Harmonised open standard for Finnish wood construction

The preparation of the RunkoPES industrial standard, a harmonised measurement and jointing system for industrial prefabricated wood construction initiated by the wood products industry is on the home straight and ready to be used by those interested in doing so. Up to now, the lack of a harmonised system has been a barrier to the development of industrial wood construction. ”This removes a significant deficiency from the industry, now that we finally have a harmonised standard,” says Mikko Viljakainen, Managing Director of Puuinfo. Markku Karjalainen, Development Manager of the Wood Construction Programme at the Ministry of Employment and the Economy believes that the open standard will accelerate the breakthrough of industrial wood construction.

During 1968-1970, the BES system for concrete construction was developed for residential construction in Finland. As a result of this system, concrete elements and their jointing details were standardised, so that contractors could get offers from and purchase finished parts for the same building from several different suppliers. The frame system gave designers great opportunities for variation in the design of room plans for dwellings. ”Without this concrete construction BES system, the record residential housing production in the 1970s would not have been possible,” says Kimmo Järvinen, Managing Director of Finnish Wood Research Oy.

The lack of a similar system for wood construction has undoubtedly hindered the breakthrough of the industrial construction of multi-storey wooden buildings. Behind the development of the RunkoPES system lay good experiences of the open BES system for concrete construction. RunkoPES makes planning easier and gives designers many opportunities for variation, speeds up and streamlines the installation of elements and enables them to be put out to tender and purchased from several different manufacturers," explains Järvinen about the benefits of the open system for wood construction.

Measurement modules, jointing principles and basic structural solutions have all been agreed in the RunkoPES system. Based on the system, the products and solutions of different manufacturers are compatible. Designers can plan a building without knowing who is going to build it. The PES system standardises only the building frame joint system used in wood construction. Standardisation neither limits the freedom of the architect to design nor the development of company-specific applications. The system is also expected to standardise the interpretation of regulations relating to wood construction across the country, which has been very variable up to now.

Open system to increase the possibilities for design and make it easier to put the procurement of structural parts out to tender

The key objective of the RunkoPES project is to create a harmonised open standard for prefabricated wood construction, which opens the way for the company-specific development of industrial wood construction. It is expected that this will strengthen the ability of the Finnish wood construction industry also to expand internationally.

According to Mikko Viljakainen of Puuinfo, it is necessary for wood construction to have an open industrial standard just like concrete construction, because this is general practice in the construction industry. ”Now we are creating the kind of rules and wood construction has time to adapt to the competition,” says Viljakainen. ”Up to now, building firms have not been very involved in the construction of wooden apartment buildings, because they have felt that the method of requesting tenders for the frame systems has been difficult. The development and compatibility of systems makes this easier. The work of contractors is also helped by the fact that wood solutions are delivered as a product part transaction, whereby the responsibility for design and installation rests with the manufacturer.

In Viljakainen’s opinion, the lack of a harmonised standard in wood construction has been a clear obstacle to the development of the industrial construction of multi-storey wooden buildings. ”As a result of platform experiments carried out by building firms in the 1990s, wood construction had a bit of bad reputation. The platform system was mainly based on on-site construction according to its foreign models, and because of that it did not gain general acceptance in Finland. On building sites, construction was at the mercy of the weather. The new industrial systems, on the other hand, also pay great attention to moisture control on the building site. The assembly of parts is done in controlled conditions in a factory hall and, at the building site, it is protected from the weather,” explains Viljakainen.

The harmonised system creates for prefabricated wood construction standardised joints for load-bearing parts including measurement systems. The system covers long-length and solid wood structures as well as column-and-beam structures. The standardised jointing solutions enable compatibility between the products and solutions of different manufacturers. Sweden, for example, uses the same kind of system in the construction of wooden apartment buildings based on modular prefabricated solutions. Up to now, the problem for industrial wood construction has been that each site has had its own individual structural solutions, and it has not been possible to pass experience and learning on to the next projects.

”Each site had to reinvent the wheel,” says Viljakainen. ”Each construction project had its own structural drawings so that, for example, problems concerning installation work had to be solved on the building site, instead of the parts manufacturer planning and doing it in advance. The RunkoPES system also pays great attention to good ‘buildability’ and quality assurance. For example, the air-tightness of structures is ensured without having to rely on the application of putty at the building site. In this sense, RunkoPES is not only more versatile in its possibilities for design competitive tendering, but is also better from a quality perspective.”

Open standard promoting a breakthrough in industrial wood construction

Markku Karjalainen, Development Manager of the Wood Construction Programme at the Ministry of Employment and the Economy believes that the RunkoPES system will accelerate the breakthrough of industrial wood construction. ”This system will really boost the competitiveness of wood construction, increase the interest of designers, developers and builders towards the industry and introduce more wood construction solutions to the market,” predicts Karjalainen.

As a result of the new system, it may be possible increasingly to move towards material-neutral invitations to tender, whereby wood builders can compete on an equal footing for all multi-storey apartment building construction. The first new wooden apartment building projects have already shown that, from a cost perspective, wood construction is highly competitive with the traditional multi-storey construction. High-quality wooden apartment buildings with excellent fire-safety properties and providing a fine domestic alternative architecturally are an interesting addition to the range of offerings for residential construction.

It is expected that the system will increasingly turn construction from the building site to the factory hall, and will increase the competitiveness of wood construction. PES reduces the time needed for construction on the building site and thus improves the profitability of wood construction. ”It must be remembered, however, that the introduction of the system will not reduce the number of jobs in the wood construction industry. It will just move them from the building site to the factory," says Viljakainen. It will also ease the construction industry's labour shortage in growth centres, and create jobs for Finns outside growth centres, where the factories usually are.

Companies will more easily be able to develop their own solutions for wood construction based on the RunkoPES system, when the same standard quality criteria are applicable to both the design and construction of buildings. The greatest level of expectation in the introduction of the PES system is targeted at the construction of multi-storey wooden buildings and at the repair and refurbishment of old concrete apartment blocks. Suppliers of wooden components are also expected to become more active in developing their product expertise.

In future, some of the PES system quality criteria will also cover the environmental impact of building materials and construction. ”PES also takes into account the energy-efficiency requirements applicable to the construction industry, some of which will already come into force this year,” says Karjalainen. According to RunkoPES, prefabricated joints must comply with all technical requirements in relation to load rating, air-tightness, sound insulation, fire safety and moisture. This will make the design of multi-storey wooden buildings much easier as well as their practical erection on the building site, says Karjalainen.


Puuinfo article service/Markku Laukkanen

More information:

Puuinfo. Managing Director, Mikko Viljakainen, tel: {0>040 526 6413,mikko.viljakainen@rakennusteollisuus.fi<}0{>040 526 6413,mikko.viljakainen@rakennusteollisuus.fi

Ministry of Employment and the Economy, Wood Construction Programme Development Manager, Markku Karjalainen,040 5832127,markku.karjalainen@tem.fi

Finnish Wood Research, Managing Director, Kimmo Järvinen, 040 7206311, kimmo.jarvinen@fwr.fi

Material about the RunkoPES system can be obtained with a training pack from Finnish Wood Research Oy (www.fwr.fi)