What size exhaust fan do I need for a Singapore HDB or condo bathroom?

Most HDB and condo bathrooms (3–5 m² floor area) need 80–110 CFM extraction. Use this rule: bathroom floor area in sqft × 1.1 = minimum CFM. In Singapore humidity we recommend +50% margin.

Should the fan be on the light switch or a humidistat?

Humidistat. If the fan runs only with the light, it stops before moisture clears. A humidistat keeps the fan running until humidity drops below ~65% — exactly when mould stops being able to grow.

Will replacing the exhaust fan stop bathroom ceiling mould coming back?

Yes — when paired with proper ceiling treatment. Treating ceiling mould without fixing ventilation usually causes recurrence within 6–12 months. Treating both extends the mould-free window to several years.

How much does professional exhaust fan installation cost in Singapore?

From $380 all-inclusive for standard replacement, $550+ for new installation with ducting, $680+ for silent inline fan with humidistat. Most Singapore households fall in the $380–$550 band.

How long does a bathroom exhaust fan last in Singapore?

5–7 years for budget fans, 8–12 years for KDK/Panasonic grade. Humidity, salt-air, and dust accelerate motor failure. Signs of failure include noisier operation, longer steam-clearing time, and visible mould returning despite recent treatment.

Ventilation as Mould Defence

Bathroom Exhaust Fan Singapore: Sizing, Cost & Mould-Prevention Guide

Singapore bathrooms run at 80–95% humidity after every shower. A correctly sized exhaust fan is the single most cost-effective mould-prevention tool in your home — provided it's spec'd right, ducted right, and triggered right. This guide covers all three, plus when professional mould removal in Singapore is the better fix.

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Why ventilation, not chemicals, is the mould-prevention answer

Mould needs three things: spores (always in the air), a food source (paint, grout, drywall), and moisture. The first two are unavoidable in Singapore homes. Moisture is the only one you can actually control — and the bathroom is where you lose control fastest. Every shower dumps 1.5–2.5 litres of water into the air; without active extraction it settles on cooler surfaces (ceiling first, then upper walls) and creates a 2–4 hour humidity spike above the 70% mould-growth threshold.

We see this every week on jobs across HDB and condo bathrooms — recurring ceiling mould treated 3 times by 3 different vendors, and not one of them looked at the exhaust fan. Bathroom mould removal without a ventilation fix is treating the symptom; the cause is moisture sitting too long.

Sizing: how many CFM does your Singapore bathroom need?

The simplest rule that actually works: bathroom floor area in sqft × 1.1 = minimum CFM. A typical 4 m² HDB master bath (43 sqft) needs ~50 CFM minimum, but in Singapore's humidity we recommend +50% margin → ~75 CFM. A 6 m² condo master needs 100–120 CFM. For full sizing including ceiling height, ducting length, and double-shower setups, see the exhaust fan CFM calculator.

HDB-specific: why so many HDB exhaust fans don't extract

A large share of pre-2010 HDB bathrooms have an exhaust opening that connects to a vertical riser shaft shared between units — not direct ducting to outside air. When the fan is undersized, dirty, or the shaft is blocked, "extracted" air recirculates back through other units' openings. Full diagnosis in the HDB exhaust fan guide.

Trigger: switch, timer, or humidistat?

Light switch — bad. Timer (15–20 min run-on) — okay. Humidistat — best. The fan keeps running until humidity drops below your set point (typically 65%), guaranteeing the bathroom hits a mould-hostile state before it shuts off. For master bedroom ensuites where noise matters, a silent inline fan + humidistat is the configuration we recommend.

Cost in Singapore

Standard replacement (KDK / Panasonic ceiling fan) — from $380 all-inclusive
New install with ducting — from $550
Inline silent fan + humidistat — from $680
Bundle with bathroom mould treatment and the $120 trip fee is waived

Full pricing on the exhaust fan installation service page.

When the fan isn't enough

If you have visible ceiling mould, blackened grout, or a musty smell that doesn't clear, you're past the prevention window. Combine fan replacement with proper mould removal in Singapore. See also exhaust fan vs dehumidifier for windowless rooms.

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Frequently Asked Questions

Why is a bathroom exhaust fan the single biggest mould-prevention tool?

Singapore bathrooms hit 80–95% humidity after a shower and stay above the mould-growth threshold for hours without extraction. A correctly sized fan clears the moisture in 15–20 minutes.

What CFM do I need?

Floor area sqft × 1.1 = minimum CFM. Use +50% margin in Singapore humidity.

Switch, timer, or humidistat?

Humidistat is best — the fan only stops when humidity is mould-hostile.

Will a new fan stop ceiling mould?

Yes, paired with proper ceiling treatment. Fan alone prevents new growth; treatment kills existing mould.

How much does installation cost?

From $380 all-inclusive for standard replacement. $550+ for new install with ducting.

Already Have Ceiling Mould?

Fix the cause AND the symptom. Treat the existing mould with our mould removal service + replace the failing exhaust fan in a single visit.

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