Timber frame construction: tips for wall construction and construction

Timber frame construction is increasingly making a comeback. Despite its millennia-old tradition, wood had long disappeared from the radar of European builders: In our latitudes, mainly brickwork and pouring from concrete since the end of the half-timbering. 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 United States, it has always been a little different: the overwhelming majority of single-family houses were and are built there on the basis of a timber frame construction. And in the meantime, wood is again coming into focus here and timber frame construction is becoming increasingly popular.

The wall structure

If you want to get an overview of the renewable alternatives to mineral building materials, you will inevitably come across a rather large confusion of terms: Sometimes we are talking about wooden houses, sometimes wooden frame construction, wooden skeleton construction and wooden frame construction. The terms revolve around the material wood, but can mean very different constructions.

The essential features of timber frame construction are on the one hand the material, on the other hand the wall structure and the distribution of the loads: a frame made of solid wood (usually KVH or equivalent) forms an internal skeleton of stands and frames, on which panels are applied from both sides. These often consist of wood or gypsum fibers. A cavity is created between the panels that receives the insulation.

The further details are not determined by the basic definition of timber frame construction: Neither the exterior nor the interior must necessarily be made of wood. In addition, the stands can have one or more floors.

Differentiation of timber frame construction from other timber construction systems

The frame and planking construction can be obtained from the factory in various stages. If both sides are already provided with the cladding and complete internals, this is also referred to as panel construction or wooden panel construction. For prefabricated houses, this is a frequently chosen construction method because the maximum prefabrication in the factories drastically reduces the construction times. It often takes no more than a day from the first wall to the topping-out ceremony.

In wooden panel construction, both sides are already provided with the cladding and complete internals.

Photo: iStock / fotojog

The wooden skeleton construction is very similar to the wooden frame construction, but there are fundamental differences: The planking of the walls in skeleton construction (unlike in wooden frame construction) does not serve as horizontal reinforcement against the effects of wind, for example. The ceilings provide horizontal stiffening for the skeleton. Horizontal loads can also be derived from massive components such as stairwells. The space-closing walls in the skeleton construction are also statically not connected to the supporting structure. They are therefore optional and can be moved as required. Huge construction grids with dimensions of twelve meters can thus be easily implemented regardless of the expansion grid.

Planning the details in timber frame construction

One is also somewhat flexible with the wooden frame construction. In advance, it is important to determine the needs of the building owners as precisely as possible, whose wishes usually revolve around questions such as the number and positioning of windows, the facade design and the 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 insulation, which further improves the already very good energetic properties of a wooden frame construction.

When it comes to placing windows in timber frame construction, you are not quite as flexible as with other construction methods.

Photo: iStock / Worawee Meepian

The builders also decide which insulation material to use. 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 protecting the environment and that of residents from toxins.

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

Cost of timber frame construction

General statements on the costs of timber frame construction are not readily possible due to the large number of different providers and individual design options. The offers do not always include all ancillary construction costs, which makes 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. Starting at around € 1, 200 per square meter, rough construction is to be planned.

It is not insignificant that, due to the better insulation value compared to wall construction, the walls are thinner, so that more usable space and living space remain with the same floor space. This results in an area gain with wooden frame walls of around 10 percent, which reduces the square meter costs.

Another cost factor is the wide range of options for performing your own work. As with classic construction, its scope depends primarily on the manual skills of the building owners. But there is a peculiarity in timber frame construction: Not all of your own work has to take place on the construction site. Many companies have their customers carry out simple work in prefabrication in the production halls and also provide the tools and materials for this. Simply painting the facade cladding is a typical, but far from the only way to reduce construction costs through your own efforts. Not least because of this, 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 your own work, have already been mentioned above.

But also from an ecological point of view, timber frame construction offers several advantages: The timber produces less CO ₂ in its production than it has bound (the wood is CO ₂ neutral). As a renewable raw material, it is also sustainable. In the long term, a low-energy or passive house based on a wooden 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 hires a local company that processes material from the region. This shortens the transport routes and saves additional CO ₂.

Timber frame construction saves time and money and convinces with its sustainability.

Photo: iStock / dpproductions

A previously justified objection to wood as a building material was the fire risk, which also explains the different building traditions in the USA and Europe. The large distances between the individual buildings, as was customary in America, did not exist here. As a result, small fires could quickly become huge catastrophes and the 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 requirements for fire protection and fire resistance, among other things through the use of fire protection panels or replacement measures. This ensures security in accordance with current regulations such as DIN 4102.

Other concerns when choosing the construction system concern above all the basic durability. Whoever builds a house wants to have something like this 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 this has no relevance for the 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 the wood worm, timber frame houses easily last over a hundred years and are in no way inferior to solid brick objects.