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Mass timber frame construction

Wood is of course a renewable material that has existed in nature for millions of years, and remains one of the most sustainable, yet underused options for construction. With excellent insulation properties and a soothing effect on human wellbeing, perhaps it is time for wood to reclaim its position as a material of choice for sustainable structures?

Sweco is co-creating solutions which will transform society together with our clients. Our innovative timber projects demonstrate how sustainable construction is – quite literally – reaching new heights. Below, we explore how our teams across the UK and Europe are pushing the boundaries of modular design and Modern Methods of Construction with new manufacturing and construction processes.

Sweco’s Nordic engineers are pioneers in structural timber, and all our UK building teams benefit from the shared experiences in timber projects already completed, including high-rise buildings, with a particular focus on structural engineering, fire engineering, acoustics, sustainability, wellness and construction.

Mauro Bono Sweco UK Technical Director and timber specialist

Timber structures: A forest of possibilities

With a focus on sustainability, increasing urbanisation, and growing pressure on land and space, timber has become a building material that suits many developments. New innovations also make the material increasingly efficient and cost-effective. However, the key to success in timber projects, from start to finish, lies in expertise and design experience. Tor Øistein Andresen, Head of Sweco Norway’s timber team explains:

“To create sustainable cities and communities in the future, we need to invest in wood as a key building material – which is in fact a stronger material than both concrete and steel relative to its own weight. Moreover, it is easy to shape and cut. Modern production techniques make it efficient to manufacture and prefabricate. Wood is also readily available and can be more easily sourced than alternatives.”

Traditionally, wood has been used mainly in smaller buildings such as agricultural structures, single-family homes, and low-rise buildings. However, with new regulations and the development of glued laminated timber (glulam), cross-laminated timber (CLT) and connections, it has become more interesting to build high-rise buildings with wood.

“In countries like Denmark, the Netherlands, and Belgium, there will be significant construction developments in the coming years, and authorities are demanding sustainable buildings. In the Netherlands, for example, there are plans to build one million new sustainable homes over the next ten years. Building with wood is a prerequisite for realising this goal.”

However, building with wood is not only renewable and environmentally friendly. In addition to growing naturally in the forest, having a low weight, being malleable, efficient to manufacture, and contributing to shorter construction and assembly times, wood also has a positive impact on indoor climate.

“It is advantageous to use wood in all types of buildings and heated areas where the design allows it. For example, we have had good experiences with using wood in school buildings and kindergartens. While we still rely on steel and concrete for foundations, wood is well-suited for the structural system, walls, and floors – and last but not least, wood offers both aesthetic appeal and a contemporary look.”

City centre Fire Station

Client: Woodcon AS
Architect: Gottlieb Paludan Architects A/S
Developer: Omsorgsbygg, Oslo KF
Contractor: WK Entreprenør
Sweco’s role: Building technology, Electrical engineering, Ventilation, and Plumbing
Area: 2600 m2

The City Centre Fire Station is a two-story state-of-the-art fire station. The lower level features materials with a charred surface, while the upper level boasts a golden wood finish. Abundant natural light floods the interior through large windows, seamlessly connecting the firefighters with their surroundings.

The building’s structural system is composed of solid wood elements for walls and floors, glued laminated timber beams and columns, as well as steel beams. The closely spaced timber forms an eye-catching coffered ceiling.

Sweco has designed and optimised the structural system and engineered the connections. Not only does the modern and minimalist design of the fire station exude aesthetic appeal, but it also prioritises the safety and comfort of the firefighters.

The building seamlessly integrates with a series of innovative and sustainable timber structures that preserve and enhance the surrounding environment. Moreover, the rooftop garden promotes ecological diversity through the use of local plant species and habitats for pollinating insects.

The station has obtained BREEAM-NOR Excellent environmental certification.

A rise in confidence

Sweco’s Nordic engineers are pioneers in structural timber, and it’s that leading edge expertise which allows our UK building teams to benefit from shared experiences in timber projects already completed, including high-rise buildings, with a particular focus on structural engineering, fire engineering, acoustics, sustainability, wellness and construction.

While, in the aftermath of the Grenfell Tower disaster, the use of timber in buildings has considerably declined, there is a general consensus that timber will again play a fundamental role within the next five years.

Mauro Bono, Sweco UK Technical Director and timber specialist elaborates:

“Net zero carbon targets, particularly in London, cannot be met without promoting the use of timber in construction. In addition, timber buildings offer a more welcoming environment to the users and investors start to appreciate the added value of timber in the user experience of their buildings.

The Construction Industry is preparing guidelines to facilitate the approval process and reduce the design/financial risks. And very soon higher market value, reduction in carbon offset cost, de-risking the design and construction process, will eliminate the current cost-premium for timber buildings. Timber and modular construction can therefore be combined to provide sustainable and engineered modular system in development comprising hotels and student accommodations.”

Read Mauro’s blog on meeting mass timber insurance challenges here.

Stora Enso is proud to co-operate with Sweco to having developed this mixed-use timber building concept. We clearly see the potential this encompasses to the construction industry, and we are happy to use the learnings from our new headquarters in maritime Helsinki where both companies have cooperated already to condense it into this all-new mixed use concept so it can be further used for many more projects around the world”

Sebastian Hernandez Stora Enzo

Timber buildings as a circular economy enabler

After two world records and nearly twenty years in the industry, Magne Bjertnæs is one of Sweco’s foremost experts in timber.

Magne enjoys working with wood because it is both renewable and malleable.

“Wood grows naturally in the forest, you can harvest it, replant, and harvest again. As long as we look after the forests, wood is one of the most eco-friendly materials we have. Moreover, wood products and building systems are industrially produced in fully automated manufacturing facilities. This allows for standardisation to a large extent but also enables variation and customization in terms of form and function.”

Magne was involved in the design of ”The Three” in Bergen, Norway – named the world’s tallest in 2015. Three years later, he broke his own record when he played a key role in the design of Mjøstårnet in Brumunddal. After groundbreaking work and many years in the industry, Magne has a unique understanding of what different suppliers can deliver.

“The advantage of working closely with suppliers is that you know what possibilities exist. It makes it easier to choose the right solutions early on, which leads to fewer changes in the detailed phase.

The challenge lies in adapting the solutions in each project to meet the specific customer’s requirements.

“Each project is unique, which is somewhat special in our industry. It is also what makes the job so exciting. It becomes experience-based. When you have worked with a customer or a supplier before, you understand what the customer wants and know what the supplier can deliver. That experience is valuable to bring into other preliminary projects and concept phases.”

Magne is experienced enough to think creatively and inter-disciplinary. Collaboration across disciplines is something he enjoys the most.

“The most exciting aspect of working on timber projects is bringing people together to work well, not only within Sweco but also with suppliers and clients. Achieving good collaboration and solving tasks together—simply doing cool things in wood, with the right people, at the right time – that’s what makes my job so meaningful.”



Client: HENT AS
Architect: Voll Arkitekter
Developer: AB Invest AS
Contractor: HENT AS
Sweco’s role: Building technology, Building physics, Acoustics, Fire design, and Project management.
Area: 16.500 m2

Mjøstårnet, situated alongside Lake Mjøsa in Brumunddal, is an impressive multipurpose building spanning 18 floors and covering 16,500m2. It encompasses apartments, offices, a hotel, a restaurant, and an indoor swimming pool. Completed in 2019, this project set a new standard for designing and constructing tall timber structures, emphasising the utilisation of local resources, suppliers, and sustainable materials. Today, it stands as an important landmark in the local community, symbolising the construction industry’s transition toward greener practices.

The structural framework of Mjøstårnet relies on glulam columns, beams, slabs, and diagonals, while the elevator and stair shafts are constructed using solid wood. This choice of materials not only reduces the building’s environmental impact, but also creates a pleasant indoor climate and comfortable living environment. The timber facade seamlessly integrates Mjøstårnet with the surrounding forests, enhancing its visual appeal.

Sweco’s engineers have made innovative contributions to the fire safety solutions in the building. In addition to effectively withstanding fire scenarios, the floors and rooms are designed as individual fire compartments to prevent the spread of fire. The building’s rounded pergola is specifically designed to reduce wind resistance. Mjøstårnet is not only a striking, safe, and functional structure, but also serves as a model for constructing a more sustainable future.

Green-conscious construction

The numbers speak for themselves – building with wood is environmentally friendly. Energy and environmental advisor Kari Ekker has several calculations to support this.

“To determine the carbon footprint of a building, you need to consider its entire lifecycle. Even though the calculations can be complex, there is no doubt that wood has a lower carbon footprint compared to materials like steel and concrete. It’s important to look at the bigger picture. The building should be beneficial for both humans and the environment.”

There are numerous environmental advantages to using wood. Experience shows that the construction of timber buildings results in less dust compared to cast-in-place concrete. Other benefits include reduced waste on the construction site, meaning less cutting and waste when the elements arrive ready-made from the factory. Where possible, locally sourced wood can also be used.

Another compelling reason to use wood is its contribution to improved indoor environment and air quality. If we use untreated wood, it will be healthier for the indoor climate compared to, for example, painted or lacquered surfaces. Sweco’s extensive network of architects and engineers across Norway enables us to assemble teams that are diverse and innovative. This diversity in disciplines and experiences allows us to think creatively and explore unconventional solutions.

“As an energy advisor, it is inspiring to be part of a process that considers both the outdoor and indoor climate, from the initial concept to the final construction stage.”

Kari thinks it’s great that wood is gaining popularity again, especially because she is part of a solid and interdisciplinary professional community.

We see a significant interest in building with wood and an increasing number of new solutions and types of buildings that can be constructed with wood. New suppliers are emerging, and we’re gaining more experience. The interest is largely driven by a desire to build sustainably, including meeting the requirements of the EU taxonomy.

Biri kindergarden and elementary school

Client: Straye Trebygg AS
Architect: Kontur Arkitekter AS
Developer: Gjøvik Municipality
Contractor: Backe Oppland AS
Sweco’s role: Design of timber structures
Area: 2220 m2 (kindergarden) + 6150 m2 (elementary school)

Located in Gjøvik municipality, Biri kindergarten and elementary school consists of two modern timber buildings designed to nurture the well-being of children and adults alike. Both the indoor and outdoor spaces are thoughtfully designed to inspire development and creativity.

The load-bearing structures are constructed using solid wood and glued laminated timber. The curved shape of the kindergarten building presents more complex structural systems compared to traditional timber constructions. The two-story school building incorporates multiple connection points in the construction to ensure optimal stability. Through close collaboration with the architect, Sweco has contributed to the creation of two beautiful buildings that leverage the stable and flexible properties of timber materials, showcasing the visual appeal of timber structures.

Interdisciplinary timber design problem-solving

Building with wood requires the alignment of various crucial factors. Geir Glasø, an expert in timber structures, could not have achieved success without his extensive experience and the support of his colleagues.

Geir is a specialist in timber construction with 14 years of experience from the Norwegian Institute of Wood Technology. Since joining Sweco in 2018, Sweco’s expertise in timber has grown significantly, aiming to be the best in the industry.

Designing a timber building involves unique considerations and conditions that differ from those of steel and concrete structures. Timber as a material has its own characteristics, and there is a significant difference in the properties of different types of timber. Designing with timber therefore requires specialist knowledge combined with solid experience.

“The detailing in timber projects can be resource-intensive, which is why we continuously work on developing good and robust solutions that can be reused.”

When building with timber, we need to work according to the characteristics of the material. Structural considerations and requirements for fire safety, acoustics, and technical installations can sometimes be conflicting. Therefore, we need to work interdisciplinary from the beginning to achieve a robust, efficient, and sustainable building.

“It is precisely these interdisciplinary challenges that make working with timber construction so exciting, and my curiosity about how we can use timber in new ways keeps me motivated every day.”

Parallel to solving timber challenges, Geir and his colleagues document their experiences.

“The result is a knowledge bank that all our consultants can easily access for new timber projects globally. Additionally, we usually pair seniors with juniors to ensure knowledge sharing and further development of expertise.”


The timber houses at Løkenåsen

Client: Boligpartner AS
Architect: TAG Architects
Developer: Boligpartner Prosjekter AS
Contractor: Boligpartner Prosjekter AS
Sweco’s role: Timber and concrete structures, acoustics, building physics, fire engineering, roads, and BIM
Area: 34 apartments ranging from 37 to 116 (128.6) m2

The timber houses at Løkenåsen are modern, sustainable, and innovative residential buildings constructed entirely of wood. The project is an award-winning apartment building, praised for its consistent architectural qualities and high environmental ambitions. The buildings have a structural system based on timber frame elements and glued laminated timber.

The distinctive facade division in vertical and horizontal directions consists of geometric solid wood columns that define the entire front of the building. The result is an honest construction; not just a timber facade, but a timber building throughout where both the materials and the structure are showcased.

Sweco has been responsible for the design of timber and concrete structures, acoustics, building physics, fire engineering, roads, and BIM, as well as the development of the project’s carbon footprint calculation. Building with timber was the main premise of the project, with the aim of combining conventional timber construction with modern and innovative solutions.

The timber houses won the award for ”Timber Building of the Year” at the Building Days 2022, among other reasons, because ”the industrialised, timber-based housing concept can be adapted to various development situations.” Today, they stand proudly as representatives of how the unique properties of wood as a building material can be combined with modern construction technology to create sustainable, cost-effective, and beautiful timber structures.


The trinity of acoustics

Sound propagates more easily in timber structures than in heavier materials. However, it does not mean that all timber buildings have poor acoustics. According to acoustician Alain Bradette, proper design is the key to success.

The main challenge with acoustics and timber is that, despite its large dimensions, wood is a lightweight material. Compared to concrete, we cannot simply consider direct sound transmission through a wall; we must think about all the paths through which sound can propagate. This requires different design methods.

“In a typical construction, you can address sound insulation by designing in 2D, but in timber projects, we have to constantly design in 3D. It is more complex and technically challenging, but also more exciting.”

“To find good solutions, acoustics should be included early in the process. Acoustics is a specialised field that intersects with many other disciplines, and the solutions interact with each other. I believe we should combine multiple functions in a single approach.

This requires close collaboration between acoustics, fire safety, and structural engineering — I call it the ”trinity.” At Sweco, we have a strong expertise in mass timber, both technically and in terms of collaboration, and that is crucial for success.”

With strong teams, it becomes easier to design efficiently, which is essential in a changing market.

“The trend is that clients want to invest less in the design phase, which means we have to reduce the number of alternatives. Previously, we would consider up to five alternatives, but now we evaluate a maximum of two. We can do this thanks to our accumulated experience. It doesn’t mean we are simply copying what we’ve done before; it means we immediately know which alternatives to develop further. You could call it efficient tailoring.”

The high competence within the teams is the result of working on various projects over a long period.

“We can’t pre-calculate everything; we have to calculate and then test a solution. Little by little, we gain experience that we carry forward, enabling us to efficiently tackle new ambitious timber buildings.”




Valle Wood

Client: NCC Constructions AS
Architect: Lund + Slatto Architects
Developer: NCC Property Development
Contractor: NCC Building Norway
Sweco’s role: Fire and acoustics
Area: 6,700 m2

With its seven floors and over six thousand square meters, Valle Wood is one of Norway’s largest mass timber office buildings. The building is located in the heart of the business area at Helsfyr, northeast of Oslo city center, and offers modern and sustainable office spaces for companies of all sizes. It is the first part of the new office complex, Valle. When completed, the complex will consist of sixty thousand square meters of office and commercial space.

Valle Wood aims to be an outward-facing public building, with shared facilities accessible to all the surrounding office buildings. Both the  exterior and interior have a distinctive aesthetic expression, with facades inspired by wood fibres and tree rings that appear in varying density depending on sunlight and views. The modern design focuses on utilising natural light, which, combined with mass timber, creates a warm and inviting atmosphere.

Sweco has developed and designed the fire concept and acoustic solutions for Valle Wood. Both designs have been developed in collaboration with the client and architect, based on knowledge and experience from the work with Mjøstårnet.

In Valle Wood, Sweco have taken the development a step further in terms of visible wood by showing part of the floors in addition to the glued laminated timber structures like in Mjøstårnet. Using mass timber is a sustainable way of construction. The material reduces emissions, allows for faster construction, and is more environmentally friendly in operation. Wood as a material also provides stable indoor temperatures and good air quality.

Valle Wood is certified as BREEAM Excellent.


World-class fire safety

The perception that ’wooden buildings burn easily and quickly’ is widespread, but it is not necessarily true. Fire consultant Leif Tore Isaksen provides insights on preventing high-rise buildings from catching fire.

Wood will never become self-extinguishing, and not all types of buildings can be constructed solely with wood. Despite this, wood has certain properties that make it well-suited as a building material, even in larger structures.

“Wood has a controlled charring, and we can easily calculate how long a construction will withstand a fire. Additionally, in the event of fire damage, it is visible on a timber structure, whereas a steel and concrete structure may suddenly collapse. In that sense, wood can be considered more predictable in certain contexts.”

Leif Tore is a fire consultant at Sweco and was the project manager for Mjøstårnet – the world’s tallest wooden building, which not only opened doors in Norway but also caught the attention of the global timber construction industry.

Sweco has developed world-leading expertise in the design of timber structures and has also developed methods to demonstrate compliance with fire safety regulations in Norway.

Designing larger timber buildings is complex. Regulations require the structural system to be dimensioned to withstand a complete fire sequence, which necessitates a conservative approach and stringent fire safety requirements during the design phase.

“When constructing Mjøstårnet, we developed new methods for calculating fire progression and charring. This formed the basis for determining the necessary protection of combustible structures. The calculations are based on tests conducted at SINTEF’s fire laboratory and consider factors such as the cooling phase and the increased fire energy associated with the use of combustible construction materials.”

The work methods developed for Mjøstårnet have been further refined and improved through the design of various timber buildings, contributing to the advancement of expertise in this field.

At Sweco, we are actively enhancing our expertise in this area. Every day, we develop new solutions and methods that enable us to build more efficiently and ambitiously with wood.




Unlocking the contemporary, through compliance

Sweco has been at the centre of some of the most technically challenging projects that incorporate Modern Methods of Construction, and we have industry leading experience with Mass Timber/Hybrid use in sustainable office development.

As Head of Sweco UK Building Control Dale Anderson expands:

“Sweco Building Control is at the forefront of change, leveraging our extensive European expertise to regulate large-scale office developments in London and the UK.

By embracing mass timber and hybrid CLT-framed construction, we guide clients through a performance-based compliance route, ensuring safety without compromising innovation.

Our rigorous checking and evidence-based approach ensures adherence to building regulations, exemplifying our commitment to sustainable development and client success. For us, it’s all about fostering trust in the regulation of safe, compliant, and cutting-edge building solutions.”