How much an interior design project costs and what it includes

“How much does the design project cost?” is almost always the first question — and the most awkward one: the price per square metre differs several times between studios, and it is not about greed on one side and generosity on the other. The same wording hides documents of very different depth, from beautiful images to a complete set a site team can build from without asking questions. Below: what makes up the price, what exactly you get for the money, and what to look at in the contract before paying the deposit.

How much a design project costs: what makes up the price

The price is calculated per square metre, and four things drive the final figure.

• The contents of the package. Visualisations, layout solutions and working drawings are three different volumes of work. A set you can build from always costs more than a set of pictures.
• Area and complexity. A small flat with a standard layout and a country house with split levels require different numbers of drawings.
• Type of property. A new-build without finishing, an older flat with a layout change and a commercial space are three different stories in terms of approvals and engineering.
• The studio's role during the works. Design supervision and procurement are separate services, and whether they are in the contract changes the price noticeably.

One thing is worth understanding: a low price per metre usually means a reduced scope, not a discount. The difference shows up not at signing but on site, when the team has questions the project does not answer.

What is included: three levels of scope

Concept design — layout, furniture arrangement, mood boards or visualisations. It answers the question “how will it look”, but not “how do we build it”. That is enough to decide on the concept and too little to budget the works.

Working documentation — the drawings the site team works from: survey plan, demolition and construction plans, wall elevations, electrical and plumbing schemes, ceiling and floor plans, junction details. This set determines whether the project runs to plan: every question left unanswered on paper becomes a foreman's decision on site, and therefore a rework or an extra payment.

Project with supervision — specifications for materials and furniture, help with procurement and design supervision are added to the documentation. Here the project stops being a folder and becomes a process: the studio is responsible for making the built result match the drawn one.

In international practice this split is formalised: the RIBA Plan of Work describes design as a sequence of stages, where each one builds on the approved previous stage. Mixing stages and expecting the price of a concept for a full working set is the main source of misunderstanding in negotiations.

Why identical projects cost differently

Two studios quote prices per metre that differ twofold, and both are honest — if you read the scope carefully. The difference usually hides in three places.

• The number of drawing sheets. Twenty sheets in one set, sixty in another. The second costs more, but you will not be calling the designer every day.
• Specifications. A project without specifications shifts material selection onto you or the foreman, and that directly affects the budget.
• Design supervision. Site visits, checking junctions, answering the team — this is paid time, and if it is not in the contract, it will not be there in real life.

That is why comparing offers by the figure per metre is meaningless. Compare the lists: what is included, how many visits, who is responsible for specifications and what happens when things change along the way.

What to check in the contract before paying

The price is only half the question. The other half is what you receive and by when.

• The scope as a list. Not “a design project”, but a list of drawings and documents with the volume stated.
• The number of revisions. How many iterations are included and what the next one costs.
• Deadlines by stage. Separately for the concept and for the documentation, with acceptance dates for each stage.
• Handover format. Printed set, files, source files — what exactly stays with you.
• Supervision terms. How many visits per month and what happens if the works run late.

The logic is the same as in the renovation contract: until the parties' duties are described point by point, any dispute is won by whoever is louder. A design project is an intellectual service, and its acceptance is just as staged as construction work.

How to tell whether the price is justified

A good test is to ask the studio three questions and listen to the answers.

First: what will the site team do if a question comes up that the drawings do not cover. A sensible answer is “they call us and we issue a solution”, not “they decide themselves”.

Second: does the project include selecting materials and furniture, and who calculates quantities. This determines whether you will be reconciling supplier quotes yourself.

Third: how are changes documented during the works. If there is no answer, changes will be agreed verbally and paid for after the fact.

A design project costs exactly as much as the uncertainty it removes. A set you can build from without daily approvals saves more during the works than the difference in design fees. The course “Home of Your Dreams” walks through the same sequence step by step, from concept to acceptance.