For the construction of wooden floors, the finishing flooring of which is installed on logs, there are a lot of technological variations. The choice of the optimal scheme depends on climatic and geological conditions, and on the financial capabilities of the owners. The method of installing a floor with joists is influenced by the type of base and the operational specifics of the building or individual room. However, no matter what principle is used to construct a wooden floor along joists, the construction of the structure is based on classical techniques and options, which will be discussed.
Logs are a rather capacious concept, including not only the well-known wooden beam with rectangular cross-section. The technical definition of a log applies to:
- plates made from logs with a cross-section in the thinnest part of at least 160 mm;
- logs hewn on both sides with cut dimensions of at least 150 mm;
- boards paired in two, mounted on an edge, with a width of 100 mm or more and a thickness of 25 mm or more;
- directly a rectangular beam, the size of which determines the upcoming load. The dimensional minimum is considered to be 100×150mm with a lag installation step of 60 cm;
- slats used for dry leveling and insulation;
- I-beam metal channel, used extremely rarely in the case of constructing a floor on reinforced concrete beams;
- plastic long products included in the package of factory systems for the formation of dry screed.
Regardless of the material from which the logs are made, they have one function: they serve as the basis for the future subfloor and finishing coating. They can rely on the mortgage crown, on support pillars, on wooden beams, concrete slabs or on pre-compacted, prepared soil.
Do you need an underground floor or not?
Depending on the geological features of the site chosen for construction, it is determined whether space between the soil and the joist system is required or can be eliminated to reduce costs and labor.
The dictator of the mandatory presence or permission to have no subfloor is the seasonal level readings groundwater:
- in case of low occurrence of hot water, simple, extremely cheap, but quite cold floors without an underfloor are installed. The logs in this version rest on the ground foundation. This type is ideal for country house construction, for the construction of baths for seasonal use. IN middle lane And southern regions it can be used if the permanent building has a high base;
- in case of high occurrence of hot water, which pose a serious threat to wood, the log system must be raised above the ground surface. To install the lag frame system, you will need to build supports-columns from bricks, monolithic concrete or foam concrete blocks.
The values of the hot water level must be determined from the local weather service before designing a bathhouse.
Classic floor schemes with joists
The presence of underground space divides all existing schemes into two classes: floors with and without underground. Structures without a subfloor are considered cold, but there are ways to insulate them. For floors with subfloors, significantly more varieties. They can be cold and thermally insulated. In insulated floors, a layer of thermal insulation can be located between the joists or between the supports.
The simplest cold floor
This is a structure erected on dry ground. In order to arrange it:
- completely remove the soil and plant layer;
- after removing all the “consequences” of the growth of organic matter, the natural soil must be thoroughly compacted;
- freed from plant residues the area is covered with sifted sand, which can be replaced with crushed stone or construction waste with sand filler;
- the filled pillow is compacted again. A homemade tool for compacting soil and backfilling can be constructed from a heavy log, nailing a transverse block to its upper plane as a handle;
- then there's a new one coming a layer of backfill made of calcined sand, slag or dense clay. This layer will become the medium and basis for installing a frame made of wooden logs, which means it should not create conditions for wood rotting. The backfill capacity should be two to three times the thickness of the timber chosen for the arrangement or a plate made from half a log;
Please note. If you plan to use slag to create a cushion, you need to buy it and bring it to the site a year before starting work. The slag needs to “stand out.”
- logs are “immersed” in the last layer of backfill, the top line of which should be flush with the plane of the base being constructed. Lumber must be treated with an antiseptic before being immersed in the ground.
The lags are laid in increments depending on the width of the floorboards. Since the installation of wooden floors in bathhouses is generally completed by laying 37 mm tongue-and-groove boards, the optimal distance between the joists will be 60 cm. Too wide boards are undesirable for arranging a bathhouse, because the wood will deform in a humid environment, and wide boards will make warping especially noticeable and inconvenient for movement.
Important. The annual rings of adjacent floorboards must be directed in different directions, so that the adjacent elements will spontaneously prevent deformation.
Insulated flooring option on the ground
- The bottom of a kind of pit for subsequent filling of a multilayer cushion is compacted and covered with insulation, which can be used as bags of lime or cement mixture, laid in two rows.
- Then crushed stone is poured in a layer of 8 cm. It also needs to be compacted and filled with lime milk.
- Roofing felt is laid on top.
- Then fiberboard 3 cm thick.
- A layer of expanded clay of small or medium fraction is about 8 cm.
The multi-layer insulating base for the floor is finally filled with lean concrete, which is dominated by sand. After the solution has set, the area of the floor being constructed is covered with sand and then proceed according to the above-described scheme.
Cold type of floor with insulated underground
Initially, standard preparation of the base is carried out. The difference is that calcined sand is not poured onto the prepared surface, but support pillars are built from solid brick or foam concrete blocks. Each support column is a separate structure with its own foundation, for the pouring of which it is necessary to carry out preliminary markings.
Please note: the finishing flooring boards are mounted “in a cross” with the joists.
The best option for laying plank floorboards is:
- parallel direction to the light flux in the rest room;
- parallel direction long wall in the washing department and in the steam room;
- perpendicular to the direction of movement in the dressing room.
If additional sheathing is not installed above the joists, the joists should be laid across the direction of the board. All distances must be measured, planned and calculated, focusing on the central axes of the posts and joists. Marks must be left on the structural element on which the ends of the joists are to rest: on the roofing material covering the grillage, on the beam of the lower trim.
The first log from the wall must be positioned so that there is a gap of 3-20 cm between its side surface and the wall, and the same on the opposite side. That is, an independent builder has the opportunity to slightly move the planned rows of columns when laying out. The foundation for the supports can be poured entirely under the entire row or under each of the columns separately. It should be noted that the foundation for the column must protrude at least 1 cm, preferably 5 cm around the entire perimeter beyond the contour of the support. This means that the formwork for pouring a strip for a row of supports must be constructed so that the foundation strip is 2-10 cm wider and longer than the row. The foundation for a separate support should be just as wider and longer.
Advice. According to the axis marked on the harness, you need to set aside half the width of the future foundation in both directions and hammer the pegs into the points projected on the ground. You need to pull the cord between the pegs and repeat all the same steps in a perpendicular direction. To fill the foundation with a strip, it is enough to break only the corners of the future local foundation.
The sequence of actions for pouring a concrete base is extremely simple:
- soil compaction;
- installation of formwork with a side height of 10 cm;
- laying reinforcing mesh on the bottom;
- pouring the concrete itself, waiting for it to harden for 3 days;
- then the foundation is covered with polyethylene or roofing felt for waterproofing and supports are built.
Please note. The upper plane of the supports should be located at the same level. Row alignment is done by applying cement mortar. If a layer of more than 5 cm is required for leveling, reinforcing mesh is “embedded” in the cement.
On top of the leveled support there should again be a waterproofing layer, on which you need to put a 3 cm thick wooden pad impregnated with an antiseptic. The logs will be placed on this, by the way, also treated with an antiseptic, and the boardwalk will be placed on top.
Without exaggeration we can say that this option flooring 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, which 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 the floor on joists is arranged 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 areas 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 environment, deform due to temperature changes, and are 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 screwing a 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 insulating 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 we neglect it, then seasonal change temperature, the floor will experience very serious internal loads, which will lead to cracking of some boards and the appearance of creaking.
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 is step by step instructions for laying wooden floors. 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 that, 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 spacers. 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 holes with threads into which a special pin is screwed, attached 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 joists, if necessary. Standard width insulation sheets are 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 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 impregnated with 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 appearance 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
| 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
A wooden floor on joists makes it possible to avoid without using reinforced concrete floor or installation of another concrete base, 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 closed metal mesh for protection 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 the exhaust duct. This ventilation scheme is the only the right 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
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 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 bearing capacity and the rigidity of the overlying layers of the floor - 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 design 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 choose 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.
Using foam plastic as insulation, polystyrene foam boards 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 wooden floor parts. In addition, mineral wool insulation, due to its better elasticity, adheres more tightly to the joists than foam plastic.
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 designs On the floors, 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 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 by required height by backfilling 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 through ventilation holes in the baseboards and the gap between the subfloor covering and the wall enters the space between the joists. Next, the air enters 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, admission warm air from the room can 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. Compact the fill soil until natural soil still fails. 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.
By building regulations There is one limitation on the floor arrangement. Since the space under the floor is ventilated through an exhaust duct natural ventilation, then it is prohibited to make the final floor covering from combustible materials: from boards, parquet boards and shields, etc. Or a non-combustible base should be provided under them, for example a prefabricated plasterboard screed, 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
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 the house pile foundation can be recommended only 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.
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| 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. |
Installing a floor on joists involves laying waterproofing and insulation 
It is necessary to insulate the floors of the first floors and concrete or brick foundations 
The size of the bars depends on the distance between the strapping links 
It is preferable to use tongue and groove boards due to the tongue-and-groove system 
Oak and pine boards will last a long time 
The distance between the lags is most often 50-70 cm 
Wooden floor construction with joists 
You can insulate the floor using expanded clay 
Scheme of a wooden floor 
