K1.1 This Part sets out the required standards for Regulation 23.
K1.2 The standards apply to all buildings except to a building, or part of a building, specified in Regulation 23(2).
K1.3 The volume of any space for ventilation purposes is the internal cubic capacity of the space, except -
a. where the space is for vehicle parking, any volume more than 3 metres above any floor level in that space is to be disregarded; and
b. in any other space, any volume more than 6 metres above any floor level in that space is to be disregarded.
K1.4 Any requirement for an area of opening may be met by a combination of areas.
VENTILATION OF BUILDINGS OTHER THAN GARAGES
K2.1* A building other than a garage must have adequate provision for ventilation by natural means, mechanical means, or a combination of natural and mechanical means, except -
a. there is no requirement to ventilate a storage room used only for storage requiring a controlled temperature; and
b. there is no requirement to ventilate a room with a floor area of not more than 4 square metres; and
c. a passive stack ventilation system is only permissible in a building of purpose group 1 with no storey at a height of more than 11 metres; and
d. a room where the cubic space per occupant is not more than 3 cubic metres must have mechanical ventilation.
LARGE GARAGES
K3.1* A garage with a floor area greater than 60 square metres for the parking of motor vehicles must have adequate provision for natural or mechanical ventilation on every storey.
SMALL GARAGES
K3.2* A garage with a floor area of at least 30 square metres but not more than 60 square metres used for the parking of motor vehicles must have adequate provision for natural or mechanical ventilation.
NATURAL VENTILATION
K4.1* Ventilation must be to the outside air, except -
a. a ventilator serving a room in a dwelling may open into a conservatory provided that the ventilation of the conservatory is to the outside air and is calculated on the basis of the total floor area of the room and the conservatory; and
b. a trickle ventilator serving a bathroom or shower-room may open into a bedroom from which it has direct access, provided the bedroom is fitted with a suitable trickle ventilator.
K4.2 Some part of the opening part of a ventilator, including a trickle ventilator, must be at least 1.75 metres above floor level.
K4.3* A passive stack ventilation system must be suitably constructed and installed.
K4.4 Each passive stack ventilation system must -
a. incorporate an automatic humidity sensitive ventilation inlet grille; and
b. where it passes through a roof space or other unheated space or where it extends above roof level, be insulated with at least 25mm thick material having a thermal conductivity of 0.04 W/mK.
K4.5 The duct forming a passive stack ventilation system serving a kitchen must be non-combustible other than where it passes through a roof space, except -
a. where the duct is totally enclosed within a casing providing at least 30 minutes fire resistance from the inside; or
b. where an automatic heat activated damper, shutter or sealing device providing at least 30 minutes fire resistance is provided immediately behind the inlet grille.
MECHANICAL VENTILATION
K4.6 Where a mechanical ventilation system serves more than one dwelling it must have a duplicate motor and be separate from any other ventilation system installed for any other purpose.
K4.7 Where a mechanical ventilation system gathers extracts into a common duct for discharge to an outlet, no connection to the system is permitted between any exhaust fan and the outlet.
K4.8 Mechanical ventilation must be to the outside air. It may be via a duct or heat exchanger.
K4.9* An inlet to, and an outlet from, a mechanical ventilation system must be suitably installed so as to avoid contamination of the air supply to the system.
K4.10*A mechanical ventilation system must be constructed to ensure, as far as is reasonably practicable, the avoidance of contamination by legionella.