Under House Sub Floor Ventilation Systems for Sydney and Melbourne from Envirofan

EF10-4-S2R-150Cul-de-sac ventilation in Sydney or Melbourne refers to an under house ventilation pocket of sub floor space which does not have any exterior vents on the external wall due to various factors:


  • Where concrete slabs surrounds the suspended floor area on 2 or 3 sides.
  • Where the ground level outside the building is at the same level or higher than the internal floor level.

To remedy this condition can be done by lowering the external ground level by retaining walls and installing adequate sub floor ventilation. Or by using flexible ducting to extract the damp air from these ‘dead spots’ or ‘dead area’. Dead meaning that air flow is non-existent. The Envirofan quad fan sub floor ventilation system as shown in the picture above is utilised for various reasons:

  • Quiet operation (27dba) which does not translate to any undue noise in the dwelling or building unlike 240v systems (27dba is approximately a third of the noise of a modern domestic refrigerator).
  • That the sub floor ventilation solution is placed at the source of the problem.
  • Being 12v this caters for significant power consumption reduction by 10x less  than a 240v systems. This is good news for Melbournians and Sydney residents. Envirofans (Solarfans) in Melbourne have been in use for over 25 years. For Sydney, Envirofans (Solarfans) it has been in use for 35 years.
  • Utilising two (2750litres/min) or four (5,500litres/min) individual fans means that the sub floor ventilation properties will continue at a slight loss if one impeller ceases to operate, whereas with a one fan ventilation system sub floor ventilation, properties would be totally lost until the one fan unit is replaced or repaired.


At the problem area where the musty smell is most pronounced inside the dwelling.
Where a brick size dual fan system cannot be installed on an exterior wall.
Where discolouration (darkened appearance or fungi) on the soil is apparent as compared to other soil appearance in the sub-floor area.
‘Cul-de-sac ventilation’ system is installed under the house where the problem area is. This sub floor ventilation system draws the damp air into the duct, pushes it through the ducting to the tc (terra cotta) vent size Envirofan grill.
Designed to ventilate ‘cul-de-sac’ areas provided that there is sufficient sub-floor access.