What Affects Interior Design Costs

Asking what interior design costs is a bit like asking what a house costs. It depends on how much of the house is involved, how detailed the drawings need to be and how many decisions are still open. This guide covers the factors that shape a design fee and the fee structures commonly used in the industry, so you can scope your project with confidence.

Reference photograph: samples and drawings, where most of the design hours go.

What moves the fee

A design fee mostly reflects time: time spent listening, drawing, sourcing and coordinating. These six factors decide how much of it a project needs.

Scope

Advice on paint and furniture takes far less time than a full renovation with walls moving. A renovation or new build involves more decisions, more trades and more meetings.

Number of rooms

Every room has its own layout, lighting and selections. Kitchens and bathrooms take the most time because services, cabinetry and waterproofing all have to be coordinated.

Documentation level

A concept board is quick. A builder-ready set of elevations, schedules and specifications takes much longer to prepare. See Design Documentation for what a full set can include.

Selections

Tiles, tapware, stone, paint and flooring all need sourcing, sampling and sign-off. The more that is still open, the more hours go into colour and material selection.

Joinery

Custom joinery needs detailed drawings and has to be checked against appliances, hardware and the cabinetmaker’s shop drawings.

Furniture

Picking a few key pieces is a small job. Fully furnishing a home through a furniture package adds sourcing, ordering and styling time.

How designers commonly charge

Across the industry, fees tend to follow one of four structures, and some projects combine two of them. None of them is automatically cheaper. What matters is how well the structure fits the scope.

Hourly

You pay for time as it is spent. This works well for advice, colour consultations and smaller jobs where the scope is still open.

ii.

Fixed fee by stage

Each stage, from concept through documentation, is priced upfront against an agreed scope. It suits clearly defined renovations and new builds.

iii.

Per room

Each space is priced on its own, which makes it easy to start with one room and add more later.

iv.

Percentage of project

The fee is tied to construction or furnishing costs. It is sometimes used for large, full-service projects where the designer’s involvement grows with the build.

Reference photograph: joinery, stone and lighting chosen together cost less to change on paper than on site.

Where the budget works harder

The costliest changes usually happen on site. Moving a power point after the plasterboard is up, or re-ordering stone that doesn’t match the cabinetry, costs far more than the design time it would have taken to get right first.

Settle the layout before you choose finishes. Document the rooms where trades meet, especially the kitchen and ensuite. If you need to stage the work, start with the rooms that are hardest to change later. Our kitchen design guide shows how layout, joinery and surfaces depend on each other.

Before the first conversation

A clear brief is the quickest way to an accurate fee proposal. Have these ready:

— Which rooms are involved, and which one comes first
— Whether walls, plumbing or electrical will move
— Existing plans, or where the builder is up to
— Selections already made and pieces you are keeping
— A working budget range and your preferred timing

To see how each stage builds on the one before, read Our Interior Design Process. For general questions, contact the studio.