Section 1 — Domestic buildings Fl

Ventilation of non-habitable rooms
not containing openable windows

1.5 In kitchens, utility rooms, bathrooms and sanitary accommodation not containing openable windows (ie internal rooms) the requirement will be satisfied if there is either:

a. mechanical extract ventilation rated as in Table 1 and the fan has a 15 minutes’ overrun and is either controlled automatically or manually t; or

b. passive stack ventilation as in paragraph 1 .2(c)ii; or

c. an open-flued heating appliance as in paragraph 1 .2(c)iii.

For (a) to (C) above, an air inlet should be provided, eg a 10mm gap under the door.

+ In rooms with no natural light it would be appropriate for the fans to be controlled by the operation of the light switch.

Ventilation of habitable rooms through other rooms and spaces

1.6 Two habitable rooms may be treated as a single room for ventilation purposes if there is an area of permanent opening between them equal to at least 1/20th of the combined floor areas and provision for the rooms was made from Table 1 for a habitable room of the combined floor area (see Diagram 2).


1.7 A habitable room ventilated through an adjoining space (see Diagram 3) would satisfy the requirement if:

a. the adjoining space is a conservatory or similar space; and

b. there is from the space to outside provision for both:

_ _ I. rapid ventilation, one or more ventilation
_ _openings, with a total area of at least 1/20th of
_the combined floor area of the habitable room
_ _and space and with some part of the ventilation
_ _opening at high level (typically 1 .75m above the _ _floor level); and

_ _ii. background ventilation, a ventilation opening _ __ (or openings) of at least 8000mm2 and

C. there are openings (which may be closable) between the habitable room and the space for:

_ _i. rapid ventilation equivalent to b(i) above; and
_ _ii. background ventilation equivalent to b(ii) above.



Diagram 2 Two rooms treated as a
single room for ventilation purposes
Diagram 3 A habitable room ventilated
through an adjoining space

Return to Top