Mari Blokhus Nordtun

Hersleth Entreprenør shared experiences

Hersleth Entreprenør AS is a family-run contracting company with main activities within traditional building and construction activities. The market area is Østfold, Follo and southern Oslo. At the meeting, CEO Reinert Hersleth talked about the company’s experiences. Reinert Hersleth talked about the company and his experience with floor dividers in wooden buildings.

– “We carry out all types of assignments in new builds, conversions and refurbishments in both the private and public sectors, including multi-purpose halls, schools and apartment buildings. Our company builds in different materials and chooses the most industrialized solution,” said CEO Reinert Hersleth, Hersleth Entreprenør. Reinert Hersleth, Hersleth Entreprenør.

In Vestby, Hersleth Entreprenør is currently building Vestbyhagen III, a new development of 64 apartments in five buildings on three and four floors. The assignment is being carried out as a turnkey contract for Husjordet AS. The apartment buildings are three and four storeys high.

– The buildings will have floor partitions in solid wood and exterior wall elements (studs) in wood from our own element production at Årvoll. We have developed the solution with floor partitions ourselves, and the construction method has been developed to achieve a more industrialized construction process. We want the same craftsmen to be able to build both the walls and the floor partitions. That’s why we’re combining stud walls with solid wood floor partitions,” said Hersleth.

– “In the area of sound, we have had innovation projects in collaboration with Brekke & Strand. It’s a key area, so it’s good that the NWC is taking a closer look at the topic of sound,” said Hersleth.

KONTUR Architects presented an interesting building

KONTUR Arkitekter AS, which has been a member of the cluster since 2019, is an interdisciplinary architectural firm that works on a wide range of construction projects, with an emphasis on residential facilities, commercial buildings, schools and care buildings. The company is headquartered in Gjøvik. At the meeting, partner Erik Brett Jacobsen talked about the company and gave a briefing on the Voldsløkka school and cultural center project in Oslo, where sound was one of the important issues.

Voldsløkka School and Cultural Center in Oslo was opened in August 2023, with Oslobygg as the developer. It is Norway’s first school with a plus house standard and combines solar and earth energy, environmentally friendly building materials, an energy-efficient building and a unique outdoor area into a European model project.

– “The project used a lot of solid wood. “We chose to deliberately highlight wooden support structures where possible for sound reasons,” says partner Erik Brett Jacobsen, who was KONTUR Arkitekter’s architect in charge of Voldsløkka School and Cultural Center, where all architectural design from preliminary project to finished building was carried out in close collaboration between KONTUR and SPINN architects.

– One of the challenges in the project was sound in rehearsal rooms and classrooms. “As a passive measure to prevent construction noise from propagating between rooms, we chose, for example, to place columns in the middle of classrooms instead of in the walls between classrooms where possible,” said Jacobsen. He explained that the cultural hall had higher sound requirements than the school building and was therefore constructed as a steel and concrete structure.

– The solution in the floor divider between the cultural hall and the areas below was a 500 mm perforated ceiling with floating screed on vibration blocks. In addition, mineral wool of varying thickness was installed above and below the main structure, air insulation layers as well as space for technical guides, a minimum of three layers of plaster and sound-absorbing ceilings. This made the floor partitions approximately 2 meters thick,” said Jacobsen.

– Voldsløkka School and Cultural Center was an exciting project to be involved in, and it required very close follow-up. Among other things, we built a solid wood structure inside the listed building that was connected to the new school building and the new cultural center. Here, we also retained the original wooden structures as environment-creating elements inside parts of the building. They did not contribute to the load-bearing capacity, but were not demolished to preserve the historical and visual aspects. It was a good solution,” says Erik Brett Jacobsen.

Want clients who set clear requirements

Hans-Jørgen Bjøralt is general manager of Backe Oppland, which was commissioned to build the school and kindergarten. The Backe Group is Norway’s largest family-owned construction company, and is the largest construction company in Innlandet (Backe Oppland and Martin M. Bakken).

– “In this project, the municipality set a number of requirements. It’s important to emphasize that these were requirements and not guidelines, which I think is absolutely essential,” said Bjøralt.

Examples of specific environmental requirements in the project:

The building must satisfy requirements for greenhouse gas emissions for materials including A1-A4, cutting and waste in A5, B4-B5 and C1-C4. The emission limit to be satisfied is 199 kg CO2/m2 GFA. Greenhouse gas emissions must be documented with calculations in accordance with. NS3720. Documentation must be available before the start of construction work.

Materials used must be low emitting. Emission requirements according to tab. 14 BREEAM Nor 2016 hea 02. The requirement applies to all interior materials and surface treatments.

– The municipality has used a number of requirements from the Breeam manual and selected requirements that are important to them. I think this is the right way to work. For this type of building, project-specific targets are more appropriate than Breeam certification. It looks different for a private developer selling a commercial building in an attractive area, where it may be worthwhile to deliver a high level of Breeam certification. But for public service buildings, a full Breeam certification can entail a lot that you have to pay for but don’t need,” said Bjøralt.

Examples of environmental adaptations in the project:

– Solid wood in all load-bearing structures, ceilings, auditorium, parts of the roof

– Wood in all interior and exterior walls

– High degree of precut materials

– Low carbon concrete class A

– Flooring with a low greenhouse gas footprint

– Waste: 99% sorting rate, 79% material recycling

– Energy: Solar cells on the roof and local, waterborne heating (also used during the construction period)

Involve the recycler from the start

Anita Storli represents Norsk Gjenvinning, which was responsible for commercial waste from the project. She said that the project has achieved a very high degree of both sorting and material recycling, thanks to early involvement.

– “It’s absolutely essential to get good results that we are involved right from the start-up meeting and follow the process. In this project, Backe Oppland has involved us right from the start, which is why we managed to achieve a 99% sorting rate and 79% material recycling rate,” she explained. Storli also highlighted other success criteria, such as ensuring resource-efficient packaging for the products, working with precap and returning as much as possible of what can be returned, such as pallets. “Waste should always be part of the construction meetings, so that you can follow the statistics and intervene when things don’t go as planned,” Storli said.

Upcoming breakfast seminars from project Climate-friendly buildings Innlandet:

• Kongsvinger Wednesday, January 31

• Gjøvik Wednesday, February 7