When a client enquires about the scope of a detailed design, they are rarely looking for a technical definition. What they need to know is much more specific: what can be built using that documentation, which decisions will be finalised, and what degree of uncertainty will remain before work begins.

Whether it’s a home, a restaurant or a hospitality venue, the difference between an appealing idea and a well-executed result lies in that level of definition. The detailed design translates the design intention into buildable information. It is the point at which layout, materials, services, lighting, furniture and details cease to be merely an aesthetic direction and become a feasible construction project.

What defines the scope of a detailed design

The scope is not the same for every commission. It depends on the type of property, its initial condition, the technical complexity and the extent of the work involved. A comprehensive refurbishment of an old flat in Barcelona does not entail the same requirements as the interior design of commercial premises within an already fitted-out structure. Nor does a flat intended for private use require the same documentation as a restaurant with a busy operation, specific regulations and a brand identity that must be conveyed at every point of contact.

Even so, a well-planned construction drawing must answer one essential question: does the site team have all the information needed to quote for and carry out the work without having to interpret what has not been clearly defined?

The answer directly affects the cost, the timetable and the final quality. The more ambiguous the document, the more decisions will be left to the site team. And decisions made in a hurry, amidst suppliers, contractors and tight deadlines, tend to be more expensive and less consistent with the initial concept.

From layout to construction details

The basis is usually a comprehensive set of drawings: plans showing the current and renovated states, layout, dimensions, demolition work, partition walls, ceilings, flooring and cladding. But to limit the construction drawings to a collection of plans would be to diminish their value.

The elements that make the space habitable must also be defined: general and ambient lighting, fittings, sockets, plumbing, air conditioning, ventilation, joinery, kitchen and bathroom fittings, and storage solutions. In commercial projects, the relationship between circulation routes, service, customer experience, maintenance and applicable regulations must also be considered.

Attention to detail is particularly important in bespoke interiors. A piece of joinery cannot be finalised simply by indicating its position on the floor plan. Dimensions, materials, thicknesses, joints, openings, handles, integrated lighting and how it relates to neighbouring elements must all be defined. It is here that a seemingly simple solution can acquire precision and character.

The scope of the detailed design in a comprehensive refurbishment

In a comprehensive refurbishment, the project must coordinate decisions that are not always visible once the work is complete. The location of a drain dictates the layout of a kitchen. The available height beneath a beam affects a false ceiling. Sound insulation can determine the thickness of a wall lining and, consequently, alter the actual dimensions of a room.

A common scenario is that of a flat with a compartmentalised layout and little natural light. The proposal might involve opening up the living areas, reorganising the circulation routes and creating an integrated kitchen. Without a detailed design, that intention remains merely a rough outline. With a detailed design, decisions are made on where to reinforce an opening, how to resolve ventilation, what dimensions the kitchen island requires, where to house the services, and what type of lighting suits each function.

It is not a question of drawing more for the sake of it. It is about anticipating where systems intersect. A good spatial solution can lose its impact if the air-conditioning system is not properly integrated, if vents are poorly positioned, or if a door does not open with the intended clearance. The detailed design safeguards the overall logic of the project before these decisions become irreversible.

Materials that are understood and can be implemented

The selection of materials must be carried out with a degree of precision commensurate with the project. Choosing a stone, a timber or a metallic finish is not merely a question of colour. The format, the cutting plan, the direction of installation, the joints, the edges, the durability and the maintenance requirements are all important.

In a hotel lobby, for example, flooring must withstand continuous footfall and retain its appearance over time. In a home, natural timber can add warmth, but its behaviour in response to damp, impact and solar radiation must be assessed. There is no such thing as the ‘best’ material in isolation: there is the right material for a specific use, lighting conditions, budget and construction method.

For this reason, specifications should leave no room for aesthetic interpretation. If the project seeks visual continuity between the floor, walls and furniture, that continuity must be explained through plans, samples and joint details. The building works require clear instructions, not merely inspirational references.

What should not be confused with the scope

A detailed design does not completely eliminate unforeseen issues. In existing buildings, concealed installations, defects, unevenness or structural elements may come to light that were not visible during the design phase. The value of the design lies in reducing uncertainty and establishing criteria for responding when an issue arises.

Nor does it automatically equate to comprehensive site management. Site management, coordination of contractors, financial control, administrative procedures and monitoring of deadlines may form part of the service, but these should be explicitly defined. A client may commission only the working drawings or request comprehensive support from the design stage through to final handover. These are different scopes of work, and both are valid provided they are clearly explained.

The same level of precision applies to furniture, styling and the purchase of items. In some projects, the design includes bespoke elements and a complete selection of fittings. In others, the interior architecture is defined and part of the décor is left for a later phase. The key is not to assume that a project visualisation includes items that have not been specified.

Budget, timelines and outstanding decisions

The scope of the detailed design is directly linked to the quality of the quotation. When the plans, measurements and specifications are consistent, contractors can assess comparable items. This allows real differences between quotes to be identified, rather than comparing figures based on differing interpretations.

A low quote may appear competitive if it omits decorative lighting, specialised joinery, finishing touches, protective features or certain finishes. Later on, these omissions resurface as extras. Defining these elements in advance does not guarantee a lower investment, but it does make the budget clearer and more manageable.

It also helps to organise the schedule. There are elements with long lead times, such as specialised enclosures, bespoke stonework, kitchens, technical lighting or custom joinery. If these are decided upon too late, they can slow down the progress of the works or force substitutions that compromise the quality of the result.

In the catering and hospitality sectors, this forward planning is even more crucial. The opening date leaves little room for compromise, but a rushed opening with operational issues or incomplete finishes carries an obvious reputational cost. Good design also means knowing what needs to be decided first.

A document to preserve the project’s intent

The detailed design is not merely a formality between the concept and construction. It is the tool that keeps the design’s intent intact whilst multiple parties are involved. It ensures that a understated atmosphere, fluid circulation or a unique detail are realised on site without relying on improvised explanations.

At FFWD Arquitectos, the work at the intersection of architecture and interior design stems precisely from this continuity: conceiving space as an experience, whilst resolving it using criteria that allow it to be built with precision. Each commission requires its own level of documentary depth. A home with standard solutions may require less detail than a penthouse with built-in furniture or a restaurant with a complex kitchen, but none should proceed with essential decisions until everything has been finalised.

Before starting a build, it is worth checking one simple thing: if the practice, the builder and the client interpret the project in the same way, the scope is doing its job. If each envisions a different outcome, the project still needs to be defined. That is where the time invested in the project ceases to be a preliminary phase and becomes built quality.