If you are installing an air-conditioning unit on the exterior of any building or which projects outwards from any building, you will need to engage a trained air-conditioning unit installer to carry out installation work.
Find a trained air-conditioning unit installer
Here you will find a List of Trained Air-conditioning Unit Installers registered with BCA.
You can use the list above to verify if the air-conditioning unit installer is trained by asking for his identification pass, which should show his name, particulars and photograph. Sample of the identification pass shown below.

Installation requirements
If your air-conditioning unit is to be installed on the exterior of any building or which projects outwards from any building, it must be supported on a stainless steel bracket or concrete ledges/casings specifically designed to hold the air-conditioning units. Air-conditioning units that are located internally within your property are not subject to this requirement. However, you should check the condition of your bracket, ledge or casing regularly and get it repaired or replaced immediately if it has deteriorated .
Note: BCA does not have any requirement on the location at which the air-conditioning unit must be installed.
Other requirements on installation of air-conditioning unit tray
Please refer to NEA or HDB’s website for more details on installation of air-conditioning unit tray.
Do note that regular checks and maintenance of the tray system (including the method of securing) is necessary under the Building Maintenance and Strata Management Act. Premises owners should get it repaired or replaced immediately if it has deteriorated.