​Metsä Group’s visitor centre in Äänekoski, in Central Finland, is a prime example of the fast construction using wood. The schedule was extremely tight, but the building project was completed on schedule, without compromising on quality or details. The 1,000 m² building showcases the versatility of Metsä Wood’s engineered wood products, combining industrially manufactured wooden elements and unique architectural solutions with detailed carpentry.

The visitor centre is located next to the enormous pulp storage towers of Metsä Group’s new bioproduct mill, with an impressive view of the mill area through its glass facade. Metsä Wood’s engineered wood products were a natural choice of building material for the visitor centre, and the visible wooden surfaces create a welcoming atmosphere in the spacious facility.

It was important for us to use natural wood materials as much as possible. Instead of hiding the wooden structure, we wanted to highlight the nature of the material.

Ulla Passoja, project's architect, UKI Architects

Prefabricated wooden elements make construction more efficient

The wooden frame and elements for the Pro Nemus visitor centre were delivered by a Finnish company VVR Wood. The frame system is based on Metsä Wood’s Kerto® LVL (laminated veneer lumber) products, which were also used to produce the massive multiple-glued columns and beams. All of the Kerto LVL products were delivered to the element manufacturer cut to customer specification.

“In structural design of wooden elements, it’s important that the element supplier is included in the process at an early stage. This ensures that all details are taken into account. Prefabrication can considerably reduce the cost of construction,” says Tero Vesanen, Managing Director of VVR.

The construction project was managed by developer Fimpec. In the construction industry, work is increasingly moving from construction sites to factories. Prefabrication is quick and efficient, and it also facilitates project management.

“Metsä Wood customised the beams to the requirements of our production lines. VVR glued the elements, added gypsum board and insulation and completed the prefabrication. The delivery was comprehensive – including the wall, intermediate floor and roof elements, it was around forty truckloads of wood products altogether,” says Vesanen.

Cooperation between element manufacturers is particularly important in major projects with tight schedules. The wall elements and the special CNC machining of wood products for Pro Nemus were completed by Punkaharjun Puutaito, which served as a subcontractor to VVR.

“It was easy for our flexible element production to take part in a tailored, customer-focused project of this type. The structural engineer submits the dimensions in digital format to our CNC machine, which drawsthe shapes and dimensions and the locations of the components on the surface of the panel. Then the element is assembled, and the wall is ready. This is a highly efficient method of industrial construction,” says Janne Tirronen, Managing Director of Puutaito.

Load-bearing structures from Kerto LVL studs, beams and bracing panels

Metsä Wood’s Kerto LVL columns and beams serve as the load-bearing structure in the Pro Nemus. Prefabricated Kerto LVL elements are used in the exterior walls, roof and intermediate floor of the building. Multiple-glued Kerto LVL Q-panels are used for bracing in the exterior wall elements and diagonal members of the grid. The intermediate floors are produced from Kerto LVL with structural gluing.

In addition to the impressive Kerto LVL columns, beams and diagonal members, wood products have been used in various ways in the visitor centre’s interior design and visual solutions. The facade cladding is made of exterior cladding panels with a dark surface treatment. The cladding was assembled as part of the exterior wall elements at the factory.

Impressive interior design solutions using wood products

The lower spaces on the ground floor of the building have impressive suspended ceilings with Kerto LVL S-beams, as well as coat rack fixtures made from birch and spruce plywood. The wall surfaces with translucent black surface treatment are made from spruce plywood. The cubicle walls and sink furniture in the toilet facilities are made from Kerto LVL. The stairway walls have birch plywood cladding, with CNC-machined patterns that improve the acoustics.

 The special features of the auditorium include its acoustic suspended ceiling, which is made from perforated birch plywood and has a white fire-retardant treatment. The stairs are made from Kerto LVL and are covered with traditional Saima parquet, which has also been used as flooring upstairs. The parquet flooring resembles the veneered side surface of plywood.

“This building combines industrial wood construction with a high level of detailed carpentry. This is just what is best about building with wood: the material itself creates opportunities for many types of processing, which are easy to implement,” says Passoja.

Invisible joints between structures

Sweco Finland Oy was responsible for the structural engineering of the Pro Nemus visitor centre. All of the element models used in the design of the centre either had been used before or were applications of existing structures. The structure of the intermediate floor element had been used in apartment buildings, and the structure of the roof element had been used in hall buildings.

“We wanted to showcase wood products and various structural solutions in the visitor centre, which required good cooperation between the architect and the structural engineer,” says Jussi Björman, Director of Technical Customer Service at Metsä Wood.

The use of prefabricated elements means specific features for structural engineering. For example, the order in which the elements are installed must be planned carefully, along with the feasibility of joints and fastenings.

“In the visitor centre, the joints between structures have been implemented innovatively: the intermediate floor elements have been hung using their top panels. No holes or grooves needed to be made in the load-bearing structures, which made the elements very quick and easy to install,” says Björman.

Wood construction often involves various types of diagonal screw joints, which was also the case with this project. Steel parts screwed into wooden structures were used in joints between beams and columns. 

The building was designed by means of information modelling, using the Tekla Structures application for structural engineering and element design, and traditional AutoCAD for the design of the details.

On a tight schedule in a tent

Building a visitor centre in the mill area was a challenge in itself. The bioproduct mill attracts a great deal of interest and a large number of visitors throughout the year. For this reason, the construction site needed to be presentable at all times, despite the tight seven month schedule.

“The schedule was by far the greatest challenge during the project. The decision to build the visitor centre was made in September, and the centre was scheduled to open in June. After the construction work had been completed, we also needed to allow time for building the exhibition,” says Tapio Vesander from Rakennustoimisto Alonen, who served as the site manager during the construction project.

“I’m proud that we stayed on schedule despite the cold temperatures and other challenges. Around 50 people worked on the site, and they were divided into two shifts at an early stage. Effective planning played a major role in this project. The requirements for the precision of the work were exceptionally strict in the Pro Nemus project, as many technical details were designed to be left visible. Every millimetre counted,” says Vesander.

The construction work was completed in a tent, which offered weather protection from start to finish. During the construction phase, key criteria that affect the indoor climate include humidity, cleanliness and dust management.

Kerto LVL is a fire-safe building material

The wooden Pro Nemus building is an exhibition space with an area of around 1,000 square metres. Kerto LVL is a fire-safe material for the frame structure, as it behaves predictably and its exact charring rate is known. In the event of a fire, the surface of the material chars, which insulates it from heat and slows down the charring of the structure.

All of the facilities in the building are covered by a fire detection system. In addition, a functional fire dimensioning was prepared for the building, which made it possible for the architects to make better use of the spacious facilities allowed by Kerto LVL.  

An unprecedented exhibition about the story of Metsä

A masterpiece of modern wood architecture, the Pro Nemus visitor centre is a completely new kind of forest experience. By building an exhibition space that combines pure nature with virtual reality and experiences in conjunction with the bioproduct mill, Metsä Group wants to lead the way and establish itself as a strong forerunner of the bioeconomy.