If you carefully examine a cross section of a tree trunk, we can distinguish the following main parts - the core ( 5), wood, cambium (2) and bark (1). (bast (3) is the outer surface of the wood. Remember, "There was a rabbit hut Bast?" If we carefully consider the cross-section of tree trunk, we can distinguish the following main parts - core (5), wood, cambium (2) and bark (1). (bast (3) is the outer surface of the wood. Remember, "There was a rabbit hut Bast?" That was a hut made of logs, peeled and cambium. Progressive was the hare, but the round logs still not figured it out.) core - a thin "tube" in the center of the barrel, it has low resistance and easily rots. Wood (part of the trunk of Luba to the core) in a cross-section is a series of concentric (annual) rings around the core. The growth of wood cell walls of wood adjacent to the core, gradually changes its composition, soaking a conifer resin, while the hardwood - tannins. Movement of juice in this part of the trunk is terminated, the wood becomes harder and less prone to rot. This part of the trunk of a conifer called the kernel, while others - ripe wood. Part of a young wood, which is located closer to the crust (it still has living cells) is called the sapwood (4). It has a large moisture relatively easy to rot, characterized by its low strength and is subject to considerable shrinkage and is prone to warping. Breed, whose core differs from sapwood darker color and lower humidity, refer to the sound (pine, larch, oak, cedar, etc.), Sang-Do tree species (spruce, fir, beech, lime, etc.) the central part of the trunk is different from the sapwood just less humidity. Do sap trees (birch, maple, alder, aspen, etc.), significant differences between the central and outer parts of the trunk can not be seen. Such a detailed description of the microstructure of wood needed in the future, to understand what the goal is pursued cylindering beams of sound wood - pine and larch. For centuries in Russia cleverly cut wooden buildings, driving log to a log, butt to vershinke skillfully thus eliminating the natural sbeg tree trunk. With the increasing scale of construction needed to simplify the process. The decision came in the form of logs (with the same diameter along its entire structural length) and sliced ??- timber. otsilindrovyvaniya mechanized technologies used in Russia and abroad at the beginning of the century. Wooden Houses of the reduction in the number of operations in the assembly easier and faster to build, in addition, the use of logs allowed the assembly to create a more rigid structure. Since the log to a log fit tightly, and improved thermal insulation properties of walls, and the building looks aesthetically. For the production of logs and profiled bar, which replaced the usual four-hole, used mainly pines. cylindering In this classic rock sound is cut looser sapwood and remains a solid, resin-impregnated core. A log of this just wins. The figure shows the layout of sawlogs under Round beam and shaped beam. Cutting sapwood leads to another positive effect - reducing the width of cracks during drying, which in turn improves the insulation of the walls. With cracking of logs are struggling deliberately provoking the appearance of cracks in the vertical plane. To this end, along the logs make a shallow vertical propyl. When cylindering, as well as the manufacture of profiled beams achieve high purity of the treated surface, the wood becomes extremely smooth, which makes it possible not to use additional materials for interior and exterior of buildings, and therefore avoid extra costs. trendsetters in the production of logs, profiled lumber and construction of these homes believe the Finnish company. Viewing logs produced by leading firms, a far cry from the traditional round profile (the upper figure shows the traditional sections of logs and profiled bar and the bottom figure, company profiles Honka). Recent profiles have special Wedge locks, which, together with insulation, laying between the logs, effectively protect the house from wind and moisture. When the construction of buildings made of logs and profiled bar used for fastening structures (as in the traditional assembly technology) pins, bolts, studs, staples, and also adjustable anchors. Assembled house necessarily gives rain, but it is much smaller than that house of the usual logs. decrease in the rainfall contributes to forced headband construction. Since the house is made from well-processed material, it basically does not require additional finishing, it is possible to live Almost immediately after its erection. Natural wood grain creates a special picture wall, and because the wood is used operational humidity, the house can be painted directly from the outside. This further protects the wood from moisture. Wooden house made of logs and profiled bar quickly erect and environmentally friendly, he combines relatively low cost with high performance. The natural beauty of wood and imagination of the architect can create from this material in a modern comfortable Zago, homes and cottages. All of the above has made these wooden houses are very popular both abroad and in our country. (Not all houses made of logs and profiled bar can be attributed to the homes of "relatively low cost." Domestic manufacturers are still able to please here zatroyschika. untwisted And such brands as the same "Honka" are sometimes more expensive than a brick house.) Note: According to its microstructure of wood is a natural polymer, forming its cell-fibers have a tubular shape and are directed along the barrel. This wood has many advantages - high strength, elasticity, low density, and hence the low weight, low thermal conductivity, resistance to the effects of chemically aggressive media, natural decorative quality, ease and simplicity of processing and assembly. However, along with the advantages of wood there are drawbacks: anisotropy (its properties are very different along and across the fibers), heart structure, hygroscopicity, and as a consequence, humidity strain putrescibility and combustibility. Most significantly the performance properties of wood affect hygroscopicity, putrescibility and combustibility. In order to reduce their negative impact is primarily used drying, impregnation of wood preservatives or antipyrine, as well as measures to prevent humidity structures during the operation (protection from the weather; isolation from earth, stone, concrete, the device good natural ventilation, etc.). Source: Website Stroykonsul
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