Building on existing buildings instead of demolishing and building new saves large amounts of resources and energy. It enables densification, extended service life and circular construction with a lower climate impact. The need for exploitation on unexploited\u00a0land is reduced at the same time as existing communications and infrastructure can be used. Timber on Top is a research project with the aim of increasing knowledge about extensions and extensions with bio-based materials and prefabricated building systems. A good example is the extension of the old industrial property Trik\u00e5fabriken in Stockholm, which has been transformed into a modern and sustainable office building.<\/p>\n