Humidity and cleanliness control ensured good indoor air quality in the Länsituuli hybrid building

The hybrid building, completed in the Tapiola district of Espoo, combines commercial services with modern urban housing. The humidity and cleanliness control measures of the new building involved implementing innovative design solutions and carrying out plenty of humidity measurements over the course of the construction project. Sweco was also responsible for the structural engineering of the building.

Known in the work phase as Kiinteistö Oy Raitinkartano, the hybrid building features a business property (Kiinteistö Oy Espoon Kauppakeskus Länsituuli) and a residential section (As Oy Espoon Tapiolan Länsituuli). The overall project was completed in the centre of Tapiola in the autumn of 2021. The building features 93 apartments and more than 20 business premises connected to Shopping Centre AINOA. The ambitious project lasted half a decade.

“From the start, the design and the construction processes were carried out in accordance with shared quality objectives. Humidity and cleanliness control was important to the property owner, in both the shopping centre and the residential section,” says construction consultant Jani Rantala from Indepro. Sweco served as the project’s humidity and cleanliness control coordinator.

Successful result ensured with comprehensive quality control

Quality assurance measures began in the planning phase. Commenting on the plans from the perspective of humidity and cleanliness control was particularly flexible and easy due to Sweco also being in charge of structural engineering as well.

One of the challenges of the project was its location in the middle of Tapiola. For example, the early-stage excavation work was carried out near the Länsimetro tunnel. “All existing buildings had to be carefully sectioned off from the worksite area and safe passageways had to be modified several times over the course of the construction process,” says Sweco’s Quality Assurance Manager Miika Virtanen.

During the construction process, Sweco’s experts were also involved in planning the contractor’s humidity control measures. “Our role was extended to cover the contractor’s quality assurance, and we carried out a large number of humidity measurements at the worksite,” Virtanen says. Special attention was paid to wet areas and the surroundings of the tower crane, for example. “The crane stood in the middle of the building for the duration of the entire construction phase, so sealing feed-throughs and controlling the intake of water had to be done precisely.”

Humidity risks minimised with innovative solutions

Combining business premises and housing in the same building brought a set of challenges to the construction process. “The hybrid building was constructed with a transfer slab between the sections of the building, which is a sensible way to transfer the load of the seven-storey residential section onto the lower structures,” says Rantala from Indepro.

The bottom floor of the shopping centre features a medical centre, the humidity and cleanliness control of which had its own special requirements. PVC flooring was used for practical reasons. “We minimised its humidity risks by installing a geotextile fabric into the sand filling under the floor. It will decrease the amount of humidity rising into the ground-supported slab.”

Successful humidity control means open co-operation

Once the building had been handed over, Sweco drew up a final report on the success rate of the humidity and cleanliness control measures of the new building. All events are documented carefully. “The quality of the end result is exactly what the client expected,” Rantala remarks happily.

He considers co-operation between the humidity control team and the worksite to be the most important thing. “When you’re thinking about things at the same level, humidity and cleanliness control is proactive collaboration and resolving matters together. This increases the client’s certainty and trust in that things have been done right.”

Virtanen applauds the main contractor of the project, Fira. “The site manager was always open to suggestions and ready to listen and talk. He understood our role well and let us work in peace. That played an enormously important role in how well the project progressed.”