Interior Architects v Interior Designers: who specifies what?


What’s the difference between an Interior Architect and an Interior Designer? (No, this isn't a joke waiting for a punchline...). And what does a Design Director, Practice Leader, Principal or Partner actually do? Why so many job titles? What do they mean? And what influence do they have over whether your building material products get specified or not?

This article aims to clarify how the big firms work in terms of specifying building products and materials for commercial interior projects: who specifies what and what level of day-to-day influence and authority they really have. We hope it helps you to see how it all comes together and who you need to get on your side if you want your building material products featured in the world’s best commercial interior projects.

America’s Top A&D Firms


For this article, we’ll focus on the big, established A&D firms with international presence. So, the likes of Gensler, Perkins+Will, HKS, HOK, AECOM, Perkins Eastman, get the picture. If large-scale commercial interior projects are your target, these are the firms you need to get inside. But, how are these firms set up and who do you need to get close to if you want a shot at the projects? Let’s get into it.

Interior Architect v Interior Designer

The debate over the realms and roles of Interior Architect v Interior Designer runs long and deep and we won’t attempt to ‘solve’ it here - we know our place. But, whilst there are some inevitable areas of overlap between the two roles, it is possible to make some distinctions.

Interior Architecture

Interior architecture focuses on structural design – creating or remodelling an interior space within a building. Whilst considering the aesthetics of interior design, interior architecture is more about the functionality and material construction of interior spaces. This includes structural elements such as window and door placements, ventilation, heating and plumbing.

Interior Architects

Interior architects are involved throughout the design process, from conceptual schemes through to technical and material specification. During this process they will regularly consult the client as well as collaborating with specialists, such as structural engineers, lighting consultants/suppliers, building contractors and material suppliers.

Interior Design

Interior design focuses on aesthetics, whereas interior architecture involves both aesthetics and building structure. Interior design is ultimately about planning within an existing space, creating cohesive and aesthetically pleasing designs for those spaces through the selection and placement of finishes, furniture and materials. The Interior Designer will liaise with clients to understand their needs and create visually pleasing, functional and safe spaces accordingly.

Interior Designers

Interior designers incorporate colour palettes, textiles, furniture placement and material specification to enhance the look and function of an existing space. During a project, interior designers may liaise with contractors, electricians, painters and plumbers to ensure the client’s brief and budget are met.

On a practical level, interior architects tend to be involved in construction or renovation projects at an earlier stage than interior designers.

Simply put, Interior Architects provide input on structural matters and the creation and repurposing of interior spaces, whereas Interior Designers consider the appearance of an indoor space once it is built.

Architectural and Interior Design in-house

As successful architecture firms grow and evolve, they often move towards a multi-disciplinary setup. First step is usually to take on some Interior Designers so projects and the conversations around them continue in-house so product choices made at the architectural level are less likely to be changed when the Interior Design team takes over.

Within these multi-disciplinary firms, the Interior Design teams usually work in one of the following ways:

  1. With the in-house architectural team

Here, the Interior Design Principal would work alongside colleagues from the Architectural discipline on a particular project. As the Architectural team focuses on a building’s massing, structure, building systems, exterior envelope and aesthetics of the building’s core and shell, the Interior Design team will then collaborate with them to complete the project to a shared understanding of the clients’ expectations.

As the project evolves, the Interior Design team may provide recommendations to the Architectural team on building lease depths, configuration of public spaces, types / distribution of amenities, daylighting opportunities and similar decisions regarding the building core and shell. Once the building’s core and shell have been resolved, the Interior Design team will shift its focus to fitting out the building’s interior spaces. During this phase, the Interior Design team will make decisions about materials, finishes and colors for the floors, walls and ceilings throughout the buildings.

  1. Independently from the in-house architectural team

Often, Interior Design teams within the large A&D firms will have a client assignment separate and independent of the firm’s architectural team. They may provide the same kind of Interior Design services working directly for a client who has contracted with a separate architectural firm for the building core and shell design services. Under such an arrangement, the services would be much the same as a fully in-house project but the contractual arrangement would be different.

In this arrangement, products specified by the architectural team are more often subject to change, simply because the Interior Design team wasn't involved in such discussions at an earlier stage.

What do Interior Architects and Interior Designers Specify?

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There is no definitive list of what an Interior architect would specify over an Interior Designer. Depending on the firm and the project, each would work together in the planning, designing, decorating and fitting out of an interior space and each would typically specify a wide range of elements and materials. Some elements, however, such as furniture, colour schemes, fabrics and textiles are more typically within the Interior Designers remit, whereas lighting, acoustic materials, sustainable materials and safety features would usually be specified by the Interior Architect. Here are some of the key things that each (or either...) would commonly specify:

  1. Furniture: The type, style and placement of furniture within a space that match the design concept and meet the client's needs.
  2. Fixtures and Fittings: Including specifying plumbing fixtures (sinks, faucets), electrical fixtures (lighting, outlets) and other hardware (handles, switches) to be used in the space.
  3. Flooring: Flooring materials, such as hardwood, carpet, tile or laminate, based on the design concept, durability and maintenance requirements.
  4. Wall Finishes: Types of wall finishes, such as masonry, paint colors, wallpapers, wall tiles, or paneling to achieve the desired look and feel of the space.
  5. Ceiling Treatments: Ceiling materials, designs and treatments, including lighting fixtures and mouldings to enhance the aesthetics and functionality of the space.
  6. Color Schemes: Color palettes and materials/finishes for walls, ceilings and accessories.
  7. Fabrics and Textiles: Fabrics and textiles for upholstery, curtains and decorative elements like throws, pillows and rugs. They would consider factors like color, pattern, texture and durability.
  8. Cabinetry and Millwork: For kitchens, bathrooms and storage spaces, interior architects specify custom cabinetry and millwork designs, including materials, finishes and hardware.
  9. Lighting: The whole lighting scheme for a space, specifying fixtures, lamps, bulbs and controls.
  10. Acoustic Materials: In spaces where sound control is important, interior architects may specify acoustic panels, ceiling tiles or other materials to meet sound quality requirements.
  11. Window Treatments: Coverings such as curtains, blinds or shades to provide privacy, work with natural light and enhance the overall design.
  12. Artwork and Accessories: Recommending or specifying artwork, decorative objects and accessories.
  13. Environmental and Sustainable Materials: In line with environmental standards, interior architects may specify sustainable materials, such as recycled stuffs, low-VOC paints and energy-efficient fixtures.
  14. Safety Features: Interior architects/designers need to ensure that safety features like fire-resistant materials, emergency lighting and exit signs are specified according to building codes and safety regulations.
  15. Custom Elements: Depending on the project, interior architects/designers may also design and specify custom elements like built-in shelving, unique furniture pieces or bespoke fixtures.

Interior Architect and Interior Designer Projects

Here are some of the types of projects that interior architects and interior designers commonly work on within the larger A&D firms:

  1. Residential Design

Single-family, multi-family and custom luxury homes including renovations and remodels: helping homeowners and developers to update and improve the functionality and aesthetics of existing spaces.

  1. Commercial Design

Offices: Interior architects design office layouts, workstations, meeting rooms, and common areas to enhance productivity and create a cohesive brand image.

Retail spaces: They create store layouts that promote product visibility and customer engagement, often collaborating with visual merchandisers.

  1. Healthcare Facilities

Hospitals and clinics: healthcare facilities with a focus on patient comfort, functionality, and infection control measures.

Dental and medical offices: creating efficient and calming environments for medical professionals and patients.

  1. Educational Institutions

Schools and universities: planning, design and fitment of educational spaces that are conducive to learning and wellbeing.

  1. Cultural and Entertainment Venues

Museums and art galleries: exhibition spaces to showcase art and artifacts, paying attention to lighting, climate control, and visitor flow.

Theaters and auditoriums: interiors of performance venues, including seating, stage design, lighting and acoustics.

  1. Hospitality Design

Hotels, restaurants, bars and nightclubs: creating ambiance and atmosphere in entertainment venues.

Spas and wellness centers: designing tranquil spaces for relaxation and rejuvenation.

  1. Public Spaces

Airports, train stations, and transportation hubs: planning and designing waiting areas, lounges, and circulation spaces for the enhanced experience (and safety) of travelers and the convenience/wellbeing of staff.

Government buildings: design and fitment public spaces within government buildings, including lobbies and meeting rooms.

  1. Sustainable Design

Interior architects increasingly focus on environmentally friendly and sustainable design practices, incorporating energy-efficient lighting, materials and ventilation systems.

  1. Specialized Design

Some interior architects and designers specialize in areas like kitchen and bathroom design, historic preservation, or accessibility design for people with disabilities.

Integrated Design

In addition to specifying products and solutions, senior interior architects and interior designers work closely with clients, contractors and other professions to ensure that the design vision is delivered within the budget and timeline constraints of the project. The collaborative result is a fully integrated, complete project under the design umbrella of one firm, overseen at every stage by the Interior Design Principal.

Refurb and Repurposing

Many of the projects completed under the Interior Design Principal/Project Leader are not new builds. Often, the Interior Design team will be working within the core and shell of an existing building. This could be an office coming under a new lease in an existing building, renovations to an existing office space upon the renewal of a lease, renovation or repositioning of an existing hotel, renovation to change the use of an existing building or restoration of an historic building.

Job Titles: who does what?

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Now we’re (hopefully) a bit clearer on the Interior Architecture v Interior Design thing, let’s take a closer look at some of the job titles you’ll come across within these disciplines in the larger A&D firms:

  1. Senior Interior Designer

Specification influence/area: Med-high/Interior Design

This role involves a higher level of experience and often includes leadership responsibilities. Senior interior designers manage design teams, work closely with clients and contribute to design strategy and decision-making within a firm.

  1. Director of Interior Design

Specification influence/area: Very high/Interior Design

This individual is typically responsible for the overall vision and strategic direction of the interior design department. They guide design philosophy, mentor and manage senior staff and ensure that design projects align with the firm's goals.

  1. Principal or Partner

Specification influence/area: Highest/Interiors + Architectural

In some architecture firms, especially those with integrated interior design services, a Principal or Partner might lead both architectural and interior projects. They play a critical role in client relationships, business development and decision-making for design direction.

  1. Chief Interior Designer

Specification influence/area: Very high/Interior Design

Similar to a Director of Interior Design, this role is responsible for leading and managing the interior design team. They often work closely with firm leadership and clients to ensure design excellence and client satisfaction.

  1. Design Director - Interiors

Specification influence/area: Very high/Interior Design + Architectural

This role involves overseeing the creative direction of interior design projects. Design Directors guide design concepts, provide design critiques, and ensure that the firm's design standards are upheld.

  1. Principal Designer

Specification influence/area: Highest/Interior Design + Architectural

A Principal Designer is a recognized expert in the field, leading design efforts on major projects. They often have significant industry influence and play a key role in setting design trends.

  1. Interior Design Practice Leader

Specification influence/area: Very high/Interior Design + Architectural (More influence at a business than individual project level)

This role focuses on developing and maintaining the firm's interior design practice. Practice Leaders drive business growth, manage client relationships, and ensure that design excellence is consistently achieved.

  1. Global Design Director - Interiors

Specification influence/area: Very high/Interior Design + Architectural

In larger international firms, Global Design Directors oversee interior design projects across various geographic regions. They ensure design consistency while considering cultural and regional contexts.

  1. Studio Head - Interiors

Specification influence/area: Highest/Interior Design + Architectural

Some firms organize their design departments into studios, each led by a Studio Head. This role involves managing a team of designers, guiding design projects, and fostering a collaborative studio environment. The common thread being their day-to-day level of influence in the studios, which is where the design and spec. decisions are made.

A Matter of Principals

Despite this confusing variety of job titles within different firms, it’s clear that it’s the Principals, Practice Leaders, Design Directors and Studio Heads that will be your most infuential target, for it’s these who work directly with the client and who understand their goals, needs, budgets, schedules and aspirations for each project. It’s the Principals who guide their clients in making project decisions and who assure the project design team delivers the results aligned with client expectations.

Principals Assure Project Success

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The Interior Design Principals play the most critical role in guiding their clients through the many decisions required for project success. And it’s the client and Interior Design Principal who ultimately determine aesthetics or theme for the design as matters of budget, sustainability, durability, maintenance and operations enter the process.

Materials and finishes chosen for floors, walls, doors and other accessories are the touch points the building’s user will feel every day. The quality of the lighting and thermal comfort of the spaces the users occupy will determine their well-being and how effective they are in their work. The Interior Design Team must be directed to make decisions on materials and finishes that will work together as a whole to achieve the client’s goals across all these aspects of the project.

This is the ultimate role of the Interior Design project leader (at Principal/Design Director/Practice Leader level) – to ensure the best environment is delivered. It’s the Principal-level Interior Architect/Designer who protects the client’s interests and who holds the true influence to choose and hold spec. for building materials and products.

The knock-on effect of changing spec.

Decisions made by the Interior Design team should be made with an eye to how they will work as part of the whole project. This is critical, as even a well-founded, seemingly minor substitution can have major disruptive impact down the line: materials may be incompatible with other products or require modification of adjacent construction to meet required clearances. And, any differing electrical or structural requirements may cause significant changes to be required. It’s at this point that the client would turn to the Principal overseeing the project for guidance.

Knowledge is Power

The choice of staying with the original product or determining all the changes the substitution may require is often not readily apparent. The Interior Design Principal is in a position of trust here to influence the clients’ decision in the best interests of the project.

When senior Interior Architects are well informed of the advantages and benefits of a particular material or product, their ability to make better choices and to defend and explain those choices is greatly improved when faced with substitution requests.

And, this knowledge can only come from building materials and product manufacturers who know and believe in the benefits of their products and who see their role more as educators than sales people. Because, every successful Interior Architect builds their preferred supplier list from manufacturers who are able to give them the knowledge and support they need to confidently hold spec. in the assured knowledge that they’re making the right choice for their client for current and future projects.

BOND-9 (5)

And that brings us squarely to the unique proposition that is Arc Interiors: 3 days and 3 nights away from the pressures and distractions of everyday life, giving you time and space to get yourself and your products into the hearts and minds of the true commercial interior project influencers from the big firms.

How we pick ‘em:

Step 1) Pinpoint the largest, most high-profile commercial interior projects in North America in design stages

Step 2) Identify the commercial design firms involved and the Principals leading the design and specification

Step 3) Invite those Principals to submit an application outlining their credentials. Accept and enrol pending final QC.

Here’s a little taster of who came to Arc Interiors this year. Look at the firms and job titles:

  1. AECOM - Principal | Associate Vice President, Interiors Practice Lead: NE Region Design
  2. AECOM - Design Director
  3. Arcadis - Associate Principal and Design Director
  4. Arcadis - Principal | Global Solutions Director, Future Workplace
  5. B+H Architects - Regional Design Director
  6. DLR Group – Principal
  7. Ewing Cole - Director of Design
  8. Ewing Cole – Principal
  9. Gensler - Principal, Mixed Use Leader, Studio Director
  10. HDR Inc - Interior Design Principal
  11. HKS - Studio Design Leader & Vice President
  12. HKS - Principal/Global Practice Director, Health
  13. HKS - Principal, Regional Director Health Interiors
  14. HOK - Senior Design Principal, Interiors
  15. HOK - Principal, Director of Interiors
  16. HOK - Principal - Director of Design
  17. MKDA - Design Principal
  18. Perkins and Will - Associate Principal

Understanding and navigating the specification process for large-scale commercial interior projects is complicated! But, within the big firms at least, it’s very much a collaborative process where the Interior Architects and Interior Designers work together under the watchful eye of the Principal-level Project/Studio Leader/Head of Specification. And it’s this real-world thinking that informs and directs our recruitment for the ‘buyers’ you’ll meet at Arc Interiors: they are North America’s true commercial interior project influencers. If they are not yet fully conversant on how you and your products can make their lives better and help them on their quest to deliver outstanding results for their clients, you should probably come and talk to them.

Mike McCaffrey