A medieval ship was reused as the ceiling of a basement built in 1244 in Constance, southern Germany. The finding came during a building study on Konradigasse by the State Office for Monument Preservation in Stuttgart.
The hull timbers of the medieval ship found in Constance, Germany. Credit: Landesamt für Denkmalpflege (LAD)
Researchers first thought the ceiling used old timber planks. A closer study showed something far more unusual. At least 19 planks form parts of a nearly continuous medieval ship hull. The ceiling covers more than 25 square meters, giving researchers a rare chance to study ship timber outside the water.
The team identified the planks through their shape, rows of nails, and wooden pegs. Some planks still sit together in the same order they held on the vessel. Traces of caulking, the material used to seal gaps between planks, also survive in places.
Early study points to a flat-bottomed cargo sailing vessel. Similar craft are known from the Lake Constance area, including a wreck found near Kippenhorn at Immenstaad and dated to the 14th century. The Konradigasse wood could offer new details about how such boats were built.
Archaeologists photographed the ship timbers to create a 3D model. Credit: Landesamt für Denkmalpflege (LAD)
The planks also carry signs of long use before they became building material. Researchers found at least four repairs where damaged sections were cut out and replaced with fitted pieces of wood. One repair uses a swallowtail-shaped insert. No close match for this repair has been found in medieval ship finds from Lake Constance so far.
The way the planks were placed in the basement adds another clue. Several pieces fit together as they did in the ship. This means the builders reused a large section of the hull rather than breaking the old vessel into small pieces.
The finding also points to how medieval builders reused costly materials. Old ships had useful timber even after they were no longer fit for sailing. Reusing their wood in houses saved work and gave worn material a new purpose.
A close-up of the medieval ship’s hull timbers. Credit: Landesamt für Denkmalpflege (LAD)
The ship remains are especially useful because most medieval wrecks from Lake Constance lie underwater. Studying them often requires work in difficult conditions. The Konradigasse timber sits in a dry basement and offers easier access for detailed study.
In August 2026, the research team recorded the remains again and made a three-dimensional model using structure-from-motion. Hundreds of photographs were combined to create a digital record of the ceiling and its timber parts. Researchers also took wood samples for dendrochronology, a method used to date trees by comparing growth rings.
Those tests should help establish when the trees were cut and could reveal more about the ship’s age. Further study of the wood, repairs, plank shapes, and caulking could also help explain how the vessel was built.
The State Office for Monument Preservation is already studying shipwrecks in Lake Constance through its “Wrecks and Deep Sea” project. The new find gives researchers a rare chance to compare an old ship preserved in a house with wrecks still under the lake.
The results are still preliminary. Yet the basement ceiling has already provided a rare record of medieval shipbuilding and timber reuse around Lake Constance.
More information: Landesamt für Denkmalpflege Baden-Württemberg (LAD)