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Timber on Top – circular biobased construction

The aim of the Timber on Top project is research within densification and extended life for flexible use of existing buildings using extensions (vertical/horizontal) with reusable bio-based prefabricated building systems.

Aim and objectivs

The main goal of the project is to facilitate the process of vertical extensions with light bio-based systems by:

• Develop, test and analyze process models, business models and technical solutions that take into account the three criteria, social sustainability, economical sustainability and ecological sustainability, for different types of actors involved in extension projects with bio-based systems

• Contribute to increased knowledge of the extension process of participating actors

• Contribute to new and expanded collaboration between participating actors

• Gather and document Best Practice in a guide to disseminate results and knowledge to other players.

Expected effects and results

The entire project is expected to lead to increased collaboration and understanding between actors involved in extension projects such as municipalities, property owners, architects, designers, contractors and building system suppliers. Through active participation in several construction projects, the project will improve collaboration between the participating parties and provide a basis for a Best Practice Guide that will facilitate other similar projects.


The project is organized into ten work packages distributed along all stages of the construction value chain; planning, program, design, construction and management. The work packages also deal in various ways with sustainability aspects in the form of social, ecological and economic sustainability.

The social sustainability aspect is mainly highlighted in work packages linked to the planning and program, where various methods of creating process support around the detailed plan and building permit process, valuation and management of cultural values, citizen dialogue but also in questions about architecture are studied. The issues surrounding architecture are mainly studied by Luleå University of Technology while RISE handles the other parts.

The ecological (technical) sustainability is mainly linked to program, planning and construction. Here, there are special issues linked to BIM for existing building including an extension, where Luleå University of Technology runs the work on the development of digital twins. RISE will mainly concentrate on generic solutions for the installation layer between the existing and the new building and process support for LCA calculations in vertical extension projects.

Economic sustainability is linked to all stages of the construction value chain, where the issue of risk to various players is particularly important. Linköping University will study business models, cost models and what points are important in collaboration agreements for this type of business with circularity in focus.


Project name

Timber on Top



RISE role in project

Part (and formal coordinator)

Project start



Total budget



Skogsindustrierna, Trästad Sverige, Linköpings universitet, Luleå tekniska universitet + 30 företag



Project website


Project members

Supports the UN sustainability goals

9. Industry, innovation and infrastructure
11. Sustainable cities and communities
Marie Johansson

Contact person

Marie Johansson

Senior forskare

+46 10 516 62 51

Read more about Marie