Abstract: The present invention relates to a ventilation system that allows air to circulate in a building but excludes pests such as birds, insects, moths and flies to enter the building. The ventilation system includes at least one vent comprising an aperture in the roof of the building and at least one fabric member adapted to be attached to the roof inside the building, below the vent(s) and between the vent(s) and the interior of the building. The present invention also relates to a building including the ventilation system, a truss arrangement that may form part of the ventilation system and a retaining rail for use in the ventilation system. The system of the invention has particular, but not exclusive, application to greenhouses and animal shelters.

Abstract: The present invention relates to a ventilation system that allows air to circulate in a building but excludes pests such as birds, insects, moths and flies to enter the building. The ventilation system includes at least one vent comprising an aperture in the roof of the building and at least one fabric member adapted to be attached to the roof inside the building, below the vent(s) and between the vent(s) and the interior of the building. The present invention also relates to a building including the ventilation system, a truss arrangement that may form part of the ventilation system and a retaining rail for use in the ventilation system. The system of the invention has particular, but not exclusive, application to greenhouses and animal shelters.