Residential interior design

In short

Residential interior design is the planning and detailing of the interior of a dwelling - apartment, villa, row house or studio - so that living, sleeping, cooking, washing, storing and moving happen comfortably within a fixed shell. Its core skill is space planning: converting a family's brief and daily routines into zones, circulation and furniture layouts that obey anthropometric clearances, the National Building Code of India 2016, local development control rules and the structural grid. It matters because Indian homes are small, multi-generational and often altered after possession, so a few hundred millimetres decide whether a kitchen works or a door jams. It is examined in B.Des / B.Sc Interior papers on space planning, design studio juries and building-services viva, and tested in interviews at Livspace, HomeLane, Design Cafe, Pepperfry Studio, Sleek, Godrej Interio, Asian Paints Beautiful Homes, Arrivae and with developers and architectural practices, where candidates are asked to lay out a 2BHK, size a kitchen or read a RERA carpet-area drawing.

Explained

Brief, user study and residential typologies

• Design brief: family size and age profile, joint or nuclear, cooking style (wet Indian cooking, tandoor, non-veg separation), domestic help, work-from-home needs, religious space, guests, pets, vehicles, budget and timeline.
• Lifestyle survey tools: user interview, activity log (what happens hour by hour), inventory of possessions (utensils, sarees, suitcases, appliances), then an area programme (room-by-room area statement) and an adjacency matrix.
• Typologies: studio / 1RK, 1BHK, 2BHK, 3BHK apartments; duplex and penthouse; row house; independent villa / bungalow; farmhouse; service apartment; co-living and hostel-type dwelling; EWS/LIG housing under PMAY.
• Indian area norms (indicative, scheme-dependent): PMAY-U carpet area limits were 30 m² (EWS), up to 60 m² (LIG), up to 160 m² (MIG-I) and up to 200 m² (MIG-II); scheme definitions change, so quote the current scheme guideline rather than a remembered figure.
• Carpet vs built-up vs super built-up: carpet area = usable floor area within walls, excluding balcony, verandah, open terrace, service shafts and external walls, while the thickness of internal partition walls *is included* per the RERA definition; built-up = carpet + walls + balcony; super built-up = built-up + share of common areas. RERA (Real Estate (Regulation and Development) Act, 2016) requires sale by carpet area, and interior quotations are normally taken off carpet area or on-site measurement.

Zoning, bubble diagrams and circulation

• Zones by privacy: *public* (entry, foyer, living, dining, powder room), *semi-private* (family room, study, kitchen), *private* (bedrooms, dressing, toilets), *service* (utility, wash, store, servant room, shafts).
• Zones by noise and moisture: dry zones (bedroom, living) separated from wet zones (kitchen, toilets, utility) which must stack over the plumbing shaft; noisy zones (TV, children) kept away from sleeping zones.
• Process: brief → area programme → adjacency matrix → bubble diagram (loose circles sized by area, linked by adjacency) → block/zoning plan (bubbles squared off onto the structural grid) → furniture layout → services and lighting layout → detailing.
• Circulation types: central corridor, peripheral, radial from a lobby, open plan with implied paths. Target 10-15% of carpet area for circulation in an apartment; above ~20% the plan is wasteful.
• Clear widths: main corridor/passage 900-1,050 mm; single-person passage 750 mm minimum; between kitchen counters 900-1,200 mm; around a dining table 900 mm for passing with a chair pulled out (600 mm absolute minimum against a wall).
• Dead ends, cross-traffic and door swings: never let circulation cut through the seating arc of a living room or across the kitchen work triangle; check every door swing against switchboards, wardrobes and other doors.
• Open plan vs cellular: open plan gives visual spaciousness, shared daylight and flexible furniture but poor acoustic/odour control (a real problem with Indian frying); cellular gives privacy and AC efficiency but needs more circulation and wall area.

Room-by-room planning standards

• Entry/foyer: 1,200 × 1,200 mm minimum for turning with bags; shoe storage 350-400 mm deep, console 300-400 mm, mirror, key drop; avoid direct view into the bedroom corridor.
• Living room: seating distance to a TV about 1.5-2.5 times the screen diagonal; coffee table 400-450 mm from the sofa, height 400-450 mm; conversation circle up to 2.4-3.0 m across; sofa depth 850-950 mm, seat height 400-430 mm.
• Dining: 600 mm table width per diner, 750-760 mm table height, 450 mm chair seat; allow 750-900 mm clear behind each chair. A 4-seater needs roughly 2.4 × 2.4 m of room, a 6-seater about 2.7 × 3.3 m.
• Bedroom: king bed 1,800 × 2,000 mm, queen 1,500 × 2,000 mm, single 900 × 1,900 mm; 600-750 mm clear on at least one long side and the foot; bedside table 450-600 mm; master bedroom rarely works below 3.0 × 3.6 m.
• Wardrobe: depth 600 mm (hanging needs 550 mm clear), shutter 450-600 mm wide; hanging rod for shirts at 1,050-1,200 mm clear height, long hang 1,500-1,700 mm; loft above 2,100 mm. Allow 900 mm clear in front of a sliding wardrobe, 1,050 mm for hinged.
• Kitchen: counter height 850-900 mm (tie to the user's elbow height minus ~100-150 mm), depth 600 mm, clear height under wall units 500-600 mm, wall unit depth 300-350 mm; work triangle (sink-hob-refrigerator) with each leg 1.2-2.7 m and perimeter 4-8 m. Hob never directly below a window or beside a door; minimum 300-400 mm landing space either side of the hob and sink.
• Kitchen layouts: single wall (small flats), parallel/galley (most Indian 2BHK utilities), L-shaped (best triangle for small homes), U-shaped (maximum storage), island and peninsula (needs ≥ 3.6 m clear width). Zone the kitchen as store → wash → prepare → cook → serve.
• Toilet: WC needs 450-500 mm clear width either side of centre and 600 mm clear in front; washbasin 800-850 mm rim height; shower 900 × 900 mm minimum; dry and wet areas separated by a glass partition or 10-12 mm step with slope 1:50 to 1:80 toward the floor trap. A common toilet of 1,200 × 2,100 mm (about 2.5 m²) is workable; 1,500 × 2,400 mm is comfortable.
• Utility/wash: washing machine 600 × 600 mm with a tap, drain point and 150 mm service gap behind; space to dry, and a sink for the pre-wash Indian households actually do.
• Study/WFH: desk 1,200 × 600 mm, seat height 450 mm, desk height 750 mm, 900 mm clear behind the chair; daylight from the side, not behind the screen.

Codes, statutory and practice framework in India

• National Building Code of India 2016 (NBC, SP 7 : 2016), Part 3 (Development Control and General Building Requirements) governs habitable room sizes, minimum ceiling heights, openings and ventilation. Widely applied figures: habitable room minimum area about 9.5 m² with least width 2.4 m (a second room may be 7.5 m²); kitchen minimum about 5.0 m² with least width 1.8 m; bath 1.8 m², WC 1.1 m², combined bath-WC about 2.8 m²; minimum clear floor-to-ceiling height 2.75 m for habitable rooms (lower for kitchens, toilets, corridors and under-beam/AC-duct conditions). State and municipal building bye-laws and the local UDCPR/DCR override these - always verify against the sanctioned drawing.
• Light and ventilation: openable window area generally not less than about one-tenth of the floor area for habitable rooms, with a minimum openable area of about 0.3 m² for bathrooms and WCs; NBC Part 8 Section 1 covers lighting and ventilation, and the relevant IS code on natural lighting of buildings supports daylight factor computation.
• Means of egress and fire: NBC 2016 Part 4 (Fire and Life Safety) - for apartments above 15 m height, no combustible false ceiling in escape routes, no blocking of fire doors or refuge areas; interior finishes in high-rises are checked for flame-spread class. Interiors must never close or obstruct a fire exit, duct or refuge.
• Structural restraint: never cut a column, beam or shear wall; a 115 mm brick partition weighs roughly 2-2.5 kN per m² of wall face (about 6-7 kN/m of line load on the slab for a 3 m high wall), so heavy stone cladding, bath tubs and water features need the structural consultant's clearance. Sunk slabs and plumbing shafts are fixed - toilet repositioning is largely limited by them.
• Electrical: IS 732 (code of practice for electrical wiring installations) and the Central Electricity Authority (Measures relating to Safety and Electric Supply) Regulations; switchboard at 1,200-1,350 mm, sockets 300 mm or 1,050 mm above counter, earthing and MCB/RCCB provision, separate AC circuits.
• Plumbing: NBC Part 9 and the Uniform Plumbing Code India (UPC-I) for fixture units, traps, vents and slopes; IS 1172 covers water requirement (commonly 135 litres per capita per day for domestic supply in planning estimates).
• Accessibility: Rights of Persons with Disabilities Act, 2016 and the Harmonised Guidelines and Standards for Universal Accessibility in India (2021) - 900 mm clear door width, 1,500 mm turning circle for a wheelchair, grab bars, no thresholds; essential in senior-living and retrofit work.
• Consumer and commercial practice: work orders under the Indian Contract Act, 1872; consumer complaints under the Consumer Protection Act, 2019; GST on interior works is generally 18% as a works contract or on modular furniture supply (slabs since 22 September 2025 are 5%/18%/40%, so confirm the current rate and HSN for each item before quoting). Society NOC, work timings and material-lift rules apply to apartment fit-outs.
• Vastu Shastra: not a statute but a strong client expectation - kitchen in the south-east (Agni), master bedroom in the south-west, entry preferred north/east, no toilet above/adjacent to a kitchen or puja, head to the south while sleeping. Treat it as a client requirement to be reconciled with function and daylight, not a technical code.

Materials, services and detailing for homes

• Finishes by zone: anti-skid vitrified or ceramic tile (wet areas, minimum R10-R11 class slip resistance), vitrified/engineered wood in bedrooms, granite or quartz kitchen counter, acrylic/laminate shutters; moisture-resistant BWR/BWP grade plywood (IS 303 for plywood, IS 710 for marine/BWP) in kitchens and bathroom vanities.
• Modular furniture: carcass 18 mm ply/HDF-HMR, shutters 18 mm with 0.8-1 mm laminate or 2 mm acrylic; hardware - soft-close hinges, telescopic channels, tandem boxes, lift-up fittings; standard base unit 600 mm deep, 720-900 mm high on a 100 mm skirting.
• False ceiling and lighting layers: gypsum board on GI framing, drop of 150-300 mm for AC ducting and cove lighting; keep minimum 2.4 m clear under the ceiling. Layer ambient + task + accent; typical illuminance targets from the Indian lighting code (SP 72 / IS 3646 series): living 100-150 lux, kitchen counter 300-500 lux, study desk 300-500 lux, bathroom mirror 200-300 lux; choose 2700-3000 K warm white for living and bedrooms, 4000 K neutral for kitchens.
• Ventilation and comfort: cross-ventilation across opposite walls, kitchen exhaust 10-15 air changes per hour or a chimney rated roughly 10 × kitchen volume in m³/h; split-AC indoor unit needs 150 mm above and clear throw along the room's long axis; drain slope for AC and washing machine must be planned before the false ceiling.
• Acoustics and odour: gypsum or AAC partitions with glass wool between bedrooms; door undercuts for airflow but acoustic seals where privacy matters; separate dry and wet kitchen in heavy-cooking homes.
• Storage rule of thumb: aim for about 10-15% of carpet area as storage volume; use lofts above 2,100 mm, under-bed hydraulic storage, staircase drawers, and 100-150 mm deep niches inside 230 mm walls where structurally possible.

Small-home and renovation strategies

• Multifunction and transformable: sofa-cum-bed, wall bed (Murphy), folding/extendable dining, study that folds into a wardrobe, convertible guest-puja room.
• Visual spaciousness: light value finishes, continuous flooring across rooms, full-height doors, mirror on a single wall, ceiling-height wardrobes, open shelving at eye level only.
• Non-structural gains: swap swing doors for sliding/pocket doors (saves ~0.8-1.0 m² per door), replace a 230 mm wall with a 75-100 mm partition, use the dead corner above the door as a loft.
• Renovation sequence: site measurement and condition survey → society NOC and permissions → demolition and debris disposal → plumbing/electrical rough-in → waterproofing (wet areas, 48-hour ponding test) → masonry and plaster → flooring → false ceiling → putty/primer → carpentry installation → painting final coat → fittings, deep clean, snag list, handover with as-built drawings and warranties.
• Drawing set: existing/demolition plan, proposed layout, furniture layout, flooring plan, ceiling plan, electrical and lighting layout, plumbing layout, wall elevations, joinery details at 1:10 or 1:5, finish schedule, BOQ. Standard scales: 1:50 for plans, 1:20 for elevations, 1:5/1:1 for details.

Key points

• Space planning - matching activity, furniture and clearance to available area before any style decision.
• Bubble diagram - area-proportionate circles linked by adjacency; the first graphic step from brief to plan.
• Zoning - grouping spaces by privacy (public/private/service), by wetness and by noise.
• Circulation - 10-15% of carpet area, 900 mm main passage, 750 mm absolute minimum; never through a seating or work zone.
• Carpet area - usable area within walls as defined by RERA 2016; interiors are quoted on it or on measured site dimensions.
• NBC 2016 Part 3 - habitable room ~9.5 m² with 2.4 m least width, kitchen ~5 m²/1.8 m, 2.75 m clear height; local bye-laws override.
• Work triangle - sink, hob, refrigerator; each leg 1.2-2.7 m, perimeter 4-8 m, no traffic crossing it.
• Kitchen layouts - single wall, galley, L, U, island; galley needs 900-1,200 mm between counters.
• Counter and wardrobe depths - kitchen counter 600 mm at 850-900 mm high; wardrobe 600 mm deep with 1,050-1,200 mm hanging height.
• Bed clearances - 600-750 mm on one long side and the foot; king 1,800 × 2,000 mm.
• Toilet clearances - 450-500 mm each side of the WC centreline, 600 mm in front, 900 × 900 mm shower, slope 1:50 to 1:80.
• Wet-area stacking - toilets, kitchen and utility must sit over the existing sunk slab and plumbing shaft; relocation is rarely free.
• Daylight and ventilation - openable area about one-tenth of floor area; cross-ventilation beats a single window.
• Lighting layers - ambient, task, accent; kitchen counter 300-500 lux, living 100-150 lux (SP 72 / IS 3646 series).
• Grade of plywood - BWR/BWP (IS 303 / IS 710) in wet zones; MR grade only in dry bedrooms.
• Accessibility - RPwD Act 2016 and the 2021 Harmonised Guidelines: 900 mm doors, 1,500 mm turning circle, grab bars.
• Vastu - a client requirement, not a code; reconcile with function, services and daylight.
• Storage target - about 10-15% of carpet area; exploit lofts, under-bed and wall niches in small flats.

Formulas and examples

Example 1 - Area statement and loading factor for a 2BHK. Rooms (clear internal): living+dining 3.6 × 5.0 = 18.00 m²; master bedroom 3.3 × 3.6 = 11.88 m²; second bedroom 3.0 × 3.3 = 9.90 m²; kitchen 2.1 × 2.7 = 5.67 m²; master toilet 1.5 × 2.1 = 3.15 m²; common toilet 1.2 × 2.1 = 2.52 m²; passage 1.0 × 3.0 = 3.00 m².

• Carpet area = 18.00 + 11.88 + 9.90 + 5.67 + 3.15 + 2.52 + 3.00 = 54.12 m² (≈ 582 sq ft, using 1 m² = 10.7639 sq ft → 54.12 × 10.7639 = 582.5 sq ft).
• Circulation = 3.00 ÷ 54.12 × 100 = 5.5% (low, because living/dining absorbs movement - acceptable).
• If walls + balcony add 9.9 m², built-up = 64.02 m²; with 30% loading, super built-up = 64.02 × 1.30 = 83.2 m² (896 sq ft). The flat is sold as "896 sq ft" but only 582 sq ft is usable - the number interiors are costed on.

Example 2 - Kitchen work triangle, galley layout. A galley kitchen 2.1 m wide × 2.7 m long, counters 600 mm deep on both long walls.

• Clear walkway = 2.1 − 0.6 − 0.6 = 0.9 m - the minimum acceptable; it fails if two people must pass or if a 600 mm wide appliance door opens.
• Sink on the left wall at 0.9 m from the window end, hob on the right wall at 1.8 m, refrigerator on the left wall at 2.4 m. Taking the walkway centre line, leg lengths across the 1.5 m counter-to-counter centre distance:
• sink → hob = √(1.5² + 0.9²) = √(2.25 + 0.81) = √3.06 = 1.75 m
• hob → fridge = √(1.5² + 0.6²) = √(2.25 + 0.36) = √2.61 = 1.62 m
• fridge → sink = 2.4 − 0.9 = 1.50 m (same wall)
• Perimeter = 1.75 + 1.62 + 1.50 = 4.87 m - inside the 4-8 m band, every leg within 1.2-2.7 m: an efficient triangle.

Example 3 - Bedroom furniture fit check. Room 3.3 m × 3.6 m; king bed 1.8 × 2.0 m against the 3.3 m wall, wardrobe 600 mm deep × 2.4 m long on the opposite wall.

• Along the 3.6 m dimension: bed length 2.0 + wardrobe depth 0.6 = 2.6 m → clear gap = 3.6 − 2.6 = 1.0 m at the foot - clears the 900 mm needed for a sliding wardrobe, but just short of the 1,050 mm preferred for hinged shutters, so specify sliding shutters here.
• Along the 3.3 m dimension: bed width 1.8 m centred leaves (3.3 − 1.8)/2 = 0.75 m each side - enough for a 450-600 mm bedside table plus passage. Pass.
• Window area needed = (3.3 × 3.6)/10 = 11.88/10 = 1.19 m² openable - so a 1.5 m × 1.2 m window (1.8 m² with about 70% openable = 1.26 m²) just satisfies it.

Example 4 - Lighting and material quantity for a living room. Living room 3.6 × 5.0 m = 18 m², target 150 lux ambient, UF = 0.6, MF = 0.8.

• Required lumens Φ = E × A ÷ (UF × MF) = 150 × 18 ÷ 0.48 = 2,700 ÷ 0.48 = 5,625 lm.
• Using 10 W LED downlights at 900 lm each: 5,625 ÷ 900 = 6.25 → 7 fittings (load 70 W, about 3.9 W/m²).
• Flooring: 600 × 600 mm vitrified tiles = 0.36 m² each; with 8% wastage, 18 × 1.08 ÷ 0.36 = 19.44 ÷ 0.36 = 54 tiles.
• At ₹95 per sq ft material, floor cost = 18 × 10.7639 = 193.75 sq ft → 193.75 × 95 = ₹18,406 before laying, adhesive and GST (confirm the current GST rate and HSN before quoting).

Example 5 - Wardrobe internal planning. Wardrobe 2.4 m long × 0.6 m deep × 2.4 m high for two adults, shutters 600 mm wide → 4 shutters.

• Vertical split: loft 2,100-2,400 mm (300 mm, suitcases); long hang 1,500 mm clear for sarees/coats in one bay; two bays of double hang (2 × 1,050 mm shirts/trousers); one bay of 6 drawers at 200 mm.
• Hanging rod capacity: a shirt needs ~25 mm of rod → double-hang bays give 2 × 0.6 m × 2 bays = 2.4 m of rod ≈ 96 garments, plus 0.6 m long hang ≈ 24 long garments.

Where it is used

• Organised interior firms: Livspace, HomeLane, Design Cafe, Arrivae, Pepperfry Studio, Sleek, Godrej Interio - roles of design consultant, space planner, 3D visualiser, project/site coordinator, with layouts standardised on modular module sizes.
• Developer and architectural practices: show-flat and sample-apartment interiors, fit-out guidelines for Lodha, Godrej Properties, DLF, Prestige, Brigade; unit-plan optimisation to maximise saleable carpet area within FAR.
• Independent practice and renovation: apartment makeovers, bungalow interiors, kitchen-only and wardrobe-only projects, heritage and old-house retrofits in Mumbai, Pune, Kochi, Jaipur.
• Modular kitchen and furniture manufacturing: design-for-manufacture, cut-lists, hardware selection, factory drawings for Hettich/Hafele/Ebco fittings and Century/Greenply boards.
• Affordable and institutional housing: PMAY units, staff quarters, co-living and student housing where every square metre is specified; NGO and government design cells.
• Allied roles: real-estate marketing (reading and redrawing floor plans), home-furnishing retail (IKEA, Home Centre) space-planning desks, and content/visual styling for home-décor brands.

Interview questions

• Q: What is the first thing you do when handed a 2BHK layout and a client brief? A: Measure or verify the plan on site, mark fixed constraints - columns, beams, plumbing shaft, sunk slab, window and door positions, electrical riser - and only then zone the plan, because those constraints decide what is movable.
• Q: Difference between carpet, built-up and super built-up area? A: Carpet is usable area within walls as defined under RERA 2016, built-up adds wall thickness and balcony, super built-up adds a share of common areas; sale is legally on carpet area and interiors are costed on it.
• Q: Explain the kitchen work triangle and one case where it fails. A: It is the sink-hob-refrigerator loop with each leg 1.2-2.7 m and a 4-8 m perimeter; it fails in a single-wall kitchen or when a doorway or island makes traffic cut across the triangle.
• Q: Minimum clear walkway between two parallel kitchen counters? A: 900 mm is the working minimum and 1,050-1,200 mm is comfortable, because a 600 mm deep drawer or appliance door must open with a person standing behind it.
• Q: How much circulation should a residential plan have? A: Roughly 10-15% of carpet area; below that rooms become connecting corridors, above 20% usable area is being wasted on passages.
• Q: A client wants the toilet shifted 2 m into the bedroom. What do you tell them? A: It depends on the sunk slab and plumbing shaft - moving the WC away from the stack needs a long slope, a raised floor or a macerator, plus fresh waterproofing and often a society and structural clearance; usually it is better to re-plan the fixtures within the existing wet footprint.
• Q: Which clearances do you check around a bed? A: 600-750 mm clear on at least one long side and at the foot, 1,050 mm in front of a hinged wardrobe (900 mm if sliding), and a door swing that does not hit the bed or bedside table.
• Q: How do you handle a Vastu requirement that breaks the functional plan? A: Treat it as a client requirement, satisfy what is compatible - kitchen to the south-east, head of bed to the south - and explain in drawings and daylight terms where a demand conflicts with services, daylight or the structural grid, offering the nearest workable alternative.
• Q: What plywood grade goes into a kitchen base unit and why? A: BWP/marine grade to IS 710 or at least BWR to IS 303, because phenolic-bonded ply resists the water and steam a kitchen base unit sees; MR grade belongs only in dry bedroom furniture.
• Q: Which code governs minimum room sizes and ceiling height in India? A: The National Building Code of India 2016 (SP 7), Part 3, with the local municipal bye-laws or development control regulations prevailing where they differ - commonly ~9.5 m² habitable room with 2.4 m least width and 2.75 m clear height.
• Q: How do you make a 1BHK feel larger without demolition? A: Continuous light-toned flooring, full-height doors and wardrobes, sliding or pocket doors to save 0.8-1.0 m² per door, multifunction furniture, mirror on one wall, and layered lighting instead of a single central fixture.
• Q: What would you include in the drawing set you hand to site? A: Demolition and proposed layout, furniture, flooring, ceiling, electrical/lighting and plumbing layouts, wall elevations, joinery details at 1:10 or 1:5, finish schedule and BOQ, followed by as-built drawings at handover.

Common mistakes

• Planning furniture from a brochure plan instead of a site measurement, then finding walls out of square and 50-80 mm short.
• Ignoring door and wardrobe swings, AC indoor-unit position, switchboards and the fridge door direction in a layout that otherwise "fits".
• Treating super built-up area as usable - quoting or planning on an area 30-40% larger than the real carpet.
• Shifting wet areas without checking the sunk slab, shaft and slope, or skipping the 48-hour ponding test after waterproofing.
• Drawing a kitchen triangle on paper but letting the main circulation route pass straight through it.
• Quoting NBC figures as absolute when the local bye-law, UDCPR or society fit-out rule governs; also quoting withdrawn IS numbers from old notes.
• Designing only ambient lighting - no task light at the kitchen counter, study desk or mirror - and dimensioning drawings in mixed feet and millimetres.

Related topics

Space planning and anthropometrics · Ergonomics and human factors · Commercial interior design: offices, hospitality and retail · Building materials and finishes · Building services: electrical, plumbing and HVAC for interiors · Estimation, costing and BOQ for interior projects