A resale flat is a different problem from a new BTO. The flat itself is years old, so the original walls, floors and any old carpentry stopped off-gassing long ago — formaldehyde fades over time, and a 15- or 20-year-old built-in is no longer the source. What matters is the new work you have just added.
Most resale renovations are partial: a fresh kitchen, new wardrobes, an overlay on the floor, maybe a new feature wall, dropped into an existing flat. That new carpentry is where the chemical smell comes from, which actually makes the DIY job smaller and more targeted than in a brand-new flat.
Treat what is new, skip what is old
You do not need to go over the whole flat. Walk through and find the carpentry and furniture that was installed or delivered in this renovation, and treat those.
- New kitchen cabinets: spray the interiors, pull-outs and under-sink carcass.
- New or refaced wardrobes: the insides, drawers and shelves — including any added to an existing bedroom.
- New feature walls, TV consoles and carpentry: any fresh plywood or laminate.
- New furniture: mattresses, sofas and flat-pack pieces brought in for the move.
If you only changed the furniture and left the carpentry as the previous owner had it, then the furniture is your whole job — treat the new pieces and you are largely done.
A note on smells that are not formaldehyde
Resale flats can also carry a musty or stale smell from being closed up, or lingering odours from the previous household. That is a different issue from formaldehyde off-gassing — air the flat out thoroughly and give it a deep clean first, so you can tell what is a genuine new-carpentry smell and treat that at the source.
Ventilate while you settle in
As with any renovation, open the windows and run fans for the first weeks after the new work goes in. Treating the new carpentry removes the source; ventilation clears what is already in the air.
What to use
For DIY work at home, we make the UCOATE Formaldehyde Remover Spray — a 500ml hand spray that runs on the same SGS-tested chemistry we have supplied to Singapore renovation contractors and resellers since 2018. It is water-based and classified non-toxic under OECD 420, so it is safe to use around children and pets when you follow the directions on the bottle. Rather than masking the smell, it binds the formaldehyde and breaks it down into water and carbon dioxide, and it works in normal indoor light — no sunlight or machines needed. In SGS laboratory testing the formulation removed 93.83% of formaldehyde. You can buy it on Shopee with delivery across Singapore.
How to apply it: shake well, spray evenly from 20–30cm onto the surface, let it dry naturally, and avoid wiping or cleaning the surface for 3–5 days. For stronger smells, give it a second coat after about 30 minutes. One 500ml bottle covers roughly 15–20 m². Skip black, water-sensitive or discolouration-prone surfaces, and test an out-of-sight spot first if you are unsure.
