The design emerges as a response to the nuances of the site. On one hand, there is a need for a relationship between the master suite addition and the non-descript existing house. On the other hand, there is a desire to engage the gracious backyard poised at the head of a dynamic canyon landscape and anchored by a large Brazilian pepper tree. The addition is characterized by the tensions that articulate it and allow it to form a coherent response to its surroundings. It is not simply attached to the rear of the existing house, but is “nested” into it and shaped by its form like a key fitting into a lock. The existing house is conventionally clad in stucco and penetrated by generic windows. The addition mimics this idea as an autonomously clad enclosure of raw steel punctured by apertures that manipulate light, air, external views and views to adjoining spaces. The addition is a bold mediator between the sublime existing house and its complex natural surroundings.