The sequence, and why the order is fixed
- Isolate and demolishWater off at the flat's main, existing fittings removed, tiles and screed chipped to the slab. 2–3 days, and the loudest part of the job — clear it with the society first.
- Plumbing rough-inHot and cold CPVC re-run, waste and soil lines re-pitched, concealed cistern and diverter bodies set. 3–4 days. Every fitting's make and model must be decided by now.
- Pressure testWater lines held at 6–8 bar for 2 hours. Half a day. Skipping it is how leaks appear behind finished tile.
- WaterproofingTwo coats of a cementitious polymer coat to the floor and 600 mm up the walls — 1800 mm in the shower zone — with fillets at every junction. 2 days plus curing.
- Ponding testFloor flooded to 50 mm for 24–48 hours, ceiling of the flat below inspected. This is not optional and it cannot be shortened.
- Screed and slopesFall of 1:80 to 1:100 to the trap, checked with a spirit level and a bucket of water before any tile is laid. 1–2 days.
- TilingFloor, then walls, with the shower niche set out to whole tiles. 4–6 days including grouting and curing.
- Fit-outWC, basin, counter, mirror unit, glass partition, CP fittings, exhaust, lighting. 3–4 days, with the shower glass measured only after tiling.
- Silicone, clean and testEvery joint siliconed, every fitting run, the flat below checked once more. 1 day.
Waterproofing — the part you pay for and never see
Every bathroom leak we have been called to fix in someone else's work traces to one of four things: no fillet at the wall-floor junction, waterproofing stopped at 300 mm instead of carrying up the shower wall, the membrane punctured by a subsequent nail or anchor, or a ponding test that was never done. The materials cost ₹95–₹180 per sq ft. The consequence of skipping it is a ceiling repair in the flat below and a society complaint that follows you for years.
| System | Where we use it | Rate, ex-GST | Note |
|---|---|---|---|
| Cementitious polymer, 2 coats | Standard bathrooms, floor and 600 mm up | ₹95–₹140 / sq ft | Dr Fixit, Fosroc or MYK Laticrete |
| Cementitious, shower wall to 1800 mm | Shower zone | ₹110–₹150 / sq ft | Non-negotiable in a walk-in shower |
| Liquid-applied PU membrane | Balcony-adjacent or terrace bathrooms | ₹175–₹280 / sq ft | More elastic; handles movement |
| Bonded sheet membrane | Over an existing suspect slab | ₹240–₹390 / sq ft | Where chipping to slab is not permitted |
| Fillets and corner tape | All junctions | ₹60–₹110 / rm | The single most commonly skipped item |
Design and build under one accountable roof
Dimensions that make a small bathroom work
| Element | Minimum | Comfortable | Note |
|---|---|---|---|
| WC centre to any side wall | 380 mm | 450 mm | Below 380 mm you cannot sit squarely |
| Clear space in front of WC | 600 mm | 750 mm | Measured to the door swing or the counter |
| Basin counter height | 800 mm | 850 mm | 820 mm for a vessel basin on a counter |
| Shower enclosure | 900 x 900 mm | 1000 x 1200 mm | Below 900 mm you touch the glass |
| Shower niche | 300 x 300 mm | 600 x 300 mm | Set out to whole tiles; 20 mm fall to drain |
| Door width | 600 mm | 750 mm | 600 mm is legal and awkward with laundry |
| Floor fall to trap | 1:100 | 1:80 | Flatter leaves standing water at the far corner |
| Mirror cabinet depth | 100 mm | 120 mm | Deeper and it catches your forehead |
What it costs in 2026
| Level | Sanitaryware / CP | Tile and stone | Total for 35–45 sq ft, ex-GST |
|---|---|---|---|
| Functional | Hindware / Cera, chrome | Vitrified 600x600, ₹65–₹110 / sq ft | ₹1,35,000–₹1,95,000 |
| Mid | Jaquar Continental / Kohler entry | Large-format 800x1600, ₹150–₹280 / sq ft | ₹2,10,000–₹3,00,000 |
| Premium | Kohler / Duravit, Grohe or Jaquar Opal | Natural stone or 1200x2400 slab tile | ₹3,20,000–₹4,50,000 |
| Add: concealed cistern | Geberit or Jaquar in-wall | — | ₹28,000–₹65,000 |
| Add: frameless 10 mm glass | Saint-Gobain or Asahi, SS 316 hardware | — | ₹1,250–₹2,100 / sq ft |
| Add: heated towel rail + geyser relocation | — | — | ₹18,000–₹42,000 |
Add 18% GST. Figures assume an existing bathroom being stripped, not a new one being created.
Decisions that must be made before the wall closes
A bathroom has an unusually high proportion of decisions that become irreversible early. In a bedroom you can change the wardrobe finish in week six; in a bathroom the concealed cistern frame, the diverter body, the shower niche position and the geyser location are all fixed the moment the wall is plastered. We freeze this list before demolition starts and ask the client to sign it, because the alternative is chipping a finished wall.
- Concealed cistern make and model. The frame dimensions differ between Geberit, Jaquar and Grohe, and the flush plate is model-specific. Deciding late means either a visible patch or an exposed cistern.
- Diverter type — two-way, three-way or thermostatic. The body is buried. A thermostatic body also needs a minimum 40 mm wall build-out, which changes the tiling setout.
- Shower niche size and position. Set out to whole tiles, at 1200–1400 mm height, with a 20 mm fall to drain. Moving it after tiling means re-tiling the wall.
- Geyser location and capacity. 15 L over the shower or 25 L in a loft above the door, each with different pipe runs and a different isolator position.
- Counter and basin type. A counter-top vessel, an under-counter basin and a wall-hung basin have three different water and waste heights.
- Exhaust fan position and duct route. 100 mm duct to an external wall or shaft; a fan that discharges into a false ceiling void is worse than no fan.
Mumbai-specific realities
- Salt air. Within 2 km of the sea, specify SS 316 for shower hardware and hinges, not SS 304. The cost difference on a shower enclosure is ₹4,000–₹9,000; the difference in how it looks after three monsoons is total.
- Society hours. Most Mumbai societies permit noisy work between 10 a.m. and 6 p.m. on weekdays only. Demolition and chipping get compressed into those windows, which adds 3–5 days to a 20-day programme.
- The flat below. Inform them before demolition and inspect their ceiling with them, in writing, before and after. It converts a future dispute into a documented baseline.
- Common stack condition. In buildings over 25 years old, the CI soil stack is often the real problem and your new bathroom will be blamed for it. Get it scoped before you start.
- Debris. A 40 sq ft bathroom strip produces 1.2–1.8 tonnes of rubble. Service lift booking, bagged removal and BMC-approved disposal: ₹6,000–₹14,000.
You can change a tile in year five. You cannot change the fall of the floor or the fillet behind it without doing the whole room again.
Greenbox principal designer
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
How long does a bathroom renovation take in Mumbai?+
18 to 25 working days for a 35 to 45 sq ft bathroom stripped to slab and rebuilt. The fixed elements are 2 to 3 days of demolition, 3 to 4 days of plumbing, 2 days of waterproofing plus a 24 to 48 hour ponding test, 4 to 6 days of tiling and 3 to 4 days of fit-out. Society working hours of 10 to 6 typically add 3 to 5 days.
Can you renovate a bathroom without breaking the floor?+
Only cosmetically. You can replace fittings, the mirror unit, the counter and the shower glass, and you can tile over existing walls if they are sound. But if the floor fall is wrong, the waterproofing has failed, or the waste line needs re-pitching, the floor has to come up — and those are the three reasons most bathrooms are renovated in the first place.
What is a ponding test and is it really necessary?+
The finished waterproofing is flooded to about 50 mm of standing water and left for 24 to 48 hours, while the ceiling of the flat below is inspected. It is the only way to find a defect before it is buried under screed and tile. It costs a day and a half of programme. Every leak we have been called in to fix in someone else's bathroom skipped it.
Should I use a concealed or an exposed cistern?+
Concealed looks cleaner and frees about 150 mm of floor depth, but it commits you — the frame is built into a wall and the make must be decided before the wall closes. Use Geberit or Jaquar in-wall systems with an accessible inspection plate, budget ₹28,000 to ₹65,000, and never a brand whose spares you cannot get in five years.
Do I need society permission for a bathroom renovation?+
In almost every Mumbai society, yes — an intimation letter and usually an NOC, plus a refundable deposit of ₹10,000 to ₹50,000 against damage to common areas. They will ask about working hours, debris removal and whether you are touching the common plumbing stack. Allow one to two weeks for this before mobilisation.