The year is 2016 and Sala municipality is planning its first major school project in 50 years. The choice of structural frame material remains open. The municipality is interested in new and sustainable building methods. When Byggpartner is contracted to construct Vallaskolan, the project takes on a clear sustainability focus, with the ambition to build the school in mass timber.
A first step into wooden construction
“In close dialogue with Sala municipality, we chose to invest in timber as the structural frame material, and Vallaskolan became both our and the municipality's first timber school building. Sala is a smaller municipality with short decision-making chains. That helped drive the process forward in a smooth and constructive way,” says Anna Kovacs, Head of Architecture Västerås, at Archus.
Vallaskolan was completed in 2020, and for Archus the project became a school in a double sense: a successful school project and the starting gun for their journey in building with mass timber. And even though it was a test bed, the work ran smoothly. All parties were involved from the start, which enabled them to find solutions that were both economically viable and environmentally sustainable.
That experience laid the foundation for the expertise Archus has continued to build on since then. Through several timber school projects, they have refined their processes and found efficient solutions that combine economy and sustainability.
“There are certainly challenges in building with timber, but as we have evolved, so has the industry. As knowledge grows, the difficulties ease,” says Anna Kovacs.
Acoustics – one of the biggest challenges
One of the major challenges in Archus's school projects was acoustics, which is particularly important in school environments. Timber is lighter than concrete, meaning sound travels more easily through the structural frame. Examples include impact sound and structure-borne sound. Solving the problem requires building up the construction and supplementing the frame to interrupt the sound path. This is particularly important in sensitive rooms, such as woodwork rooms and music rooms. But views on how acoustic challenges should be addressed can vary between different acousticians and projects.
“A solution that works well in one project doesn't necessarily fit in another. But as more buildings are constructed in timber, knowledge spreads, and acousticians are becoming increasingly experienced in working with timber frames,” says Margareta Löfgren, architect at Archus in Västerås.
Since acoustics can sometimes be a cost driver, it is important to engage consultants with experience in timber. Incorrect or over-specified measures can easily become costly, Margareta Löfgren points out.
“One positive aspect of acoustics is that exposed mass timber walls have a beneficial effect on room acoustics regarding airborne sound. Timber absorbs and diffuses sound waves in a pleasant way, which reduces the need for wall absorbers.”
Fire protection and regulations in development
The development of fire protection has also taken major strides forward. Issues that previously caused uncertainty have now been replaced by well-proven solutions and a growing knowledge base.
One approach is to install sprinkler systems, which enables both exposed timber surfaces and shorter escape routes. Without sprinklers, more emergency exit doors are required and the timber surfaces need to be clad in plasterboard. That was the approach Arboga municipality took at Gäddgårdsskolan, to reduce investment costs and future maintenance of a sprinkler system.
“In the ten years since we built our first timber school, knowledge among our industry colleagues has increased markedly, and technology has developed at a rapid pace. Today there are both more suppliers and more consultants with deep experience of timber,” says Anna Kovacs.
Another recurring challenge has been the interpretation of local plans. Since timber often requires somewhat deeper floor slabs than concrete, the building can end up taller than what the plan specifies. At Kvarngärdesskolan in Uppsala, Archus has been able to influence the building height during the review period.
“It is becoming increasingly common for municipalities to allow for timber already in local plans. With greater awareness and dialogue, more opportunities are created to realise timber buildings,” says Anna Kovacs.
Collaboration and a maturing approach to wood
All of Archus's timber schools have been built as partnering contracts, where architects, structural engineers, contractors and consultants sit down at the same table from the very beginning.
“That is really a prerequisite for being innovative. If all disciplines are involved early and share their previous experience, the risk of costly detours further down the line is reduced,” says Anna Kovacs.
In parallel with the industry's growing knowledge of timber construction, municipalities' expertise in the field has also developed. Archus's first mass timber school projects were often driven by enthusiasts – people within municipalities or building contractors who, with courage and curiosity, wanted to try something new to advance sustainable development.
But now Archus is seeing that change.
“Knowledge throughout the entire chain has increased enormously. There is a built-up experience bank that did not exist to the same extent when we started in 2016,” says Mikael Hassel, architect responsible for sustainability.
With each new school, both clients and contractors have become more experienced, and the sustainability requirements in procurements are being tightened more and more. The level can still vary between different municipalities, but development is progressing rapidly and the exchange of experience between municipalities is growing – something that benefits the whole industry and drives the transition towards more sustainable construction. The industry has simply caught up.
Perhaps Archus's greatest lesson has been how perceptions of timber have changed over the years. Previously, a timber building was automatically classed as sustainable. That is no longer the case, Mikael Hassel argues.
“You shouldn't simply build in as much timber as possible. It's about material efficiency, flexibility and having the right material in the right place. We increasingly advocate post-and-beam systems over solid load-bearing walls. That reduces material use and makes the building more adaptable over time. A school should be able to adapt to the pedagogy of the future, not be locked into today's floor plan,” he says. Margareta Löfgren adds:
“Exposed timber creates a calm environment. Research shows that natural materials can reduce stress and promote wellbeing. It becomes a positive side effect. We build for the climate and get a better learning environment into the bargain.”
Text: Mattias Boström Photo: Archus
