Singapore is one of the most humid places on earth. Average relative humidity hovers between 80% and 90%, and during the northeast monsoon season (December–March) it can exceed 95%. For residents of HDB blocks, which account for over 80% of the island's housing stock, this means a constant battle with moisture, mould and musty odours.
Why HDB Flats Are Especially Vulnerable
HDB buildings in Singapore are constructed from reinforced concrete, which has high thermal mass. Combined with air conditioning, this creates a "cold wall" effect — water vapour from the air condenses on cooler surfaces. The problem most commonly appears:
- On walls adjacent to air-conditioned rooms
- In built-in wardrobes against exterior walls, especially those with limited ventilation
- On bathroom ceilings without mechanical ventilation
- In lower kitchen cabinets that sit directly on the floor
Measuring Humidity: The First Step
Before investing in solutions, measure the actual humidity in your flat. A digital hygrometer costs between 8 and 25 SGD on Shopee SG. According to NEA (National Environment Agency) guidelines, the comfortable indoor humidity level is 60-70%.
Place the hygrometer in different spots for 24 hours — you may find that the bedroom reads 68%, but the wardrobe is already at 85%. This data will show you where the problem is most pressing.
Dehumidifiers: Which Type to Choose
Two types of dehumidifiers work well in Singapore's conditions:
Compressor (Refrigerant) Dehumidifiers
Most effective at humidity levels above 60% and temperatures above 20°C — precisely the conditions found in Singapore. Models with a 12-20 litre daily capacity are sufficient for a 3-room HDB flat (approx. 65 m²). Popular brands include Mitsubishi Electric MJ-E16VX (around 380 SGD) and EuropAce EDH 3120V (around 280 SGD).
Desiccant Moisture Absorbers
Small containers filled with silica gel or calcium chloride. Ideal for wardrobes, drawers and storage spaces. The Thirsty Hippo brand (around 3-5 SGD for a 3-pack at NTUC) is a standard in every Singaporean home. Replace them every 4-6 weeks or sooner when the container fills with water.
Daily Prevention
No device can replace good habits. Here is a routine that genuinely works:
- Morning: Open windows for 20-30 minutes (unless it is raining or haze conditions prevail). Air circulation reduces moisture stagnation.
- After showering: Run the bathroom exhaust fan for at least 15 minutes. If you do not have an exhaust fan, leave the door open with a standing fan aimed inside.
- While cooking: Use the range hood. Steam cooking raises kitchen humidity by 10-15% within 30 minutes.
- Before bed: Set the air conditioner to "Dry" mode for one hour. This lowers humidity by 15-20% without overcooling.
- Once a week: Wipe bathroom walls with a vinegar solution (1:1 with water). This prevents mould growth on grout.
Structural Solutions for HDB Owners
If the problem is severe, consider investing in infrastructure:
- Anti-mould paint — Nippon Paint VirusGuard or Dulux EasyClean have antifungal properties. Cost: 50-80 SGD for 5 litres.
- Exhaust fans — essential in windowless bathrooms. KDK 15EGKA models (around 65 SGD) are quiet and energy-efficient.
- Wardrobe thermal insulation — polystyrene panels (2-3 cm) between the wall and the back of the wardrobe eliminate the cold wall effect.
When to Call a Professional
If mould covers an area larger than 1 m², is dark green or black in colour, or reappears within 2 weeks of cleaning — contact a professional company. In Singapore, mould remediation services are offered by firms such as De Hygienique (from 200 SGD per room) and System Hygienics. Before hiring, check that the company holds a BCA (Building and Construction Authority) certification.