In my practice I spend about equal amounts of time working on interiors as exteriors. What I mean by that is that the ideas that we are working through on a project are usually not formal ones, but rather more narrative. So, neither interior or exterior form drives the project. A successful project is one where there is a dialogue between the two - sometimes reinforcing each other, other times a complimentary juxtaposition. Each component of the project adds to that, from the overall building form to the roof material through the interior finishes, light fixtures, etc.