The protected Women’s Hospital will be renovated to make it functional in terms of structural and building physics
The A section of the 90-year-old Women’s Hospital was renovated in one go, from the tunnel layer to the roof. Sweco’s structural engineers helped to preserve the appearance of the protected façade, while replacing the high-risk structures with safer alternatives. Sweco was also responsible for the moisture and cleanliness control of the renovation site.
Designed by architect Jussi Paatela, the Women’s Hospital has served patients in Meilahti, Helsinki, since 1934. The renovation of the protected hospital began in 2017 from section C. In autumn 2024, the renovation of section A was completed. The building has outpatient clinics, inpatient wards and a maternity unit, as well as corridors to the New Children’s Hospital and the L section.
“The 90-year-old main building has been renovated to varying extents in different eras with varying solutions that do not necessarily meet today’s requirements,” says Olli Siira, Project Manager at HUS Real Estate Ltd, describing the need for renovation. “Our goal is to create healthy and safe facilities that meet the needs of modern hospital operations.”
During the renovation, the rest of the hospital will operate normally, which is why it was decided to repair section A at once, from the tunnel layer to the roof. “It’s wiser than repairing a few floors at a time, because it disturbs the users of other spaces less,” Siira says.
Sweco started as the structural designer of section A in the project planning phase in 2020. However, Tommi Mutanen, who was responsible for structural design, has experience of the Women’s Hospital’s space changes all the way back to the early 2000s.
“Tommi has a long experience of the hospital area, so he was already familiar with the characteristics and risk structures of the building,” Siira says with satisfaction.
Cleaning of intermediate floors improves indoor air quality at the Women’s Hospital
The collaborative project management project required brainstorming, information modelling and compliance with the HUS Energy Efficiency Guidelines from all design disciplines. In addition, takt production was tested.
“At first, it felt laborious to plan, but in the end, everyone felt that it was a good way to build,” Siira says. Completion was completed more systematically, as the construction proceeded one floor at a time from top to bottom. “Along the way, we had time to learn a lot as we moved towards the lower floors.”
From the point of view of renovation structure design, section A was very diverse. About 50 different types of structures were drawn up. “The hospital contains a huge amount of technology, so there were also a lot of new penetrations, holes and shafts,” Mutanen adds. In addition, acoustics played a key role in the maternity hospital, the solutions of which affected not only user satisfaction but also the details of the structural solutions.
The biggest challenges in the 1930s were caused by the general structure: double slab intermediate floors. The formwork boards of the old concrete castings and all other organic material were removed from them. Finally, the intermediate floors were dry-ice-blasted, and the cleanliness of the surfaces was ensured by random microbial samples.
“Because the formwork boards were dismantled from below, double plasterboard was added to the underside of the intermediate floors, which replaces the bottom slab and improves fire safety and the sound insulation of the structure,” Mutanen says.
In the cold attic of section A, new facilities for the ventilation machine room were designed and built, which is why the entire roof was raised in connection with the replacement of the machine-seam roof, with the exception of the protected terrace. The engine room was placed on top of a new composite slab, and the loads in accordance with the current regulations of the roof were transferred to the old load-bearing solid brick wall structures with a steel frame structure.
The Women’s Hospital in Helsinki is protected in its entirety, so the plastered solid brick facades are also protected. The windows were renovated to match the old ones. Mutanen prepared a report on the repair work of the façade plaster, which is a less common task for a structural designer. “The plaster on the solid brick walls was repaired, and the façade was painted with lime paint under the supervision of the City Museum in the same shade as originally.”
Preserving the origins, the rooftop terrace, stairwells and the old elevator on the top floor were also renovated. In addition to cost-effective renovation, attention was paid to safe material choices. “For example, the basement floor screeds had to be as airtight as possible, permeable to water vapour and safe in terms of indoor air,” Mutanen says.
Humidity and cleanliness control protected a functioning hospital
The renovation was carried out under weather protection, and at HUS’s request, stone partition walls that are physically reliable were selected for the wet rooms. “The policy for coating the floors was also strict, and the drying times for concrete castings were longer than the general regulations,” says Jonna Heinonen, the project’s moisture and cleanliness control coordinator at Sweco. The limit values were in accordance with the moisture control document prepared by Sweco’s structural designer.
The drainage solutions for the protected façade could not go completely according to current standards. The downspouts were replaced, but left inside the façade in the old model. However, the immersion against the solid brick wall was waterproofed, and the downpipes were implemented with double piping. The foundation walls of the building were also waterproofed, and the building was drained.
Cleanliness management was carried out in accordance with the P1 cleanliness class. As the A section is attached to the operating hospital wing, closed partitioning walls were used to delimit the construction site on all eight floors. “Doors were added to a couple of floors for emergency evacuation, and they came in handy when there was a small fire in section B during construction,” Heinonen adds.
Care was taken to filter the air blown out of the site. Dirty air was not allowed to come close to the windows or air conditioning intakes of the operating premises. In addition, the exterior debris shafts used during the demolition work were covered, preventing the spread of dust.
Sweco continues as the structural designer of the Women’s Hospital’s B section
Siira is pleased that Sweco was chosen to continue as a structural engineer during the final part of the renovation. Part B is larger than Part A, but built at the same time, so many of the lessons learned can be used as such.
“When the place, the environment and the contact persons are already familiar, the designers do not need to be familiarised with the solutions made in Part A, but we can continue with the same system.”
After the renovation, the structural solutions will be uniform in all building parts of the Women’s Hospital, which is also pleasing to the users. “The users have been satisfied with the solutions in section A, and the renovation has also achieved its other most important goals so far, such as staying on schedule,” says Siira.