Built on the site of a former movie theatre between an existing tenement and a single family house, a sophisticated transition between height and front plane was required.
To address the change in scale from the four storey Victorian tenement to the right hand side of the site to the two and a half storey Georgian house to the left, the building is carefully integrated into the street by stepping the façade in both section and plan. A contextual approach also informs the selection of materials, with the main facade being predominantly red sandstone - used as a rain screen to reflect the nature of the building structure - and Reglit cast glass, which references the historical industry of Portobello and provides a durable and visually lightweight material. Upper level and rear facades are formed in dark grey zinc cladding to reference adjacent slate roofs.
The format of the building follows the traditional Scottish tenement model, with a central shared stair providing access to the flats and also to a shared garden on the roof.
A ‘shell and core’ approach to the build has been adopted, which has enabled individual owners to take on varying degrees of fit out in their own flats, thus further reducing build costs.
The scheme is designed to Passivhaus equivalent levels of energy use and uses a CLT for its embodied energy and low carbon credentials. High levels of insulation render a central heating system unnecessary and all remaining electricity is either generated via photovoltaic panels on site or procured from 100% renewable energy – the building is designed to be completely fossil fuel free.
The building is constructed from Cross-Laminated Timber made from radiata pine. The growth of timber for the frame absorbed 114 tonnes of carbon emissions – an average UK resident’s emissions for approximately 12 years. The basic structure was assembled by three joiners in nine days. The balconies are built using a laminated larch frame.
The superior strength and spanning capability of the CLT panels meant that, aside from the internal central stairwell, there was no need for internal load-bearing walls, allowing each family to design their own personalised layout with stud walls and different combinations of rooms. This clever design essentially future-proofed the flats, as the layout can be easily changed later. Each flat was finished to an empty shell to allow residents individual fit-out solutions.
In order to deliver the project, the future residents formed a 'Baugruppe' (building group), a form of cooperative very common in mainland Europe. In this model, the owners are the developers. One in ten new homes built in Berlin are procured this way; in the last five years hundreds of schemes have been built there providing thousands of new homes. The pioneering project in Bath Street, Portobello has shown that it can work just as well in the UK. Find more information about group custom build here.
Images: John Reiach
RIAS Awards 2018 Best Use of Timber (Wood for Good Award)
Edinburgh Architectural Association Wood Award 2018
JKA Blog - from planning to site start, proposals, setting up a communal self-build scheme