Extension of the Pfahlbaumuseum Unteruhldingen

It takes science and imagination to find out how people lived in the Stone and Bronze Ages. The Pfahlbaumuseum Unteruhldingen on Lake Constance has been focusing on this combination for over 100 years. And the success speaks for itself: Germany’s oldest archaeological open-air museum, supported by a private association, attracts over 300,000 visitors annually. In June 2024, the new extension building was opened. The highlight of the wooden building with nearly 1,300 square metres of usable space is an open roof truss with an expressive suspended frame construction made of laminated timber.

With the extension, the museum, which was founded in 1922, is preparing for the future. For over 100 years, the museum has offered insights into 3,000 years of human history. In the open-air area, visitors can see 23 pile dwellings reconstructed to reflect the Stone and Bronze Ages. The new building houses a modern visitor centre and a new exhibition on the pile dwellings, which are a UNESCO World Heritage Site. The original remains of the pile dwellings are located underwater just a few metres from the museum. The design originated from a competition in 2018, in which our office won first place.

The nucleus of the design is the image of a dugout canoe from the Bronze Age, which is pulled ashore and turned over in winter, providing weather protection for objects stored underneath, such as tools. Using this metaphor, we developed a longhouse with a gabled roof that, like an overturned boat, protects the exhibits. The house was widened in the middle, where visitors enter from the reception annexe. At the generously glazed gable ends, the building narrows. This geometric trick twists the open roof structure and creates a fascinating symmetry in the interior. The wooden frames consist of laminated timber beams made from untreated local spruce, spaced 1.60 metres apart, with intersecting bracing. A gallery, suspended from the roof structure with steel rods, provides additional exhibition space.

Understated and “simple” construction
The new building blends harmoniously into the surroundings of the small community of Uhldingen-Mühlhofen on Lake Constance. The urban scale and roof shape echo the nearby buildings on the lakeside promenade. The new main entrance is prominently located and easily visible on the newly designed museum forecourt. On the lakeside, the building is slightly set back, so as not to dominate the reconstructed pile dwellings of the open-air museum. This also creates a new, attractive outdoor area with a terrace by the lake.

Many components of the approximately 45-metre-long extension, mostly made from cross-laminated timber, were prefabricated, allowing for a short construction period of 18 months. The building was erected on 81 pile foundations that reach up to 20 metres into the lake bed. To visually match the façades to the up to 100-year-old pile dwellings of the museum, the longhouse and reception building were clad with pre-weathered square timber made from durable larch. The bronze-coloured window and opening casements blend harmoniously into the understated façade. The interior fitout is dominated by wood: the wall cladding is made from white fir, the ceilings are covered with wood acoustic panels, and the flooring on the gallery is made from darker industrial parquet. The bright flooring on the ground floor is made from polished screed with aggregates from the sandy lake bed, which visually blends well with the wooden ambiance.

The new museum building directly adjoins the existing structure on the west side, which houses all the building services and the newly designed sanitary rooms. This allowed the new exhibition hall to be executed in a low-tech construction method according to the “simple building” principle. The hall is supplied with sufficient daylight through generous skylights. For a positive energy effect of the entire museum, photovoltaic panels were added to the existing roof during the extension to provide self-sufficient power supply. A unique feature of the extension is that two public sewer lines run under the reception area. Therefore, the foyer was built with subordinate components that can be removed quickly if necessary.

The next extension is envisaged
As part of the competition entry, we already developed a second construction phase east of the current extension. As a mirrored twin, another exhibition hall is to be built there in future, for example for special exhibitions. The building permit for the next extension has already been granted, but the museum, supported by an association, must first secure the funding. The future addition is already evident in the open space design.