By the Vibrant Design Team · · 27 min read
Renovating a lived-in flat in Navi Mumbai: what to keep, what to strip, society NOC and timings, rewiring and damp, week-by-week schedule and honest cost bands.
A full renovation of a lived-in 2 BHK in Navi Mumbai usually takes 8 to 12 weeks and lands between ₹6 lakh and ₹12 lakh, with ₹7–9 lakh typical for a comfortable finish. A single kitchen or one bedroom takes 3 to 5 weeks. Budget roughly 15 to 20 per cent more than the same work in an empty new flat, because old material has to come out, hidden services have to be repaired, and society rules cut your working hours.
That premium is not a designer marking up an old building. It is demolition labour, debris hauling down a lift the society will not let you use freely, chipping walls to trace forty-year-old wiring, and the two days lost every time a plumber opens a chase and finds a corroded line that was not in anybody's drawing. None of that exists in a brand new CIDCO handover flat where the walls are blank and the services are documented.
The rest of this article is the practical version: surveying an old flat, what is worth keeping, what the society will allow, how to sequence trades so you are not repainting twice, a week-by-week schedule, and where renovation budgets overrun. Written for flats in Nerul, Vashi, Sanpada, Kharghar, Airoli and the older sectors where most of our renovation work happens.
Homeowners usually arrive with one of two situations. Either they have lived in the flat for eight or ten years and it has simply worn out, or they have bought a resale flat and want it liveable before they shift in. The decision is not emotional, it is a simple test: how much of the existing work can carry another ten years without being touched again?
If the answer is more than half, renovate selectively. If it is less than a third, strip the flat and treat it as a fresh interior project with an extra demolition line in the budget. The worst outcome is the middle path taken by accident, where you keep old wardrobes because they still look alright, and then eighteen months later the shutters sag, the hinges give way, and you are calling a carpenter back into a finished home.
For a resale purchase, do the assessment before you close the deal if you can. A flat that needs full rewiring, new plumbing and bathroom waterproofing carries ₹2.5–4 lakh of invisible work before a single piece of furniture is made. That number belongs in your purchase decision, not in a nasty surprise three weeks after registration.
If you are moving into a brand new possession rather than an older flat, the sequence is completely different and much simpler. Our New Flat Interior Checklist covers that route separately, so do not mix the two approaches.
A renovation drawing made without a proper site survey is guesswork. Before any design work starts, the flat should be walked with a measuring tape, a torch, a screwdriver and a moisture reading, ideally with the electrician and plumber present rather than only the designer. What you are looking for is not style, it is condition.
Measure the carpet area yourself. Older flats in the original sectors of Vashi, Nerul and Kopar Khairane often have plaster added over decades, so the real internal dimension can differ from the agreement drawing by 50 to 75 mm across a room. That is the difference between a wardrobe that slots in and one that has to be scribed on site at extra cost.
Open one switchboard and one plug point. Look for aluminium conductors, cloth or brittle PVC insulation, and joints made inside the box rather than in a junction. Open the kitchen sink cabinet and the bathroom duct access. Press the ceiling under the upstairs bathroom with your thumb. Look at the internal face of every external wall in the flat during or just after monsoon if the timing allows.
In a well-built 1990s or 2000s flat, several things are frequently better than what you would buy new at the same price, and keeping them frees budget for the parts that actually matter.
Solid main doors, teak or good hardwood door frames, vitrified flooring in decent condition, granite kitchen platforms, and the structural plaster are the usual keepers. A sound granite counter can be reused with a new sink cut and polished edge for ₹8,000 to ₹15,000, against ₹35,000 or more for a new one. Good flooring that is only dull can be polished or overlaid rather than broken, which also removes a week of demolition and around ₹40,000 of debris and re-levelling from the project.
Old carpentry is the one category where sentiment costs the most. A ten-year-old wardrobe carcass in commercial ply may look intact from outside, but the back panel and the bottom shelf are where moisture damage shows first. Pull the drawers fully out and look.
Anything that will be buried behind new work and cannot be replaced later without breaking that work should be renewed now, even if it looks serviceable today. This is the single most useful rule in renovation and it decides most of your hidden budget.
Concealed wiring older than twenty years, concealed water lines in GI pipe, bathroom waterproofing, and the entire bathroom below dado level fall in this category. So do old modular kitchen shutters with MDF cores, chipboard lofts, and any false ceiling that has visible sag or water staining. Replacing a ₹40,000 false ceiling now is cheap. Replacing it after your ₹1.5 lakh of lighting, paint and furniture is in place is not.
Every renovation involves some civil work, and every renovation has a hard limit. Columns, beams, structural slabs and shear walls are never touched. Not chipped for a niche, not drilled through for a pipe, not shaved by twenty millimetres so a wardrobe sits flush. Most towers in Navi Mumbai are RCC frame structures where the columns carry the entire building, and reducing a column section on the eighth floor is a structural decision, not an interior one.
Internal brick or block partition walls can usually be removed, but the society and the building's structural consultant should confirm which walls are non-structural before anything is broken. In many older CIDCO buildings the internal walls are load-bearing in parts of the plan, particularly around the staircase core.
The other structural rule is loading. Do not add a heavy stone floor over an existing floor without checking, do not build a full masonry wall where a partition existed, and do not create a sunken bathtub in a flat that was not designed for it. If you are still weighing who should handle this work, our comparison of Turnkey vs Contractor vs Carpenter explains why structural judgement is the point at which a labour-only contractor stops being cheaper.
Plumbing is where renovation budgets quietly break. In buildings from the 1990s and early 2000s, concealed supply lines were commonly galvanised iron. GI scales internally over twenty years, so the pipe bore narrows, pressure at the shower drops, and pinhole leaks appear at the threaded joints inside the wall. You will not see this from outside until a patch of damp appears on the far side.
The standard fix is to replace all concealed supply lines in the flat with CPVC or PPR, run in fresh chases with proper clamping, and pressure test the network for at least twenty-four hours before any tile goes on. Budget ₹35,000 to ₹80,000 for a 2 BHK depending on how many points you are adding and whether the kitchen is being relocated.
Drainage is the second half. Old floor traps and the bathroom drain often carry decades of build-up and a smell that no amount of new tiling hides. Replace the traps, use a proper anti-siphon arrangement, and make sure the new floor level still gives you at least a one-in-eighty fall to the trap. Sloppy fall is the reason so many freshly renovated bathrooms hold water in one corner.
A flat wired in 1998 was designed for a fridge, a television, two fans and a couple of lights per room. It was not designed for two air conditioners, a microwave, an induction hob, a dishwasher, a water purifier, a washing machine and thirty low-voltage light points. The existing distribution board typically has three or four circuits where you now need eight to twelve.
Full rewiring for a 2 BHK, including a new distribution board with individual MCBs, a residual current device for shock protection, proper earthing at every socket, and forty to sixty new points, runs ₹70,000 to ₹1.6 lakh depending on point count and wire quality. It is the part of the budget you should never trim.
Two additions worth the money in any renovation: an inverter circuit covering fans, a few lights and the fridge, and dedicated 16 amp circuits for every air conditioner and for the kitchen's heavy appliances. Also check that the society's meter and the flat's sanctioned load actually support what you are adding. In several older buildings the sanctioned load needs an application to be raised before the new appliances go in.
Navi Mumbai gives a building three months of heavy rain and nine months of coastal humidity. Damp is the single most common complaint in flats over ten years old, and the cause is nearly always one of four things: bathroom waterproofing that has failed, an external wall crack, a leaking window seal, or seepage from the flat above.
Diagnose before you spend. Damp that is worst at the bottom of a wall and rises in a band points to the bathroom or a floor-level pipe. Damp high on an external wall, worse after rain, points to a crack or window. Damp on a ceiling is almost always the flat above, which makes it a society matter and not something you can fix from your side alone.
Bathroom waterproofing should be redone whenever the bathroom is retiled. That means breaking to the slab, cleaning, filling the joints and the plumbing chase, applying a polymer-modified or acrylic membrane with proper coving at the wall junction, taking the membrane 300 mm up the wall and full height in the shower area, then a twenty-four hour ponding test before tiling. Skipping the ponding test to save a day is the false economy that produces a leak into the neighbour's ceiling in the first monsoon.
Almost every co-operative housing society in Navi Mumbai requires written permission before interior work starts. The process is usually simple but it is not instant, and starting work without it is the fastest way to have your material stopped at the gate.
The typical requirement is an application letter describing the work, an undertaking that no structural member will be touched, a refundable deposit, a list of workers with identity proof, and sometimes a contractor's undertaking. Deposits in Navi Mumbai societies commonly run ₹10,000 to ₹50,000, refunded after the work is done and the common areas are inspected. Some societies also charge a non-refundable maintenance or lift usage fee.
Allow one to three weeks between applying and getting the letter, because many committees only meet monthly. Apply early, before you finalise the start date with your contractor. A two-week gap between the contractor being ready and the society being ready costs you either idle labour charges or a lost slot in the contractor's schedule.
Most Navi Mumbai societies permit interior work between 9 am and 6 pm on weekdays, with a lunch break, and many prohibit noisy work on Sundays and public holidays entirely. Some restrict chipping and drilling to a narrower window, often 10 am to 5 pm, because of infants or night-shift residents in the wing. Ganpati, Diwali and society events frequently mean two or three lost days.
Debris is the second friction point. A 2 BHK renovation with bathroom and kitchen demolition generates three to six tempo loads of rubble. Societies almost always require it to be bagged, carried down at specified hours, and removed the same day rather than heaped in the compound. Budget ₹12,000 to ₹30,000 for debris removal in a full renovation, and confirm who pays for it in your contract before work starts.
Lift protection is non-negotiable and cheap. Line the lift car with plywood or thick corrugated sheet, protect the floor of the lobby and the passage from lift to door, and cover the staircase railing if material is being carried up. Damage to a lift interior is the most common reason a security deposit is not refunded in full.
A renovation is eight to twelve weeks of noise and dust for people who are getting nothing out of it. How that is handled decides whether the project runs smoothly or spends its life being reported to the secretary.
Tell the immediate neighbours, the flat above and the flat below, before work starts. Give them a rough duration and a phone number, yours and the site supervisor's. Tell them honestly which two weeks will be loudest, which is nearly always the demolition and chipping phase. People tolerate a known nuisance with an end date far better than an open-ended one.
If the work involves bathrooms, kitchen, flooring or full rewiring, move out. If it is limited to carpentry and painting in one or two rooms, staying is manageable with planning.
The reason is not comfort, it is speed and cost. A vacated flat lets trades overlap, lets material be stored inside, lets the floor be used as a working surface, and removes an hour a day of covering and uncovering. In our experience a vacated 2 BHK renovation finishes two to three weeks earlier than the same scope in an occupied flat, and the contractor's labour cost is lower because there is less unproductive handling.
Weigh that against rent. Two to three months of rented accommodation in Navi Mumbai for a family in a comparable 2 BHK is a real cost, so the honest comparison is rent plus shifting against the extra time, extra handling charges and the discomfort of living in a construction site with a child or an elderly parent. For many families the middle answer works: shift to a relative's home or a serviced flat for the six to eight weeks of wet and dusty work, and return for the final carpentry and painting stage.
When moving out is not possible, the flat is renovated in zones, typically ten to fifteen per cent more in labour but slower and liveable. One zone is sealed and worked on behind a hard partition with its own dust route while the rest of the flat carries on.
The usual sequence for an occupied 2 BHK is: bedroom one, then bedroom two, then the bathrooms one at a time so a working toilet always exists, then the kitchen, then the living and dining area last. The living room goes last because it becomes the family's storage and living space through the earlier phases, and because it is the zone the workers must pass through.
If you are planning the layout as well as the repair, our guide on 2 BHK Interior Design Ideas in Navi Mumbai covers the space-planning side that this article deliberately does not repeat.
Dust from tile cutting, chipping and sanding is fine enough to travel through a closed door, settle inside a wardrobe and sit on top of a fan blade three rooms away. Plastic sheeting taped over a doorway does very little on its own because every time someone walks through, the sheet lifts and the dust follows.
What works is a sealed partition, not a curtain. A framed board or gypsum partition with a proper door, taped at the edges, across the opening between the working zone and the living zone. Add a wet doormat on the clean side, seal the gap under the door, and cover any air-conditioning indoor unit in the working zone completely so the coil does not clog.
Plan a deep clean at the end and price it in. A professional post-renovation clean for a 2 BHK, including glass, grouting, fan blades, ducts and inside all new cabinetry, costs ₹6,000 to ₹15,000 and is the difference between moving into a finished home and moving into a site.
This is the schedule we work to for a vacated 2 BHK of roughly 650 to 750 sq ft carpet, with two bathrooms, a new kitchen, full rewiring and new flooring in two rooms. Ten weeks on site, preceded by three to four weeks of design and approvals. An occupied flat adds two to three weeks.
No week is left empty as a buffer, so a genuine delay of a few days will push the end date. Anyone quoting six weeks for this scope is either not doing the services work or is going to be late.
Partial renovations are far more common and their schedules are compressed but not proportionally, because the setup, protection and cleaning overheads are close to fixed.
A kitchen-only renovation takes three to five weeks: one week to demolish and repair, one for plumbing, electrical and tiling, one for the counter and modular installation, and a few days for chimney, hob, snagging and cleaning. The counter is the item that most often causes a delay, because the stone is templated only after the carcasses are fixed and then takes four to seven days to cut, polish and deliver.
A single bathroom takes two to three weeks, and that number is set by chemistry rather than by labour. Breaking down to the slab, repairing the concealed plumbing and coving the wall junctions is four or five days of work. The waterproofing membrane then needs its curing time between coats and after the final one, and the bathroom is ponded with water for twenty-four hours before a tile goes down. Those days cannot be compressed by adding men, and a bathroom promised in eight days has lost one of them.
One bedroom with a new wardrobe, a bed unit and fresh paint is also two to three weeks, and it is stayable if the rest of the flat is sealed off. Paint and lighting across a whole flat, with no carpentry and no wet work, is eight to twelve days. None of these scale down in proportion to their scope, because protection, society entry paperwork, mobilisation and the final clean cost close to the same whether you redo one room or six.
Renovation is priced the same way as any interior project, on carpet area and specification, with the demolition and services repair added on top. On carpet area, a smart and functional renovation runs ₹800 to ₹1,000 per sq ft, a comfortable well-finished one ₹1,100 to ₹1,500, and a premium specification ₹1,600 to ₹2,200 and above. Add roughly ₹120 to ₹250 per sq ft for the demolition, debris, rewiring and plumbing repair that a new flat does not need.
Translated into whole-flat numbers, a 1 BHK renovation sits at ₹3.5 lakh to ₹5 lakh for a good functional job and ₹6 lakh to ₹8 lakh for a premium one. A 2 BHK runs ₹6 lakh to ₹12 lakh with ₹7 lakh to ₹9 lakh the common landing point. A 3 BHK or duplex runs ₹10 lakh to ₹18 lakh, more in premium towers where lift restrictions, longer material carries and higher specification all push it up.
The costs that exist only in a renovation are worth understanding before you sign. Stripping out an old modular kitchen and carting away the carcasses, shutters and platform rubble is ₹15,000 to ₹30,000, spent before the new kitchen is even measured. Reusing a sound granite counter with a fresh sink cut saves ₹20,000 or more against new stone. Chase cutting for fresh wiring and plumbing, then filling and plastering those chases, adds ₹20,000 to ₹50,000 in a 2 BHK. And a bathroom costs more here than in a new flat because you pay twice for the floor: once to break the old tiles, screed and membrane down to the slab, and again to build the assembly back.
For a fuller breakdown of how these numbers are built up, including the material and labour split behind each line, see our detailed article on Interior Design Cost in Navi Mumbai. The point to hold on to here is that in a renovation, twenty to thirty per cent of the budget goes into work you will never see.
A family of four in a 690 sq ft carpet 2 BHK, lived in since possession. Flooring in good condition, main door solid, aluminium windows serviceable. Kitchen shutters delaminating, both bathrooms tired, wiring adequate but short of points, no damp. They wanted a well-finished home, not a premium one, and stayed with relatives for seven weeks and returned for the final carpentry and painting.
The figures below came to ₹9.42 lakh including a contingency that was partly used when one bathroom's chipping exposed a corroded concealed line that had to be rerouted. Nine weeks on site against an eight-week plan. This kind of scope is typical of what we do for clients looking for an Interior Designer in Kopar Khairane, where most of the housing stock is now in exactly this ten-to-fifteen year window.
A couple bought a twenty-four-year-old 3 BHK of about 1,020 sq ft carpet and had six weeks between registration and their intended move-in. The survey found aluminium wiring in two circuits, GI concealed plumbing, one bathroom with a live leak into the flat below, and a ceiling stain in the master bedroom traced to the flat above.
The honest advice was that six weeks was not possible and that the ceiling issue was not theirs to fix alone. The project was rescheduled to fourteen weeks: two weeks for the society NOC and the upstairs neighbour's leak repair, then twelve weeks on site. Total came to ₹15.6 lakh, of which ₹4.3 lakh was services and repair work that produced nothing visible.
Three lessons from that project apply to almost every resale purchase. First, the services assessment belongs in the buying decision. Second, anything involving a neighbouring flat needs to start on day one because it is the item you do not control. Third, a fourteen-week honest schedule that holds is far better than an eight-week optimistic one that slips to sixteen. Clients who come to us as a Flat Interior Designer in Kharghar after a resale purchase are usually surprised by the services number and never by the furniture number.
If your flat is a 3 BHK and you want the space-planning side rather than the repair side, our article on 3 BHK Interior Design in Navi Mumbai covers layouts, storage strategy and zoning in detail.
Overruns in renovation are predictable. They come from one of six sources, and five of the six can be managed by better surveying and a better contract at the start.
The first is scope discovered after demolition. You cannot see behind a wall until it is open, so a genuine ten per cent contingency belongs in every renovation budget and fifteen per cent in anything over fifteen years old. The second is scope added by the client mid-project, which is the largest single cause in practice. A wardrobe added in week six costs more than the same wardrobe in week one, because the carpenter's material order, the electrical layout and the painting sequence all have to be reopened.
The third is material upgrade drift, where each individual decision is small and the total is not. Switching from a mid-range laminate to an acrylic finish across a kitchen and two wardrobes moves the number by ₹80,000 or more. The fourth is delay cost, because a site that runs four weeks over carries supervision, storage and often rent. The fifth is society-related, from deposits to lift charges to repairing a damaged common area.
The sixth is the one nobody plans for: appliances and soft furnishing. Curtains, a new sofa, a dining set, a chimney upgrade and lights bought outside the contract routinely add ₹1.5 lakh to ₹4 lakh to what the family actually spends, even though none of it appears in the interior quote.
Renovation quality is largely a function of order. Trades that run out of sequence create rework, and rework is what turns a ten-week project into a fifteen-week one. The rule is simple: anything that makes dust or gets buried comes before anything that is finished or fragile.
The correct sequence is demolition, then civil repairs, then concealed plumbing, then concealed electrical, then waterproofing, then tiling, then false ceiling, then putty and primer, then carpentry installation, then final paint, then electrical fittings and sanitary ware, then glass and mirrors, then cleaning, then soft furnishing and appliances.
The classic sequencing failure is fitting light fixtures and switch plates before the final paint coat, which then requires masking, produces poor edges, and usually ends with paint on the plate. The second classic failure is installing wardrobes before the floor level in that room is final, which leaves a gap under the shutter that no filler hides convincingly.
A one-line quote saying full renovation of 2 BHK for ₹8 lakh is not a quote, it is a number. In renovation the itemisation matters more than in new work, because the disputes are almost always about what was and was not included in the repair scope.
Every quote should separate the demolition and disposal, the services work, the civil work, the finishes and the furniture, and should state the specification for each. For carpentry it should name the core material, the finish, the hardware brand and the warranty. For electrical it should give the point count and the wire and switch brands. For plumbing it should say which lines are being replaced and which are being retained.
It should also state what is excluded. Appliances, curtains, loose furniture, society deposits and charges, and anything discovered behind a wall are the standard exclusions, and they should be written rather than assumed. Our Flat Interior Design Services quotations are built this way for exactly this reason: an itemised document is what lets you compare two contractors honestly instead of comparing two totals.
For humid coastal flats, the material rules are firm. Use boiling water resistant plywood for anything in the kitchen and both bathroom vanities, and marine grade or a proper waterproof board under the sink. Use edge banding on every exposed edge including the back ones nobody sees, because moisture enters at the edge. Prefer stainless or good quality anodised hardware and avoid mild steel fittings anywhere near a wet zone.
Laminate remains the sensible default for a renovation because it takes daily use, matches a wide range of existing finishes, and costs a fraction of acrylic. Reserve acrylic or a lacquered finish for one focal area rather than spreading it thin across the flat. Our interior materials guide sets out the comparison properly, including where the extra spend genuinely returns its value.
For kitchens specifically, the layout decision usually matters more than the finish decision, and old kitchens in Navi Mumbai flats are often narrow galleys where the wrong layout costs more comfort than any material choice. Modular Kitchen Ideas for Indian Homes covers the layout side with cooking habits in mind.
The problems below repeat across projects, they are all avoidable, and they mostly come from decisions taken to save either money or time at exactly the wrong moment.
The single most expensive mistake is finishing over unresolved services. New tiles over an old leaking pipe, new paint over damp that has not been traced, new false ceiling under a slab that seeps. In every case the finish is destroyed within a year and has to be done twice. The second most expensive is starting carpentry before the layout is genuinely final, because a carcass once made cannot be shortened by 80 mm without looking like it was. The third is picking a contractor on the lowest total rather than the itemised scope. The cheaper quote is usually cheaper because demolition, debris carting, chase cutting and chase filling were left out of it, and all four arrive as extras once the walls are open.
The fourth is optimism about the timeline. A family that gives notice on a rented flat based on a contractor's cheerful eight-week promise ends up either paying double rent or moving into an unfinished home with the carpenter still working. Plan on the honest number and be pleasantly surprised.
Everything below should be done and settled before demolition day. A renovation that starts with these items complete runs to schedule far more often than one that starts because everyone was impatient.
The first week of a renovation is irreversible, and every hour spent on this list before that week buys back a day later.
Renovation rewards patience at the start and punishes it later. The projects that finish on budget are the ones where four weeks went into surveying, drawing, selecting and paperwork before a single hammer was lifted. The ones that overrun are almost always the ones that started in a hurry with an unresolved question about damp, a wall, or a wardrobe.
Vibrant Interior Designer has been working across Navi Mumbai since 2011, with 500+ projects delivered and a structured eight-step process that covers survey, design, approvals, execution and handover. We have renovated flats in the older sectors of Vashi, Nerul and Kopar Khairane, resale homes in Kharghar and Panvel, and commercial spaces across Sanpada and Turbhe, so the building conditions in this article are the ones we deal with every week.
If you want to see finished work before you commit, our Interior Design Gallery has photographs from completed homes and offices. When you are ready to have your flat surveyed and get an itemised, honest estimate rather than a single number, Contact Us or visit the studio at G-12, Ground Floor, near Juinagar Railway Station, Sanpada, Navi Mumbai 400705, or call +91 70214 61667.
A full 2 BHK renovation takes 8 to 12 weeks on site if the flat is vacated, plus 3 to 4 weeks earlier for design, material selection and society NOC. An occupied flat adds 2 to 3 weeks because of dust partitions and restricted working hours. A kitchen alone takes 3 to 5 weeks and a single bathroom 2 to 3 weeks, including the waterproofing cure.
A 2 BHK renovation runs ₹6 lakh to ₹12 lakh, with ₹7 lakh to ₹9 lakh being the common landing point for a well-finished home. On carpet area that is roughly ₹1,100 to ₹1,500 per sq ft, plus ₹120 to ₹250 per sq ft for demolition, debris, rewiring and plumbing repair that a new flat does not need. Expect 20 to 30 per cent of the budget to go into work you never see.
Yes. Almost every co-operative housing society in Navi Mumbai requires a written application, an undertaking that no structural member will be touched, a worker list with identity proof, and a refundable deposit of typically ₹10,000 to ₹50,000. Committees often meet monthly, so apply one to three weeks before your intended start. If a wall is being removed, most societies also ask for a structural consultant's certificate.
Only for limited scope. Painting, lighting or a single bedroom's carpentry is manageable while living there. Anything involving bathrooms, kitchen, flooring or full rewiring means moving out for six to ten weeks. A vacated flat also finishes two to three weeks faster because trades can overlap. If moving out is impossible, the flat is renovated zone by zone with sealed partitions, which costs about 10 to 15 per cent more in labour.
If the flat is over fifteen years old, yes. Older wiring was designed for a fraction of today's load and often has aluminium conductors or missing earthing. Full rewiring for a 2 BHK with a new distribution board, RCD protection and 40 to 60 points costs ₹70,000 to ₹1.6 lakh. It is the least visible part of the budget and the one you should never reduce, because redoing it later means breaking finished walls.
Only non-structural internal partition walls, and only after a structural consultant confirms it in writing. Columns, beams, slabs and shear walls are never chipped, drilled through or reduced, because the building's frame carries every floor above you. In some older buildings internal walls near the staircase core are load-bearing. Toilet and drainage positions are also effectively fixed, since shifting a WC needs a new line with correct slope.
Four causes account for nearly all of it: failed bathroom waterproofing, external wall cracks, leaking window seals, and seepage from the flat above. Diagnose before spending. Damp low on a wall usually means plumbing or bathroom failure; damp high on an external wall points to a crack; ceiling damp is the upstairs flat and needs society involvement. Never paint or tile over untraced damp, because the finish fails within a year.
Keep 10 per cent for a flat under fifteen years old and 15 per cent for anything older, held separately from the contract value. Renovation always reveals scope after demolition, such as corroded concealed pipes, hollow tiles or failed waterproofing that no survey can see through a closed wall. Release contingency only against a photograph of the discovered problem and a written variation note with its own price and time impact.