It is known even to a novice builder that chopped houses have two main disadvantages - thin walls and shrinkage of crowns. The latter occurs due to shrinkage of wood. Therefore, methods are used that prevent the deformation of the walls and contribute to their effective insulation. According to existing standards, the walls of the house should be no thinner than 20 cm.
To solve this problem allows the double-beam technology, which was first used by the builders of Finland. The country has a small number of fairly thick trees 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 were able to develop a technology that allows you to build warm wooden houses at a relatively low financial cost. She received the name "double beam". In fact, this technology has little in common with timber in the usual sense. Its essence lies in the fact that in order to achieve the proper thickness of the walls, two grooved boards are used, between which there is a layer of insulation.
The houses using the double-beam technology are distinguished by improved thermal insulation characteristics, compared to houses from a solid beam of a similar section. Compared with insulated glued beams, this technology does not use adhesives. The insulation is often ecowool or mineral wool.
Double beam: production
The production of material for the construction of houses using double-beam technology is different from the manufacture 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:
- manufacture of blanks;
- drilling holes for mounting edged boards;
- cup cutting;
- grooving;
- cutting blanks;
- removal of residues;
- marking;
- insulation with material;
- packaging.
Benefits
The main advantage of a double-timber house is high energy saving. The thickness of its walls does not depend on the diameter of the log or beam. The insulation layer is selected in accordance with the requirements specified in the generally accepted heat engineering standards. The second advantage of the technology is minimal shrinkage of walls, fluctuating in the range of 1-2%.
You can start full-fledged operation of a house built according to Finnish technology at the completion of the assembly of walls and roof. Ordinary houses from timber can not be used immediately, since you need to wait until the tree dries and the crowns "fall" into place. In this case, there is no need to wait.
Installation of a house from a double beam is relatively simple, not laborious and does not require the use of complex construction equipment, which favorably affects the time of construction of the house and financial costs. In parallel with the assembly of walls, thermal insulation works are carried out , filling the space between the boards. The walls in houses made of double timber should not be additionally insulated and finished.
disadvantages
“Double beam”, despite many advantages, has several disadvantages. Shrinkage of insulation is considered to be the most significant, but it occurs only when using mineral wool. There is also the possibility of cracking.
They can be formed due to uneven shrinkage of the cladding of the external and internal boards used for houses constructed using the “double beam” technology. The reviews of the builders assure that in practice such problems do not arise at all. At least there were no comments.
Application experience in the domestic market
Recently, the technology has been used in the domestic market, therefore no one will guarantee that wooden houses will fully perform their functions in our climatic conditions. You just need to trust the Finnish experience in house building, as they have been building double-timber houses for over 20 years and successfully operating buildings in their more severe climatic conditions.
It is not possible to independently build a house using this technology, since for its high-quality construction, boards processed on special machines are needed. It is also necessary to cut the spikes, grooves and connecting recesses intended for corner joints. Without a team of specialists and the acquisition of a home kit, there is no way to do it. Therefore, saving on financial costs is problematic.
Structural strength
Double-beam technology is not comparable to conventional frame construction, where the insulation is between two thin walls. In this case, everything is held on the uneven bars. There is also a subspecies of this technology - the “double mini-bar”. Its construction is similar, but its walls are thinner.
Ceiling beams also provide increased structural strength if they are cut into walls during the construction process. In technology, exclusively dry lumber can be used, which largely affects the strength of the house as a whole. This is due to the fact that drying the beam leads to a loss of 13% moisture, due to which molecular bonds are broken. In the future, the beam will give exactly the same amount of moisture that it will absorb. Therefore, deformation will not occur.
Vapor barrier
For the construction of houses, the walls of which consist of several floors, an important issue is vapor barrier. Without its consideration, it is not recommended to carry out construction. A double beam is an exception, despite the fact that the walls of houses built using this technology will inevitably absorb moisture after a certain time. Therefore, there is an opinion that the insulation between the bars is a place of rot formation. At the same time, construction companies specializing in the construction of houses using this technology, claim that a double beam did not previously cause any problems. Owner reviews coincide in the fact that it is enough to apply 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 of this, since it will not allow the walls to "breathe" freely, but they can last much longer.
Ecowool as a wall heater
When building a wooden house that is not saturated with unhealthy synthetic resins, the best option is to use a harmless insulation. The 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 - condensation will not occur under standard conditions;
- insulation - 0.13 m 2 for each m 2 of the wall;
- heat conductivity coefficient - 0.2 W / m 2 .
Ecowool is blown dry in the inter-beam space. 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 the frame walls. If the wells are closed in the latter and it is not difficult to achieve the required density, then the material falls asleep more and, as a result, can settle. Experienced builders have found a way out of this situation and use a special blowing unit. Recently, mineral wool has still found great use.
Mineral wool as a heater
Material differs in reliability, environmental friendliness and relative cheapness. If mineral wool is used as insulation, then it is necessary to organize the vapor barrier of the room (for ecowool this is not done). Moreover, over time, it coalesces and, as a result, empty cold cavities form in the walls. Therefore, the material will have to be coated with an antiseptic inside and out.
Sawdust
For wall insulation, it is recommended to use stale sawdust. If you have only fresh ones at hand, you can soak them for a day in lime and only then knead. The procedure is as follows: m 2 sawdust and two bags of cement are poured into the mixer. All moisten a little, mix, fall asleep in the space between the walls and ram. A significant drawback of the material is mice, mold or damping.
Bulk pulp
The material effectively performs the task of wall insulation. Often during construction, the insulation is not used at all, since it is believed that the air itself is an excellent insulation. 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 a large number of cavities with "still" air.
Sometimes polyurethane foam is used, but it is relatively expensive, so it has not been widely used in construction. In this case, the material releases toxic substances and after a certain time is destroyed.
Box walls are insulated with linen fiber. Crushed straw or other material that does not cake over time is also suitable. It is also important to remember its compatibility with wood.
Stages of building a house using the technology of "double beam"
Reviews convince that self-construction of a house will only be at a loss to its quality, so specialists can’t do without it. Building a house includes the following steps:
- Sketch development (project). It includes the selected construction plan, drawing the facade of the building, the choice of architecture. Typically, firms specializing in the sale of materials for construction, offer services for creating projects of houses, so you can ask for help from them. You can also find a suitable plan on the Internet, but this is not always the best option.
- Creating a working version of the project. Designers take into account all your wishes and draw a diagram of all the products needed for the construction. A working draft can be completed for free. But this will happen only when you sign a construction contract with the company. In the case when you want to start preparing all the necessary documentation, rather than a full-fledged construction, the service will cost about 400 rubles / m 2 (in Moscow).
- Preparation of parts for timber house kit. This is one of the most difficult and requiring special attention stages of building houses using the “double beam” technology. Responses from builders say that it takes an average of 1 month to produce a house with a total area of over 100 m 2 , regardless of the complexity of its architecture.
- Construction erection. This is the final stage at which the product is assembled. They do not use any nails or glue, but only “fit” all the nodes and joints. Lock joints provide high strength and durability of the structure.
Cost
Houses built using the “double beam” technology are more expensive than log cabins made of solid wood. The average price of 1 m 2 of insulated walls will cost 5,500 rubles. The cost of a solid beam with a thickness of 150 mm will be cheaper - 3,500 rubles. But it is important to understand that even a 20 cm thick timber requires warming.
The double insulated wall technology provides a finished structure that does not require additional work and, therefore, costs.
For comparison, we will make a simplified estimate for the wall from a profiled beam. As already noted, the average cost of a “bare” wall with a thickness of 15 cm is 3,500 rubles / m 2 . Insulation, for example, 20 cm ecowool, costs 800 rubles / m 2 . Work on the installation of the frame, as well as cladding lining - an additional 600 rubles / m 2 . That is, additional work on the insulation of the log from the beam will cost approximately 1,400 / m 2 . As a result, 4,900 rubles / m 2 - the price that will have to be put on m 2 in a house from a double beam. The reviews at the same time convince that the relatively small difference in price is not so significant, since the technology has a large number of advantages.