28 November 2012

Niklaus Ledergerber: "Reviving Strickbau wood log houses"

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A conservation effort in Appenzell, Switzerland,  could lead to the revival of local heritage buildings made with the unique Strickbau construction technique

Niklaus Ledergerber, president of the cultural heritage preservation commission of the Swiss canton of Appenzell, is an expert in local building history. He tells youris.com about the possible rehabilitation of the Strickbau, which is a type of log construction typical of the Appenzell region. It is characterised by layered wooden beams enmeshed at the corners with a so-called dovetail connection to give the building strength.

The Strickbau was developed in the beginning of the 18th century. Why did it happen just in the canton of Appenzell?
In the Appenzell region, wood as building material existed everywhere. Everyone had access to it. Most of the farmers could handle it on their own. Only the most important buildings such as the churches, schools, rectories and town halls were built primarily with stones. Another reason for the widespread use of the Stickbau in the region is that it can withstand its relatively high humidity thanks to its corner connections that have no excess endings and therefore present no weak spots. So, we can say, that mainly the landscape and the climate made the Strickbau suited for Appenzell.

Today the Strickbau is no longer the first choice of building style.  How did that change happen?
In the end of the 19th century, wood became scarce as a building material. Those who did not own their own wood sometimes were forced to use the so-called bolt-building technique. This involves filling a wooden frame with clay or bricks. From the 1950´s onwards, the bolt-building technique became more and more established due to a change in the choice of building material—as low priced isolation mats came onto the market—and the mechanisation of the construction technique. The bolt-built houses were also less costly in terms of labour.
Why are many of the old Strickbau buildings being demolished?
Wood is not a permanent building material. It is very fragile and can be subjected to structural damages. A replacement building often makes more sense than undertaking extensive restoration of a Strickbau. There is also a law, which requires that for every new farm house being built, the existing farm building has to be demolished. This is to preserve the landscape with single, detached, farm houses. Fortunately, today we also have the possibility to declare the most unique Strickbau buildings as historic monuments. Only one of six criteria, related to their historical or folkloristic importance, has to be fulfilled.

Is getting an old Strickbau refurbished a realistic way to keep such buildings?
Some Strickbau buildings do get refurbished. But they do not always respect the original construction, nor conservation principles. Often important partition walls, floors or even roof structures are removed to allow better room shapes. Now we have to look at whether we can modernise old Strickbau buildings while conserving them. The trials of the 3ENCULT project going in that direction are now in their third year. Primarily, we hope that we can show people living in old Strickbau buildings how they can improve their energy efficiency and renovate them easily to achieve the same level of comfort as new homes. We are working on two key aspects: an ecologically friendly insulation and an adaption of the floor height to accommodate people taller than 1.70 meters.

Do you think the future of the Strickbau is safe?
I am sure that there is a future for the Strickbau, in the same way that many people today reclaim the original, old and simple materials they are made of. However, the Strickbau has to be adaptive. The results of 3ENCULT project will help to preserve their traditional and elaborate structural technique. It will therefore contribute to keeping the important heritage of this type of construction alive.

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