Anti-Condensation Cluster
Air Con Ledge Sweating & Bulkhead Condensation — Why the Concrete Around Your Aircon Drips
That damp patch on the air con ledge (the concrete lip above or beside your aircon unit) or bulkhead framing the unit isn't a refrigerant leak. It's condensation forming on a surface directly bridged to the cold evaporator. Left alone, a sweating air con ledge stains paint, feeds ceiling mould, and drips onto the floor.
Quick Answer
Aircon ledges and bulkheads sweat because the concrete around the fan coil unit is chilled below dew point by refrigerant piping. Insulating the pipework and coating the ledge with Shield22 Pro raises the surface above dew point and stops the sweating; ledge and bulkhead treatment starts from S$380. Wiping or repainting with ordinary emulsion does not work because the surface temperature is unchanged.
Based on: HVAC Mould Prevention Study Field Data Verification Pico X Health Case Studies
Why the air con ledge sweats
The air con ledge — the concrete lip framing your split-unit aircon — sits in direct thermal contact with the aircon's cold coil housing. Concrete conducts heat well — a small cold spot at the aircon becomes a large cold patch across the ledge. When it drops below room dew point (usually below 20°C in an aircon room), humidity condenses on it.
What NOT to do
Don't assume it's an aircon fault — real refrigerant leaks make the coil ice up visibly and drip from inside the unit. Don't paint over with regular ceiling paint — no thermal barrier, condensation re-forms and peels the new coat. Don't just raise the aircon setpoint as the only fix — it reduces but rarely eliminates the sweat, and you sleep warmer forever.
The Shield22 Pro fix (S$380 per ledge/bulkhead)
Isolate aircon overnight. Sand and clean the concrete. Apply thermal-bond primer. Two coats of Shield22 Pro at 500 microns. Total time 3–4 hours; ready to run aircon next morning.
Common Singapore installations
HDB corridor-facing bedroom aircon ledges (BTO era 2015+). Condo master bedroom bulkheads directly above the bedhead. Office cassette-style aircon corner bulkheads. Landed home aircon ledges above stairwells.
Shield22 Pro — the coating that stops condensation at source
Thermal micro-ceramic coating that raises the surface temperature above dew point so airborne moisture stops condensing. From S$18/m². 5-year condensation-free warranty. Non-toxic, low-VOC, safe for occupied rooms.
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Frequently Asked Questions
- Should I call an aircon technician first?
- Only if there's ice on the coil, burning smell, or the unit itself is dripping. If the wet patch is on the concrete around the aircon and the aircon runs normally, it's condensation.
- Does the aircon need to come off the wall?
- No. We work around the installed unit.
- Will this void my aircon warranty?
- No. We coat the concrete surface, not the aircon.
- How long before I can turn the aircon back on?
- 8 hours after the second coat.