Foundation and static consolidation

Bild von Fenster außen statische Konsolidierung
Façade detail © SNP Architektur

Before the restoration began, the Lehár Villa showed many cracks, some of them significant. According to geological investigations, these could clearly be attributed to the unfavorable subsoil conditions.

Immediately along the Traun, fluctuations in the groundwater level repeatedly led and still lead to changes in the subsurface. Sandy fine particles of the heterogeneous, gravelly soil, which has a thickness of approx. ten meters, are washed out, which changes the material composition and ultimately the load-bearing capacity of the subsoil to such an extent that irregular settlements occur that cannot be absorbed by the building without damage.



Bild Fenster innen statische Konsolidierung
Cracking of building interior wall © Federal Monuments Authority Austria


From a depth of approx. nine meters, the material composition of the soil changes. Sediments are becoming more and more densely deposited.

Against this background, it was necessary to find a foundation that would use the load-bearing layers below the existing building at a depth of nine meters or more. At the same time, this foundation was not allowed to cause any significant change in the groundwater runoff, as this could have had a detrimental effect on other properties in the immediate vicinity. The solution consisted of the installation of so-called micro piles, 52 of which reach to a depth of 14 meters and thus bind solidly into the load-bearing soil. The thin, cement-pressed steel rods with a self-drilling head do not pose an obstacle to groundwater runoff and can be produced inside the building with comparatively simple equipment.



Bauarbeiten Erdgeschoß Gründung Foto von SNP Architektur
Construction work on the ground floor foundation © SNP Architektur

Since the load-dissipating piles could not be placed directly under the load-bearing outer and inner walls, a floor slab was installed that not only rests on the piles but is also interlocked with the load-bearing walls.

Subsequently, the strong cracks were further opened, cleaned, and sealed with material typical of the building. In this way, a form fit was created in the wall surfaces.

The reinforcement of the top floor slab and repair work on the roof truss are also part of the structural consolidation measures.

Bild von Bewehrung Bodenplatte Erdgeschoß © SNP Architektur
Reinforcement floor panel, ground floor © SNP Architektur

Geology: Ingenieurbüro für Geologie, Peter Baumgartner
Statics: ZTW Weilhartner, Hans Weilhartner, David Wimmer
Executed by: ZeBau Bau und Zimmerei, Greiffenhagen Bohr- und Sprengtechnik