Ventilation

Ventilation products let fresh air into a building and carry moist or stale air out. This category covers passive vents such as air bricks, louvred, hit-and-miss and draught-reducing vents, through-wall vent sets and cowls, internal grilles and door vents, round and flat-channel ducting with bends and adaptors, and cooker hoods.

Passive vents and air bricks

• Size and material: vents come in sizes such as 9 x 3, 9 x 6 and 9 x 9 inches, and in plastic, aluminium, steel, brass and terracotta. Measure the opening before choosing.
• Through-wall sets: an outer vent, an adjustable sleeve through the wall and an inner grille, often with a draught-reducing or hit-and-miss cover.
• Suspended timber floors: air bricks ventilate the space under the floor and should be kept clear.
• Gas appliances: never block an air vent that supplies a gas appliance, as a lack of air can lead to carbon monoxide.

Extract ventilation

Extract fans and cooker hoods remove moisture at source. As a guide for new homes in England, Approved Document F gives intermittent extract rates of 15 litres per second for a bathroom, and 30 litres per second for a kitchen when the extractor is next to the hob or 60 litres per second elsewhere. Match the size and shape of the ducting, round or flat channel, to the fan or hood outlet, using adaptors where they differ.

Installation

Ventilation work should follow Building Regulations Part F. Wiring a fan in a bathroom is electrical work in a special location: in England, it is notifiable under Part P and must be done by a registered competent person or notified to building control.

For fans and air conditioning, see air conditioning and ventilation; for sealing around ducts, see sealants.