Interior Designer vs Architect: Who Does What on a Renovation or New Build?

An architect is primarily responsible for the building and its architectural resolution; an interior designer is primarily focused on how the internal environment functions, feels and is used. On substantial renovations and new builds, the strongest projects can involve both. On a completed apartment that only needs furnishing, you may need neither in a full-service capacity.

What does an architect typically own?

Depending on the engagement, architects can develop the building design, planning response, spatial organisation, envelope, approvals documentation and coordination with consultants. Their exact legal and professional role varies by jurisdiction and scope.

What does an interior designer typically own?

Interior designers can develop internal layouts, finishes, lighting concepts, joinery, furniture planning and the detailed experience of rooms. The Australian Bark overview of residential interior designers frames the role around both appearance and function.

When do you need both?

When architecture and interiors are changing together. Kitchen positions, window locations, ceiling details, joinery, services and furniture clearances can influence each other. Bringing the interior perspective in early can prevent the architecture from being 'finished' before the way you will actually live in it has been tested.

What if you already have a builder?

A builder can tell you what is practical to construct, but that is not automatically the same as owning the design brief. A 2026 r/AusRenovation thread asking whether to use a building designer, interior designer or floor-plan reviewer shows how often consumers reach this point after the builder is already lined up.

What if the project is only furniture and decoration?

Then full architectural services are generally not the relevant tool. If the apartment shell is resolved, the problem may simply be circulation, furniture scale, materials, sourcing and installation. See DORSA's guide to deciding between full design and a furniture plan once it publishes, or start with furnishing from a floorplan.

How should you vet the interior-design side?

Check experience, scope and professional signals. The DIA Accredited Designer framework considers qualifications, professional experience, conduct, continuing development and professional indemnity insurance.

Bottom line

Use an architect for architectural problems, an interior designer for internal design problems, and involve both when those problems overlap. If your only unresolved layer is furniture, choose a narrower furnishing service rather than buying an entire professional scope you do not need.