An older flat rewards you with space, mature estates and location. Then it asks for work a new flat never needs. Here is what that means for cost, time and sequence.
By Alderic Tan · 3dots · Updated 16 August 2026
Quick answer
The same renovation scope costs 20% to 40% more in a resale flat than in a BTO, because the money goes into infrastructure before it goes anywhere near design.
Published 2026 ranges put a standard 4-room resale renovation at roughly $55,000 to $83,000.
Hacking, rewiring, replumbing, waterproofing and floor levelling all come before the first cabinet is built.
Keep a real contingency. What sits behind old tiles and walls is unknown until work starts.
The cost gap between resale and BTO is not about taste or finish level. It is about work that has to happen before your renovation properly begins, none of which you will see once the flat is finished.
Hacking and removal. Old floor and wall tiles, dated built-ins, sometimes non-structural partitions.
Electrical rewiring. Older flats were wired for far fewer appliances, and the distribution board often needs replacing.
Plumbing. Aged pipework, low water pressure and outdated routing to kitchen and bathrooms.
Waterproofing. Once bathroom tiles come off, the membrane below has to be redone properly.
Levelling and patching. Decades of overlays leave floors uneven and walls needing skimming.
If you are still choosing between units, these are worth checking at viewing. They change the renovation budget more than the asking price does.
When the flat was last renovated. A unit updated five years ago needs far less than one untouched for twenty.
Ceiling and wall stains, particularly in bathrooms and below windows, which suggest leaks above or failed waterproofing.
The age and condition of the distribution board, and how many power points exist per room.
Water pressure at every tap, and how quickly floor traps drain.
Window frames and glass, since replacement is a permitted-work item with its own cost.
Whether previous owners did unauthorised work, which you may inherit responsibility for reinstating.
Add one to two weeks to a comparable BTO timeline. Hacking and rectification sit at the front of the schedule, and until they are done the trades that follow cannot start. Older flats also spring surprises that need a decision before work continues.
Our timeline guide covers the stage-by-stage sequence, which is the same in a resale flat — just with more happening in the early weeks.
Resale renovations touch exactly the things HDB regulates: hacking, floor finishes, bathroom works and windows. Approval must be in place before work starts, and only contractors on HDB’s Directory of Renovation Contractors can apply on your behalf. Our permit guide sets out what needs approval and what is never allowed.
Spend on infrastructure. Wiring, plumbing and waterproofing are buried behind finishes. Redoing them later means undoing everything in front.
Spend on the wet rooms. Kitchen and bathrooms are the most disruptive rooms to revisit.
Hold back on trend-led carpentry. It is the easiest thing to add in a second phase once you have lived in the flat.
Hold back on the rooms you have not decided about. A spare room can wait until you know how you use the home.
We survey the flat properly before quoting, so the groundwork appears in the proposal instead of arriving as a variation halfway through. Where we cannot know something until hacking starts, we say so and set an allowance rather than quoting a number that will change.
Typically 20% to 40% more for the same scope. Published 2026 ranges put a standard 4-room resale renovation at roughly $55,000 to $83,000, against $40,000 to $62,000 for an equivalent 4-room BTO. The difference is infrastructure work: hacking, rewiring, replumbing and waterproofing.
Look at when it was last renovated, ceiling and wall stains that suggest leaks, the condition of the distribution board and number of power points, water pressure and drainage, window frames, and any signs of unauthorised previous work you might have to reinstate.
Usually one to two weeks longer. Hacking and rectification have to finish before other trades can start, and older flats more often reveal conditions that need a decision mid-project.