What is a wooden frame

Timber frame construction: Tips about wall construction and construction

Timber frame construction is increasingly celebrating a comeback. Despite its millennia-old tradition, wood had long disappeared from the radar of European builders: in our latitudes, since the end of the half-timbering, mainly masonry and concrete has been poured. Wood was still used in roof trusses, but no longer in the construction of the load-bearing walls of residential buildings.

In North America, especially in the USA, it has always been a little different: the overwhelming majority of single-family houses there were and will be built on the basis of a timber frame construction. And now, in this country too, the focus is on wood again and timber frame construction is enjoying growing popularity.

The wall structure

Anyone who wants to get an overview of the renewable alternatives to mineral building materials inevitably comes across quite a lot of terminology: Sometimes there is talk of wooden houses, sometimes of timber frame construction, of timber frame construction and timber frame construction. The terms revolve around the material wood, but can mean very different constructions.

The essential characteristics of the timber frame construction are the material on the one hand, and the wall structure and the distribution of the loads on the other: A frame made of solid wood (mostly KVH or equivalent) forms an internal skeleton of uprights and frames to which panels are attached from both sides. These are often also made of wood or gypsum fibers. A cavity is created between the panels that accommodates the insulation.

The other details are not determined by the basic definition of the timber frame construction: Neither the exterior nor the interior must be made with wood. In addition, the stands can be single or multi-storey.

Differentiation of timber frame construction from other timber construction systems

The construction of the frame and planking can be obtained from the factory in various stages of expansion. If both sides are already provided with the cladding and complete fixtures, one also speaks of the panel construction or the wooden panel construction. In the case of prefabricated houses, this is a frequently chosen method of construction because maximum prefabrication in the factories drastically reduces construction times. It often doesn't take more than a day from the first wall to the topping-out ceremony.

The wooden frame construction is very similar to the wooden frame construction, but there are fundamental differences: The planking of the walls in the frame construction (unlike in the wooden frame construction) does not serve the horizontal stiffening against the effects of wind, for example. The ceilings provide horizontal reinforcement for the skeleton. Horizontal loads can also be transferred via massive components such as stairwells. The space-enclosing walls in the skeleton construction are also not statically connected to the supporting structure. They are therefore optional and can be moved as required. Huge construction grids with dimensions of twelve meters can be implemented without any problems, regardless of the expansion grid.

Planning the details of the timber frame construction

The timber frame construction is also somewhat flexible to a lesser extent. In advance, it is important to determine the needs of the builders as precisely as possible, whose wishes usually revolve around questions such as the number and positioning of windows, facade design and interior fittings. Almost anything is possible here. The standard grid of 62.5 centimeters is the most common, but not mandatory.

With larger grids, the proportion of wood can be reduced in favor of the insulation, which further improves the already very good energetic properties of a wooden frame construction.

The building owners also decide which material is used for insulation. Ecological insulation materials are a useful addition to the natural material wood: wood fibers, cellulose or hemp are protected against pest infestation with harmless impregnations. They also meet the requirements for the protection of the environment and that of the residents from toxins.

The insulation materials, together with the diffusion-open structure, ensure a pleasant climate: U-values ​​of 0.2 W / (m2K) or even lower as well as phase shifts of ten or more hours can be achieved. This applies regardless of the ultimately chosen design in the visible area and regardless of whether the outer walls are rear-ventilated or not. Plastered facades, cement panels or combinations thereof do not necessarily reveal the construction method and are attractive alternatives to the wood look.

Cost of the timber frame construction

General statements on the costs of a timber frame construction are not easily possible due to the large number of different providers and individual design options. Not all building costs are always included in the offers, which makes the classification even more difficult. Basically, however, it can be said that timber frame construction is no more expensive than other construction methods with concrete or bricks. Approximately € 1,200 per square meter should be planned for the shell construction.

A not inconsiderable effect is that, due to the better insulation value compared to the building of the wall, thinner walls are used, so that more usable and living space remains with the same floor space. This results in a space gain with wooden frame walls of around 10 percent, which lowers the costs per square meter.

Another cost factor is the wide range of options for doing work on your own. As with classic construction, its scope depends primarily on the craftsmanship of the builder. But there is one special feature of timber frame construction: not all of your own work has to take place on the construction site. Many companies let their customers do simple work in the production halls in the prefabrication and also provide the tools and materials for this. Simply painting the facade cladding is a typical, but by no means the only way to reduce construction costs through your own contribution. Not least because of this, the timber frame construction is an attractive building system.

Advantages and disadvantages of timber frame construction

The advantages of timber frame construction are manifold: The fast construction time due to high prefabrication, as well as the cost savings through personal contribution have already been mentioned above.

But timber frame construction also offers several advantages from an ecological point of view: The construction timber causes less CO in its production2 than it has bound (the wood is CO2-neutral). As a renewable raw material, it is also sustainable. In the long term, a low-energy or passive house based on a timber frame construction saves a lot of energy and not only relieves the wallet, but also the environment. Anyone who pays particular attention to the environment commissions a local company that processes material from the region. This shortens the transport routes and saves additional CO2 a.

A previously justified objection to wood as a building material was the risk of fire, which also explains the different building traditions in the USA and Europe. The large distances between the individual buildings, as they were common in America, did not exist here. As a result, small fires could quickly turn into huge catastrophes and wood fell behind as a building material in densely built-up Europe. But these problems are a thing of the past: Current timber construction systems meet all fire protection and fire resistance requirements, including the use of fire protection panels or replacement precautions. Safety in accordance with the current regulations such as DIN 4102 is thus guaranteed.

Other concerns when choosing the construction system mainly concern the basic durability. Anyone who builds a house wants to have something from it for as long as possible. The USA also plays a role here: low-quality buildings, poorly insulated and with thin walls, were not uncommon there for a long time. But that has no bearing on German quality standards. A comparison with the ancient beams in European half-timbered houses is more revealing in this regard. With a little care and spared from wood worms, timber frame houses can easily last for over a hundred years and are in no way inferior to solidly bricked objects.