In the case of this house renovation project, we were involved from the Development Application stage, and the interior architecture was integral to the overall function of the space, and how it connected to the attached rear deck.
As the design of internal and external areas was essentially ‘in the mind of one’ the exterior and interior approaches could be integrated. This allowed the joinery to provide not only a functional benefit, but it created a strong material reference between indoor and outdoor.
In summary, if your project does not involve structural changes internally and does not directly link to external areas, then separating the consultants may work. If you are looking for a fully integrated architectural result we would suggest letting one designer with the relevant skills manage the design project complete.
Our recently completed project here on the northern beaches at Curl Curl confirmed the importance of having the same designer manage the interior fitout as well as the broader architecture. As a result, this residential project demonstrated a more integrated and complete design solution.
We have worked on projects previously where clients have preferred to use an interior designer to manage interior fitout separate to the architectural consultancy. This system can work well in our experience if the consultants are aligned in their thinking, and if the architectural intent does not rely on seamless integration of ideas.