Building a building within a building

The designs for twin barn farm had to negotiate the challenges of permitted development planning policy (part Q). The design team therefore had to convert the 80s steel framed shed with minimal impact on the external aesthetic.

The engineer’s appraisal suggested that the existing steel frame would require substantial bracing to avoid potential flex affecting the air-tightness and internal finishes of a newly converted dwelling. The team also concluded that the steel frame would present numerous cold-bridging issues, especially around the foundations so instead decided to build a building within a building. This has resulted in a timber framed building, which is insulated to Passive House standards yet still retains the agricultural aesthetic of the existing barn.


The inner and outer shells of this building never actually touch, leaving a 50mm void (minimum) at all times. A few of the details point towards these eccentricities: For example, a secondary gutter enters the hopper on the southern gable, unconventional, yet necessary for the twin roof. The reinstated cement roof includes voids for the Lamilux rooflights behind and cedar shutters sit on runners between the two skins to give the inhabitants privacy and manually controlled solar shading

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