Petter Kronqvist from Sito has been involved in the project since 2011 as the chief geotechnical designer.
“This has been a challenging project for everyone involved. The building, completed in 1840, is an important element of the architectural entity designed by C.L. Engel around the Senate Square in Helsinki, and Finland’s National Board of Antiquities has been actively involved from the start to ensure that one of Finland’s most historically valuable buildings gets the treatment it deserves. The building is culturally significant even on a European scale, as it is one of only a few historic buildings to have functioned as a library throughout its life cycle,” explains Kronqvist. For this reason, a comprehensive report on the history and architecture of the building was made to serve as the basis for the renovation. The geotechnical work began with a foundation investigation to ensure that the building is firmly founded on rock.
“Geotechnical work is an important part of the project, as new spaces are being excavated into the base rock to house the cloakroom and public washroom facilities and the spaces required by modern technical building services with their deep canals. The most distinctive feature of the geotechnical work is that all the excavation has been carried out by using non-explosive methods,” says Kronqvist. The methods used are wire sawing and hydraulic splitting. It is slow and expensive, but this way it can be ensured that no damage is done to the building during the work. This was also highlighted in the Rakennuslehti jury’s justification.
“The ongoing excavation phase and the related tasks during construction will continue for another few months. A special feature of the basement spaces will be the wire-sawed rock pillars which will remain visible as load-bearing structures supporting the handsome brick vault built in 1880. The exposed rock actually happens to be visually exceptionally striking. The space will house much-needed additional premises for the use of the library. They will be open to the public, so when the project is completed, everyone can come and admire them,” Petteri Kronqvist notes. “I’m very pleased to be involved in this project with Sito. Naturally it also feels good that this was selected as the Construction Site of the Year,” he adds.
As a result of the merger with Fundatec, Sito now has more solid expertise in the geotechnical planning of demanding construction projects, both for new buildings and renovations.
“Starting from the renovation of the Finnish National Theatre in 2000, I’ve been involved in many renovation projects for important buildings in central Helsinki. These projects are close to my heart,” remarks Petteri Kronqvist.
Sito was also involved in last year’s Construction Site of the Year. The Construction Site of the Year title has been awarded since 1986.