Master mortar from the Middle Ages

The Hohenwaldeck castle ruins above the Schliersee exert a special fascination.

It will be a while before visitors can roam between the historic walls again.

Schliersee – Gunter Köster was fascinated by the Hohenwaldeck castle ruins around 30 years ago.

At that time he was still a student in Miesbach and trudged up to the old walls as part of his archeology elective.

Now he has examined Hohenwaldeck again, but this time as a civil engineer and managing partner of the Bergmann office in Pfaffenhofen, which specializes in historical buildings, among other things.

A project like the castle ruins at Schliersee has not yet come under the experts.

"An absolute specialty," says Köster.

Because: The castle ruins are almost in their original condition.

"Other high medieval castles were rebuilt umpteen times," says the engineer.

Not the one at Schliersee.

Admittedly: it has fallen into disrepair, measured by the fact that at most minimal work was undertaken to preserve the walls,

there is still a lot.

And that is due to a particularly resistant mortar that the builders used at the time.

Location at 1000 meters a show of force?

Back then means: towards the end of the 13th century, when the lords of Waldeck built the castle on Schliersee.

The location at 1000 meters above sea level, more than 200 meters above sea level, must have made supply difficult.

Possibly the complex was not inhabited in winter.

It could simply have served as a symbol of power or as a refuge.

The Waldeckers were in conflict with the diocese of Freising and achieved so-called imperial immediacy in 1454, so they were their own masters.

The family died out with the death of Wolfgang von Waldeck in 1483. The castle had probably not been used for a long time by then, a rock fall at the end of the 15th century made it finally uninhabitable.

Medieval mortar 'rivals modern ones'

What is left of the plant today is held together by a special mortar mixture that “can easily compete with modern ones,” says Köster.

The civil engineers analyzed the material.

It probably comes from the immediate vicinity, dolomitic limestone, which is burned and mixed with lime chips as a so-called aggregate and water to form mortar and holds the stones together.

The fact that this mixture lasted for centuries was perhaps due to luck, but probably also to the master builder's experience.

The Bergmann office used its findings to reconstruct the medieval master mortar.

"It works well," says Köster.

It will be used in the restoration of the castle ruins, whereby only the current condition will be preserved.

Köster: "Nothing will be copied." Any damage will be repaired.

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Gunther Koester

© Office Bergmann

Despite the wonderful mixture: Castle ruins have been closed to day-trippers since 2020

Because even the miracle mixture had not been able to prevent this.

As is well known, the castle ruins have been closed since 2020 for security reasons.

It seems unlikely that it will be released again this year.

The state forests in Schliersee are responsible for the property of the Free State of Bavaria.

Its manager Jörg Mayer says: "The first work may possibly take place in the summer months." That depends on various factors.

The measures must be agreed with the monument and nature conservation authorities.

They also want to be paid.

At least as far as that is concerned, there was good news from the state parliament this week.

200,000 euros are to be set aside for the project in the state budget this year (we reported).

One thing is clear: Helicopter flights will be necessary again, and the nesting peregrine falcon must not be disturbed,

which means a time constraint.

The votes are running.

State forests want to “improve the experience”

When examining the ruins, the Bergmann office also discovered construction joints and scaffolding holes.

According to Köster, this indicates that the plants "were not built in one go, but in several construction phases".

Information about further findings from the extensive data collection will be provided later on the spot.

Mayer speaks of "improving the experience".

He also emphasizes: "The character of the ruins is preserved." The master mortar makes it possible.