Prysmian Sky Project, Kirkkonummi

We built a tower for the manufacture of submarine cables for the Prysmian Group's production plant in Kirkkonummi. The tower is 185 meters high and is currently the tallest building in Finland.

High Technology in the Tower

Prysmian Group is implementing a new, higher vertical vulcanization line in the tower, which is state-of-the-art in cable manufacturing. The tower has two vertical vulcanization lines that isolate high-voltage submarine cables. Vertical vulcanization is an important part of the manufacturing process of high-voltage cables. The production technology had to be installed on the tower from top to bottom, layer by layer as the construction work progressed. In addition, the production lines of the cable tower require exceptional stability for the building: for the entire height of 185 meters, the tower must not bend by more than 20–30 millimeters.

The tower's frame was implemented with sliding casting technology and the work proceeded uninterrupted 24 hours a day. The weather conditions, especially the wind speed, affected the casting process and the lifting of the crane. During the lifting of the crane, the wind speed had to be less than ten meters per second and during the sliding casting the limit was 15 meters per second.

Multi-skilled Project

The built site is located in a very small space in the factory area, and the production of the adjacent factory was running without interruption during construction. The project has required extensive expertise, utilizing the expertise of the customer, YIT and partners in seamless cooperation. 

In addition to the new cable tower, the investment includes several other new production facilities. In addition to the tower project, we built four new hall building expansions and the construction of a new material storage facility in the area. The new premises have an area of approximately 26,000 m². The contract includes a lot of demanding foundation construction work, concrete and steel construction work, as well as technical building work.

Promoting the Green Transition

By investing in Kirkkonummi, Prysmian Group is responding to the growth in demand for land and sea cables spurred by the energy transition and related technology. High-voltage submarine cables are used for the electricity transmission of green transition investments, such as offshore wind farms.

YIT was chosen as the implementation partner for the cable tower project in the summer of 2023. The tower reached its ridge height of 185 meters at the end of 2023. The tower was completed early and commissioned in May 2025.

Facts:

• The volcanization tower has a diameter of 24 meters
• On average, the tower increased in height by 2.4 meters per day
• The outer wall of the tower has a thickness of 600 mm
• 11,500 cubic metres of concrete were used for the tower and 1,600 cubic metres for the foundations
• The tower weighs approximately 30,000 tons

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