A leaking balcony usually shows itself in a few ways: cracked or missing grout between the tiles, loose tiles that sound hollow when you step on them, yellowish stains or damp patches on the walls or ceiling next to or below the balcony, and paint that peels or bubbles. The most common cause is a waterproofing membrane under the tiles that has worn out or failed, often together with poor drainage. It can be fixed by hacking up the tiles and re-waterproofing, or without hacking, by injecting polyurethane (PU) into the cracks or applying a clear penetrative treatment. This guide explains how to tell if your balcony is leaking, what causes it, and how it is repaired.
Signs your balcony is leaking
- Cracked or missing grout. This is one of the clearest signs. Grout wears away over time from mopping and from the small movements of the floor, and water then gets under the tiles.
- Loose or hollow-sounding tiles. If a tile moves or sounds hollow when you step on it, or water oozes out around it, it is no longer sealed and is letting water through.
- Yellowish stains or damp patches on the balcony finishes, or on the walls and ceiling of the room next to or below the balcony.
- Peeling or bubbling paint on balcony walls or nearby interior walls.
- Water coming indoors after rain, for example along the door frame or onto parquet or timber flooring.
- Mould or a musty smell near the balcony.
Spotting these early keeps the repair smaller. A leak that is left alone spreads into walls and floors and, in bad cases, can reach electrical points.
What causes balcony leaks
Balconies in Singapore are exposed to strong sun, heavy rain and high humidity all year round, so they wear out faster than indoor areas. The most common causes are:
- A waterproofing membrane under the tiles that has worn out or failed
- Waterproofing that was applied wrongly, or a system that is not suited to an exposed balcony
- Poor drainage, a blocked floor trap or a floor without enough slope, so water stays on the balcony
- Broken tiles, deteriorated grout and cracks in the skirting tile seals
- Cracks in the concrete slab or walls, caused by the structure expanding in the heat and contracting at night
How to find where the water is getting in
- Clear the balcony. Move furniture, plants and mats so you can see the whole floor and the skirting.
- Check both sides. Look at the balcony itself and at the walls and ceiling inside the home, or in the unit below, for stains and damp.
- Check the drainage. Clear debris from the floor trap and drains and watch whether water drains away or pools.
- Do a simple water test. Pour water from a bucket or hose over one area at a time and watch where it appears inside.
Many leaks do not come from where the stain appears, because water can travel through cracks before it shows. If you cannot find the source, a professional inspection will save you from repairing the wrong area.
How balcony leaks are fixed
The right method depends on where the water is getting in, which is why the source is found first.
Hacking and re-tiling
The traditional repair is to remove the old tiles, apply a new waterproofing membrane and lay new tiles. It replaces everything, but it is noisy, dusty and takes the longest.
PU injection grouting (no hacking)
With PU injection grouting, liquid polyurethane is injected under pressure into the cracks and pores in the concrete. It expands to fill them and hardens, sealing the path the water was taking. It can be done while the area is still damp and it stays flexible after curing. See the 5 steps of PU injection grouting.
Clear penetrative treatment (no hacking, no drilling)
For leaks through tiles and grout, a transparent penetrative waterproofing solution can be applied on top of the existing tiles. It soaks into the surface and reacts with it to form a waterproof layer, without drilling or removing tiles.
Sealing joints and fixing drainage
Sealing external joints with a polyurethane-based sealant adds another barrier against water. Clearing or correcting the drainage stops water from sitting on the balcony in the first place.
Keeping it from coming back
- Check the grout and skirting every few months and reseal small cracks early.
- Keep the floor trap and drains clear, especially before the rainy season.
- Don’t leave water standing on the balcony after washing or heavy rain.
- Act on the first stain or hollow tile rather than waiting for a drip.
Frequently asked questions
Can a balcony leak be fixed without hacking the tiles?
Often, yes. PU injection grouting and clear penetrative treatment are both done without removing the tiles. Whether they suit your balcony depends on where the water is getting in, which is checked during the inspection.
How long does a balcony leak repair take?
It depends on the method and the weather. At SWC Construction, most jobs take an estimated 1 to 3 days, and rain can extend that.
Is there a warranty?
SWC Construction gives a 1-year warranty, up to 3 years depending on the service.
Get your balcony checked
SWC Construction is a BCA-registered, bizSAFE Level 3 waterproofing contractor with 900+ Google reviews at 4.9 stars. If you are seeing any of the signs above, see our balcony leakage repair service or contact us to arrange an inspection.
