CLT was developed in the early 1990s in Austria. CLT elements form a construction. They consist of cross-laminated wooden elements that are glued to larger firmer elements under high pressure. The glue is formaldehyde-free, therefore extremely environmentally friendly. As a raw material, coniferous wood is used, which is technically dried up to a moisture content of 12%, thus ensuring natural protection of wood from parasites. CLT can be used to build a complete house or building, including structural elements, floors, walls and ceilings.
In terms of designing family homes, we try to interest our clients to opt precisely for massive CLT wooden houses. Interest, in Croatia, is slowly growing, but it is necessary to educate the public about this type of constructive system. It was only after the recent earthquakes that investors' interest in timber construction increased significantly.
Advantages of building with CLT as constructive elements
The advantage of building with CLT elements is obtaining a solid wooden structure without thermal bridges with exceptional anti-sealing and fire properties. One of the main advantages of cross-laminated wood is its fire resistance because the fire, due to the effect of „ shilling“ the front of the plate, does not penetrate the very core of the plate, which then continues to function during the period of fire resistance.
Due to the cross-stick wooden elements, which form the massive CLT wooden board, high strength and stiffness, stack and high resistance to vertical and lateral loads ( earthquake or wind) are obtained.
Compared to other structural construction systems, due to the slenderness of CLT structural elements, of only 10 cm, the net surface of the building is larger, therefore, we get a larger interior space for the same external dimensions of the building and the same thickness of thermal insulation.
The advantage of building with solid wood CLT can significantly reduce carbon emissions as solid wood continues to emit carbon from the atmosphere even after installation.
In single-family homes, replacing concrete and steel for wood, combined with long-term carbon storage in CLT buildings, can reduce by a total of almost 75 percent of total traditional construction emissions.
The advantage is the speed of construction with such a system of constructive elements that, already prepared in the factory, come to the construction site and are installed on site in just a few days.
After a detailed architectural project has been developed to meet the needs of the owner and the construction site, the workshop designs are sent directly to the factory. The wooden elements are precisely constructed in the factory and are transported to the construction site exactly when necessary, avoiding stockpiling and minimizing interruptions and delays. The house is assembled on a construction site, creating up to 50 percent faster process with less noise, dust and pollution.
Finally, wood is a natural insulator. Soft wood (spruce) generally has about 10 times the thermal insulation capacity of concrete, and 400 times the size of steel. This reduces the energy required to heat the house.
The wooden CLT house is in itself energy efficient, which means that it does not conduct cold in winter and does not overheat in summer, and combined with the elements that make it passive, we get additional A+ energy quality home.
Another benefit for people staying in such a house, which has a constant circulation of fresh air through the recuperation system, is the prevention of inhalation of dust and allergens that are prevented from staying in the space of the house or on the surfaces.
Annual required energy for heating a modern passive house ranges up to 15 kWh/ m2, low-energy house consumes up to 40 kWh/m2, and in Croatia there are still the largest number of houses that consume up to 160 kWh/m2 for heating.
Given that the number of houses currently being built in Croatia with this constructive system is still small, we are pleased with the enthusiasm of investors who want something more for themselves than the prescribed standards and although construction itself brings a certain dose of stress, using CLT, we minimize that stress.
In our office, we design wooden houses also from other constructive systems, such as a skeleton constructive system.
The skeleton structure consists of frames in which there are pillars and horizontal stiffness of different dimensions. As exterior and interior cladding there can be various panels (OSB wooden fiber boards, plasterboard, wood-cement panels, plywood).
The space between the panels is filled with thermal insulation ( natural insulation materials such as pulp, wood wool, coconut, hemp, cotton or artificial materials such as mineral, glass or stone wool).