Embracing a tree - school extension in Frankfurt, Germany

Architectural Review, The, Sept, 1996 by Peter Blundell Jones

This is the first of three articles about buildings by Peter Hubner which demonstrates in very different ways an intense awareness of the importance of ecological and human concerns while approaching each with inventive imagination and the latest developments in design and building technology.

The Odenwaldschule is a private residential school built just after the turn of the century as part of the progressive School Reform Movement.[1] Set in hilly countryside near Frankfurt, it consists of a series of villa-like boarding houses designed by Metzendorf in the irregular picturesque manner derived from the English Arts and Crafts and brought to Germany by Muthesius.[2] The ethos of such schools has been to promote independence of spirit and personal responsibility, so that pupils will think and act for themselves, yet in a way which also benefits the community. The emphasis on communal service and self-sufficiency is reflected in the pupils being expected to make and repair things in the school workshops under skilled craftmasters, and to grow their own food in the school gardens.

A few years ago some extra classrooms were needed, and a limited competition was held to choose an architect. Peter Hubner, known and invited for his participative work in the Stuttgart area, was chosen because of his intention to involve the staff and pupils in the construction.

The school lies on the side of a steep valley, and Metzendorf built his now listed villas of stone with high retaining walls on the downhill side, leaving the so-called deer park between them with its now magnificent great trees. Hubner chose neither to extend the villas nor to imitate them, but to build a modest new building on one of the main connecting paths between them. The most convenient site was a clearing that had just opened up with the death of a pair large maples, but before they could be felled, one of them burst into leaf again and recovered. Even with the tree present, the site still seemed the best available, so Hubner's task became to build around and within it: a project soon dubbed `the eagle's nest'. It was important not to disturb the roots which have roughly the same spread as the branches above, so a structure was devised that could sit on just two short concrete piles. The tree could grow through the middle untouched, with enough room to put on more annual rings as the years pass. It was also essential to preserve the humidity of the soil, so rainwater from the roof of the building is deposited close to the trunk. The tree provides a centre for the building and shade from the sun. Although the entrance and two main classrooms are at ground level, the ground drops away so fast that the balcony on the west side seems like a real tree-house, some six metres from the ground.

The design went through several versions. Although at first an exclusively timber building was planned, the structural forces turned out to be so great that the laminated timber struts needed would be too big and heavy to handle (access to the site is difficult). The building was therefore achieved in two stages, with two different methods and technologies. First a platform was made in the hillside consisting of a concrete plate linked to the two pile foundations by a network of 12 steel struts. Then the classroom building was built on top with timber frame and timber cladding, the walls and roof finished with Alaskan cedar shingles.

The frame design for both steel and timber was carried out on a sophisticated three-dimensional computer system which provides data for every component to be cut out by a robot cutter, using standardised joints but varying lengths. Such transfer of information electronically allows complex geometries, cuts out much redrawing and specification work, and reduces errors; but it also requires specialised firms.

So the initial intention of complete self-build was gradually eroded, and in the end contractors were employed for all the heavy jobs. None the less, a significant proportion of the building was undertaken by the pupils and their workshop masters. As one has come to expect with Hubner, the participation of staff and pupils in the building's design and construction shaped it in ways that he could not have predicted, and has allowed them an identification with it that was present from the day it opened. He freely admits that the involvement of users in the building process is far more important than cost savings, but all the same costs were modest, the equivalent per square metre only of normal domestic work. The building won the prize for environmentally friendly building in wood for the region of Hesse in 1993.

[1] A progressive German reform movement in response to the changes brought by unification and industrialisation, which took effect mainly after the First World War. Of particular significance was the Bund entschiedener Schulreformer founded in 1919 under the leadership of Paul Ostreich. The Odenwaldschule prepares pupils both for the normal academic exams and for manual occupations.