Fix poor ventilation in a Singapore maisonette bathroom
Maisonettes are two-storey HDB flats, and the upper bathroom often traps moisture because it sits far from the front windows. This HDB Renovation Guide Singapore walks through a clear 5-step plan to improve a maisonette bathroom's ventilation, with realistic cost ranges. The core answer is that you should fix airflow before you fix finishes, because no tile or paint will survive a damp room that cannot breathe.
Why maisonette bathrooms struggle with air
In a maisonette, the upstairs bathroom is usually internal. There is no exterior wall on two sides, so natural cross-ventilation is weak. Steam from showers settles on the ceiling and the cabinet edges, and within a year you may see peeling paint or a musty smell. Good ventilation is not a luxury here, it is the thing that keeps the rest of the renovation from rotting.
A 5-step ventilation plan
- Measure the room and count the air changes you need. A small maisonette bathroom of about 2.5 square metres wants a fan that moves roughly 100 to 150 cubic metres per hour.
- Pick the duct route. The shortest path to an exterior wall or the roof vent wins, because every metre of duct loses pressure.
- Choose the fan type. A wall or ceiling exhaust fan is cheaper; a ducted system costs more but runs quieter.
- Pair the fan with a humidity sensor so it switches on automatically after a shower.
- Add a small louvred vent or a transom slot to let fresh air in, since a fan can only push air out if air can come in.
Costs and HDB rules
A straightforward exhaust fan installation with a short duct costs about S$300 to S$800. A full ducted system with a humidity sensor and a new ceiling opening runs S$1,200 to S$3,000. Any cutting into walls, ceilings, or the original RC structure needs an HDB renovation permit, and only HDB-registered contractors may do regulated works. Windows must be handled by HDB-approved window contractors using shatter-resistant glass, so do not drill the window frame yourself. Noisy works like hacking are allowed Monday to Saturday, 9am to 6pm, and never on Sundays or public holidays.
Tips to keep the air moving
- Run the fan for at least 15 minutes after every shower, not just during it.
- Keep the bathroom door open a crack when the room is empty.
- Use mildew-resistant paint on the ceiling, but treat it as backup, not the main fix.
- Check the duct yearly for lint and blockages.
- Wipe the window track so condensation does not pool near the frame.
Frequently asked questions
Can I just open the window instead of fitting a fan? If the bathroom has no usable exterior window, a fan is the only reliable option. Many maisonette upper baths do not.
Will HDB allow me to cut a new vent in the wall? Only with a permit and an HDB-registered contractor, and only where the wall is non-structural.
How long does the work take? A fan job is one to three days. A ducted system can take a week once the permit is approved.
Ventilation is the quiet hero of a maisonette bathroom. Get the air right first, spend the rest of your budget on the finishes you can actually enjoy, and the room will stay fresh long after the renovation photos are taken.
