What a strip-out finds
These are the five discoveries that account for most bathroom renovation variations. All five are cheaper to find on day two than on day twelve, which is why we open up before we finalise the budget wherever the client allows it.
| Discovery | How often | Cost to resolve | Why it matters |
|---|---|---|---|
| No waterproofing membrane at all | Roughly 1 in 3 pre-2000 bathrooms | Already in scope | Explains the stain on the ceiling below and why the last repair failed |
| Corroded cast-iron or GI supply pipe | 1 in 3 pre-1995 | ₹18,000 – 55,000 | Replacing after tiling means opening the new wall |
| Soil stack corroded at the joints | 1 in 4 pre-1990 | ₹55,000 – 1,10,000 per stack | Shared line; needs agreement with the flats above and below |
| Floor falling the wrong way | 1 in 4 | ₹12,000 – 30,000 | New screed and a higher finished floor level, which affects the door |
| Damaged or saturated slab soffit | 1 in 8 | ₹25,000 – 90,000 | Structural repair before anything is laid; a genuine programme risk |
| Electrical with no earth in the bathroom | 1 in 5 pre-1995 | ₹8,000 – 22,000 | Safety, and it has to be corrected before the walls close |
Frequencies are from our own survey records on Indian apartment and house renovations. Hold 15% of the budget against this table.
The sequence, and why it cannot be compressed
- Protect and strip out — days 1 to 3Protect the route in, remove sanitaryware, tile, screed and, on pre-2000 work, everything down to the slab. Debris bagged and removed daily. Photograph everything that is exposed.
- Discovery review — day 3Walk the stripped bathroom with the client. Agree, in writing, what has been found and what it costs. This one meeting prevents almost every later dispute.
- Services first fix — days 4 to 7Supply and waste pipework, chases cut and made good, electrical circuits with a proper earth, the extract duct route. Pressure-test the plumbing before anything covers it.
- Screed to fall — days 7 to 9A 1:80 to 1:100 fall to the trap, tightened to 1:60 in the shower zone, formed in the screed. Then a cure — typically 48 to 72 hours before the membrane goes on.
- Waterproofing and the pond test — days 9 to 13Two coats at right angles, 150 mm up all walls and 1,800 mm in the shower, with a fillet at every junction. Cure between coats, then plug the trap and pond for 48 hours. Photograph the start and end levels.
- Tiling and grouting — days 13 to 20Polymer-modified adhesive over the tested membrane, setting out from the most visible corner. Epoxy grout in the wet zone, cement elsewhere, with a day between tiling and grouting.
- Fit-out and commissioning — days 20 to 28Vanity, sanitaryware, glass, mirror, lighting, extract, then a second short pond test after all penetrations are made, and snag closure.
Everything you find behind the tile was always there
Living through it
- If you have two bathrooms, do them one at a time. It costs 8–12% more than doing both together and it is almost always the right decision.
- If you have one, phase it. We refit the WC temporarily at the end of the services stage and remove it again before tiling. That adds about two days and removes the need to move out.
- Dust is the real intrusion, not noise. A zipped dust screen at the bathroom door, a negative-pressure fan venting outside, and floor protection along the route. This costs about ₹8,000 and it is what people remember.
- Agree the working hours before day one, and hold the contractor to them. Demolition in the first three days is the only genuinely disruptive phase.
- Expect the water to be off for parts of four or five days, not continuously. A written schedule of which days matters more than a promise that it will be brief.
- Keep one usable washbasin somewhere else if at all possible, even a temporary one in a utility area.
What to keep and what to replace
| Element | Keep if | Replace if |
|---|---|---|
| Wall tiling | Sound, well bedded, and you like it | Hollow when tapped, or the room is being replanned — patching never matches |
| Floor and screed | Fall is correct and the membrane tests sound | Pre-2000, or the fall is wrong, or there is any stain below |
| Supply pipework | CPVC or copper, under 20 years old | GI or cast iron, or any sign of corrosion at a joint |
| WC and cistern | Under 10 years and the flush mechanism is available | Older — spares become the problem, not the ceramic |
| Vanity | Solid carcass, and it suits the new layout | MR ply, swollen at the plinth, or the wrong size for the new plan |
| Shower mixer | A known brand with available cartridges | Unbranded — a cartridge you cannot buy makes the whole mixer disposable |
| Extract fan | Ducted to outside and adequately sized | Discharging into the ceiling void, or under 85 m³/h |
The client who lets us open a wall for two hours before signing the budget pays less than the one who wants a fixed price on a bathroom nobody has looked inside.
Greenbox principal designer
Where the money goes
For the itemised rate bands — per square foot of floor area by specification level, and what each level includes — see bathroom renovation cost in India, or run your own figures through the bathroom renovation cost calculator. As a shape, expect roughly a third on civil work and waterproofing, a third on tiling and sanitaryware, and a third on joinery, glass, lighting and the extract.
Choosing a contractor for this specific job
A bathroom is the smallest job in a home and the one with the largest downside. Six questions separate a contractor who has done a hundred from one who has done a few.
- ‘Do you strip to the slab?’ The answer on pre-2000 work should be yes without hesitation, and they should be able to say why.
- ‘What membrane do you use, and how many coats?’ A brand, a type — cementitious or polyurethane — and two coats at right angles. ‘Waterproofing chemical’ is not an answer.
- ‘Will you pond test it, and will you photograph it?’ A contractor who has not heard of a ponding test has not been responsible for a failure.
- ‘What is your fall, and where is it formed?’ A number, and ‘in the screed’. Anyone who says they will set the fall in the tile bed is telling you the floor will pond in the corners.
- ‘What happens if we find a corroded stack?’ A rate, a method and an honest statement that it needs the neighbours’ agreement.
- ‘Who comes back if it leaks in month four?’ A named person, a stated response time, and a defects liability period in writing. Five per cent retained for sixty days concentrates this remarkably.
Design, and the city
If the bathroom is new or being replanned from scratch, the clearances, fall gradients, IP zones and tile setting-out are on bathroom interior design. If you are in Mumbai, society rules, cast-iron stacks and the neighbour-below problem are covered on bathroom renovation contractors in Mumbai.
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
How long does a bathroom renovation take?+
Eighteen to twenty-eight working days for a single bathroom. The sequence is set by cure times — screed cure, two membrane coats with a cure between them and a 48-hour ponding test account for four or five of those days and cannot be shortened by adding labour.
Should I strip a bathroom back to the slab?+
On anything built before about 2000, yes. Roughly one in three of those bathrooms has no waterproofing membrane at all, and relaying over an old failed membrane means you have bought somebody else's problem along with a new floor. On newer work with a sound, correctly falling floor, an overlay is defensible.
How much contingency should a bathroom renovation carry?+
About fifteen per cent, held unallocated against discovery. Corroded supply pipe, a soil stack failing at the joints, a floor falling the wrong way and a bathroom circuit with no earth are all common, and all of them are cheaper to resolve on day three than on day twelve.
Can I live in the house during a bathroom renovation?+
Yes, in almost all cases. With two bathrooms, do them one at a time — it costs 8–12% more and is worth it. With one bathroom, the WC can be temporarily refitted at the end of the services stage and removed again before tiling, which adds about two days. Dust control matters more than noise: a zipped screen, a negative-pressure fan and floor protection along the route.
What is the right order of works?+
Strip out, discovery review with the client in writing, services first fix with a pressure test, screed to fall with a cure, two-coat waterproofing with a 48-hour pond test, tiling and grouting, then fit-out and a second short pond test after all penetrations are made. Reversing any two of those creates rework.
Is it worth keeping the existing tiles?+
Only if they are sound when tapped, well bedded and you actually like them, and the layout is not changing. Patching around a new vanity or a relocated shower never matches, because tile batches, sizes and rectification standards all change. If more than about a fifth of the tiling is coming off, take it all off.