The interior design guide. A definitive knowledge base for interior designers.

From first principles to the finishing touches: shell, surfaces, space planning, furniture, electrics, plumbing and joinery, in the order a project runs.

The Lexicon.

Every term, in plain words.

From hue and light reflectance to bonding and kick space, every term the guide uses has a short definition, what to know in practice and the pages that use it.

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The interior design guide.

A definitive knowledge base for interior designers.

Eleven chapters take a home from first principles to the moment you show it to the client. Start with Foundations and read in order, or search for a topic, a term or a rule of thumb.

Chapters.

Eleven steps, from principles to presentation.

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Where to go next.

Sections.

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Where to go next.

Use,

turning what people do into spaces that work.

A room is only as good as the activities it serves. Start from who uses it and what they do, then decide how much space each activity needs, what sits near what, how people move between them, how one space opens into the next, and how it all changes over time.

Program.

Define what the space needs to do.

A program turns the brief into spatial requirements. Identify who uses the space, what they do, how many people are there at once, and the equipment, storage and conditions each activity needs. Record priorities, constraints and likely future changes. Then build a space schedule listing each area’s function, capacity, target size and essential relationships. Include the supporting activities, such as deliveries, cleaning, waste and storage: they often decide whether the main spaces work. Review the schedule with the client before drawing layouts, and use it to judge the options.

Three-bedroom home
General office
Full-service restaurant
Limited-service hotel
One floor, four briefs. Each block’s area is its share of the internal area.

Zoning.

Give activities the conditions they need.

Group activities by what they need in privacy, noise, daylight, access and services. Put the functions people visit often where they are easy to reach, and protect the ones that need concentration or seclusion from passing traffic. Zones do not always need walls: furniture, lighting and a change of floor can define an area, while acoustic or visual privacy may need enclosure. Test the activities that happen at the same time. A dining table can double as a desk, but the two uses clash on a shared working day. See zoning.

Activities
Public to private
Quiet to noisy
One flat, read three ways: by activity, from public to private, and from quiet to noisy.

Adjacency.

Decide what belongs near what.

List which functions need direct access to each other, which benefit from being close, and which should be kept apart. Base these relationships on real tasks: a restaurant kitchen needs quick access to the dining room, and dirty dishes and incoming supplies need workable return and delivery routes. Record the priorities in an adjacency matrix, then explore several bubble diagrams. Test them against windows, structure, entrances and services before fixing room boundaries. Being near is not enough: a room next door can still be awkward to reach. See adjacency.

Adjacency matrix
Bubble diagram
Plan
The same five functions as a matrix, then bubbles, then a plan. Bright marks need direct access.

Circulation.

Plan movement alongside furniture and activities.

Trace the everyday journeys between entrances, destinations and shared facilities, including visitors, staff, deliveries and cleaning where they apply. Look for bottlenecks, crossing paths and routes that cut through occupied areas. Test the furnished layout with chairs pulled out, doors open and storage in use, and tell apart the space needed to do a task from the space needed to pass behind it. Coordinate routes with stairs and lifts, and check the accessibility and escape rules that apply. See circulation and clearance.

Obstructed route
Clear route
The same room twice: furniture in the way, with rings where the route pinches, then moved so the route runs clear.

Connection.

Shape how spaces meet and relate.

An opening gives access, but where it sits also decides what people see and how they read the next space. Use sightlines to reveal destinations, and thresholds to mark a change in privacy or activity. Decide on purpose where views, materials and light carry on and where they stop. A glazed partition keeps a visual link while separating activities, but needs the right acoustic performance where privacy matters. Test transitions in section as well as plan, including changes of level and connections to outdoor spaces.

Access

The route from room to garden: through the doorway, up two steps and out across the terrace.

Sightlines

From where a person stands, the view runs through both openings to the tree beyond.

Thresholds

The doorway, the step up, the glazed wall and the step down: each marks a change of privacy, level or floor.

Material continuity

The same floor runs from the second room out onto the terrace, so inside and outside read as one.

Adaptability.

Make changing use practical.

Work out what changes daily, occasionally, or over the life of the project. Separate the fixed constraints, such as structure, drainage and major services, from what can move: tables, screens and storage. Draw the alternative layouts rather than assuming the room is flexible, and check power, acoustics, circulation and where the unused furniture goes in each. Consider who makes the change and how much effort it takes: a layout is adaptable only when people can realistically rearrange it.

Focused work
Meeting
Presentation
One room set up three ways, seen from above. The column, the floor power boxes and the storage bay, in the bright line, stay fixed; tables and chairs move, and what a layout does not need stacks in the bay.

Keep reading.

Where to go next.

Questions.

What people ask most about planning how a space is used.

How do you decorate an open floor plan?

Treat it as several rooms that share one space. Give each zone an anchor, such as a rug under the seating, a pendant over the table or a run of cabinets, and turn the furniture to face into its own zone. Keep the main route between zones clear, and repeat one or two colours or materials across the whole space so the zones still read as one.

How do you separate spaces in an open floor plan without walls?

Use furniture, light and floor finishes rather than partitions. A sofa back, a shelving unit or a kitchen island marks an edge while keeping the view open. A change of rug, ceiling height or lighting level tells people they have entered a different area. Where noise or privacy matters, a glazed screen or a sliding panel separates the activity without losing the light.

What is space planning in interior design?

Space planning is working out how a space will be used before choosing finishes: which activities go where, how much room each needs, what sits next to what and how people move between them. It runs from the program through zoning and adjacency to a furnished layout, tested against real furniture sizes and clearances.

What is architectural programming?

Programming follows the brief and survey, at the start of a project. It turns the brief into a list of spaces, with the activities, users, sizes and relationships each one needs, plus the budget and timescale that frame them. The result, often called the program or space schedule, is the yardstick every later design option is judged against.

What is a bubble diagram in architecture?

A bubble diagram is a quick sketch of a plan in which each space is a loose circle, sized roughly by its area, with lines joining the spaces that must connect. It lets you test arrangements before committing to walls. Sketch several, keep the strongest links short, then check the best ones against windows, entrances and structure.

What is an adjacency matrix in interior design?

An adjacency matrix is a grid that lists every space along the top and down the side, and marks each pair by how close they need to be: directly connected, nearby or kept apart. It records the relationships from the brief in one place, so nothing is forgotten when you move on to bubble diagrams and plans.

How much space should you leave between furniture for walking?

Allow about 90 cm for a main route through a room and about 60 cm for a secondary path, such as behind a chair or beside a bed. Leave 75 to 90 cm behind a dining chair so someone can stand up and others can pass. Test the layout with chairs pulled out and doors open, not just on an empty plan.

What is the standard width of a hallway?

In homes, hallways are usually 90 to 110 cm wide, and building codes typically set a minimum of around 90 cm. Where a wheelchair needs to pass or turn, plan for 120 cm or more, and check the accessibility rules that apply where you are building.

What is a flexible space?

A flexible space is a room designed to change use without building work, such as a study that becomes a guest room or an office floor that switches between desks and meetings. It needs fixed services in the right places, furniture that is light enough to move, and somewhere to store what each layout does not use.

How do you transition paint colours in an open floor plan?

Change colour where the architecture gives you an edge: an inside corner, a doorway, a column or a change in ceiling height, never in the middle of a flat wall. Keep the colours related by undertone, or keep one colour on the trim and ceiling throughout, so the space still reads as one.

Units