Solid wood house
A solid wood house is a special form of wooden house, which is in the tradition of log house construction and can have different wall constructions. A common feature of all solid wood houses is the construction (solid wood construction) made of prefabricated wall elements that are assembled on site in a comparatively short time to form a solid wooden house.
The term solid wood house is currently not subject to any official and generally applicable definition. The solid wood house construction is practically defined by the similarities and the differences to the most closely related construction methods. These are the classic block construction ( block house ) and the timber frame or timber frame construction with a high degree of prefabrication (wooden prefabricated house).
Origin and development
10,000 years BC One-storey huts and houses were built with wooden beams and support structures. Different timber construction systems for the construction of buildings developed from this. Today the following basic types can be distinguished, the lack of selectivity of which often leads to contradicting usage:
- Log construction
- Half-timbered construction
- Stand construction
- Frame construction
- Skeleton construction
- Panel construction
- Room cell construction
Solid timber house construction combines various elements of the above-mentioned timber construction methods and can accordingly be viewed as a further structural development.
Related construction methods
The classic log house has a single-shell, also called monolithic outer wall. This consists of hewn tree trunks , more heavily processed round logs or milled round or square timbers, which are referred to as logs or logs. In traditional block construction, one layer by layer is layered on top of one another, the interlocking corner connections ensure stability . In newer forms of block construction, the individual planks are joined together to form block panels (pre-elementing), which are then joined together as whole wall elements during construction. In this respect one could also speak of block panel construction with these constructions. Prefabricated houses are completely or at least partially prefabricated at the factory, the final assembly takes place on the construction site. The general usage designates houses made of wood and prefabricated houses as prefabricated wooden houses.
The single-shell log house exterior walls are usually erected without additional heat and sound insulation . The log walls are statically load-bearing, which means that the ceilings and roof structure rest on them. In contrast to the single-shell log houses, solid wood houses are double-shelled, they have an outer and inner shell with insulation in between and, ideally, an installation level for electrical installations in order not to damage the airtightness to the outside. In contrast to the prefabricated wooden house with Holzleichtbau- or wood composite walls following distinction can be made: In the solid timber boards not but be Bohlen used. According to DIN standard 4074 for construction timber, planks have a thickness of at least 40 millimeters compared to boards.
It should be noted that solid wood houses are not, as the name suggests, made exclusively from solid wood, ie "from one trunk". Some of them can be made from solid structural wood ( solid wood ). Solid structural wood is more dimensionally stable than solid wood and the load-bearing capacity of the processed wood is higher than with originally left wooden stands.
Features of the solid wood house
Solid timber houses combine features of block and prefabricated timber construction. The wood is technically dried before processing and thus has the best possible structural moisture content . This drying and the overall construction prevent the settling phenomena known in simple block construction, which result from the shrinkage of the wood due to its hygroscopic properties; which requires a high level of maintenance and can lead to structural problems. The solid wood elements used for walls, ceilings and roofs can consist of glued laminated timber , board stack elements, block panels and similar solid wood materials or wooden construction elements. The solid wood walls are completed by additional insulation, external plaster, etc. The main building material is the renewable and therefore sustainable natural building material, wood, which in an average single-family house can contain around 30 to 40 cubic meters.
Double-shell wall constructions
One of the more recent developments in solid wood house construction are massive double-shell wall constructions. As is customary in timber frame and timber frame construction, they consist of load-bearing vertical posts , supplemented by two log shells inside and outside. In between these double block pile walls there is a heat and sound insulation layer as what is known as core insulation . Since this insulation layer is protected from the weather inside the wall, its insulation value is retained over the long term. The prefabrication of the wall elements in the factory enables a joint-free, flat, continuous insulation level.
Since wood has poor thermal conductivity - depending on the type of wood <0.2 W / (m · K) - the combination of double-shell wooden logs and additional core insulation provides both winter and summer thermal insulation. Special constructions have a further insulated installation level on the room side, which ensures even lower heat losses and thus a lower annual heating requirement. Solid wood houses thus meet the requirements of the Energy Saving Ordinance (EnEV), which was tightened again in 2014 , and in some cases these are even exceeded. Also can KfW - Efficiency House standard can be achieved. The double-shell wall structure has a physical effect on the sound insulation . In contrast to single-shell or non-insulated houses, solid wood offers improved sound insulation. The double log wall proves to be particularly windproof, which the house manufacturer should prove by means of blower door tests in the shell construction phase and before the client moves in. If no vapor barriers or rigid foam insulation panels are used in the outer walls , the low vapor diffusion resistance of the wood comes into play: the entire construction is then vapor diffusion open. The combination of vapor diffusion-open walls and dry construction with technically dried wood ensures a room climate without mold-promoting moisture. From a building health point of view, this property is extremely important. Solid wood in the interior is able to buffer large amounts of moisture, i.e. to absorb it from the room air and to release it again. Wood is also characterized by the fact that its surface temperature is relatively high in comparison to other materials, which avoids radiation cold and has a positive effect on the temperature sensation.
Architecture and prefabrication
The double-leaf log walls, including doors and windows, are prefabricated in the factory to form complete wall elements and assembled on site. The pre-element construction in a production-optimized environment ensures a constant quality standard. However, standardization in the manufacturing process is not contrary to architectural individualization. The statically load-bearing wooden framework enables a wide variety of architectural styles , and large window fronts and fixed glazing are also possible without any problems.
The quality and safety of solid wood houses is proven by the following markings:
- The conformity mark ( Ü mark ) proves that a product complies with the required technical rules and, as in this case, the specifications of the building inspectorate approval.
- RAL quality marks identify products and services that are manufactured or offered according to high, precisely defined quality criteria. For timber house construction, the RAL quality mark sets a uniform quality standard that is relevant for manual and industrial timber house construction. The RAL-GZ 422 quality mark certifies the quality of the prefabricated elements and the quality of the execution on the construction site.
Everyday knowledge suggests that houses a higher compared to houses in wet type wooden combustibility have. However, the classification in building material class B2 according to DIN 4102-4 (fire resistance) proves the suitability of wood as a normally flammable building material. In the event of a fire, wooden beams pose a lower safety risk than beams made of concrete or steel. On the one hand, they show a more predictable collapse behavior and, on the other hand, the carbon layer created by the fire isolates the stabilizing girder core. The comparable fire risk of (solid) wooden houses and solid houses is now also recognized by the insurance industry and it sets insurance premiums that differ little for both types of construction .
Due to their construction, solid timber houses have the following disadvantages and peculiarities:
- With solid wood construction, the number of floors is subject to building law limits.
- The span of wooden beam ceilings is limited.
- Unplastered solid wood facades are more susceptible to weathering than plastered surfaces. This results in increased demands on the " constructive wood protection". For example, care must be taken to ensure that there is sufficient distance from the floor; additional roof overhangs are required.
- The sound insulation of solid wood houses (as well as prefabricated wood houses) is worse than that of solid houses. Both house manufacturers and research institutes have tackled this problem and optimized the sound insulation in prefabricated wooden houses.
- Wooden facades and wooden elements such as windows and doors require regular maintenance and care. In addition, it should be checked at regular intervals whether the substance is at risk from pest infestation .
- Lothar Macha: Historical development and systems of timber construction . In: BDF eV and team of authors teaching-research-practice (ed.): Modern timber construction in prefabricated construction. Weka Media, Kissingen, 2011, p. 21.
- Lothar Macha: Historical development and systems of timber construction . In: BDF eV and team of authors teaching-research-practice (ed.): Modern timber construction in prefabricated construction. Weka Media, Kissingen, 2011, p. 32.
- Holzbau Deutschland - Bund Deutscher Zimmermeister im Zentralverband des Deutschen Baugewerbes eV www.holzbau-deutschland.de/mit_holz_bauen/holzbau_im_wandel/ , last accessed on December 8, 2014.
- Schöner Wohnen (Ed.): The prefabricated house book. Modern architecture - sustainably built. Reports, trends, innovations. G + J AG Co KG, Hamburg, 2011, p. 194.
- biz Verlag (ed.): Solid wood construction. In: Das dicke deutsche Hausbuch, 1, 2015, p. 74.
- see the article en: Brettstapel in the English Wikipedia
- biz Verlag (ed.): Solid wood construction. In: Das dicke deutsche Hausbuch, 1, 2015, p. 74.
- RAL German Institute for Quality Assurance and Labeling eV www.ral-guetezeichen.de , last accessed on April 30, 2019.
- Gütegemeinschaften BMF eV, GDF eV and GHAD eV www.ral-holzhaus.de , last accessed on April 30, 2019.
- Information service wood: wooden houses. Value and durability. Wood manual. Row 0. Part 5. Episode 1. Sales promotion fund of the German forest and wood industry Holzabsatzsfonds, Bonn, 2008, p. 21.
- http://www.wohnen-magazin.de/fertighaus/articles/fertighaeuser-aus-holz.html , last accessed on February 18, 2015, emphasis in the original
- See Information Service Holz: Holzhäuser. Value and durability. Wood manual. Row 0. Part 5. Episode 1. Sales promotion fund of the German forest and wood industry Holzabsatzsfonds, Bonn, 2008, p. 21.