The interior design guide
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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.

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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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Sections.

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Where to go next.

Furniture types and selection,

for the people, the purpose and the place.

An empty room is defined by its architecture, but its furniture decides how people live in it. A table makes a place to gather, a sofa a setting for conversation, a desk a corner for work.

Selection begins with the people who will use a room, not with a catalogue: what they do, how many they are, what they already own, and how their furniture must fit.

Start from the brief.

People before catalogues.

A family living room, a hotel lounge and a workplace reception may hold similar sofas and tables, yet ask very different things of them: more or fewer users, harder wear, other patterns of movement, other expectations of comfort.

Begin with the project brief. How many people will use the room, for which activities, and how often? Are there children, pets, older occupants, or people with particular accessibility needs? Which existing possessions must stay? The answers make a functional brief for every major piece.

Work at first with generic furniture categories and approximate sizes, and refine them into specific products as the layout develops.

The principal furniture families.

Classified by what they support.

Grouping furniture by the activity it supports is a useful way to set a room’s requirements before choosing any particular piece.

The seven families at one scale; each is lit in turn.
FamilyCommon typesMain considerations
SeatingChairs, sofas, armchairs, benches, stoolsComfort, posture, occupancy, flexibility
TablesDining, coffee, side, console and meeting tablesHeight, surface area, access, stability
WorkstationsDesks, worktables, office systemsErgonomics, equipment, adjustability
StorageCabinets, shelves, wardrobes, dressersCapacity, access, security, organisation
SleepingBeds, bed bases, bedside furnitureDimensions, comfort, circulation
Modular furnitureSectional seating, modular shelving, workspace systemsReconfiguration, compatibility, assembly
Specialist equipmentReception desks, display units, treatment chairsTask requirements, services, safety

Families overlap. An ottoman can be a seat, a footrest or storage; a console table a display surface or a desk for an afternoon. Hybrids help most in compact interiors, as long as they never compromise the main activity.

Loose, modular and built-in.

How furniture relates to the building.

The same room three times. Loose pieces move freely; modules recombine; built-ins use the awkward places but stay put.

Loose furniture

Chairs, tables, sofas and freestanding cabinets can be moved or replaced without touching the architecture. They let an interior evolve over time.

Modular furniture

Repeatable, interchangeable components: sectional sofas, open-plan workstations, modular shelving. They assemble in several configurations, and can often be reused when needs change.

Built-in furniture

Fitted storage, window seats and custom cabinetry are made for one place. They use irregular or tight spaces well, but need closer dimensional and construction coordination.

The boundaries are not absolute: a freestanding unit may still need anchoring to the wall for safety, and a modular office system may depend on fixed power connections.

New and existing furniture.

Not everything needs to be new.

Existing furniture, inherited pieces, artwork and objects of sentimental value are often part of the brief. Assess each before replacing it: its dimensions, condition, usefulness and fit with the proposed interior.

Some pieces stay as they are; others are repaired, reupholstered, refinished or moved to another room. Doing so keeps a room’s character and controls cost: a familiar armchair beside contemporary pieces, or an old dining table as the organising element of a new scheme.

Keep a simple inventory of what to retain, refurbish, relocate, sell or remove. Photograph and measure every retained item, with its full operating footprint.

The room before and the proposal. Choose a piece in the inventory to find it in both plans.

Understanding furniture dimensions.

The footprint is not the space it takes.

Furniture is described by width, depth and height, but those numbers rarely say how much room it occupies in use. A dining chair slides back when someone sits; a cabinet needs room for its doors and drawers; a recliner extends well beyond its footprint.

Product dimensions

The physical size of the object itself: width, depth and height.

Operating dimensions

The extra space needed to use it or move its parts: a chair pulled back, a drawer pulled out, a door swung open.

Access clearances

The free space people need to approach it, pass around it or use it.

A desk, a task chair and a cabinet, in plan and elevation. Put them in use to see the space they really take.

Early plans can use approximate blocks; detailed layouts must eventually carry the dimensions of the selected products.

Typical furniture dimensions.

Ranges for testing a room, not for ordering.

Sizes vary between manufacturers and markets, but approximate ranges tell you quickly whether a room can hold what it must. Choose a piece to see its size, the body that uses it and the space around it.

Typical dimensions in elevation, with the person using the piece, and in plan with its operating space.
FurnitureTypical dimensionsWhat to verify
Dining chairSeat height 430–480 mmTable compatibility, seat depth, chair movement
Lounge chairSeat height 380–460 mmComfort, recline, back support
Dining tableHeight 720–760 mmKnee clearance, seating capacity
Coffee tableHeight 300–450 mmRelationship to seating, access
Fixed deskHeight about 720–750 mmUser posture, adjustability
Bar or counter stoolSeat height about 600–800 mmCounter height, footrest position
SofaOverall depth about 800–1050 mmSeat depth, armrests, backrest
WardrobeInternal hanging depth about 550–600 mmDoor type, garment clearance
Double bedMattress width commonly 1350–1800 mmFrame dimensions, bedside access

For preliminary planning only: take exact sizes from the manufacturer before a furniture plan is issued. Nominal sizes are not outside dimensions either: a bed sold for a 1600 mm mattress can have a much wider frame.

Ergonomics and comfort.

Furniture fits bodies, and bodies vary.

Bodies vary in height, proportion, strength, mobility and posture, and the right dimensions depend on the activity as much as the person. A seat for relaxed conversation sits lower and leans back further than a dining chair.

Three seated activities in elevation. Values are illustrative, not mandatory.

Seating

Seat height decides how easily people sit down and stand up; seat depth decides thigh support and whether the backrest can be used; armrests help posture and movement.

A very deep sofa is fine for lounging and poor for upright conversation; a low armchair can be hard to leave. Test furniture whenever you can, rather than trusting photographs or numbers.

Tables and desks

The gap between seat and work surface sets arm position, legroom and posture. Overall height is not enough: aprons, rails, legs and bases can catch knees and feet.

For long hours at a screen, adjustable furniture fits a wider range of bodies and working positions.

Different users

What suits an average adult may not suit children, older occupants or people with reduced mobility.

An inclusive scheme plans for variation, not for one assumed body.

Materials, construction and durability.

What it is made of, and how.

A sofa may combine a timber or metal frame, suspension, foam or other cushioning, upholstery and mechanical connectors: its durability depends on all of them. Judge construction alongside appearance. A sound frame, reliable joints, replaceable parts and suitable upholstery greatly extend a piece’s useful life.

An armchair taken apart, layer by layer; and a veneered cabinet panel in section: core, veneer, edge.
MaterialTypical applicationsMain considerations
Solid timberChairs, tables, framesMovement, repairability, finish care
PlywoodCabinetry, moulded furnitureLayer construction, edge treatment
MDF or particleboardCabinets, veneered panelsMoisture resistance, fixing strength
SteelFrames, supportsStrength, weight, corrosion protection
AluminiumLightweight framesFinish, joint design
GlassTables, shelvingSafety, edge treatment, scratching
Upholstery textilesSeating, padded panelsAbrasion, cleaning, fading, flammability
LeatherSeatingWear, patina, care
Plastics and compositesChair shells, outdoor furnitureAgeing, repairability, environmental impact

Commercial projects may need particular strength, stability, fire-safety and durability performance: check the manufacturer’s testing and certification against the intended use.

Upholstery and soft furniture.

Comfort, character and care.

Upholstery shapes comfort, visual character, maintenance and durability. Tightly woven fabrics suit seating in daily use; delicate decorative textiles are better kept for occasional pieces. Choose by abrasion performance (the Martindale rub count), seam strength, cleaning, colourfastness, pilling and the furniture fire-safety rules that apply.

One shape, four treatments. Piping, legs, skirts, tufting and seams change the same chair entirely.

Fixed upholstery

The fabric is fitted directly to the frame, for a controlled, often more tailored look. Replacing it may need a professional upholsterer.

Removable covers

Covers come off for cleaning or replacement, but need a stable fabric, the right fastenings and laundering that will not shrink them.

Furniture selection in practice.

Compare against the same criteria.

Balance function, appearance, cost and life cycle. A cheap chair becomes expensive if it must be replaced often; a very durable one is no use if nobody local can repair it; and top performance may be wasted in a lightly used private room. Compare several products against common criteria rather than on looks alone.

Three lounge chairs compared on the same criteria. Switch the setting to see which suits it.
CriterionQuestions to ask
FunctionDoes it support the intended activity?
DimensionsDoes it fit, physically and in use?
ComfortDoes it suit the intended users?
AppearanceDoes it serve the design concept?
DurabilityWill it withstand the expected use?
MaintenanceCan it be cleaned, repaired or refurbished?
CostDoes it fit the budget?
AvailabilityCan it be delivered within the schedule?
SustainabilityCan it be kept, reused, repaired or recycled?

Checklist.

Before you choose.

Go through the list for each room. Your ticks are kept in this browser.

Furniture selection

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Where to go next.

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5 · Furnishing

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Furniture layout and installation

Units