At all times in Rus', baths were built from strong, fresh logs - on a flimsy foundation, without special treatment of the walls or intricacy of the layout. And all because the forest was always available - and after 5 years the bathhouse, which had become obsolete, was not difficult to rebuild with a new one. But today the construction of a steam room is already quite expensive, and quality timber- worth its weight in gold. That is why economical technologies for construction from logs in other countries began to penetrate so actively into Russian architecture. And the most interesting and fresh of them is “double timber”, the main advantages of which are excellent heat and sound insulation.
Particularly popular are houses built using the “double timber” technology abroad - only there they use not so much logs as a fairly thin carriage, but even that is good. For the harsh Russian winter, the thicker the wall material used, the better.
What is the advantage of the “double beam” technology?
Here are the main advantages of this construction technology:
- Virtually no shrinkage.
- Easy transportation of building materials.
- Possibility to start arranging a bathhouse right away.
- There is no need for additional equipment to construct the frame.
- No cracks or warping.
- No vapor barrier is needed - this is a huge plus: your bathhouse will truly “breathe”.
- Inter-crown seals and dowels are not used.
- Warm, and quite noticeable.
And finally, build baths according to new technology made from double timber is not difficult, and can be completed in almost a month.
Thanks to the significant lightweighting of the structure due to the internal space, it really is not present in the “double beam” - less than 1%. Which, of course, makes life a lot easier for many bathhouse owners.
One of the valuable advantages of this technology, which is actively advertised, is the absence of the need for finishing. Like, clean timber with its unique aroma - what could be better? For a bathhouse, this option is not the best, of course, but if you are building a house from timber with your own hands, then you can leave it like that. The fact is that high humidity sooner or later it will play its role - even if the bare timber remains only in the rest room. Therefore, be sure to use special impregnations and antiseptics. And yes, there is good news for you: you can start decorating the walls immediately after construction is completed.
What gives the structure such strength?
Of course, double beam technology is not even comparable to frame construction, where the insulation is surrounded on both sides by only flimsy thin walls. Remember that no matter how you look at it, everything here rests on the uneven bars! By the way, there is also a subtype of double beam - this is a “double mini-beam”. The technology for its construction is the same, but the walls are thinner.
Floor beams also give additional strength to the structure - if they are cut into the walls during construction. And no one has yet canceled aesthetics. But with this technology, you can only use absolutely dry lumber measuring 160x50. This is the secret of its strength - when the timber is dried, it loses up to 13% of its moisture content, and at the same time the molecular bonds in it are broken. After this, as much moisture as the timber takes in, it will give back as much - and deformation will not occur.
But the majority of Russians are still looking at the new Finnish technology with some caution: is it possible to assign load-bearing beams, which the manufacturer under dual technology reduces to 45 mm in thickness? On the other hand, the practice of such construction so far shows that such baths stand and stand firmly, without warping or deforming. Moreover, the steam room itself is traditionally small.
Does double timber need a vapor barrier?
This is almost a rhetorical question among those who build using the “double beam” technology. The fact is that a bathhouse or a house made of timber will, over time, still begin to absorb moisture from environment- It's unavoidable. And many believe that such insulation between the beams is an ideal place for rot to spread. At the same time, those companies that build in this way have been claiming for almost ten years that there is nothing of the kind - until now the owners of such houses have not complained. Therefore, special film should be used only in ceilings - that’s enough.
But still, some bathhouse owners are still worried about the lack of a complete vapor barrier and use it during construction windproof membrane- applying it after the insulation. Unfortunately, among builders this method is jokingly called “putting kisses on top of natural cotton linen” - after all, walls made from such double timber will definitely not “breathe”. Although they will, of course, last much longer.
What is the best way to insulate the space between the beams?
This question cannot be answered unequivocally. Basically, in this matter, they are guided by the fact that when insulating ecowool, the heat flow itself is always as close as possible to the calculated one, but when using slab materials, expect noticeable losses.
So, if you take Izospan as insulation, proceed from the following calculations: for the wall, take 110 g for each square meter, and for the floor and roof - 110 and 90 g per meter on opposite sides. And, if, for example, if you insulate with ecowool, then the calculations will be as follows:
- Acoustic isolation – 46 decibels
- Dew point – at normal conditions there will be no condensation at all
- Insulation - 0.13 cubic meters per square meter of wall
- Thermal conductivity coefficient – approximately 0.2 W/m2kv
Ecowool must be blown into the space between the beams using a dry method, but with a height of no more than three meters. This needs to be done in stages. And here a certain difficulty often arises: ecowool is blown into a double beam in the same way as inside frame walls. But only the latter have closed wells, which is why it is not difficult to achieve the required density. But here it is more filled up than blown out - and therefore will settle. That is why, for such a process, experienced builders use a special technique - a “blowing machine”.
Also note that when filling ecowool between the beams, the following problem may arise: at an ambient temperature below 0°C, when the force reaches the required density of 70 kg/cub.m. your workers can simply overdo it - and the walls risk becoming bulging. It will be difficult to fix.
That's why in last years Instead of ecowool, our compatriots began to more often use mineral wool and its analogues as inter-beam insulation. It is more reliable, tested and no less environmentally friendly, and costs less. But it is precisely with basalt that vapor barrier is needed - what is its disadvantage, while ecowool almost never creates a dew point due to its special properties - it can be safely laid in double timber without any membranes. Although mineral wool quite warm - in terms of its resistance, its thickness of 100 mm corresponds to 390 mm of solid wood.
Also, do not forget that mineral wool does often shrink, and when using it you will have to coat it with an antiseptic both inside and outside.
If you use sawdust as insulation, then it is better to take them stale. If you got fresh ones, then soak them in lime for one day and only then knead them. Like this: pour into the mixer cubic meter sawdust and add two bags of cement. Lightly moisten, mix well, pour between the beams and compact. But there are significant disadvantages of sawdust - mice, mold and dampness. And here some craftsmen show miracles of ingenuity - they buy sawdust from basalt slabs almost for nothing, and they can be obtained at the site of production.
They are also insulated quite effectively with bulk cellulose. And today they also practice such construction when they do not put insulation at all - believing that the air itself is the insulation. But one thing is not taken into account: the air serves as thermal insulation only when it is motionless, and in wooden bath it may well “walk” thanks to natural convection. This is the task of insulation materials - sawdust, ecowool, polystyrene foam and mineral wool - to simultaneously create many small cavities with air that will not allow it to move.
By the way, all communications connections will have to be made during the construction process - double timber allows you to conveniently lay electrical wiring in such walls, which is another significant advantage of this technology.
If you want to order such a turnkey bathhouse, as is fashionable today, we have to disappoint you - the price for its construction today is still too high, more than 15,000 rubles for each cube of wooden part of the wall. Why in Russia so far no more than a hundred bathhouses and houses have been built using this technology - after all, laminated veneer lumber is not much worse than the new Finnish method, but it costs almost one and a half times less. But all this does not stop you from building a warm and environmentally friendly bathhouse with my own hands– did you find something difficult in the end?
Even a novice builder knows that log houses have two main drawbacks - thin walls and shrinkage of the crowns. The latter occurs due to wood shrinkage. Therefore, they use techniques that prevent wall deformation and promote it. effective insulation. By existing standards The walls of the house should be no thinner than 20 cm.
The double beam technology, which was first used by Finnish builders, allows us to solve this problem. The country has a small number of trees thick enough that could be used to build houses, while protecting them from severe frosts, characteristic of the region.
What is the essence of the new technology?
Finnish engineers have managed to develop technology that makes it possible to build warm wooden houses at relatively low financial costs. It was called “double beam”. In fact, this technology has little in common with timber in the usual sense. Its essence lies in the fact that to achieve the proper thickness of the walls, two tongue-and-groove boards are used, between which there is a layer of insulation.
Houses using double timber technology are distinguished by improved thermal insulation characteristics, compared to houses from solid timber similar section. Compared to insulated laminated veneer lumber, this technology does not use adhesive compositions. The insulation is often ecowool or mineral wool.
Double beam: production
The production of material for the construction of houses using double-timber technology differs from the production of conventional profiled timber. It is carried out on special equipment - a fully or partially automated cup-cutting line.
It is carried out in several stages:
- production of workpieces;
- drilling holes intended for fastening edged boards;
- cup cutting;
- grooving;
- cutting the workpiece;
- removal of residues;
- marking;
- insulation with material;
- package.
Advantages
The main advantage of a house made of double timber is high energy saving. The thickness of its walls does not depend on the diameter of the log or timber. The insulation layer is selected in accordance with the requirements specified in generally accepted thermal engineering standards. The second advantage of the technology is the minimal shrinkage of the walls, fluctuating in the range of 1-2%.
Begin full operation of a house built according to Finnish technology, can be done once the walls and roof are assembled. Ordinary houses made of timber cannot be used immediately, since you need to wait until the wood dries and the crowns “fall” into place. In this case there is no need to wait.
Installation of a house made of double timber is relatively simple, not labor-intensive and does not require the use of complex construction equipment, which has a beneficial effect on the construction time of the house and financial costs. In parallel with the assembly of the walls, they fill the space between the boards. made of double timber there is no need to additionally insulate and finish it.
Flaws
“Double beam”, despite many advantages, also has a number of disadvantages. The most significant is the shrinkage of the insulation, but it occurs only when using mineral wool. There is also the possibility of cracks appearing.
They can form due to uneven shrinkage of the cladding of external and internal boards, used for houses built using the “double beam” technology. Reviews from builders assure that in practice such problems do not arise at all. At least there were no comments.
Application experience in the domestic market
The technology has been used on the domestic market only recently, so no one can guarantee that wooden houses will fully perform their functions in our climatic conditions. You just need to trust the Finnish experience in house building, since they have been building houses from double timber for over 20 years and successfully operate buildings in their more severe climatic conditions.
It is not possible to build a house on your own using this technology, since its high-quality construction requires boards processed at special machines. It is also necessary to cut tenons, grooves and docking recesses intended for corner connections. There is no way to do it without a team of specialists and the purchase of a house kit. Therefore, saving on financial costs is problematic.
Structural strength
Double beam technology is not comparable to conventional frame construction, where the insulation is located between two thin walls. In this case, everything is held on the bars. A subtype of this technology also exists and is used - “double mini-beam”. Its construction is similar, but its walls are thinner.
Increased structural strength is also ensured if they are embedded into walls during the construction process. The technology can use exclusively dry lumber, which largely affects the strength of the house as a whole. This is due to the fact that drying the timber leads to a loss of 13% moisture content, due to which the molecular bonds are broken. In the future, the timber will give off exactly the same amount of moisture that it will absorb. Therefore, no deformation will occur.
Vapor barrier
For the construction of houses whose walls consist of several floors, vapor barrier is an important issue. Without its consideration, it is not recommended to carry out construction. Double timber is an exception, despite the fact that the walls of houses built using this technology are later certain time will inevitably begin to absorb moisture. Therefore, there is an opinion that the insulation between the beams is a place for rot to form. Wherein construction companies, who specialize in building houses using this technology, claim that double beams have never caused any problems before. Reviews from the owners agree that it is enough to use the film only in ceilings.
But there are exceptions. Some owners are concerned about the lack of vapor barrier as such, so during construction they use a windproof membrane, which is applied after the insulation. Experienced builders are skeptical about this, since it will not allow the walls to “breathe” freely, but they can last much longer.
Ecowool as wall insulation
When building is not impregnated with harmful synthetic resins, the best option will be the use of harmless insulation. Optimal material is ecowool, the main component of which is cellulose. It does not rot, does not shrink and is not subject to fire.
The calculations for the material are as follows:
- acoustic insulation - 46 dB;
- dew point - under standard conditions, condensation will not occur;
- insulation - 0.13 m2 for every m2 of wall;
- thermal conductivity coefficient - 0.2 W/m 2.
Ecowool is blown dry into the space between the beams. The height should be no more than three meters. The procedure is carried out in stages. But here certain difficulties arise: ecowool is blown into the “double beam” in the same way as inside frame walls. If the latter have closed wells and it is not difficult to achieve the required density, then more material is filled in and, as a result, can settle. Experienced builders have found a way out of this situation and use a special blow molding installation. IN Lately Mineral wool has nevertheless found great use.
Mineral wool as insulation
The material is reliable, environmentally friendly and relatively cheap. If mineral wool is used as insulation, then it is necessary to organize a vapor barrier for the room (this is not done for ecowool). In addition, over time it cakes and, as a result, empty cold cavities form in the walls. Therefore, the material will have to be coated with an antiseptic inside and outside.
Sawdust
It is recommended to use old sawdust to insulate walls. If you only have fresh ones on hand, you can soak them in lime for a day and only then knead them. The procedure is as follows: m 2 sawdust and two bags of cement are poured into the mixer. Moisten everything a little, mix it, pour it into the space between the walls and tamp it down. A significant disadvantage of the material is mice, mold or dampness.
Bulk pulp
The material effectively performs the task of wall insulation. Often, during construction, insulation is not used at all, since they believe that air itself is an excellent insulation agent. But it is important to understand that it serves as thermal insulation only when it is motionless. This is the task of other materials: they create big number cavities with “stationary” air.
Polyurethane foam is sometimes used, but it is relatively expensive, so it is not widely used in construction. In this case, the material releases toxic substances and after a certain time is destroyed.
Box-shaped walls are insulated using flax fiber. Chopped straw or other material that does not cake over time will also work. It is also important to remember its compatibility with wood.
With the advent high-quality insulation materials the industry began to actively develop frame construction. One of the solutions is the construction technology of double timber, which appeared in the mid-90s of the last century in Finland, gradually spreading throughout the countries of the Northern Hemisphere.
Construction technology
In its principle, double beam technology is similar to “sandwich” panels. A double wall is laid from it, inner space which is filled with insulation. Thanks to this, high heat conservation and sound insulation are achieved.
The building construction process is as follows:
- Project preparation. There are several dozen standard projects for which all calculations have been made, but you can order an individual one.
- Preparing the foundation. Due to the light weight of the walls, the size of the foundation can be significantly smaller than for brick house. It is allowed to use a pile or column solution.
- Preparing the kit. After completing the project and agreeing on all the details, a drawing of a set of walls made of double timber is sent to production. There, all the crowns, rafters and ceilings are prepared. Each element is marked and sent to the construction site. If necessary, technical holes are made for laying cable channels for electrical wiring.
- Walling. When the foundation is ready, the assembly of the building begins ready-made kit. It is produced according to the installation diagram and markings on the parts. The assembly and insulation process takes 1-2 weeks depending on the size.
- Roof installation. After the walls are assembled, the rafter system is installed and the roof is laid.
Each stage of work can be carried out in isolation from the rest, so the construction of a building from the moment the project is approved until completion construction work takes up to 1 month. Work on the construction of the foundation and the preparation of a set of timber is carried out in parallel, and the set rafter system performed during the construction of walls.
Construction using double timber grew out of classical methods laying of the log house, therefore inherited the connection method. To do this, a groove with a depth of 25% is selected at the connection points on the board on both sides. When laying the crowns, the boards of the next row are inserted and fixed into these grooves. There is an overlap of half the width of the board relative to the previous row. The use of this connection allows you to quickly and efficiently build a wall in a short time.
To protect against blowing, a lock is selected on the horizontal planes of each beam. Most often it consists of a tenon on the top plane and a groove on the bottom. When installing one on top of the other, the tongue of the bottom board fits into the groove of the top one. This is how it is achieved high quality insulation connections without additional sealing.
Features of the “Double Beam” technology
With great similarity with other types wood construction, double beam technology has the following features:
Flaws
In addition to the significant advantages that make the technology stand out against the general background, there are several serious disadvantages.
Firstly, the requirements for wood are much higher than for construction using laminated veneer lumber. The interior and exterior of the building are in completely different temperature conditions with different humidity. When using low-quality material, the house shrinks unevenly, cracks may occur, horizontal seams may diverge, and the geometry may change.
You can get rid of this drawback quite easily. To do this, you need to carefully select wood and trust only reputable suppliers. The moisture content of the timber should be less than 12%, then the house will practically not shrink.
Secondly, high requirements to the insulation. It should not cake or sag throughout its entire service life. The internal cavity in which it is located is inaccessible after construction is completed. Because of this, replacing the insulation with a new one is impossible without partially dismantling the building.
1. Ecowool
2. Corrugation or cable duct for electrical wiring
Thirdly, difficulties with replacing crowns. This problem occurs with all technologies that use timber or logs - to replace a broken or rotted crown, partial dismantling of the structure is necessary. Compared to glued, double loses physical indicators and breaks more easily on impact, so the need for replacement arises more often.
The need for vapor barrier
It is believed that external moisture will be easily absorbed and penetrate into the wall, contributing to the appearance of mold and mildew. Experience in operating buildings in various countries the world shows that there is no need for vapor barrier of walls. At correct selection material and wood treatment with water-repellent compounds, the wall does not absorb moisture. Precipitation simply drains without penetrating inside.
When condemning vapor barriers, they often talk about the wall losing its ability to “breathe.” Indeed, when using a vapor barrier, it loses its ability to absorb and release excess moisture. But with properly designed ventilation, a vapor barrier is not needed. A wall made of timber will cope with the removal of excess moisture on its own.
It is worth noting that high-quality water-repellent impregnations can replace vapor barriers. If you promptly update the water-repellent layer using quality materials, then problems with excess moisture and there will be no mold. But a vapor barrier will not protect outer beam from rotting when using low-quality impregnations.
The technology of construction from double timber is time-tested; houses have been in use for more than 30 years without any complaints. Buildings using this technology can be erected in any climate zone of the country; it is important to choose a reliable contractor and not make a mistake when choosing the material.