Cracks in your new BTO flat: what to check on the walls and ceiling, and what to report

Most new owners spend their key collection tapping tiles and testing taps, and walk right past the walls and ceiling. Cracks are easy to miss on fresh white paint, but they're worth a slow look: some are cosmetic, some point to a problem behind the plaster, and all of them are easier to get fixed before you renovate.

Why new flats crack

Concrete, plaster and paint expand and contract with heat and humidity, and a new building is still settling. HDB's own home maintenance guide says wall cracks typically come from this natural expansion and contraction of building materials, often at wall joints. So a few fine lines in a new flat are not unusual. That doesn't mean you should ignore them. You can't tell from the surface whether a crack is only in the paint or goes deeper, so the safe move is to report what you find and let the Building Service Centre (BSC) assess it.

Where to look

Cracks show up in the same few places in almost every flat. Check each room in this order:

1. Corners of door and window openings. Look for short diagonal lines running out from the top corners of each frame.
2. Where walls meet the ceiling. A line along the whole joint, or a gap opening up, is worth noting.
3. Where two walls meet. Vertical cracks in corners, especially between a concrete wall and a lighter partition wall.
4. Around the household shelter. Check the walls and ceiling around the shelter door.
5. Bathroom and kitchen ceilings. Look for cracks, bubbling paint, water marks or brown stains. These rooms are where moisture problems show first.
6. Above and below windows on external walls. Cracks here can let rain in later.

How to spot them

• Bring a torch, even in daytime. Hold it flat against the wall and shine it along the surface. Raking light makes hairline cracks and uneven plaster cast a shadow you'd never see head-on.
• Stand back, then go close. Scan each wall from the middle of the room first, then walk the edges.
• Look up. Ceilings are where people forget to check. Walk each room looking only at the ceiling.
• Check after rain if you can. A damp patch or stain near a crack is more serious than a dry crack on its own.

Which cracks to worry about more

You don't have to diagnose anything, but some signs mean you should flag a crack clearly and ask the BSC to look at it properly:

• Cracks that are wide enough to fit a fingernail or a coin edge into, or where one side sits higher than the other.
• Cracks with damp, staining, rust marks or bubbling paint around them.
• Cracks on the ceiling with bulging or flaking plaster around them.
• Cracks that are clearly longer or wider when you check again a few weeks later.

Fine hairline cracks in the paint are normally a minor touch-up job. Report them anyway in your first list: it costs you nothing, and it's on record if they get worse.

Mark and photograph each one

A crack that's obvious to you in person can be invisible in a photo, so be deliberate:

1. Put painter's tape next to the crack, not over it, and write a number on the tape, for example #14.
2. Take a close-up with the torch shining across the wall so the crack shows up. Put a coin or ruler beside it for scale.
3. Take a wider photo showing the tape and where the crack is in the room.
4. Write down the spot: "Bedroom 2, top left corner of window frame, ceiling side".

When two bedrooms look the same, a note on a floor plan saves a lot of "which room?" back and forth with the BSC.

Report it before you renovate

Once your contractor skim-coats, repaints or builds carpentry against a wall, an existing crack is hard to prove and easy to blame on the renovation. Submit cracks with the rest of your defects list in the first weeks after key collection, and keep your photos.

Check again before your DLP ends

Some cracks only appear after a few months of heat, rain and air-conditioning. Walk the flat again around month 10 or 11 of your defects liability period and look at the same spots, especially window corners, ceiling joints and bathroom ceilings. Compare against your old photos so you can show what's new or has grown.

For the longer term, HDB's maintenance guide notes that new flats come with a 10-year warranty for spalling concrete, which can sometimes first show up as ceiling cracks. If you see cracks with flaking concrete or rust stains on a ceiling later on, report it to HDB rather than painting over it.