Building up with
timber

Low carbon redevelopment and extension of existing buildings

Arent Janszoon Ernststraat 700, Amsterdam

Claris 89, Barcelona

Gramophone Works, London

Use the
Tool!

What is

Optoppen?

"Optoppen," a Dutch term translating as "topping up," refers to a construction method aimed at maximising the usable space in our cities through the addition of lightweight, low-carbon roof extensions.

Why

Optoppen?

Densifying urban neighborhoods through increased floor area provides a low embodied carbon solution that delivers new homes while funding retrofit and renovation efforts by reusing existing structures.

The

Optoppen

tool

A web based tool to assess the number of storeys and increased floor area that can be added onto your building.

Check Out

“Architects and engineers have long recognised that most of our existing buildings are structurally over-specified, capable of supporting additional load. Vertical extensions that use lightweight materials, such as industrialised timber, can add even more floorspace – and if they are bio-based, the carbon avoided, and the carbon locked away for the next 100 years of the building’s life, is a sell for organisations like ours, and for our tenants, who want to tread lightly.” - Frederic Schwass, General Projects

“By adding... floors to the building stock we already have, we’re able to densify our city in a sustainable way and provide much needed housing in our city, which in turn supports the local businesses, shops, venues and cultural sites.” - Lotte Terwel, Vice Mayor of Amsterdam Centrum

“For our cities to densify successfully, we need to focus on multi-home, rather than single-home buildings. Topping up is a key solution because it uses our current housing stock, infrastructure and facilities.” - Laetitia Nossek, Dutch Green Building Council