Where Mumbai penthouses are
| Area | Typical carpet | The view | ₹ / sq ft |
|---|---|---|---|
| Worli, Prabhadevi, Lower Parel | 2,000 – 4,000 sq ft | Sea link, Arabian Sea, city | ₹3,600 – 6,800 |
| Bandra West, Bandstand, Khar | 1,800 – 3,500 sq ft | Sea, Bandra fort, Sea Link | ₹3,400 – 6,500 |
| Malabar Hill, Walkeshwar | 2,200 – 5,000 sq ft | Back Bay, Marine Drive | ₹3,800 – 6,800 |
| Powai and Hiranandani | 1,600 – 3,000 sq ft | Powai lake, hills | ₹2,700 – 4,200 |
| Thane and Ghodbunder | 1,800 – 3,400 sq ft | Yeoor hills, creek | ₹2,500 – 3,800 |
| Navi Mumbai and Palm Beach | 1,800 – 3,500 sq ft | Creek, hills, golf course | ₹2,500 – 3,900 |
Carpet area basis, ex-GST, interior only. Terrace at ₹1,500–₹5,500 per sq ft depending on how much of it is covered and serviced.
The terrace, in a monsoon city
- Waterproofing is laid between October and May. A membrane applied to a damp deck in the monsoon debonds within one season, and the failure appears in the room below yours, which is your own bedroom. This is the single most important programme constraint on a Mumbai penthouse.
- Use a warranty-backed specialist, not the general contractor. A polyurethane or APP membrane with a written warranty, a documented 48-hour ponding test and photographs. Budget ₹250–₹650 per sq ft.
- Two drains minimum, both accessible. Mumbai rain arrives at 60–100 mm an hour in a heavy spell, and a single blocked outlet floods the terrace and then the flat.
- Root barrier under any planting bed. Roots find a membrane joint within three years, and the repair means lifting everything above it.
- Fall of 1:100 minimum, formed in the screed and verified with water before anything is laid over it.
- Specify a lifted deck over the membrane, on pedestals, so the membrane can be inspected and repaired without demolition. It costs ₹350–₹900 per sq ft more than a bonded finish and it is worth every rupee at the top of a Mumbai building.
Sea view, salt air, and a hundred inches of rain
Salt and wind at height
- SS 316 on everything outside — railing fixings, pergola bolts, light fittings, furniture frames, the terrace tap. On a Worli or Bandstand terrace, SS 304 shows pitting within two years and rust staining on the stone shortly after.
- Corrosion-protected AC coils on every outdoor unit. Uncoated coils on a sea-facing terrace lose efficiency within three years and fail within six, and replacing a unit at the twenty-fifth floor is not a small job.
- Anodised aluminium at 25 microns for any external frame, or a marine-grade powder coat over a properly prepared substrate.
- Laminated glazing on the weather elevation. A sea-facing high floor takes wind-driven rain at pressure, and single-glazed casements leak at the sill regardless of how new they are.
- Wind is a structural input for the pergola. A shade structure at the twenty-fifth floor on the sea side needs an engineered connection, not a fabricator’s judgement. This is a genuine safety matter.
- Plant for exposure, not for the photograph. Frangipani, bougainvillea, agave, ficus and most palms cope; anything with a large soft leaf will be shredded by June.
The roof, which is not yours
| Question | The usual Mumbai position |
|---|---|
| Do I own the terrace? | Usually the flat has exclusive use, not ownership; the structure belongs to the society |
| Can I build a permanent structure on it? | A permanent roofed structure generally needs society approval and, depending on area, may raise a planning question |
| Can I put a plunge pool on it? | Only with a structural certificate and society consent; many societies refuse on water and loading grounds |
| Who maintains the waterproofing? | Usually you, since you have exclusive use — check the society’s bye-laws, because the liability for a leak below follows this |
| Can I access the roof above me? | Only where the society grants it; the overhead tanks, lift machine room and antennas often sit there |
| Can I run services up to the terrace? | Water and power, usually yes with approval; gas, generally not |
Get the position in writing from the society before the design. Exclusive use and ownership are different things and the difference matters when a leak appears.
A Bandstand client had a beautiful terrace laid in June because the contractor said it would be fine. The following April we opened it up, and the membrane came off the deck in sheets.
Greenbox project manager
Five things we check on a Mumbai penthouse survey
- The waterproofing history. When it was last done, by whom, and whether there is a warranty. Ask the society and the flat below; on an older building, a stain in the ceiling underneath tells you more than any document.
- Where the outdoor units can go. Six to ten condensers need a screened, ventilated, serviceable position that is not on the view side and does not sit against a neighbour’s terrace. On a Mumbai penthouse this is frequently the hardest single item to resolve.
- Water pressure on the top floor. The overhead tank is often barely above your ceiling, which means almost no gravity head. A rain shower on a Mumbai penthouse usually needs a booster pump, and it is better to know before the bathroom is specified.
- Lift access to the terrace level. Some buildings stop the passenger lift a floor below the penthouse, which turns every material delivery into a stair carry.
- What is on the roof above you. Overhead tanks, the lift machine room, antennas and solar panels all sit there, along with the people who maintain them. Noise, access and any leak from above are all worth understanding first.
Programme and logistics
Twenty-two to thirty-two weeks, and the sequence is set by weather rather than by trades. Internal work runs all year. Terrace waterproofing, external painting, stone laying on the terrace and any PU polishing are October to May. Material reaches the top floor last in every lift queue, so slots are booked for the whole programme in week one. And because a penthouse sits above every other flat in the building, the society’s tolerance for noise, debris and lift occupation is lower than usual — we run these projects with a written weekly programme circulated to the committee, which has prevented more stoppages than any deposit ever has.
The design principles
Designing to a view, the roof heat penalty, terrace loading and wind specification are set out on penthouse interior design services. For a two-level penthouse see duplex interior designers in Mumbai, and for high-specification work generally, luxury interior designers in Mumbai.
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
What does a penthouse cost to do up in Mumbai?+
₹2,500–₹3,900 per sq ft of carpet area in Thane, Navi Mumbai and Powai, and ₹3,400–₹6,800 in Worli, Bandra West and Malabar Hill, for the interior. The terrace is separate at ₹1,500–₹5,500 per sq ft depending on how much of it is covered and serviced. All ex-GST.
When should terrace waterproofing be done in Mumbai?+
October to May, never in the monsoon. A membrane applied to a damp deck debonds within a season and the failure shows up in the room directly below, which is your own. Use a warranty-backed specialist at ₹250–₹650 per sq ft, insist on a documented 48-hour ponding test, and lay the finish on pedestals so the membrane stays inspectable.
Do I own my penthouse terrace?+
Usually you have exclusive use rather than ownership — the structure belongs to the society. That distinction matters because the liability for a leak into the flat below generally follows whoever has exclusive use and maintenance responsibility. Get the society's position in writing before you design anything on it.
What does a sea-facing Mumbai penthouse need specifically?+
SS 316 on every external fixing including railing bolts, pergola connections, light fittings and the terrace tap; corrosion-protected AC coils on every outdoor unit; anodised aluminium at 25 microns on external frames; and laminated glazing on the weather elevation, because a sea-facing high floor takes wind-driven rain at pressure.
What planting survives on a Mumbai terrace?+
Frangipani, bougainvillea, agave, ficus and most palms cope with wind, salt and full sun. Anything with a large soft leaf will be shredded by June. Use heavy pots, a wind break on the exposed side, a root barrier under any planting bed, and an irrigation line — a terrace garden without one is dead by the second summer.
Why does a Mumbai penthouse take longer to build?+
Twenty-two to thirty-two weeks, because the sequence is set by weather rather than trades. Internal work runs all year but terrace waterproofing, external painting, terrace stone and PU polishing are October to May. Material also reaches the top floor last in every lift queue, so slots are booked for the whole programme in week one.