the base beams perpendicular to the light flux from the window.
2. In places where people constantly move, the joists should intersect the path of movement, and the floor boards should be directed along the movement of the flow.
3. When installing a floor in an apartment building, place a soundproofing pad under the joists.
4. Leave a gap of up to 3 centimeters wide between the walls and joists.
5. When using ceramic tiles as a finishing coating, plan the distance between the joists to be no more than 30 centimeters; install moisture-resistant plywood as a subfloor, and then a sheet of gypsum fiber board.
6. To increase the rigidity of the subfloor fastening, you can use the construction of wooden logs in the form of a grid in increments of up to 1 meter. This design is usually necessary if you plan to use a laminate board as a topcoat.
7. If you plan to use parquet, we recommend that you use adjustable joists, which will ensure the ideal horizontal level and the required ventilation.

The process of attaching joists to the foundation

Having completed the installation of the foundation of a house of one type or another, you can begin installing the floors of the first floor. They are based on wooden beams or rounded logs laid horizontally directly on the base of the house. It is possible to do such work with your own hands only after carefully studying all the features of the process.

Beams as they are

Floor beams are currently represented by a fairly large list of different products. The simplest option is a timber beam of regular rectangular cross-section, determined based on specific construction conditions.

A more complex type of floor joist, which requires a lengthy manufacturing process, is I-beams with a cross-section in the form of the letter H, placed on one of the sides. They are made from high-quality dried and planed wooden blocks and strips of OSB or high-quality moisture-resistant premium plywood.

The operating principle of I-beams in the form of floor joists involves the distribution of the main forces in the form of bending loads along flat stiffeners. Thanks to this, with a small mass, they are able to withstand very heavy loads. In addition, manufacturing technology and strength make it possible to produce I-beams for openings with a width significantly exceeding the standard 6 meters.

Laying logs on the foundation is carried out according to certain rules, which will be discussed later. Immediately before installing lumber, it is necessary to properly prepare it for further use. You should choose high-quality bars made of oak, aspen or coniferous wood. The main requirements for them are as follows:

• The humidity of the lag should be in the range of 14-18%. This is achieved by simple atmospheric or better chamber drying. It is strictly forbidden to use damp, freshly sawn wood, since it will not be possible to correctly lay the logs on the foundation due to subsequent warping when they dry.
• The logs must have the correct geometry in length and cross-section. Before placing the logs on the foundation, they are subjected to additional mechanical processing in the form of planing with electric planers. High quality beams can be achieved by using pre-glued parts.
• In order to avoid subsequent destruction of lag wood under the influence of moisture, they must be carefully protected using protective compounds. This is done by spraying or using paint rollers in two layers with intermediate drying. A cheaper treatment method is to coat the floor joists with used machine oil. If used, treatment must be carried out a week before installation to remove the characteristic odor.

Attaching joists to the base of the house

Options for attaching joists to the base of the house

An important point is the correct fastening of the logs to the foundation of the house. At the same time, the abundance of base options requires certain installation features for each of them. Let's consider each specific case separately.

Attaching beams to strip foundations

A fairly common type is. It is a base up to half a meter wide, raised above the soil by 0.4 - 1 meter. Not all novice builders know how to attach joists to this type of foundation. There are two main ways:

1. The first of them involves installing timber directly onto the base of the house. In this case, the work on installing the joists is combined with the installation of the side walls of the house. Depending on the frame material used, the logs can be laid by cutting them into a beam or log, covering them with bricks or blocks, making preliminary recesses in them according to the size of the floor parts. This option is convenient as it requires minimal additional preparation.
2. The second method involves preliminary installation of strapping beams along the entire perimeter of the base of the house. In this case, even before pouring the foundation or directly during the process, anchor foundation bolts are installed in the concrete, protruding 150 mm above the surface. After the mixture has hardened and hardened, holes are marked on the strapping bars and holes are drilled at the locations of the heads of the threaded rods. After laying, the wooden parts are pulled to the base of the house with nuts and washers, sinking them into the wood. After this, the logs can be laid on the foundation, step-by-step instructions for which will be located below.

Regardless of the chosen option for laying floor beams, it must be carried out in compliance with a number of mandatory requirements, which should be discussed in more detail.

Before laying logs on the foundation, it is necessary to correctly calculate the required number of beams. They are installed in increments determined based on the expected thickness of the boards used for flooring. Thus, in the case of designing lumber for finishing covering with a section of 20x100, 20x150, the distance at which the logs are installed on the foundation is only 0.3 meters.

Assuming a floor covering made from a standard tongue-and-groove floor board with a thickness of 30-35 mm, the timber installation step can be increased to 0.5-0.6 meters. If you choose 50x150 lumber for the floor, you can safely lay the logs at a distance of 1 meter from each other.

Before laying logs on bricks or wood, it would be a good idea to determine the geometric parameters of the floor beams. For their calculation, the determining value is the width of the overlapped span, that is, the width of the room. So, with a distance from one wall to another of 2 meters, you can use lumber with a section of 110x60, 3 meters - 150x80, 4 meters - 180x100, 5 meters - 150x200, and 6 meters - 180x220 mm.

Installing joists on a slab base

If the base of the house is manufactured in the form that is recommended, the lags can be attached to the foundation in a way different from those described above, but in compliance with the specified installation parameters. It consists of using dowel nails installed through the timber into pre-drilled holes in the concrete.

The process technology is not complicated and is accessible even to novice builders. To install joists with your own hands on such a concrete floor, you can use a hammer drill or a drill with an impact mechanism. Pre-drill holes in the timber using a wood drill. Then the parts are laid at the installation site and recesses in the concrete of sufficient depth and diameter are made through them.

Fastening joists to a slab base

Dowel-nails with a diameter of at least 12 mm are installed in place and pressed with a half-sledgehammer or a hammer with a striker weighing at least 1 kg flush with the surface of the wooden beams. As a rule, with the correct selection of fastener parameters, installing joists on the foundation in this way ensures high quality of their fastening.

This method is applicable when using logs with a cross-section of at least 150x150 mm. This allows you to lay a sufficient amount of backfill or slab insulation made of mineral wool under the subfloor, since it is impossible to lay the floor on a foundation without high-quality thermal insulation.

Installation of joists on the floor

When performing work inside a residential building or apartment, the problem of installing joists on a finished concrete floor often arises. This type of work is used if it is necessary to insulate the lower surface of rooms, level it, or lay one or another type of floor covering. In this case, two installation methods can be used.

The first method involves rigidly fixing the bars to the base, which can be done in the same way as fixing the logs to the foundation in the form of a concrete slab. To install the logs in this case, you can use dowel nails or plastic dowels with self-tapping screws of the appropriate length.

Using preliminary markings, or using pre-perforated logs as templates, we drill holes in the floor. Their diameter should allow the fasteners to be tightly installed. Next, we fasten the logs using self-tapping screws or dowel-nails, controlling the horizontalness of the surface of the beams and the overall flatness.

Subsequently, after attaching the logs to the concrete floor with your own hands, you can insulate the base by placing the selected type of insulation in the gap between the bars. Before installation, do not forget to thoroughly treat the wooden parts with antifungal stains and fire retardants, which reduce their flammability.