The staircase
| Construction | ₹ range | Footprint | Note |
|---|---|---|---|
| Existing RCC flight, clad in stone | ₹2.5 – 5.5 L | As built | The default when the developer provided the flight; stone, riser lighting, balustrade |
| Existing RCC, clad in timber | ₹3.5 – 7.5 L | As built | Warmer and quieter underfoot; needs a proper sub-frame, not tiles of timber |
| New MS stringer with timber treads | ₹5.5 – 11 L | Roughly 45 – 60 sq ft per floor | Lighter visually; needs a structural connection at both levels |
| Cantilevered treads from a wall | ₹9 – 18 L | Roughly 40 – 55 sq ft | The most striking and the most demanding; requires a designed structural wall |
| Spiral | ₹3 – 7 L | 28 – 40 sq ft | Saves area and is genuinely difficult to carry furniture on. Think twice |
| Balustrade, glass | ₹2,800 – 6,500 per running foot | — | 12 mm toughened, spigot or channel fixed |
| Balustrade, MS or brass | ₹1,800 – 5,500 per running foot | — | More characterful, easier to fix, needs a competent fabricator |
Ex-GST. Riser height 150–180 mm, going 250–300 mm, headroom 2,000 mm minimum measured vertically from the nosing.
Splitting the two floors
- Public below, private above, in almost every case. Entrance, living, dining, kitchen and a powder room on the lower floor; bedrooms above. It matches how visitors move and it keeps the noisy half at the bottom.
- Put one bedroom downstairs where you can. Parents, guests, or your own room in twenty years. A duplex with every bedroom upstairs is a home that stops working when somebody cannot climb.
- The kitchen stays on the entrance floor. Groceries, deliveries and waste all arrive at the front door, and carrying them up a flight daily is a design failure.
- The utility follows the kitchen, with a second washing point upstairs only if the household genuinely needs it.
- A powder room downstairs is not optional. Guests should not be going up to the private floor.
- Put the study where the quiet is, which is usually upstairs at the end away from the stair.
The staircase is the plan, not a detail in it
Impact noise between floors
This is the one complaint every under-designed duplex generates. Footsteps, a chair dragged, a dropped object — all of it transmits through the slab as structure-borne noise, and it is far more intrusive than airborne sound.
- A resilient layer under the upper floor finish. A 5–10 mm acoustic underlay under tile, timber or stone costs ₹90–₹280 per sq ft and is the single most effective intervention available.
- Carpet or a rug where people walk most. Unglamorous, and it works better than anything else.
- A suspended ceiling below with an air gap and insulation. A 100 mm void with 50 mm mineral wool and resilient hangers helps with airborne noise and, modestly, with impact.
- Isolate the staircase from the structure where you can. An MS stringer bolted rigidly to the slab transmits every footstep into the lower floor as a drum.
- Put the upstairs bathrooms above the downstairs bathrooms or the kitchen, never above a bedroom or the living room. Plumbing noise at night is the second most common duplex complaint.
- Soft-close everything upstairs. A drawer closed sharply on the upper floor is audible on the lower one.
Services, twice
| Service | What a duplex needs | Why |
|---|---|---|
| Electrical | A distribution board per floor, each with its own RCBO | One DB for both floors means an upstairs bathroom fault kills the downstairs lighting |
| Water | A riser with isolation valves on each floor | Isolating a leak on one floor without shutting the whole home |
| Hot water | A geyser per bathroom, or a central unit with a return loop | A single geyser downstairs means a two-minute wait upstairs, every time |
| AC drainage | A condensate route per floor with its own fall | Draining an upper-floor unit through the lower floor ceiling is a future leak |
| Data | A cabinet on one floor and a cabled point on both | Concrete slabs defeat Wi-Fi between floors more than walls do |
| Lighting control | Two-way switching at the top and bottom of the stair | Sounds obvious; it is omitted surprisingly often |
| Backup | One inverter, with circuits taken to both floors | Sizing and position decided early, because the cable route is easier before finishes |
Every duplex we are asked to fix has the same two problems: you can hear the upstairs floor, and the geyser is on the wrong level. Both are decided in week two of the design and both are expensive in week forty.
Greenbox principal designer
Double height, if you have it
A double-height volume over the living area is the reason many people buy a duplex, and it comes with four consequences worth planning for. It is acoustically live, so the room needs soft surfaces or conversation becomes tiring. It needs a lighting plan that can be maintained — a pendant at six metres requires either a winch, a scaffold or a very long ladder, and one of those has to be decided at design stage. It is thermally awkward, because cooled air falls and the upper level stays warm, so the air conditioning is zoned rather than shared. And it needs a guard rail or a balustrade at the upper level that is designed rather than added, with 1,100 mm height and no climbable horizontal members if there are children.
What sits under the stair
The volume beneath a straight flight is between 35 and 60 cubic feet and it is the most wasted space in most duplexes. Five things use it well and one uses it badly.
- A powder room, where the drainage allows it. Needs 1,600 mm of headroom at the WC position and a drain within reach of the stack; where both are available it is the best use of the space.
- Full-height storage with the doors following the rake. Three or four doors of decreasing height, each a separate compartment. More expensive to make than one big cupboard and vastly more usable.
- Pull-out drawers on runners. The deep end of the space is unreachable from a door; a drawer brings it out to you. This is the detail that turns the stair void from theoretical storage into real storage.
- A reading nook or a desk at the high end, which needs 1,900 mm of headroom over the seated position and a light.
- Shoe storage at the entrance end. Ventilated, slatted, and exactly where people take their shoes off.
- Not an open display. The space under a stair is visually busy already; adding objects makes the lower floor read cluttered from every angle.
Related and local
For city constraints — society rules on internal stairs, mill-land tower duplexes and local rates — see duplex interior designers in Mumbai. A duplex on the top floor with a terrace is a different brief; see penthouse interior design. For a standalone house on multiple levels, villa interior design and row house interior design.
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
What does a duplex staircase cost to finish?+
₹2.5–₹5.5 lakh to clad an existing RCC flight in stone, ₹3.5–₹7.5 lakh in timber, ₹5.5–₹11 lakh for a new MS stringer with timber treads and ₹9–₹18 lakh for cantilevered treads, all ex-GST. Balustrade is separate at ₹2,800–₹6,500 per running foot in glass or ₹1,800–₹5,500 in MS or brass.
How do you stop hearing footsteps from the floor above?+
A 5–10 mm resilient acoustic underlay beneath the upper floor finish at ₹90–₹280 per sq ft is the single most effective measure, followed by rugs where people walk most and a suspended ceiling below with a 100 mm void, 50 mm mineral wool and resilient hangers. Isolating the staircase from the structure matters too.
Should bedrooms be upstairs in a duplex?+
Most of them, yes — public below and private above matches how visitors move and keeps the noisy half at the bottom. But keep one bedroom downstairs where the plan allows, for parents, guests or your own use later. A duplex with every bedroom upstairs stops working the day somebody cannot climb.
Where should upstairs bathrooms go?+
Directly above the downstairs bathrooms or the kitchen, never above a bedroom or the living room. Plumbing noise at night is the second most common duplex complaint after footsteps, and stacking the wet areas also shortens every pipe run and reduces the chance of a leak.
Does a duplex need two distribution boards?+
Yes, one per floor with its own RCBO protection, plus water isolation valves on each level, a geyser per bathroom or a central unit with a return loop, and a separate condensate route per floor. Running an upper-floor AC drain through the lower ceiling is a leak waiting to happen.
What should I know before committing to a double-height living room?+
It is acoustically live and needs soft surfaces; the lighting at six metres needs a maintenance method decided at design stage, whether a winch, a scaffold point or a reachable position; the air conditioning has to be zoned because cool air falls and the upper level stays warm; and the upper-level guard needs to be 1,100 mm with no climbable horizontals.