Are wall cracks in an HDB flat serious?

Why a wall crack in an HDB flat appears

HDB's home care guide on walls describes cracks along the joints between, or in, the block wall and reinforced concrete elements. HDB explains that different materials expand and contract with temperature changes, and over time this differential movement causes cracks along the joints. This is HDB's explanation for joint cracks.

Before you decide what to do, look closely at the crack. Note where it runs, how wide it is, whether it has grown since you first saw it, and whether the wall or ceiling around it is dry and flat. Those details tell you whether you have a hairline joint crack you can seal, a wider crack for a contractor, or something else, such as concrete that is cracking and bulging.

Hairline or wider: what HDB says to do

For a hairline crack, wall repair is mostly a painting job. HDB's walls guide says to re-paint the wall with a flexible sealant or elastomeric paint to seal the cracks. For wider cracks, HDB says to engage a contractor to carry out the repair. HDB also lists two preventive measures: facilitate cross-ventilation in the flat and re-paint the walls regularly.

A hairline crack is a very fine line in the paint or plaster. Treat a crack as wider if it is clearly open, keeps growing, or reopens soon after you paint over it. When you cannot tell which kind you have, ask a contractor to look before you paint.

Damp changes things. If the wall around the crack is wet, stained or growing mould, sealing the crack alone does not deal with the damp. Find and fix the source of the moisture first. The guide to painting over mould covers what to do before you repaint a wall that has had mould.

Seal a hairline crack yourself

If the crack is a thin line along a joint and the wall is dry, you can usually seal it yourself. These steps are practical guidance, so always follow the instructions on the product you buy.

1. Check the crack. Make sure it runs along a joint and the wall around it is dry, with no bulging or stains.
2. Clean the surface. Scrape off loose or flaking paint along the crack and brush away the dust.
3. Seal the crack. Apply a flexible sealant or elastomeric paint along the crack, as the product label says.
4. Repaint the wall. Once the product has cured, repaint the wall so the repair blends in.

If you would rather not do it yourself, compare handyman painting services and ask whether they will take on a single wall.

When it is spalling concrete, not a crack

Not every crack is a joint crack. Concrete that bulges, flakes off or shows rusty steel points to a different problem, which the guide to spalling concrete covers in more detail.

HDB's home care guide on spalling says it is common in older buildings, especially in damp areas such as kitchens and toilets. It is largely caused by carbonation, which corrodes the steel bars in the ceiling slab so the concrete cover cracks and bulges. HDB says not to delay the repair, because the affected area becomes larger over time and, left unattended, spreads and weakens the building structure. If the patch is large, HDB says to engage a contractor promptly before more concrete dislodges and causes injury.

Cracks in a new flat

For a new flat, HDB's page on defects in new flats says all newly completed HDB flats are covered by a 1-year Defects Liability Period (DLP) from the date of key collection. HDB asks you to report items within 1 month of key collection and before your renovation works begin, which saves investigating whether a problem came from construction or from renovation. Within the DLP, submit a rectification request online, using the QR code in the Welcome Kit, or at the temporary Building Service Centre (BSC) near your home. The BSC arranges a joint inspection.

Treat a crack as an item to report, not automatically as a defect. Use the BTO defects checklist to go through the flat before your renovation starts.

What repainting costs

FROM THE HOMEZYPRO DIRECTORY

Published home painting rates

For the most common unit (per job), the lowest published home painting rates from 6 companies run from S$50 to S$250 per job (middle rate S$150), for anything from one wall to a whole flat, so check what each price covers. The middle figure is a real published rate, not an average. Each figure is one company's own advertised rate with its conditions, not a quote.

See 8 published home painting rates and sources

Lowest matching advertised rate per company, in SGD as published. "From" marks a starting price and ranges are shown in full. Check the source for minimums, GST and inclusions.

Company	Service as listed	Rate	Source
Herofix.sg	Major Paint Peeling + Putty	S$50 to S$300 per job	herofix.sg
Handy Expert SG	HDB & condo painting - First Hour	S$60 to S$80 per hour	handyexpertsg.com
My Handyman SG	Professional Painting & Wall Touch-Ups	From S$120 per job	myhandymansg.com
Arshinogor Pte Ltd	Nippon Paint - Standard Emulsion	S$150 per job	arshinogor.com
Repairhome.sg	Painting (room, HDB, condo, move-in or handover)	From S$150 per job	repairhome.sg
Home Fix SG	Painting Services	S$200 per job	homefixsg.com
Handyman AZ	One-room painting	From S$250 per job	handymanaz.sg
Tuba Engineering & Renovation Pte Ltd	Painting package, 2-room	S$500 to S$900 per package	tuba-eng.net

8 companies publish a home painting line. 6 of them price it per job, from S$50 to S$250 per job, with S$150 in the middle, a real published rate as printed. The other two use different units: one prices the first hour at S$60 to S$80 per hour, and one prints a 2-room package at S$500 to S$900 per package. The scope as printed runs from one wall to a whole flat, so check what each price covers.

See handyman rates for other jobs, or browse handyman companies and the areas each one says it covers.

Questions