We were appointed post-planning to deliver the Paragraph 79 House project to high sustainable standards and against stringent planning conditions. The strikingly rugged design is dominated by a stone facade that seamlessly wraps over the whole building - combining the wall and roof, with relatively large areas of glazing and deep, chamfered reveals. These elements combined to pose significant technical challenges, not least in the context of Passivhaus and the fact the super-structure was a lightweight timber frame! However, with the help of a dedicated team, leading a series of design workshops and collaboration with many specialists, we were able to successfully overcome the many technical issues. So specific were the design parameters of this project, that we produced 3D sequencing details to convey how the building would be constructed, ensuring both the stringent environmental and aesthetic needs could be met by the construction process. In addition, details were modelled and thermal bridge calculations undertaken to test their performance. ?The modest challenge of designing a stone facade and roof connected to a lightweight timber frame involved dialogue with stone-masons, engineers, facade specialists and rain-screen cladding experts. The result - a design that features a self-supporting stone facade and rain-screen stone roof: elegant, waterproof, breathable, thermally superior to many buildings and most importantly, exceeding the brief!