Elementit-E modular wood construction

Elementit-E specialises in modular school buildings. Construction with prefabricated wooden modules incorporating Kerto® LVL (laminated veneer lumber) is extremely fast, light and green.

The cases for Kartano School in Järvenpää and Helilä School in Kotka are the same; the old schools’ indoor air problems created a need to obtain new temporary school spaces quickly. Both cities decided to order a school from Elementit-E, a family business and frontrunner in modular school construction in Finland. The schools can also be relocated easily thanks to the modular design. The City of Järvenpää bought their school; the city of Kotka leased theirs.

“We’ve leased the space for Helilä school for five years. We don’t know yet how it will be used after that. The buildings can be transferred to another location, which adds value and can affect the future use,” says Tero Huusko, Office Manager of the City of Kotka.

Helilä School consists of three buildings, whereas Kartano School has two, which are joined together by a corridor. Both schools have two storeys. The design allows the modules to be easily dismantled and the school to be quickly rebuilt on a new foundation.

“Dismantling is possible because of the very durable modules. We use a lot of Kerto LVL in them; it is a strong yet light material and stands the test of time. Our schools can be used for between 50 and 100 years,” says Veli Hyyryläinen, CEO of Elementit-E.

Kerto LVL S-beams are used in the floor, internal wall and roof elements.

“We’ve already been in the industrial wooden construction business for a long time, which gives us an advantage in the current market. In our schools, even the floors are made from wood, and concrete is used only in the foundation. Environmentally friendly Kerto LVL ensures low CO₂ emissions,” says Hyyryläinen.

Efficient and fast process

Elementit-E prefabricates wooden modules in its own factory in Kouvola and takes care of the on-site erection of the buildings. On the assembly line, the various elements for schools are assembled, resulting in “mega-modules”, which range from 60 to 80 m² in size.

The production timetable for Kartano and Helilä Schools was really fast, because it takes only about one day to finish a new module – a classroom, for example. The biggest modules were 6.6 x 10–12 metres.

Load-bearing structure

“Kerto LVL is a great match for modern module production. We receive the dimensionally stable S-beams at the assembly line from Metsä Wood in the right sizes at the right time,” says Hyyryläinen.

The modules are assembled at a factory, which is a safe environment with dry and predictable conditions. The prepared modules for Kartano School in Järvenpää and Helilä School in Kotka were weather-protected with plastic. To avoid traffic, the modules were loaded in the afternoons and transported to the building sites during the evening and at night.

Thanks to industrial prefabrication, construction was quick. It took only three to four months from the order for a school to be ready for its pupils. For example, Helilä School, consisting of three buildings, was built and brought into use in phases. The construction and installation of the first ten-module building were done in just three weeks.

“The acquisition of the new space was done to a pretty rapid timetable. We moved our personnel and pupils to the new school in three phases; each group after a new building had been erected,” says Huusko.

Frame with prefabricated LVL beams

The load-bearing structure consists of various Kerto LVL S-beam applications. The internal walls include diagonal support, and S-beams are glued and screwed together to stiffen and stabilise the buildings.

“The rigid structure transfers the loads to the foundation,” says Hyyryläinen.

The floors consist of Kerto LVL S-beams with customised product dimensions in the frame, combined with a honeycomb structure. The floor has an insulation layer between the beams, and the panel is on top. In the upper floors, the lighting, air conditioning and acoustic systems are connected to the beams. The unique structure allows floors with a long open span.

Strong connections with screws and glue

In both schools, the different elements, including Kerto LVL S-beams, were connected to each other with screws, and glue was also used between the beams. This ensured a stiff construction.

In Helilä, the wooden modules were placed on a concrete foundation; in Kartano, the wooden modules were placed on a grate and tubular steel piles.

Highly fire-resistant

The structures of both two-storey schools were planned and built in accordance with fire safety regulations. Both Kartano and Helilä schools were built in accordance with the P2 fire class, with no need for sprinklers.

Fire resistance is 30 minutes for the Kerto LVL S-beams used in the roof. In the walls, the S-beams have been covered with gypsum board or plywood, and floors have a stone wool layer, which protects the S-beams from fire from above.

Uniform quality

Hyyryläinen is satisfied with the cooperation with Metsä Wood, which has lasted for a long time. The most important factor is the quality of Kerto LVL.

“Consistent quality is important, because it ensures that our production runs well. We’ve also developed things with Metsä Wood that are beneficial for everyone. They’ve also started to produce Kerto LVL blockings between the floor joists in floors and intermediate floors, and we can focus solely on the assembly part,” Hyyryläinen says.