Every owner wants to have a bathhouse on his personal plot, therefore these household structures are often erected before the completion of the construction of the main house. And, despite the fact that it is much easier to equip a country cottage with a modern bathroom with a hydromassage system or a mini-sauna with a Turkish bath and a rain shower, many homeowners prefer to build a free-standing bath, equipped with a stove, steam baths, and sometimes supplement it next to located pool.

When implementing these plans, the owner of the site, first of all, faces the following questions: what material for the construction of the bath will be optimal, where to get it, how much it will be needed, and who will carry out the construction of the bath itself and the equipment of the bath premises.

What materials are used to build a bath

When deciding on the construction of a bath, it must be remembered that it is a rather complex engineering structure that requires compliance with rather stringent measures to ensure safety during operation. At the same time, the question of which material is better for building a bath is, to a certain extent, rather prosaic. No room for washing and receiving bath procedures can be built from one material. Additional building and finishing materials will be required for pouring the foundation, heat and vapor insulation, and roofing.

When choosing the best material for building a bath, they can be divided into the following categories:

• wall materials;
• heat-steam-waterproofing roll or sheet products;
• roofing materials;
• finishing products.

Of course, basic costs and labor will be needed to build the walls. Today, depending on the region, soil and climatic zone, the financial capabilities of the owner for the construction of the wall structure of the bath room on the site, the following are most often used:

• mineral building materials - bricks, gas silicate blocks, natural sawn stone;
• wood - a sanded log, ordinary, profiled or rounded timber;
• wood concrete, which is a hardened cement mortar filled with wood waste - usually wood shavings or sawdust;
• frame structures for the manufacture of which various materials can be used.

Some gardeners and summer residents boast that they managed to build a bath from scrap materials.

Paying tribute to the cheapness of such construction, it should be noted right away that it is impossible to build a comfortable washing and steam room from the boards, boxes and plywood left over from the main construction.

Currently, completely new materials are also used for the construction of a bath, news about the practicality and durability of which can be found on the relevant forums, information resources and construction portals on the Internet.

It is generally accepted that the best material for the construction of a bath is wood, which can be used for the construction of walls, the arrangement of floors, ceilings and for the manufacture of elements of rafter and roof structures.

Features of wooden baths

When choosing a finishing material, the greatest attention is paid to the products intended for the cladding of the steam room and the washing department. There should be no knots in the carriage board, because with several heating-cooling and wet-drying cycles, these knots will surely fall out, giving the wall panels an unaesthetic look.

The most widespread for interior decoration was lining made of linden, alder, aspen and maple.

Of course, you can use beech, cedar or oak lining, but its cost is much higher.

When facing the walls of the entrance vestibule and changing rooms, no special requirements are imposed on finishing materials. Here you can use any lining or edged, grooved board, afterwards treating it with stain, soaking it with linseed oil and varnishing it.

The greatest difficulty in the construction of a bath is the choice of material for the arrangement. The floor surface works in more severe temperature conditions. From below, it is exposed to atmospheric temperatures, and inside it perceives the temperature and excess humidity of the steam room. For the durability of the floors, one should not only choose the highest quality materials, but also when laying them, it is necessary to provide for all measures to ensure high-quality hydro-steam-thermal insulation.

Do not think that the choice of materials for the construction of a bath ends after the construction of the walls, the arrangement of the roof and flooring. The homeowner has yet to choose the type of heater and purchase materials for its construction.

Owners of country houses sooner or later think about building a bath. After all, the bathhouse is an excellent place for recreation. There you can easily cleanse your body and soul, have fun with friends and family, get a charge of positive emotions and a healing effect.

The efficiency, aesthetics and durability of a building directly depend on the building materials. The bathhouse is built from wood, brick, blocks, etc. Consider the demanded options for building materials separately.

Wooden bath

The traditional and most rational construction option. Wood is a natural, environmentally friendly material that will enhance the healing effect of bath procedures. The pleasant forest scent and attractive appearance will create a cozy and welcoming atmosphere.

Characteristics of wooden building materials:

• Environmentally friendly materials do not emit harmful toxic substances;
• The tree is easy to install. Installation of a wooden frame will take 1-2 weeks;
• Keeps warm for a long time;
• With proper care, the bath will last 70-80 years;
• Aesthetically attractive appearance;
• Light weight does not require expensive deep foundation, which reduces construction costs;
• It does not require external and serious interior decoration, which saves a large part of the budget. After all, finishing makes up 50-70% of the cost of building a building;
• Ease of processing - wood can be easily varnished and painted in any color;
• Low material cost due to the availability of raw materials.

For a wooden bath, a log or a bar is chosen. Both of these materials have the above characteristics, but there are differences between them. First of all, they relate to appearance and shape.

Lovers of Russian style and space will appreciate the rounded log. The material of the correct cylindrical shape will harmoniously fit into the surroundings and create an exquisite appearance of the building.

Glued or profiled timber is characterized by a square shape, which will create a practical European style.

The choice of a bar or log is a matter of taste. However, keep in mind that building a log bath will be cheaper. After all, the timber requires additional costs for interior decoration in order to avoid the appearance of cracks and cracks.

The brick is distinguished by high thermal conductivity. Therefore, reinforced wall insulation is required. After all, long-term preservation of heat in the room is the main thing for a bath. In addition, laying brick walls is physically demanding and time-consuming.

Characteristics of brick building materials:

• Durability and strength of the material;
• Requires a deep and expensive foundation, which increases the cost of construction;
• Heavy and labor intensive installation;
• Requires serious interior decoration and reinforced thermal insulation gaskets due to high thermal conductivity;
• The material heats up longer;
• Easily absorbs and permeates moisture;
• Resistant to fire.

Thus, brick construction is not the best option. It will take a long time and take a lot of effort. In addition, such a bath requires a serious foundation and careful finishing.

Bath made of foam concrete blocks

Foam concrete is made in the form of blocks. The material is superior to brick in terms of thermal insulation quality and saves foundation costs. However, the microclimate in such a bath will be completely different than in a wooden one.

Characteristics of foam concrete:

• A standard wall foam block replaces 13 sand-lime bricks;
• Ease of installation - it is easy to install the foam block by yourself without professional training;
• Resistance to dampness;
• Difficulty installing ventilation and vapor barrier.

Foam blocks are more suitable for building a bath than bricks. However, the health-improving effect in such a room decreases several times than in a natural bath. At the same time, foam concrete makes it difficult to carry out vapor barrier and ventilation.

Frame structure - walls in the form of a lattice from a bar of various sections. The cells of the frame are filled with heat-insulating materials and sheathed outside and inside with boards, clapboard or imitation of a bar.

Frame technology characteristics:

• Ease and speed of construction;
• Good thermal insulation;
• The light weight of the structure does not require a deep expensive foundation;
• Cheapness of materials and construction;
• The fragility of the structure.

A frame bath will not require large expenses. However, a fragile structure will last much less than a bath made of wood, brick or block.

What material is better for building a bath

Regardless of the choice of material, wood will have to be used in any case. For cladding walls and ceilings, you will need a wooden lining, for laying a shelf - boards. Internal partitions, doors and window frames, sunbeds and shelves, cooperage products - all this is made of wood. Should you spoil the atmosphere with artificial materials?

A solid wooden bath will last a long time and create a unique atmosphere. The tree perfectly retains heat and has a beneficial effect on the human condition. In such a room it will be easy to breathe and it will be pleasant to be.

The company "MariSrub" offers dozens of turnkey log bath projects. In the catalog you will find projects with an attic, a terrace, a recreation room. For you - baths of various sizes and layouts. We will carry out an individual project, taking into account the characteristics of the land plot and the wishes of the client.

The choice of material for the construction of a bath and interior decoration largely determines the quality and appearance of the bath. As it turned out, in addition to tastes, material opportunities, traditions, it is necessary to take into account a number of factors that leave their mark on the choice of building material, so in this article we will consider which materials are best used for building a bath.

What material is the bathhouse made of:

• rounded logs;
• timber;
• brick;
• concrete;
• various types of panels.

The best material for a bath - Log walls

Most often, baths are built from wood. Particular attention is paid to the strength and quality of the material: any irregularities or loose spots can cause tangible heat loss.

You can talk endlessly about the advantages of a log bath, and the best material for a bath is:

• Aesthetics. For many, when choosing between a log building, aesthetics are one of the main factors.
• Environmental friendliness. Wood is an environmentally friendly material, absolutely safe for humans.
• Low thermal conductivity. Long-term preservation of heat is provided due to the low thermal conductivity of wood compared to other materials (brick, concrete, panel). There is no need for additional thermal insulation.
• Durability. By this criterion, timber baths are significantly superior to panel and frame buildings. Longevity depends on many factors - from the selection, harvesting and storage of the forest to the maintenance of the building. Subject to the technology of building a bath, proper and timely care, such a bath will last quite a long time. The estimated period, subject to all standards, is 75 years.
• Low cost. Planed wood is a relatively inexpensive material, and the cost of building from it is much lower compared to the cost of a brick bath. Mainly for the construction of baths, conifers are used - pine, larch. Pine is distinguished by a small number of knots and the largest straight trunk. Larch is denser than pine and more resistant to decay, resistant to moisture, but its price is higher compared to pine.

As for the fire safety of a wooden bath, of course, a lot depends on compliance with construction standards. To increase fire resistance, wood is impregnated with fire retardants, the choice of which is huge.

Building material for a bath - Bar

However, the construction of a bath in a summer cottage can be carried out in another way - using not logs, but a bar. This construction reduces material costs. But, on the other hand, if the owner wants to improve the appearance of the building, he will have to spend money on finishing materials ..

If we talk about preferences when choosing between a bar and a log, then a log is usually considered a more acceptable material for building a bath. However, it would be wrong to say that a log bath is better than a log bath. These materials for the construction of a bath have approximately the same characteristics, so the preferences in the choice are rather arbitrary and are determined by the appearance and cost.

Brick walls for the construction of a bath

Building a good bathhouse out of brick and stone is more difficult than building it out of wood. However, in some cases, when brick and stone are more accessible than wood, you have to build from them not only the foundation, but also the walls. Using brick during construction, you can maintain a high temperature in the room during the day, but such material will warm up much longer. A brick bath is more durable and less fire hazardous. Its main drawback is large heat losses due to high thermal conductivity. To reduce it, it is recommended to sheathe the bath from the inside with clapboard, placing a thick layer of steam and thermal insulation between it and the brick wall. Any brickwork absorbs and allows moisture to pass through, so the contact of the walls with the ground is not allowed.

Moisture-resistant materials for a bath include:

• moisture resistant drywall, used in the interior decoration of the bath and requires the application of an additional primer;
• moisture resistant panels.

Concrete walls for a bath

The microclimate in a brick or concrete bath, of course, will not be the same as in a wooden one. It is possible to build a bath from foam concrete, but vapor barrier and ventilation from inside the premises in this case require perfect execution, otherwise it is better not to use foam concrete.

When performing masonry work from a foam block, it is necessary to remember about the additional waterproofing of the material. It can be bituminous soil (liquid bitumen) with preliminary treatment with deeply impregnated soil.

During the panel construction of the bath, the external walls are erected on a frame basis of sandwich panels. So far, this option for building a bath is not popular, although it allows you to save on the basis of the construction. Due to the lightness of the walls being erected, it will be enough for a panel bath

Currently, the Canadian technology for the construction of country houses from OSB sandwich panels is gaining more and more popularity. It is possible to build a bath from this material, and such a bath will have a number of advantages:

• construction time is very short,
• the bath does not shrink and is immediately ready for use,
• the cost of the foundation for the bath is minimized due to the lightness of the structure,
• walls made of OSB - panels with 150 mm thick insulation do not freeze in winter and provide quick heating of the interior space, keeping heat for a long time.
• and finally, OSB - panel is the ideal roughing panel for any interior and exterior decoration.

The service life of a panel bath depends on the quality characteristics of interior finishing materials and averages 25 - 30 years. In operation, a panel bath is no different from baths made of other materials.

Conclusion: what material to build a bath from

Materials for building a bath, such as brick, foam concrete and sandwich panels, have their own advantages, but they are artificial. The best material for a bath is natural wood and should be preferred when building a bath. You can build from wood at any time of the year, be it cold winters or dry summers. Wood serves as an excellent heat insulator, as it has an excellent property of accumulating heat and retaining it for a long time, which is important when heating a bath. The baths, built of rounded logs, combine the old Russian traditions of erecting wooden buildings and modern production technologies, which makes them unsurpassedly beautiful.

From the point of view of a civil engineer, an object with a special thermal and humidity regime... Therefore, in comparison with conventional "dry" buildings, the requirements for materials are increased here. Materials for construction are selected for performance. This is:

• thermal conductivity- it is largely responsible for the heating rate;
• strength- not the main criterion for a one-story building, but it must also withstand a solid layer of March snow, and this is several tons;
• durability- largely depends on the first two qualities, however, such an object should be enough for several decades.
• density and porosity b. In many ways, these are close concepts. Since it experiences a powerful steam and heat "attack" at least once a week, its walls should be vapor permeable.

can build made of wood, brick, various types of cellular blocks (foam concrete and gas silicate). And with the advent of modern high-quality heat, steam and waterproofing materials, baths began to be erected on a mixed, so-called frame technology.

In addition, the choice of the applied technology is influenced by the traditions of the "bathing business" of a particular region, and simply the availability of certain building materials. So, in Karelia, it would never occur to anyone to "cut down" from anything other than wood, and in the steppe regions of the Russian Federation they will prefer high-quality bricks. Let's start the review with him.

Brick version of the bath

First of all, let us clarify that for construction you can use only red fired ceramic bricks... White silicate easily absorbs moisture and is not recommended for "pair procedures". And although no one doubts its strength and durability, it will take a long time to warm up such a structure.

The main disadvantage of a brick bath- large heat losses due to high thermal conductivity. To reduce it and at the same time create a relaxing heat and humidity atmosphere, the walls should be veneered from the inside. reflective vapor barrier(for example, one-sided foil foamed foam), and additionally upholstery on top of it.

The most important and indisputable plus bricks - high fire safety. Agree that for a building that is heated, this is an important factor.

Block variant

You can often find cinder block baths(not to be confused with cellular blocks!), which have good thermal performance. However, slags themselves are concentrators of heavy metals, causing direct harm to human health. In general, cinder blocks should be considered only as a forced stage in the development of the building materials industry, which in the 50s became a response to a sharp shortage of quality. Now the time is different, and it is unacceptable to use such blocks for the construction of living quarters and baths.

Replaced by vibropressed blocks made from concrete mix. An excellent building material in terms of strength and ease of installation, but it has one drawback - weak thermal protection, which requires additional. Therefore, the next step in the "block" direction was the use of honeycomb blocks, which have increased thermal resistance.

Cellular blocks there are foam concrete and aerated concrete. Moreover, the latter are much better than the former. Them Benefits - durability and non-flammability... But the walls of them should also be revetted from the inside with the same materials as brick ones. Of course, such blocks do not burn and do not support the fire.

Bath frame

Frame technology, which has occupied a significant segment in cottage construction, is trying to penetrate the bath "market". The essence of the frame is a well-thought-out and conscientiously laid in a wall structure "pie" from layers of vapor barrier, and waterproofing (if listed in the direction from the inside of the house to the outside). Outside and inside, such a wall should be lined with decorative panels.

The heat engineering highlight of the technology is that the material must be kept dry... Otherwise, it completely loses its insulating properties. And if in an ordinary living room a vapor barrier successfully copes with such a task, then in conditions of regular heat-and-humidity "attacks" it will not be easy for him to resist them for a long time. Somewhere yes there is a crack, hot wet steam will penetrate into the body of mineral wool (100-150 mm thick) and disable the thermal insulation. Therefore, the modern technology of the "frame" has not yet found wide application in the bathing business.

Wood is different

In Russia, it is customary to build from wood - the most environmentally friendly material. Due to the ability of wood to pass air well, rooms from it independently regulate humidity. Wood has little thermal conductivity and retains heat for a long time, which is especially important in.

However, there are stains in the sun, and wood has imperfections. Wood, as a natural natural product, rotting... Therefore, wooden ones are less durable compared to the same brick ones, for example. The main "eaters" of wood are constant rains, aggressive insects and, unfortunately,. However, applied science has already invented its own "antidotes" against all these troubles. Some special chemical compounds will protect against spider bugs, and others will protect against fire.

Important: do not follow the lead of aggressive advertising and hope that one universal composition will protect against everything in the world. According to experts in the field of household chemicals, you should not use formulations with a catchy name like "all in one". For fire protection, get one special solution, and against bugs - another.

What types of wood should you prefer?

Aerobatics in the bathing business is considered dry swamp spruce... But is there a lot of it and where to find it?

Traditionally used dry and... Different regions of our vast homeland have their own preferences based on the prevailing type of local wood. So, for example, in the Primorsky Territory, baths are made from or from... Yes, they put the log so that its northern side, which is more dense by definition, is outside. The trick is not great, but you also need to take it into account.

One more detail - presence of resin in rocks... On the one hand, it favors the bath process. But not everyone will be pleased to feel it literally on oneself. In order to exclude resin from the bath space once and for all, experts advise heat thoroughly for at least a day... This will completely evaporate the resin from all sinuses.

Also used for cladding indoors board: there is no resin in it initially.

Choice of design

Having decided on the types of wood, we turn to the structures. Here can be used either traditional or planed.

If we talk about preferences, then the image still lives in the minds of our people

Bath ventilation is divided into general and preserving ventilation. We call preservative ventilation drying a bath after water procedures. If in the bathroom and shower the main difficulty is drying towels and floor mats, then in baths it is most difficult to dry wood, especially on floors and in crevices.
Drying of baths, bathrooms and showers is carried out by aerodynamic methods - dry ventilation air enters the area of ​​humidified materials, evaporating water. Water vapor is released into the air. Through the exhaust ventilation humidified air is removed and fresh air is supplied. Thus, the drying process includes several stages and is far from simple.

Let's make a reservation right away that if we consider the problem broadly, then we should not talk about drying, but about the normalization of wood. The fact is that in dry high-temperature saunas the wood sometimes does not get wet, but, on the contrary, gets overdried, and after the end of the bath procedure it is again moistened due to the equilibrium hygroscopicity. In steam and humid baths, wet wood must also be dried not to an absolutely dry state, but to a certain level of humidity. That is, conservation ventilation is not just wood drying, but drying, taking into account the specific bath process, the characteristics of wood, its possible morbidity and possible consequences of overdrying (warping, cracking) and underdrying (decay).

Moistened - dry

For all its advantages, wood also has many disadvantages, which makes it a problematic material for baths. Fire hazard, low hygiene and the ability to quickly rot - these are the main features on

natural wood, which at one time put an end to the prospect of using wood in urban public baths for hygienic purposes.

In individual baths, wood continues to be used in a periodic (episodic) mode with mandatory subsequent drying, despite the possible chemical treatment of wood.

Wet wood is susceptible to all three types of biological destruction - due to bacteria, fungi and insects, and dry only due to insects. If wood rot is slimy with an unpleasant odor, it is most likely bacterial rot. If plaque, colors (stains of foreign color), mold with an earthy smell are formed on the wood, these are probably microscopic fungi (fungi, micromycetes). Bacteria and micromycetes are not so dangerous for individual country baths, which will stand for many years even with colors. But for representative and apartment baths, micromycetes are the number one scourge, since they spoil the appearance of the finish. But the most dangerous for the baths are macromycetes - large, real mushrooms with characteristic fruit caps, living right on the wood (like mushrooms, tinder fungus, sponges). Many summer residents, surprised to see the brown fan-shaped mushroom caps sticking out of the floor in their bathhouse, at best they will only scrape them off and smear the growing area with vitriol or chromopic, not realizing that these caps are only the fruit bodies of a house wood-destroying mushroom. The mushroom itself is hidden in the floor, walls, foundation (both in a tree and in a brick) in the form of a system of branching threads (single GIFs - cords up to 1 cm in diameter), forming a mycelium several meters in size, so that the development of the fungus can only be stopped antiseptic treatment of large areas. The normal temperature for the development of house mushrooms is 8 - 37 ° С, the relative humidity of the wood is 25 - 70%. Under optimal conditions, the fungus destroys the bath in one season, forming brown fissured rot, which breaks down into large prismatic pieces that are easily ground into powder.

It is believed that the development of the house fungus is suspended when the relative humidity of the wood is about 18% and below. Considering the wood hygroscopicity curves from this point of view, several conclusions can be drawn. Firstly, to maintain the moisture content of wood at 18% and below at all temperatures of fungal development (5 -40 ° C), a relative humidity of no more than 80% is required. Otherwise, even completely dry (but not treated with water-repellent compounds) wood will be moistened above this level by itself (without contact with room water) due to the absorption of moisture from the air. So in tropical countries there are more problems with timber than in the north. Secondly, considering the curves of wood hygroscopicity in other coordinates (Fig. 1), it can be noted that wood, which is humidified arbitrarily at a temperature of 30 ° C and an absolute air humidity above 0.03 kg / m3 (that is, at a calculated relative humidity air 100% and higher relative to the temperature of the wood), dries at a temperature of 40 ° C to a humidity of 11% (and only up to 11%!), and at a temperature of 80 ° C to a humidity of 2.5% (and only up to 2.5%! ). All this is extremely unusual: non-porous materials would dry out completely under these conditions. For marble, metal and plastic, only two states are possible: when there is water on them (and no matter how much) and when there is no water on them at all.

In this regard, let us recall how dry wood is moistened. If you splash water on a wooden board, it will gradually be absorbed into the depths of the wood: first into the intercellular spaces (vessels, pores between fibers), then into dense (dried) cell cavities, then into the cell walls. All of these pores are capillaries with wettable walls. Due to the formation of concave menisci of water surfaces, the saturated vapor pressure above the water inside the wood is less than above the water poured over the surface. Therefore, not only water, moving along wetting surfaces, but also its vapors rush into the capillaries (intercellular and cellular), moisten (and then dry quickly). Water in them is called free, its content in wood can reach 200%. Small capillaries (in the cell walls) are moistened (and then dry) slowly, the water in them is called bound (hygroscopic), its content in wood reaches up to 30% (it is shown in Fig. 1). Thus, a board that looks "dry" without water droplets can contain 100% or more moisture, and this moisture is extracted from the wood in the form of water vapor during drying and can humidify the air. This effect is used not only when drying a bath, it is also used to create a condensation climatic regime in a Russian steam bath, when due to the high relative humidity of the air near the ceiling (for example, when water is supplied to hot stones), the ceiling is first moistened (preferably a massive log). Then, in the periods between giving, a high absolute humidity is created at the ceiling - above 0.05 kg / m3. Under these conditions, a metal ceiling would not just "drip" without retaining moisture, it could only create a quite definite relative humidity of the air at its surface, equal to 100%. A wooden ceiling (like any porous one), in principle, can create only a quite definite relative humidity of the air at its surface, and with a fixed humidity of wood (due to the massiveness of the walls, for example), the relative humidity of the air not only at the ceiling, but also in the room can be maintained also practically constant regardless of how the room temperature changes. The effect of stabilization of the relative humidity of air in wooden residential buildings (in brick and plastered ones too) is associated in everyday life with the property of wood to "breathe", take moisture from the air and release it into the air in the form of water vapor. So a plastic sauna and a wooden sauna even with the same steam generator give different climatic conditions. Indeed, let us imagine that the sauna is completely dry at a temperature of 20 ° C and at a normal relative humidity of 60% (that is, at an absolute air humidity of 0.01 kg / m3). In accordance with fig. 1, the relative humidity of wood under these conditions is 12%. Now, hypothetically, let us heat this sauna (without ventilation and without humidification) to a temperature of 70 ° C. The bold dashed horizontal arrow in Fig. 1 shows that the absolute humidity in the sauna jumps up to 0.14 kg / m3, just right to steam with a broom! Where did the water come from! The wood began to dry and humidified the air. By the way, it is the water vapors coming out of the wood that "pull" the "smells of wood" that are so appreciated in apartment saunas. This phenomenon serves as another additional reason for the need to ventilate even dry apartment saunas, so that they do not unexpectedly become steam rooms. And if the sauna is ventilated during heating with fresh air of the same absolute humidity of 0.01 kg / m3, then the air in the bath will be kept dry, and the moisture content of the wood in the bath will decrease and sooner or later will drop to 1% (see vertical bold dotted arrow in Fig. 1), that is, as they say in everyday life, the boards "dry up". And then, after the end of the bath procedure, they will be moistened again due to the sorption of air moisture to a moisture content of 12%. In the language of meteorologists, "wood tries to keep the relative humidity of the air constant." Indeed, in the wood bath discussed above, the wood "kept" the relative humidity in the bath at the level of 60%, which can be achieved under conditions of a rise in temperature only by humidifying the air with wood. There can be nothing like this in a plastic bath: when it is heated, the absolute humidity of the air remains constant, but the relative humidity drops. It is glass, sheet metal and plastic that are ideal materials for dry physiotherapy and room saunas. And if you use wood, then only thin, specially treated to prevent hygroscopic absorption of moisture from the air. The craze for decorative wooden finishing of baths (not always justified) leads to the fact that even bath hygrometers are sometimes made in wooden cases (!), "Keeping" the relative humidity inside themselves constant, regardless of the temperature and true humidity in the bath. By the way, recall that the measuring thread of the hygrometer, located inside the case, stretches when wetted (like an ordinary woolen thread) and thereby shows how wet it is. And it is moistened hygroscopically (due to its porosity) according to the same laws as wood. That is, the thread is moistened and lengthened mainly only when the relative humidity of the air changes. This is the basis of the principle of operation of hygrometers with natural thread. By the way, wood fibers stretch and shrink only when the relative humidity of the air changes. In rural life, the simplest, but very accurate "hygrometers" in the form of a thin, peeled and dried bifurcated wooden branch are well known. A thick mustache (the main branch is about 1 cm thick) is cut 10 cm above and below the fork and vertically nailed to the wall (baths, houses, cellars). A thin mustache (shoot about 0.3 cm thick and 0.5 m long) is directed upwards parallel to the wall. In dry weather, a long thin mustache of a branch slopes, moves away from a thick one ("bulges" with an increase in the acute angle of the fork), and if it rains, it approaches a thick one. If you have a certified industrial hygrometer, then this homemade hygrometer can be calibrated with marks on the wall opposite the location of the tip of the thin mustache at different relative humidity. The principle of operation of such a hygrometer is that during drying, the underlying wood fibers of the main branch are shortened and pull the shoot down (from the trunk of the main branch).

Thus, the processes of moistening and drying wood take place in the bathhouse not only on the floors due to compact water and are associated not only with bath procedures. If wood can be moistened with both compact water and water vapor, then it can be dried only by removing water vapor from it. The drying process takes place in several stages. First, water evaporates on the surface of the wood, then free water in the large capillaries of the intercellular and intracellular spaces, then water in the small capillaries of the cell walls. The latter, as we established above, determines the hygroscopic moisture content of wood, which exists and changes even in a dry, unheated bath. Therefore, the drying of the cell walls can actually be controlled in the greenhouse conditions of dry built-in saunas, although bound water, in principle, can support the processes of decay of wood, especially, as we have noted, in warm and humid climatic conditions.

The phased drying process is also typical for other porous materials, including bricks, plaster and soils (earth). Drying them is also important for the bath, if they are part of it. In this regard, we recall the fundamental, although related only indirectly to the topic of the article, the question of the mechanical deformation of porous bodies during the primary removal of bound water from them. It is known that warping and cracking of freshly cut wood occurs during the drying process, mainly in the last final stage, when hygroscopic moisture is removed from the cell walls. If, during the initial drying, the board is nailed or clamped in a vice, then it will retain the shape given to it (for example, arcs), and the better, the better the wood is dried. Under the conditions of primary natural atmospheric drying at 20-30 ° C, wood is dried only to a moisture content of 10-15% (after 2-3 years of drying), and with high-temperature stone drying at 100-150 ° C (including in a bath ) can be dried to a moisture content of 1 - 2 96. With such a significant dehydration, especially at high temperatures, irreversible changes occur in the cell walls, and the wood actually ceases to be wood and begins to exhibit the properties of inanimate material. Similarly, clay soaked in water, during drying and heat treatment, first loses its plasticity, then cracks, and then becomes a brick, which does not change its shape and properties in the future when it comes into contact with water. also by immersion in a hot anhydrous heat carrier (paraffin, oil products).

The mechanism of primary drying of freshly cut wood differs in that the walls of its cells have not yet been destroyed, the vapor and water permeability of the membranes is low and the wood dries for a long time, deforming during the destruction of the integrity of the cell wall membranes (and they, in fact, are wood - a combination of cellulose, lignin and hemicellulose). In the course of subsequent dryings, the wood dries faster and already behaves like "lifeless", since the cell walls have already been torn. At the same time, dry wood as a porous material has specific features that distinguish it from other materials, in particular, anisotropy of properties, secondary warpage, etc.

Drying dynamics

Water spilled on the surface of the wood evaporates just like water poured into a bathtub or pool. Recall that there are two opposite modes of evaporation - kinetic and diffusion. In the kinetic regime, the fastest molecules, overcoming the energy barrier equal to the latent heat of evaporation (condensation) 539 cal / g, fly out from the surface of compact (liquid) water and are irrevocably removed. The kinetic regime is realized during evaporation in a vacuum. Due to the high speed of the primary act of vaporization (the release of water molecules from the surface of compact water), which at bath temperatures amounts to thousands of kilograms of water per hour from 1 m2, the water is strongly cooled (since only slow molecules remain in it) until it turns into ice, which is used in industrial freeze drying. In the diffusion mode, the primary act of vaporization remains the same and is just as strongly dependent on temperature. But the escaping water molecules enter the air (a mixture of nitrogen and oxygen molecules) and, as a result of frequent collisions, only very slowly move away (diffuse) from the water surface, experiencing strong resistance from the air environment. As a result, the overwhelming number of escaped molecules again "flies" into the water (condenses). Thus, in the diffusion mode, tons of water turn into steam and immediately condense (which we do not feel in any way), and only a very small amount of water (kilograms) completely evaporates. It is this diffusional mode of evaporation that takes place in the bath: both during the evaporation of sweat from the human body, and during the evaporation of water from the shelf. It becomes clear that if the concentration of water vapor molecules everywhere in the bath is equal (including at the surface of the human body), then no evaporation processes are possible (homothermal regime). But at the same time, it becomes clear that if tons of water per hour evaporate and condense in the bath at the same time, then it can be assumed that this should manifest itself sometime. Indeed, if the air in the bath is dried, then the rate of evaporation of water will increase. If the surface of the water is blown with dried air, then the evaporation rate will increase even more, since the air stream removes those molecules of water vapor that previously condensed. For orientation, we point out that at a relative humidity of 5096, the rate of evaporation of water at a temperature of 30 ° C is approximately 0.1 kg / m2 / hour. When air moves at a speed of 1 m / s, the evaporation rate approximately doubles, but it should be noted that the air speed in a room is always much higher than directly above the water surface, and all quantitative indicators are extremely indicative. Experimental pool formulas can be used for estimates. In any case, the characteristic rate of drying floors in baths is 0.1-1 mm / h (0.1-1 kg / m2 / h) increases with an increase in the floor temperature and with a decrease in air temperature (that is, with a decrease in the absolute humidity of the air). So, for example, in outdoor pools at a constant water temperature, evaporation is maximal not at all during the day, but at night in cold air, as well as in winter. In the daytime, in hot weather, evaporation may stop, even condensation of water vapor from the air on the surface of the pool may be observed, just as water condenses on human skin in a condensation-type steam bath in a mode higher than a homothermal one. For any pool with a certain water temperature, any floor, wall and ceiling, each bath has its own "homo-thermal" curve that separates the modes of water evaporation and condensation of water vapor, summarizing the above processes of evaporation and condensation on the water surface. Let's call it conditionally condensation. In terms of condensation curves, drying looks like this. In fig. 2 shows the condensation curves for a floor with a temperature of 20 ° C (curve 1) and for a ceiling of a steam bath with a temperature of 40 ° C (curve 2). The modes below the curve correspond to the evaporation of water, the modes above the curve correspond to the condensation of water vapor on the surface of the given temperature. Thus, if the air in the bath has a temperature of 40 ° C and a relative humidity of 6096 (it does not matter whether the air in the bath is stationary, whether it circulates or enters outside in the form of ventilation), then in this mode (point 3) the ceiling is dried and the floor is moistened ... In other words, air with such parameters transfers water from the ceiling to the floor, but even if the ceiling were dry, the floor would still take moisture from the air, that is, dry it (in this case, to a relative humidity of 40%). The floor can be dried only if you reduce either the air temperature or its relative humidity, or better both, so that the air characteristics are below curve 1, for example, if the mode corresponding to point 4 is implemented. The fact of possible air movement (blowing the floor) does not change the quality picture, but only affects the rate of evaporation or condensation. By the way, it is this mechanism that works in case of catastrophic humidification of the subfields of a residential building, to which a bathhouse with leaking floors is attached. Warm humid air from the hot water discharged to the ground spreads over long distances and produces condensation on the cold subfloors and foundations of the entire apartment building.

The main conclusion is that conservation ventilation is not just a change of air in a damp bath room. It is necessary to supply air with the lowest possible temperature and relative humidity, or rather the lowest possible absolute humidity. In addition, it is necessary to keep the surfaces to be dried as warm as possible, and the higher the absolute humidity of the air, the higher the temperature of the surface to be dried. This means that it is not the air that needs to be heated, but the floor of the bath, for example, with infrared radiation. And if, nevertheless, it is possible to warm only the air, then it must be dried, as is done in washing machines and dishwashers. Note that the sometimes recommended methods of drying a bath with the release of hot humid air through the floor in the underground lead only to additional humidification of the cold (and therefore the most problematic) elements of the bath. Better to release hot, humid air through the upper vents, in which condensation is impossible. In fact, in almost all baths general ventilation is used for conservative drying of the interior.

With the complete evaporation of water from the surface of non-porous materials, drying can be considered complete. But when we are dealing with wood, it is also necessary to remove the internal water. If the wood is treated with water-repellent compounds, then the pore walls are not wetted with water, which means that the water vapor pressure in the pores is greater than on the wood surface. This leads to the "evaporation" of water from the pores on the surface of the wood in the form of droplets, which then evaporate again as described above.

Water filling pores with wetted walls, including untreated wood, evaporates in a diffusion mode, and the removal of steam is extremely difficult. Although wood contains 50 - 90% of voids, the tortuosity of the pores leads to the fact that the real path of removal of water molecules can be several times larger than the characteristic dimensions (thickness) of a wood product. In this case, possible air flows, even very small ones, can strongly affect the drying rate. The "permeability" of materials is characterized by a parameter called vapor permeability, equal, for example, for mineral wool 8 - 17, for pine along the grain -10, pine across the grain - 2, brick - 2, concrete - 1 in units of 10 "6 kg / m / sec / atm.So, with typical static pressure drops due to wind of 104 atm.real values ​​of drying rates for porous materials with a thickness of 10 cm at 20 ° C are less than 1 g / m2 / day for vapor-insulating materials (hydraulic concrete, asbestos cement, extruded polystyrene foam ), 1-20 g / m2 / day for vapor-permeable materials (wood, brick, plaster), more than 20 g / m2 / day for vapor-permeable materials (mineral wool), more than 1000 g / m2 per day for superdiffusion materials (perforated membranes The rate of drying increases with an increase in the temperature of the wood, with a decrease in the temperature and humidity of the blown air, just as in the case of evaporation of water from the surface. experimentally, depending on the degree of moisture and the season, but the temperature of the internal elements of the bath has a much greater influence. The analysis of wood drying issues could be continued and the most reasonable solutions for preservative ventilation could be considered. But there is no point in deceiving: the centuries-old experience of operating wooden baths shows that no matter how sushi the wooden floors are, there are still no guarantees of the quality of drying, they still rot. Indeed, if 1 m2 of a wooden floor conventionally absorbs 1 kg of water, then drying it at a rate of 20 g / m2 will last 50 days. Therefore, wherever possible (and not only in baths), wood is covered with roofs, awnings, but in this case it is also capable of moistening. condensation from the air (for example, under iron roofs) and rot (brown, darken, crumble), especially in poorly ventilated places. The presence of air vents, that is, holes and slots larger than 3-5 mm, is an indispensable condition for the preservation of unheated zones of wooden structures. On the contrary, airs with a size of less than 1-3 mm are stagnant, poorly ventilated zones, moisture evaporates from them slowly, which creates conditions for rapid decay, especially in contact with vapor-impermeable materials, and even more so with constantly humidified ones. The question is not about how to dry wood qualitatively, but about how to remove it from the bath altogether or reduce its wetting and reduce the rate of decay. This is typical not only for wood, but also for all porous mineral materials (brick, foam concrete, gypsum) and rusting steel. After all, no one makes floors from foam concrete and then makes incredible efforts to dry it. In the same way, rusting steel is painted, rather than trying to dry quickly after each rain. In modern saunas, all wood that can come into contact with water must be impregnated with water-repellent compounds (preferably under pressure, as is done in the case of railway sleepers and ship masts), and protected from above with waterproof paint and varnish coatings, as well as shelters, not to mention antiseptic and fire protection. The wood in the bath is a problematic material, and the widespread opinion that the bath is good only because it is wooden and there should not be any "chemistry" in it is absolutely groundless. Of course, in the conditions of a built-in amusing sauna, operated in a greenhouse environment of an apartment corridor, untreated wood is permissible even on the floors, but even there only in the form of a removable, dried grate.

STEAM INSULATION OF CEILINGS

Methodically more difficult is the question of ventilation of wood in the upper parts of the walls and ceiling. The task of preservative ventilation here is to supply dry air to humidified areas to dry them. Therefore, in each specific case, it is necessary to clarify what and how can be humidified, and only then decide where and how to supply the ventilation air.

The ceiling (or rather, the ceiling slab) can be moistened by precipitation in case of emergency roof leaks and steam condensation. Previously, humidification was predominant due to trivial leaks, since until the 19th century in cities and until the 20th century there were no bath roofs in the villages, except for wooden (boards, shingles), thatched and Kamyshevs. Log walls and ceilings in the event of a malfunction of the roof could absorb hundreds of liters of water in the rain. Therefore, there was no need to talk about any possibility of their periodic drying after constant leaks, although the wooden roof itself worked precisely in this mode of constant moistening and drying (as a result of which the wooden roof was made thinner so that it got less wet). The task was simple: to prevent leaks, but if they happened by chance, then the walls and ceiling had to be dried sooner or later, but be sure to dry them. This was achieved by constant ventilation of the attic space, by organizing air vents, gaps and cracks in log and plank structures wherever possible, that is, the same techniques were used as in the natural drying of firewood in woodpieces, but, of course, while maintaining the heat-insulating ability of the walls and ceiling.

Currently, individual developers do not take leaks seriously, relying on the reliability of steel and slate roofs, although the issue remains serious and the consequences are most dangerous. So what happened, as a result of which everyone around began to talk about the indispensable need to vapor barrier the walls and ceilings of the bath as the most important thing? Indeed, for centuries before, in black logs, and then in white steam baths, they did not know about any vapor barrier, and steam humidification is so insignificant in comparison with leaks that they cannot create a dangerous moisture level of wood above 18 percent for a long time (especially in dry built-in saunas ).

Immediately, we note that the issue of vapor protection of wood and heaters first arose in baths in connection with the appearance in everyday life of soft waterproofing roofing materials (which are also often used not for their intended purpose), and dangerous levels of wood moisture have acquired an exclusively local long-term nature. However, before moving on to this issue, let us consider the general features of moistening wood with condensing steam.

Usually in the literature, the humidification process is described briefly and simplistically: humid air is filtered through porous wood from the inside to the outside, and where the temperature of the wood drops to the dew point of humid bath air of 40 ° C, local condensation of steam occurs and the wood is humidified only at this point. In fact, the process is more complicated. Firstly, wood is a wettable porous material, so the condensate released is absorbed by the wood and is distributed along the wetting pore walls over a large volume of wood (blotting effect). By the way, then l<е самое происходит и в других смачивающихся пористых материалах: кирпичных, гипсовых, пенобетонных. Во-вторых, древесина является непросто смачивающимся пористым материалом, она имеет и мелкопористую составляющую, обуславливающую гигроскопичность материала (способность впитывать пары воды из воздуха). Для таких материалов характерно отсутствие четкой точки конденсации. На рисунке 3 изображена еще раз перестроенная в иных координатах кривая равновесной гигроскопичности древесины в зависимости от температуры. Это фактически график влажности древесины по срезу стены бани, имеющей температуру внутренней поверхности стены - 100°С (справа) и температуру наружной поверхности стены - 0°С (слева), при условии движения влажного воздуха изнутри наружу (справа налево). Мы видим, что при влажности воздуха, например, 0,05 кг/м3 (точка росы 40°С) равновесная влажность древесины на внутренней стороне стены равна 2 процента, затем по мере углубления в стену влажность древесины плавно, но быстро повышается и по мере приближения к точке росы 40°С резко возрастает до бесконечности. Это означает начало конденсации в крупных порах, но вся вода из воздуха в этой точке росы отнюдь не выделяется. Несколько осушившись, воздух продолжает перемещаться влево, непрерывно и постепенно отдавая воду уже при новых пониженных точках росы (например при влажности 0,017 кг/м3. Таким образом, увлажняется довольно протяженная зона, причем находящаяся у внешней стороны стены, которая впоследствии высыхает с выделением водяных паров наружу, но которая отнюдь не прогревается горячим воздухом при сушке интерьера бани. Так что очень большое значение имеет не столько температура воздуха в бане при ее сушке, сколько сухость этого воздуха, а также направление движения воздуха, фильтрующегося через стенку.

If the wall material is not fine-pored (for example, like mineral wool, which practically does not have capillaries) or if the material is treated inside with a water-repellent agent and is not wetted, then the wood moisture curve is converted into a vertical dotted line at a dew point of 40 ° C, that is, at temperatures above dew point such a non-hygroscopic material does not absorb moisture from the air at all, and at temperatures equal to the dew point and below, constant condensation of moisture from the air occurs in the same way as described above. However, in the case of non-wetting of the inner surfaces of the porous material, the released condensate cannot be distributed over large volumes of walls (that is, it cannot be absorbed) and inevitably accumulates in separate zones, including forming droplets. When using mineral wool, drops of condensate flow in streams onto the lower elements of building structures, for example, on wooden beams, logs, crowns, greatly moistening them. In any case, in vapor-permeable (air-permeable) walls, it is advisable to make ventilation ducts (air vents) in areas near the dew point, as well as near load-bearing wooden elements. In particular, a good solution is to upholster the log house with planks (boards, clapboard, siding) inside and outside so that the gap between the boards and logs plays the role of steam exhaust ducts (ventilating facade).

Needless to say, there has always been a desire to keep water out of the walls at all.

So, in particular, in stone (brick) city baths, the walls remained moist for years, despite the ventilation. Therefore, the inner surfaces of the walls, wherever possible, were protected with ceramic tiles, paintwork, natural stone. Of great importance was the introduction into everyday life of cheap soft roll waterproofing vapor-proof materials, including roofing materials (first - roofing felt based on wood or coal tar, then - roofing felt and glassine based on bitumen-rubber mastics, synthetic polymer films and metal sheet foil). They began to be widely used in individual rural baths, first for their intended purpose - as roofing, and then to protect the outer sides of ceilings and walls from rain and wind, especially frame ones, insulated with non-waterproof materials (moss, paper, shavings, fiber boards, arbolite, cross-section straw moistened with glass wool). It is quite natural to want to cover, for example, a layer of shavings lying on top of the ceiling with something impervious or to upholster the plank walls of the bathhouse outside with roofing material to protect it from wind and rain. As a result, the shavings, which were previously moistened only with rare leaks, and when moistened under the action of steam penetrating from the bath, immediately dried out, under a layer of roofing material, they lost the ability to dry out after any moistening. More precisely, the shavings under the roofing felt can dry only when the moisture is removed back to the bath, which is very difficult. Therefore, between the shavings and the roofing material, it is necessary to make a ventilated gap (air) or make punctures in the roofing material for ventilation. Instead of roofing material, special roll materials, called windproof, were developed for these purposes. They do not allow compact water (raindrops) to pass through due to non-wetting and at the same time slightly allow air with water vapor due to porosity or perforation, but protect against wind gusts. It should be noted that gusts of wind create pressure drops up to 10 "atm., Exceeding the pressure drops due to air heating in the bath 10 5 atm., Therefore, the wind pressure certainly plays the main role for drying the walls. It is these pressures that are saved by windproof materials, although air The fact is that the gas-dynamic resistance of the windproof material is much less than the gas-dynamic resistance of the protected wall of logs. Therefore, the logs practically do not "feel" the windproof material. At the same time, if the wall is not made of logs, but from an easily blown insulation , then here wind protection plays a decisive role, limiting the speed of the air flow through the wall. The simplest windproof is the traditional upholstery of the walls with clapboard (boards), so that the upholstery can play not only a purely decorative and hygienic role.

At the same time, windproof materials cannot completely solve the problem of humidification. Indeed, covering the shavings on the ceiling with a windproof material, we will only be sure that an accidental roof leak will not moisten the shavings, and if it nevertheless gets wet (in any way), it will dry out sooner or later. But if the temperature of the wind protection layer is below the dew point, then moisture will condense on this layer, which in a liquid state cannot pass through the wind protection. Since moisture enters the windproof material in the form of vapor in the air flow from the inside to the outside, it is advisable to protect the ceiling from the inside with a vapor-insulating layer (airtight film). Such a sandwich-type structure with three layers (wind protection - insulation - vapor barrier) is the basis of modern enclosing structures. A general technical requirement is to install vapor barriers in areas with temperatures above the dew point. If the vapor barrier is made in the form of a wall cladding (plastic, steel, ceramic), then questions about its installation usually do not arise. But what if the vapor-proof film is placed inside the walls? For example, is it necessary to make a gap between aluminum foil and decorative clapboard? The answer is simple: if compact water can be there, then a ventilated gap is necessary. For example, it is very difficult to make a gap on the ceiling. And if you open the ceiling of a steam bath after several years of operation, you will see that where there was no water (in the center of the ceiling), the back (top) side of the lining is absolutely fresh. And closer to the walls, where there could be water, there are dark spots of damaged wood.

The vapor barrier prevents the penetration of steam into the wall, but at the same time stops the through-blowing of the walls and, thereby, makes it difficult to dry them when the roof leaks. Therefore, having prevented the penetration of steam, it is still desirable to restore the possibility of blowing through the wall by organizing air vents along the outer, and preferably along the inner side of the vapor barrier, although the general ventilation of the room can take on the role of preserving ventilation on the inner side. In this case, the supply and exhaust openings of the air vents should go out into the street or rooms adjacent to the bath (dressing room, vestibule). To assess the required dimensions of the airflow, consider a log bath with a volume of 10 m3 and an area of ​​enclosing structures of 25 m2. Let us take the degree of emergency humidification equal to 20 kg of water. Based on the characteristic vapor permeability of log walls at the level of 20 g / m2-day, the duration of natural drying in diffusion mode at wall temperatures of 10 - 20 ° C will not exceed 40 days (the value is quite large). In the presence of a vapor barrier of logs, such a duration of wall drying can be achieved at a wall ventilation rate of 1 m3 / hour, which is significantly lower than the ventilation rates of the bath rooms - 10 m3 / hour or more. Such a speed can be provided by the supply and exhaust openings of the air vents between the logs and the vapor barrier, the total cross-sectional area of ​​10-50 cm2, that is, in fact, slots (along the entire perimeter of the bath), less than 1 mm wide, which is ensured by inaccuracies in the mechanical processing of wood and assembly of structures ...

In log walls, wood plays the role of both windproof, heat-insulating, and load-bearing material. The modern construction of construction, including multi-storey buildings, implies the development of insulating materials for narrowly specialized functions and only sometimes combined functions. So, for example, waterproofing, windproof, vapor barrier, thermal insulation materials are, as a rule, completely different materials. At the same time, specialized film (roll) and tubular (cord) moisture-removing materials that can be laid inside the walls and which, playing the role of air vents, could remove moisture from the most difficult-to-reach places in any form (in the form of compact water or in the form of steam). It is these drainage materials that, apparently, will become in the future the basis of progressive solutions for the preservative ventilation of walls. Indeed, how to dry (or keep dry) massive brick walls that have been damp for years, the walls of city public baths, laundries, swimming pools? Neither elevated bath temperatures, nor maintaining a relative humidity of 40-60 percent in laundries and swimming pools can completely ensure the dryness of walls, even those protected by ceramic tiles. Recently, hollow building materials (slotted bricks and concrete blocks with cavities, foam materials) have begun to be widely used, but these voids in the walls must somehow be connected to each other and closed to centralized supply and exhaust devices that regulate the speed of preservative ventilation within the required limits. This role will be assumed by new ventilation materials, primarily in ventilated facades and roofs.

One way or another, using ultra-modern or traditional materials and structures, it is necessary to provide air vents (ventilation ducts) in all places of walls and ceilings where compact water can appear. The transverse size of the vents (slots - 1 mm or holes with a diameter of 3-10 mm) is not so important, the main thing is that the vents cover all problematic parts of the walls (especially supporting structures) and are ventilated exclusively with outside air under the influence of wind back pressure. With a large size of air vents, it is advisable to close the ventilation ducts to local supply and exhaust openings, the flow sections of which can be adjusted if necessary. It is not advisable to combine the supply and exhaust ventilation of the bath room with the wall ventilation system due to the possible increased humidification of the walls with humid bath air.