Norway´s first multi-storey student housing project built from Cross Laminated Timber (CLT), the Palisaden, was constructed in 2013. Three years on more than 80% of student housing in Norway is built from timber. When the extension to Moholt student village by MDH arkitekter is completed in December this year, it will be the largest use of CLT in Europe. Following the struggles of timber to infiltrate a conservative construction industry, why and how did this breakthrough occur and what can we learn from it?

The implementation of function-based building codes in the late 1990´s lifted national restrictions on the use of timber in Norway. In the ensuing years, a number of public and private initiatives sought to stimulate growth and innovation within the industry. Programmes such as Treprogrammet, Trebyen Trondheim and Norwegian Wood, gathered actors from across the building sector and supported projects including Svartlamoen by Brendeland & Kristoffersen (2005) and the Pulpit Mountain Lodge by Helen & Hard (2008). These projects brought international attention to the structural and architectural potentials of CLT, in addition to the increasing awareness of its environmental properties. Despite these initiatives, timber construction projects in Norway remained largely isolated and bespoke, and in 2010 the largest national producer of CLT, Moelven Massivtre, was forced to close due to a lack of demand.

The construction of Palisaden in Ås by BAS Architects, can be seen as the start of a timber breakthrough in the student housing sector, an industry previously dominated by conventional steel and concrete systems. Built in 2013, it was the first multi-storey student housing project in Norway to be constructed in CLT. By 2017, more than 4000 student residences will have been built using the same model of development and construction.

Student housing typology

An important factor in the ability for this breakthrough to occur is the nature of the student housing typology. The student welfare associations are both the clients and future managers of the student housing they commission. They accumulate a deep understanding of their residents´ needs and a long-term perspective on construction, use and maintenance. This gives them a better background for assessing and accepting risk than commercial developers. The temporary nature of student residency has facilitated a greater leniency in respect to building regulations, in particular accessibility and sound insulation, enabling an easier introduction for new timber solutions. A restricted financial model and need to align with academic semesters places a high priority on efficiency in time and cost, providing an incentive to find faster and cheaper construction methods. In addition, the cellular programme and repetitive structure of student housing fits the properties of CLT building systems. It is also worth noting the student associations´ connection to their educational institutions, which in the case of NMBU in Ås, is deeply engaged in environmental issues and timber research.

Knowledge creation

The timber programmes and initiatives of the early 2000´s, prepared the foundations for a breakthrough in CLT by accumulating material and technical knowledge within Norway and established connections to international producers. Key to the growth of CLT in student housing, was the ability of the various project management teams to pool this expertise and facilitate knowledge transfer between building contractors and CLT suppliers. Through an educational program with contractors and consultants, the projects raised the collective competencies and brought together actors with the necessary expertise to develop solutions that met building requirements.

Project management

Another key factor was the positioning of the project management teams between the client and the constructors. This enabled them to control the flow of information in the initial phases of the project where decisions are made about choice of materials. In order to counter the risk of uncertainty pricing from contractors, the management team of the Palisaden project priced the CLT solution directly with the suppliers prior to tender. Having proved itself to be competitive on both time and price, the system was quickly adopted by other student welfare associations in Haugesund, Tromsø and Trondheim. The choice to use CLT in the recently completed student housing at Hønefoss was the first of these projects to be initiated by the contractors.

Moholt 50|50, student housing built with cross-lamiated timber elements. MDH Arkitekter 2016

Moholt 50|50

The extension to the Moholt student village consists of five student-housing towers, a kindergarten and a library. When completed it will be the largest cubic meter use of wood in construction in Europe at 6300m3. As such, it signifies a key moment in the story of the timber breakthrough in student housing and provides an opportunity to stop and reflect on the use of timber and CLT in Norway today.

The project was won in a wildcard competition in early 2013 by MDH arkitekter (with Arne Henriksen), organized by SiT (Studentsamskipnaden in Trondheim). The competition brief had a vision to “create an attractive, exciting and robust student village”, that should be realized in a “rational and modest way.” Notes from the jury´s report gave special commendation to the winning proposal´s urban strategy, establishing a new identity for the student village and creating a central urban space framed by community activities.

There was no specific ambition to use wood when the original competition was published. The winning project was designed with a steel skeleton carrying columns and pre-fabricated concrete slabs providing a rational and cost-effective building solution. Brick cladding was originally proposed to the facade, taking inspiration from the existing surrounding buildings. The change to timber was initiated by I-Tre, the project managers from the earlier CLT student projects, who approached SiT, suggesting that CLT could present a competitive alternative. This tied in with SiT´s existing environmentally friendly and innovative development profile. Following this, the architects were challenged to adapt the design to facilitate the use of timber.

Arriving at the corner of Jonsvannsveien and Frode Rinnans veg on a crisp, sunny October morning, the nine-storey timber towers present a striking and bold new urban frontage to the student village. Elegantly clad in horizontal bands of vertical timber, the towers stand out amongst the surrounding three and four-storey brick clad buildings dispersed throughout the site. The towers were increased from eight to nine-storeys after the competition in order to increase the number of residences. Eight-storeys represents a threshold regarding fire safety, yet the length of the escape ladders in the Trondheim fire department facilitated going up an extra floor. Interestingly, the secondary external escape stair was not required by legislation but was installed at the request of SiT to give the inhabitants an increased feeling of safety.

The detailing of the timber cladding to the towers is particularly well considered, exposing a level of flatness and lack of attention seen in other timber-clad projects. In choosing not to correspond with the window openings, the horizontal bands create a well-articulated surface pattern to the façade that manages to free itself from the structural logic behind. The bands are formed from a slate-like layering of the vertical timber slats, which continues neatly around the corners and to just above the ground. The pattern is enhanced by the integrated solar blinds, which, when down, reveal different dominant colours for each tower and a subtle tonal variety thereafter. An additional fire treatment required to the lowest cladding band is unobtrusive and almost unnoticeable.

Described by MDH in an interview, the main concept of the masterplan was to make a small urban centre for Moholt, the biggest student village in Trondheim, and open it up to users from the wider community. The five towers frame a central area that will soon contain a small library, and open up on the south to a new kindergarten. Also designed by MDH and constructed in timber these will, when finished, modulate the urban character currently dominated by the towers. Public functions including a hairdresser, laundrette, doctors office and training studio, share the ground floor with student residences. However, these public facilities have little presence on the public realm and little visual or functional interaction between internal and external spaces. This appears to be a result of the mix of private and public functions at ground level combined with the wish for continuity of the façade design and limitations within the structural system.

The Y-shaped plan is a smart and unique solution, offering the observer a slender impression of the towers whilst cleverly concealing a larger footprint and avoiding long corridors. Exposed timber surfaces in the central staircase make this compact functional space more welcoming, with playful punctuations in the central wall. Student residences are grouped on each floor, with 15 private rooms and shared accommodation. The common kitchen and living room receive plentiful daylight and the exposed timber ceiling and partially exposed timber walls help the space feel less institutional. The exposed ceiling is made possible by the reduced requirements for sound insulation between the floors in the shared areas. In the private rooms the timber slab is covered with an acoustic ceiling for improved sound insulation. The rooms are compact and bright, with most having at least one exposed timber wall giving a warmer feeling and a greater freedom to pin up pictures and decorations.

Overall the project is a good addition to the student village and the greater area, and is clearly much appreciated and valued by the client and students. The young architectural practice has shown maturity and skill in mastering a new material in a rational way within a tight budget and programme. A visit to the kindergarten reveals a freedom and greater level of enjoyment in the use of CLT and variety of spaces it can create. The main criticism is in how the buildings meet the ground; where the public facilities feel closed off from the new urban space and the programme of shared facilities could have been explored further to create greater social opportunities.

Successes and limitations of the timber breakthrough

The success of the timber breakthrough in these student housing projects is in establishing CLT as a construction material that is able to compete with concrete and steel in regards to both time and cost. As the projects have evolved, they have facilitated further research into the development of technical solutions that meet with the building regulations. This has included fire and acoustic testing of full-scale built prototypes prior to construction at both Palisaden and Moholt. Post construction analyses of these structures has also improved knowledge and experience that can be brought to future projects.

By 2017, more than 4000 student housing units will bi constructed using CLT elements.

A criticism of these projects is their adaption of CLT to traditional construction models associated with concrete and steel. Evidenced at both Palisaden and Moholt, these housing projects adhere strongly to the system logic of slabs and shear walls, with loads transferred along continuous vertical lines. These systems do not explore the inherent properties of CLT, for example the cantilevering potential of the stacked CLT elements or the ability to form different shapes from the planar construction as recently shown in the Sørhauggata project by Helen&Hard. These projects bring into question whether the use of CLT benefits from, or reinforces, the institutional cell-like typology associated with student housing. The projects also question if it is enough to use timber construction as a rational and environmentally friendlier alternative to steel and concrete? Or should we be continually pushing the development of timber construction and its industrial processes, to reveal its own characteristics and give new qualities to our urban environments.

Masters studios as laboratories

Changes to the building codes in Norway, together with new timber solutions and technologies, have expanded the architectural potential of timber and facilitated its reinvention as an urban building material. With a growing awareness of the sustainable merit and urban potential of wood, educational institutions play an important role in advancing knowledge in its use as a modern construction material.

Between autumn 2013 and spring 2016, Professors Marius Nygaard and Børre Skodvin ran six master-level studios at the Oslo School of Architecture, exploring the technical and architectural potential of timber in an urban context. The studios were set up as laboratories for systematic architectural exploration within the Wood Be Better (WBB) research project. The research project was established in 2013, with the principal aim to “produce and publicise knowledge that will facilitate increased use of wood in buildings in urban areas.” Funded by the Norwegian Research Council´s BIONÆR programme, WBB is a large interdisciplinary project with the Oslo School of Architecture and Design (AHO) as the leading and coordinating partner, partnered with the Norwegian University of Life Sciences (NMBU) and the Norwegian Institute of Bio-economy Research (NIBIO). A number of international research partners, Norwegian architectural firms and forest owners are also associated with the project.

Sigurd Eide from the Norwegian Institute of Wood Technology supervises student Siri Idland at AHO.

Model from Siri Idlands thesis project “Above Oslo”, a timber high-rise. AHO 2016.

Five work packages were included in the original research proposal utilising the expertise from within the interdisciplinary team, including research into the structural properties of various timber structural systems and their connections, as well as research into the climate effects and service life of timber envelopes. Work package two was titled “design-based research” and proposed the use of masters level studio courses at AHO as laboratories.

The intention of the studios was produce a series of integrated designs that would explore the effects of wood application on the functional, technical and architectural quality of whole buildings and areas. This is not possible in ordinary research projects because it is too expensive or too slow. It also represents a type of architectural research that utilises the core competence of architects. This is to structure and transform large amounts of data and complex sets of requirements into integrated architectural solutions. As part of the research project the students had access to an interdisciplinary team of lecturers and individual tutoring at a level not usual in master studios.

The timber courses were organised as two masters studios. The autumn courses, led by Marius Nygaard, explored complex urban projects with a particular focus on the use of Cross-Laminated Timber (CLT) and had a strong structural and technical perspective. The spring courses, led by Børre Skodvin, were more experiential, oriented towards finding the different uses of wood and specific properties and integrating them into architecture in a deliberate way. In total, 75 students participated in these studios, creating 56 projects. In addition many students chose to continue the study of timber solutions into their diploma projects, acting as a welcome extension to the research project.

Interdisciplinary collaboration between masters’ students at AHO and NMBU. Step 1: Input from architect students Marte Guldvik, Ole Fredrik Kleivene and Gro Krüger. Principle solution for housing block: Main goals, building spans, apartment types. Step: 2 Analyzes carried out in the master's thesis by engineer student Ole Bjerk of NMBU, summarized in "rules of play" for cantilevered CLT that also carry roofs and covers. Step 3: Architectural students' Illustrations of architectural possibilities within the defined limits of cantilevered CLT. Attachment to Ole Bjerk's master thesis.

The studio projects tasks were located in typical urban development areas in Oslo and Akershus, ranging from two to eight storey buildings following a hypothesis that this would be the dominant typology in the future timber city. One set of projects explored the adaptable use of timber in an infil site, set within an existing urban context dominated by conventional construction materials. The students were tasked with considering the potential architectural language of timber construction and structures that could contain a mix of functions and adapt over time. Other courses explored the potential use of timber in low-rise high-density developments, a market interesting for its great potential in timber construction, yet somehow still dominated by concrete.

The ambition of both courses was to carry ideas from concept to detailed design and make drawings that resembled working drawings. The students considered the material properties of timber early in the design process and used this to help develop the architectural expression. Aided by the interdisciplinary consultants involved in the research project, the students were able to develop projects to a high level of detail. In this way, they could verify the potentials of new technologies and bring to light some interesting new areas of research.

Kindergarten as urban intervention. Model from thesis project by Truls Schiefloe Sandbak and Jonas Østhagen Hamar, AHO 2015.

The main contribution to research are the many and varied student projects exploring timber as a main building material in different urban scenarios in Oslo. Away from the economic and programmatic constraints of practice, students were free to explore architectural form and its technical resolution, and make a contribution to the development of timber architecture. The students´ positive feedback to the detailed and technical content of the studios supports both the importance of these types of courses within architectural schools and the real potential in student projects to test and develop innovative architectural solutions to complex problems. However, a lot of time was taken early in the semester to develop the students technical competence, which could be improved by having two courses in a row or including these types of courses earlier in architectural education.

An additional effect has been the embedding of knowledge and interest in timber as a building material to the next generation of architects. Described by Børre Skodvin as being “a kind of future yield, a little bit like in the forest. You plant the seed and you wait for a generation, and maybe you get a nice tree.”

Wood/Be/Better studio course, fall 2014

Student projects

Downtown Timber, Oslo. Three masters’ thesis projects, AHO 2015

Students: Marte Guldvik, Ole Fredrik Kleivene and Gro Krüger

Each project is an example of a typical urban programme: A new city block, an infill project and a roof extension. How to solve each of these challenges with the use of timber? Timber structures can be adapted to different programmes and situations, and can be easily altered over time as functions and requirements change.

Downtown timber: Urban block: Sørenga. Infill: Skippergata. Superstructure: Vika.

Courtyard block, Sørenga

Balconies activate the facade.

Two roof extensions in Vika, light timber superstructures.

Infill Nordre gate 20/22, Oslo, Oslo. AHO student project 2014

Students: Ingrid Engøy Henriksen and Katrine Hamre Sørlie

A faceted building volume around an inner courtyard, with roofs that rise to meet the surrounding buildings but open up to let light into the block. The open ground floor exposes the timber structure, with laminated posts and beams and cross-laminated timber floor slabs. Stairs and lift cores provide bracing. The volume is clad in heartwood pine.

A flexible timber building with high density. The facade is open at street level.

The top windows break the parapet line.

The roof shape lets light down into the back yard.

Window detail at the junction of roof and wall.

9 in timber. Suburban densification, Oslo. Student project, AHO 2015

Students: Eskil Frøyen Nybø

A row of houses is introduced into an existing suburb. Each has two main volumes that are shifted horizontally and vertically to adapt to the topography and provide sheltered outdoor spaces. The main structure consists of stacked cross-laminated timber elements supported at the intersection points. The elements are only half a storey high, which opens a wider variation of spaces and views in the interior.

The stacked timber elements combine to give great variation of spaces and levels.

Row houses introduced to densify an area of existing single-family houses.

The CLT elements are a half-storey high, stacked across with concrete cores providing the bracing.

Spydeberg Library, Østfold. Student project, AHO 2016

Students: Synnøve Solberg and Anna Willemark

The location of a library at the town centre square is typical in the deve-lopment of small towns. The project is organised around a bracing concrete core, and the rest of the structure is in timber, with bundles of columns supporting timber girders. The book-shelves are part of the structural system.

Axonometric of the structure.

Library, fasade towards the plaza and main street facade.

Structural model. Beams and columns cross, partitions are integrated in to the columns.

Library shelves are fixed directly into columns.

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