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Delivering new floorspace and creating mass timber carbon sinks on top of our cities.

Kelly Harrison


Optoppen, or topping up, increases the usable space in an existing building through lightweight timber roof extensions, supporting both urban decarbonisation targets and densification strategies.  With Europe’s cities facing housing crises, Optoppen is an alternative to demolishing a structure to build newer and bigger, saving existing embodied carbon while enlarging the building’s floorspace with a low-carbon material that itself stores carbon. 

Central to the project is the development of an interactive and dynamic website and assessment tool that allows asset owners and urban planners to quickly understand the potential for vertical extensions in their portfolios and cities, providing a high-level structural assessment and reporting the possible amount of floor space that could be created, and the amount of carbon stored in the mass timber. The online platform will focus on common building types in European cities, with a focus on the UK, the Netherlands and Spain, with estimates available at both building and city levels. 

The initiative also encompasses compiling an inventory of case studies along with an overview of current policies in the focus markets. Communications and outreach activities will take place in the UK, the Netherlands, and Spain, with events open to interested stakeholders from Built by Nature's networks and beyond: developers, investors and city officials.  


Read the press release: Built by Nature awards €211,000 to demonstrate potential of timber-based vertical building extensions in European cities 



Whitby Wood

We are Whitby Wood, a creative team of engineers, working with fantastic clients and visionary architects on imaginative ambitious schemes. We are an international engineering practice working on projects across the UK, Europe, India, the Middle East, south-east Asia, sub-Saharan Africa and the USA — operating from our collaboration hubs in London, Brighton, Bristol, Cambridge, Dubai, Mumbai and Belgrade. Our projects are local, regional and international, and our engineers are highly experienced in the British and international construction industries. We are independent, forward-thinking and we love a challenge.

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Institute for Advanced Architecture of Catalonia (IAAC)

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