The building material from the forest makes a comeback
More and more houses in Germany are being built out of wood. You haven’t noticed that yet? That is not surprising, as a wooden house may not be immediately recognisable as such. On the contrary, many wooden houses hide their base frame made of renewable natural building material behind a plaster facade or solar panels. But in their core, also many modern houses are made from the oldest building material in the world.
Most wooden houses are so-called prefabs. This means that they are prefabricated in factories, regardless of the weather, and transported to the construction site as large units. On site, these individual wall elements are combined to make a house within one or two days. The house parts that weigh tonnes are transported by crane to their places in the cellar or to the paving slab, where the construction team assembles them. The prefabrication is usually done with computer-operated, high-precision tools and machines. This enables companies to offer a high quality of prefabricated houses. Many companies can also prove this with certifications. The fact that prefabricated houses are highly popular is shown by the figures of the Bundesverband Deutscher Fertigbau (BDF – Federal Association of German Prefabricated Building). In 2014, the market share of prefabricated one and two-family wooden houses increased by over 16 percent. In Baden-Wuerttemberg the 30-percent-mark will soon be reached.
But why are wooden houses becoming more and more popular? One reason is the material itself. Wood is very robust and durable, weighing relatively little. This is the reason why earthquake-resistant buildings are often made of wood. In addition, new wood is regularly produced in nature: it grows back, especially when it is from sustainably managed forestry, which is standard in Europe. The trees bind carbon dioxide, which has a positive effect on the climate. Due to its low thermal conductivity, wood is also a material that makes it possible to build particularly energy-efficient buildings. This is a big advantage in view of the stricter building regulations concerning energy-efficiency. Not least because of the building material, the prefabricated building industry is regarded as particularly innovative when it comes to energy-efficiency in the area of housebuilding. Energy-plus houses that provide more energy than their inhabitants use, can easily be built out of wood. Another advantage that is gaining importance regarding sustainability and protection of the environment is that a wooden house, built without foils and artificial substances, can be demolished and is then fully recyclable.
Moreover, many inhabitants of wooden houses would not want to swap the pleasant room climate that radiates this special comfort for anything else. Untreated wood has the ability to absorb moisture from the air and release it later. This way, the building material aids in regulating the room moisture. Wood is a real allrounder, as it creates a healthy climate for living, is environmentally friendly and helpful when it comes to saving energy.
However, not all wooden houses are alike. In the course of the centuries, various building techniques have developed. In timber-frame construction, walls are made of supporting timber studding. The panels, meaning the space between the timber, used to be filled with bricks or straw clay. The principle is similar to the one used today, except that the panels are filled with efficient insulation and are covered with planks or glass. This design has slowly developed into wooden post-and-beam structured building, in which the supporting construction of vertical columns stretches over more than one storey. Horizontal and slanting timber connects the construction. For this type of wooden construction, the term ‚frame construction‘ is often used. The level of prefabrication is generally lower than with wood panel construction, which is used to build standard prefabricated houses. When using this method, the basic wood construction is panelled on both sides with wood materials or plasterboard. The gaps are filled with highly efficient insulation. Finally, the house is assembled from these self-supporting panels. The log house is regarded as being the ultimate wooden house. Traditionally, it consists of thick round planks that are placed upon one another and which form the walls of the house. However, there are also log houses that are set up with square beams. Log walls out of massive wood are also still used in new buildings nowadays. However, these walls are prefabricated to be extremely dense and without settling in the factory, in order to fulfil the requirements of the Energy Saving Ordinance.