From projects to processes – apartments are completed in a controlled manner, even ahead of schedule
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YIT Corporation News November 9, 2020 at 09:00
Rainy winters at site
More important than individual innovation is the establishment of common, simple ground rules for the industry, as they can prevent up to 80% of all issues.
Global warming is advancing faster than ever before, resulting in various alarming phenomena around the world. In the North, the rapidly melting polar glaciers have become the symbol of global warming. The climate emergency is also impacting the everyday lives of Finns on a smaller, though still significant, scale: the past few winters have been exceptionally warm, especially in southern Finland. According to Statistics Finland, the southern and western parts of Finland did not experience a proper winter in 2019–2020. In the South, thermal winter did not take place until the end of February, only lasting for five days.
In addition to all the other severe consequences, climate change causes issues in the construction industry where the control of humidity and other conditions have traditionally been based on a climate featuring dry, cold winters. Interim Executive Vice President, Housing Finland and CEE at YIT Marko Oinas and Development Manager Arto Ylikangas are aware of the challenge and its extent.
“The increased rainfall is one of the many problems we are facing, but other weather phenomena, such as slanting rain, have also become more common,” says Oinas.
Slanting rain refers to rain falling at an angle due to heavy winds. Instead of hitting the waterproof roof of the building like normal rain, slanting rain falls onto facades and their structures. This allows the water to penetrate the structures through even the tiniest cracks.
“This creates optimal conditions for mould. In Helsinki, for example, areas such as Jätkäsaari, Kalasatama and other coastal neighbourhoods will increasingly face such weather strain.”
This elevates not only the risk of mould and condensation but also the risk of frost weathering in old concrete facades. The impact of slanting rain must now be taken better into consideration in lead-throughs, fastenings, seams and the capping of window openings, for example.
“More attention must also be paid to lifecycle maintenance,” says Oinas.
Planned and systematic approach crucially important
Taking weather conditions into account in the planning stage and erecting the building appropriately primarily means that the building is weather-protected. However, this point is not reached until months or years into the construction project. Controlling the conditions in an unfinished, open building is much more challenging, especially now that mild, rainy winters are becoming more common.
“Snow is easy to remove, but water runs right through structures. Structures, especially concrete, also hold large amounts of moisture that must be drained. Operators in the construction industry are now starting to understand the full scope of how much time and energy this all takes,” says Oinas.
Sensors monitoring humidity, evaporation rate and the temperature of the space in real time have proven particularly useful.
As Finland is starting to experience a more “British” climate, construction operators have started opting for weather covers, another important new innovation.
“The use of weather covers has surged; they were quite rare only ten years ago. On the other hand, the entire frame is not usually covered unless the building is being thoroughly renovated or after the completion of the frame of a new building, if necessary. In new construction, weather covers are not ideal as the building keeps rising,” says Ylikangas.
However, Ylikangas agrees with Oinas that paying attention to controlling the indoor air is the most important change.
“Today, operators start thinking about indoor air control right from the beginning of the project. This work has become much more systematic.”
Vedenvälke reflects years of experience and best practices
YIT’s most recent example of humidity and conditions control can be found in Tampere. In September 2021, the company will complete its project of apartment buildings for As Oy Tampereen Vedenvälke on the banks of Lake Näsijärvi. As the project was only recently launched in July, the construction will mostly take place during the rainy months.
Site Manager Arto Pitkänen modestly explains that the purpose of the project is not to reinvent the wheel.
“We are focusing on a systematic approach and a thorough execution. This has yielded excellent results in our previous locations. Our cooperation partner RKM-Group Oy has played a key role in measurements and managing the drying equipment.”
Windows and balcony doors will be installed on each floor as soon as possible. The floors will immediately be heated with a temporary heating system and the drying equipment is installed at the same time. The temperature and humidity of the floors will be remotely monitored throughout the project. Temporary vestibules, insulated with polystyrene, have been placed in front of the ground floor entrances. Due to access requirements, the ground floors are cooler and more humid than the other floors, but this is a functional solution to the problem. The roof is constructed as the final step.
Construction of business premises may pose even more challenges
According to Kalle Isometsä, Vice President of Construction at YIT, moisture control in business premises comes with its own challenges.
“The production is much more driven by the developer and the client than in apartment construction. The client assigns the developer organisation and hires the designers, after which the contractor executes the project. Understanding the functionality of the design solutions as a whole is one of the major challenges. As a contractor, we simply follow the instructions, whereas in self-developed projects, we are responsible for every step of the way.”
For example, according to Isometsä, the company sometimes seeks inspiration for structures and materials from more southern countries. However, the selected material, design solution or structure may not be viable for Finnish conditions.
A great deal of development has been seen in the use of weather covers, for example.
“Some years ago, clients would not state a clear decision in their requests for tenders on whether to install the outer shell under a weather cover. Now, clients nearly always demand that the erected frame should be covered before continuing with the rest of the project.”
In recent years, moisture control coordinators in charge of running through the entire design process and monitoring the production have become more common in construction projects. The coordinators are paired up with experienced foremen who are in charge of the execution.
“This has considerably improved each party’s understanding of moisture control.”
Common ways of action minimise most of the damage
The impact of climate change on construction is so vast that the necessary plans and solutions cannot be developed in isolation. What is more important than individual innovation is the establishment of common, simple ground rules for the industry, as they can prevent most of the issues.
Kuivaketju 10 is an operating model for moisture control in construction projects. It reduces the risk of moisture damage throughout the life cycle of the building. The management of moisture risks is based on a chain where risks are prevented in each stage of the construction process and the success of the preventive measures is reliably verified. The operating model includes a list of risks as well as verification instructions presenting ten key moisture risks. By following the instructions, operators can avoid more than 80% of the consequences of moisture damage.
The Finnish Construction Industries Training Centre RATEKO also offers eKosteus online training for construction industry workers and white-collar employees. Ylikangas, who was involved in the development of the training module, says that YIT is interested in the module and is considering implementing it this autumn.
In addition to raising awareness, steps have been taken in engineering to considerably reduce the issues resulting from moisture and humidity. Modular construction in particular often comes up in discussions.
“In modular construction, the percentage of completion may be up to 80–90%. The modules can be manufactured in ideal conditions in terms of humidity and heat as well as protected during transport and storage all the way until installation,” says Oinas.
Modular construction is also extremely quick. The frame of YIT’s modular wooden apartment building Tampereen Tohtori, for example, was erected in less than a week, whereas the traditional construction method would have taken six months. Moreover, modules can also be used for building individual parts of a building. For example, the roof of West Terminal 2, completed at the Port of Helsinki in 2017, was produced as modules.
“Erecting the roof in just one day means that the drying process can be started very quickly,” says Isometsä.
For further information, please contact:
Marko Oinas, Interim Executive Vice President, Housing Finland and CEE, YIT Corporation, tel. +358 40 506 7430, firstname.lastname@example.org
Johanna Savolainen, Communications Manager, YIT Corporation, tel. +358 (0)44 305 4594, email@example.com
YIT is the largest Finnish and a significant North European construction company and urban developer. We develop and build apartments and living services, business premises and entire areas. We are also specialised in demanding infrastructure construction. Together with our customers, our nearly 8,000 professionals are creating more functional, attractive and sustainable cities and living environments. We operate in 10 countries: Finland, Russia, Sweden, Norway, the Baltic countries, the Czech Republic, Slovakia and Poland. In 2019, our revenue was approximately EUR 3.4 billion. YIT Corporation's share is listed on Nasdaq Helsinki Oy. www.yitgroup.com