What does an interior designer do?
When imagining a finished home, most people picture not just the rooms and layout but the way the spaces feel: the colour of the walls, the softness of a rug underfoot, the gleam of brass taps, or the elegant drop of a pendant light over a dining table. These details are what bring a home to life – and designing them is the job of an interior designer.
This is the fifth in our series explaining the different roles during a residential construction project.
Each role brings a different set of responsibilities, skills and professional focus. This post outlines the core duties of the Interior Designer and explains how those duties interact with the wider team.
Interior design is sometimes mistaken for surface decoration, but in practice it is a complex and time-consuming discipline. It involves deep knowledge of materials, supplier relationships, spatial planning, budget control, and coordination with the wider construction team. For residential clients, a good interior designer can help transform a well-built structure into a home that feels refined, comfortable and entirely personal.
There are two main areas of focus in interior design: specification of fixtures, finishes and fittings (often referred to as interior specification), and the procurement of loose furniture and styling. Some designers specialise in one or the other, but many offer both.
1. Fixtures, finishes and fittings
The first core responsibility of an interior designer is the specification of all fixed and fitted interior elements. This includes:
Floor finishes: timber, tile, stone, carpet
Wall finishes: paint, wallpaper, specialist plaster, panelling
Tiles: for kitchens, bathrooms and flooring
Ironmongery: door handles, knobs, hinges, bolts
Sanitaryware and brassware: basins, taps, showers, baths, toilets
Lighting: wall lights, ceiling lights, integrated joinery lighting
Joinery: finishes and detailing for built-in furniture such as wardrobes, bookcases, bathroom vanities and kitchen units
Window treatments: recessed blind boxes, curtain tracks, pelmets
Sockets, switches and cover plates: material selection and finish
Each of these elements must be carefully selected, coordinated and documented. Interior designers produce finish schedules, ironmongery sets, sanitaryware specifications and joinery intent drawings to ensure that the construction team has accurate and coherent information. These documents need to align with both the design vision and the technical requirements of the build.
This work is detailed and time intensive and is its own distinct package of work. Designers are expected to guide clients through multiple options, source and test samples, coordinate with suppliers and contractors, and produce comprehensive documents to support accurate pricing and installation.
Once construction begins, the interior designer’s work does not stop at the drawings and schedules. They become actively involved in ensuring that every finish and fitting is implemented as intended. This stage can be as time-consuming as the design itself, as it requires frequent site visits, detailed inspections, and close collaboration with the contractor and specialist trades.
For example, the setting out of tiles for a bathroom or kitchen is rarely straightforward. The designer may need to check the layout on site before tiling begins, ensuring that cuts fall in discreet areas, that grout lines align with sanitaryware and joinery edges, and that decorative patterns or borders are correctly positioned. They often mark out layouts on walls or floors and return during installation to check progress and correct issues before they become costly to rectify.
Joinery requires similar attention. Before fabrication begins, the designer reviews workshop drawings from the joiner to confirm that every detail – from proportions to shadow gaps and door reveals – matches the design intent. Samples and prototypes of finishes such as veneers, paint colours or edge profiles often need to be signed off. Once installed, joinery must be checked again to ensure that finishes match the approved samples, that doors align and operate correctly, and that integrated lighting and hardware are correctly positioned.
Other typical site-stage tasks include:
Verifying that specialist plaster finishes or wall panelling are applied to the correct thickness and finish quality
Checking stone or timber flooring deliveries for colour consistency, natural variations and any damage before they are laid
Reviewing the alignment of sockets, switches and cover plates with panelling lines or other fixed features
Assessing sanitaryware on arrival for defects and ensuring that it has been installed to the right height and set-out
Coordinating with kitchen suppliers on delivery schedules, checking that units and worktops fit as drawn, and sometimes being present on installation day to resolve unforeseen alignment or spacing issues
Inspecting lighting installations to ensure fittings are placed as intended and that integrated joinery lighting has the correct colour temperature and effect
Liaising with curtain makers, blind installers and decorators to coordinate last-stage works so that nothing clashes with fitted joinery or lighting positions
Much of this work involves resolving small but important site issues in real time – for instance, adjusting the height of a wall sconce to clear a mirror frame or tweaking tile layouts to avoid awkward slivers. These decisions have a cumulative effect on the overall quality of the finished interior.
In high-end residential projects, this hands-on involvement is what ensures that the interiors look deliberate, feel cohesive, and perform well. It also saves clients the stress of making technical decisions on site and prevents costly remedial work later.
2. Loose furniture and styling
The second major area of interior design focuses on loose furniture and soft furnishings – the freestanding elements that are placed in the home once construction is complete. This includes:
Freestanding furniture: sofas, beds, dining tables, side tables, wardrobes
Soft furnishings: curtains, blinds, cushions, headboards, bedding
Rugs and textile layering
Decorative lighting: table lamps, floor lamps, pendants
Wall pieces: mirrors, art, sculptural elements
Accessories and styling: ceramics, books, plants, candles and everyday objects
This part of the process often begins with a room-by-room furniture layout, followed by concept images or mood boards to communicate the overall tone. Designers then source individual items, manage showrooms and sampling, suggest colour palettes and materials, and present furniture and styling proposals for approval.
Procurement is a significant part of the process. Designers place and track orders, manage logistics, and arrange deliveries. Where requested, they also oversee installation, ensuring each piece is placed correctly, with accessories styled in line with the concept. In some cases, they will design bespoke pieces in collaboration with furniture makers, upholsterers, or lighting specialists.
This service can make a dramatic difference to how a home feels. A well-considered layout with comfortable, proportionate furniture and a layered, consistent palette elevates the whole experience of the house.
Interior design begins at concept stage
Although furniture and finish installation typically happen towards the end of the project, the design process itself begins much earlier – ideally at the concept stage. The interior concept informs layout decisions, material language, lighting strategy and even joinery locations. Starting early avoids rushed decisions and ensures the design is cohesive from the ground up.
An interior designer may begin by establishing the mood and atmosphere of the home, drawing from a palette of materials, tones and textures that support the architecture. This concept is then developed into room-by-room proposals, with detailed specification documents created during the design development and technical stages.
By Stage 4 of a typical construction programme, many of the decisions about finishes and fittings should be finalised so they can be incorporated into contractor tender packages and construction drawings. Delaying these decisions can lead to last-minute changes, additional costs, or compromised outcomes.
Loose furniture and styling tend to follow later, once construction is nearing completion and measured site dimensions are available.
Clear boundaries and coordination
Because interior design work often overlaps in timing with architectural design and construction detailing, it’s important to have clear boundaries and coordination between teams. Interior specification involves a high level of detail and focused time, and it is typically treated as a distinct area of work.
For large or complex projects, appointing an interior designer by the end of Stage 2 ensures their input can be properly integrated. Early involvement also makes it easier to coordinate finishes with lighting and joinery layouts, ensuring no design intent is lost in translation.
Good coordination relies on open communication, clear responsibilities, and structured drawing packages. Interior designers, architects, and contractors all benefit from working in sync, and the result is a more fluid and enjoyable process for the client.
What an interior design package includes
Interior design packages vary depending on the designer’s style and the client’s goals, but they typically include:
Concept development: mood boards, style references and palette proposals
Finishes specification: finish schedules, material samples and supplier lists
Lighting specifications: Chandelier, pendant lights, wall lights, recessed and hidden lights, floor lights
Ironmongery specification: decorative fittings, faceplates, handles, knobs, etc
Sanitaryware specification: Toilets, basins, taps, sinks
Bathroom fittings: Towel rings, toilet roll holders
Joinery design detailing: Designing wardrobes, kitchens, cupboards, shelves. finishes, handle details, joinery mood boards
Furniture design: In some instances to get the design exactly right, designing chest of drawers, bedside cabinets, sofas and coffee tables.
Furniture layouts: Assessing the space and seeing what furniture will look best placed where and what sizes will fit. This will be the first step in defining what furniture to procure.
Styling services - Sourcing packages of decorative objects to layer your home space and give it the final touches of personality and style.
Procurement and supplier coordination
Installation and styling
Some designers will also offer post-occupancy support, helping to layer in further styling or source items over time as the home settles.
How we work
At Nancy Gouldstone Architects, we offer interior specification and furniture procurement as a separate, dedicated services for clients who want a fully considered interior. This work is led by a member of our in-house team and often begins at concept stage alongside architectural design.
We create clear, cohesive proposals for finishes and fittings, aligned with the overall design intent of the home. Our team can produce schedules, coordinate with suppliers, and attend site to support the contractor through installation. For loose furniture, we offer a tailored sourcing and procurement service, including layout drawings, mood boards, showroom visits, and delivery coordination.
This interior design service can be offered as part of a wider architecture and project management package, or as a standalone appointment. Some clients bring in their own interior designer, which we are always happy to support and coordinate with.
Our goal is always the same: to help create homes that are beautifully resolved, inside and out. Interior design plays a vital role in that journey.