Selecting an Interior Designer for a London Renovation: How to Brief, Evaluate, and Work With the Right Person

The interior design appointment is made at a stage in most London renovations when the client is already committed to an architect, a contractor, and a significant financial exposure — and when the question of who will "do the interiors" feels like a secondary consideration compared to the structural and technical decisions already made. This ordering is wrong. Interior design decisions — the spatial layout of rooms, the position of joinery, the selection of stone and tile, the specification of lighting positions — interact directly with architectural and M&E design decisions. An interior designer appointed after the architect has finished their work and the contractor has started construction is working with constraints that could have been avoided.

The correct sequence: appoint the interior designer at or before RIBA Stage 2 (Concept Design), so that the interior design vision informs the architectural layout decisions and the M&E engineer designs services to positions that the interior designer specifies.

What an Interior Designer Actually Does

The scope of an interior designer varies widely — from a decorator who selects fabrics and furnishings for a completed shell, to a full interior architect who designs the spatial layout, specifies all materials and finishes, coordinates all specialist trades, and manages the interior design delivery from concept through to installation.

For a prime London renovation, the full-scope interior designer's role typically includes:

Spatial design: Designing the internal layout of rooms — the position of joinery, the arrangement of furniture, the location of openings. This overlaps with the architect's scope and must be coordinated; the best outcomes arise when architect and interior designer work together from early in the design process rather than sequentially.

Material and finish specification: Selecting and specifying every material, finish, and surface in the building — stone floors, wall tiles, paint colours and sheens, timber stains, metal finishes for hardware, upholstery fabrics, wallcoverings. Each specification is documented in a finish schedule that is issued to the contractor and subcontractors as a contractual reference.

Lighting design: Specifying the position, type, and control of every light fitting in the building — in coordination with the electrical engineer and lighting control system designer. The interior designer is responsible for the aesthetic outcome of the lighting; the electrical engineer is responsible for the technical delivery.

Bespoke joinery design: Designing and briefing all fitted joinery — kitchens, wardrobes, libraries, dressing rooms, window seats, media units. The interior designer produces drawings and specifications for the joinery maker; manages the design and approval process; and coordinates the installation with the construction programme.

Furniture and soft furnishings: Specifying and procuring all freestanding furniture, soft furnishings, curtains and blinds, rugs, and decorative objects. This procurement is typically managed through the designer's trade accounts — they have access to trade pricing and trade-only product ranges not available to the public.

Site coordination: Attending site regularly (typically weekly or fortnightly) to review the delivery of the interior design specification — checking that materials are correct, that lighting positions are as designed, that joinery is being installed to drawing, that trades are executing to specification. Issuing site instructions where deviations are found.

Installation and styling: Managing the final installation phase — furniture delivery, artwork hanging, soft furnishings installation, styling — that transforms a completed shell into a furnished home.

Fee Structures

Interior designers operate on several fee structures; understanding them before negotiating is important.

Percentage of project cost: A fee calculated as a percentage of the total cost of the interior elements — typically 15–25% of furniture, soft furnishings, and decorative items, and 8–15% of construction and joinery costs within the designer's scope. This structure aligns the designer's income with project scale but can create a perverse incentive to specify more expensive items. Appropriate for larger projects where the scope is defined but the specification is not yet priced.

Fixed fee (design fee + procurement fee): A design fee for design services (drawings, specifications, site coordination) priced as a fixed amount, plus a procurement fee (typically 15–20% of all items purchased through the designer) for procurement management. This structure separates design value from procurement margin and is transparent. Appropriate for projects where the client wants clarity on cost.

Day rate / hourly rate: Used for smaller projects or phases of work. Senior designers: £200–£500 per day. Appropriate for specific consultancy tasks, not for managing a comprehensive renovation.

Retainer: A monthly retainer covering ongoing availability and regular site visits, supplemented by additional fees for major deliverables. Less common; appropriate for multi-year relationships where the scope is ongoing and varied.

For a prime London whole-house renovation (£800,000–£2,000,000 construction budget), the interior design fee — design services plus procurement management — typically runs £80,000–£250,000. This is not a peripheral cost; it is the investment that determines whether the construction budget produces a generic or exceptional result.

How to Evaluate an Interior Designer

The evaluation of an interior designer is a more nuanced process than evaluating a contractor. Capability — the technical ability to produce drawings, specifications, and coordinated deliverables — is a baseline requirement. The more important question is fit: does this designer's aesthetic sensibility, working method, and communication style align with the client's own preferences and working style?

Portfolio review: Review a minimum of 5–8 completed projects. Look for: consistency of quality across different briefs; evidence of original thinking (not just reproduction of a house style); range across different aesthetic directions (a designer who only does one look will impose that look on your project); detail quality (the specification of hardware, the resolution of junctions, the quality of finish at skirting level reveal capability more than hero photography).

Client references: Speak to 2–3 previous clients — specifically ask about: communication during the project (did the designer respond promptly, keep the client informed?); delivery against programme (did the furniture arrive on time? did the installation go smoothly?); value for money (did the client feel the fee was commensurate with the service received?); and what they would do differently.

Chemistry meeting: Meet the designer in person before any appointment — ideally in one of their completed projects, or at their studio. The working relationship with an interior designer is close and extended (typically 2–3 years for a whole-house renovation); the personal chemistry must be right. A brilliant designer with whom the client cannot communicate comfortably will produce a worse result than a very good designer with whom the working relationship is easy.

Scope clarity: Before appointment, agree the scope of services in writing — exactly what the designer is responsible for, what they are not responsible for, the interface with the architect, and the interface with the contractor. Ambiguity about scope is the most common source of fee disputes in interior design commissions.

Common Mistakes in Interior Designer Appointments

Appointing too late: As noted above — appointing the interior designer after architectural design is complete means the interior design is retrofitted into constraints that could have been avoided. Appoint at RIBA Stage 2.

Confusing decorator with interior designer: A decorator selects paints and fabrics; an interior designer designs spaces. Both have their role; knowing which you need prevents a mismatch between brief and capability.

Letting the designer select all trades without competitive pricing: An interior designer's preferred contractor relationships may not deliver the best value. For major subcontracted items — kitchen joinery, stone supply and fixing, soft furnishings — it is reasonable to require two or three competitive quotes even if the designer has a preferred supplier.

Not establishing a variation process: Changes to interior design specification mid-project (a different stone, a different fabric, a different furniture piece) affect cost and sometimes programme. Establish at the outset that all specification changes must be documented in writing with a cost impact before execution.

Confusing the design fee with the total interior budget: The designer's fee is the cost of the service; the interior budget is the cost of the goods and works that service specifies. A client with a £100,000 furniture budget who appoints a designer on a 20% procurement fee needs to budget £120,000 total — the fee is additional to the goods cost, not included within it.