The wood for a long time in history was a material used in construction, but with the advent of reinforced concrete was a material almost forgotten. In recent years, however, have rediscovered the features and advantages of this material sustainable construction that protects against noise pollution, air pollution and electromagnetic, cost-effective, lightweight, invulnerable to the earthquake but also influenced by environmental conditions in which it is inserted.
REFERENCE STANDARDS FOR WOODEN
The existing European standard of reference and the Eurocode 5, which guarantees the quality of products of wood and the traceability of the production process. With the Technical Standards for Construction of 2008, Italy has laid down the rules for wooden buildings, for the use of this material and the characteristics that must have to be used in construction. The law in fact has planned three paragraphs into three chapters on, the structural checks for new construction and existing buildings (Chapter 4, section 4), the dissipative behavior of the wood for seismic actions (Chapter 7, Section 7) and finally, the methods for certification and qualification (chapter 11, paragraph 7).
THE ADVANTAGES AND DISADVANTAGES OF THE WOOD
Wood as a building material each has advantages and disadvantages which must be taken into account, both in the design phase for the technician, both during the purchase for the buyer. The wood is a sustainable material, since the energy used in the production process is much lower than that which is necessary for the realization of housing with reinforced concrete or brick. A lower cost and in less time than is possible to demolish wooden items where the latter can be used again in other areas. Has a good resistance to both thermal and mechanical, because the wood is able to withstand tensile stresses in the fiber direction in the same order of magnitude of the cement. Important, however, is a good design because the stresses induced perpendicular to the fibers, the resistance drops, so it is very important to the design of the nodes. Also it is a material with a very low stiffness and this allows the wood to absorb the energy of the earthquake, a wooden building very light responds much better under stress. The wood is also a material of fast installation, in fact a wooden house can be realized according to the plans and to the surface area from 2 to 6 months. Unfortunately, however, the useful life of a building in wood varies according to the characteristics of the site in which it is inserted and to which the maintenance is carried out. In fact, the NTC 2008 assign three classes of service to this type of construction.
TYPES OF CONSTRUCTION WOOD
In Italy, the wooden buildings can be traced to two types:
- The frame structure
- The structure of a load-bearing panels
The frame structure is a structure consisting of beams and columns rigidly connected to each other through the insertion of structural panels, nailed directly on the frame or with linear elements such as wooden rods that form lattice structures. The structure with load-bearing panels is constituted by structural elements instead plans that have an isotropic mechanical behavior allowing greater speed of edification.
Wood is a material with good thermal insulation due to its porous structure allowing you to have a comfortable building. It has a strong affinity with water, in fact according to moisture is able to absorb and release water molecules. When the humidity in the environment increases, the wood absorbs the excess that then transfers when the air is dry, thereby improving the air quality. Its thermal conductivity is lower by about 10-15 times compared to that of the concrete. A good wall in plywood with good thermal inertia may give the phase shift of about 10/12 hours.
Important in a wooden construction is running, in fact small cracks can cause heat loss that could permanently damage the material, decreasing the indoor thermal comfort.
The wooden houses have variable costs due to the type of wood chosen, the environmental conditions in which you enter the building, the square footage and the number of plans to build. Depending on the type it can be estimated a price varying from 350 to 550 € / sq m which, however, must be added the transport, assembly, foundations, facilities, fees and other optional charges until you get finished at a cost of about 1200 euro / sq m compared to € 1,700 / sq m for a home in reinforced concrete and 2,000 € / sqm for a brick house.
Translated via software
Italian version of ReteIngegneri.it