Garage Conversion Ventilation - what are the requirements

All rooms within a dwelling need to be ventilated and the requirement varies upon the type of use for each room. A garage conversion simply used as a room (bedroom, study, dining etc), simply requires trickle background ventilation. These are adjustable vents usually within the window frames.

Garage conversions containing moisture producing appliances or fittings require forced or mechanical ventilation such as extractor fans. There is a minim extract rate requirement under building regulations and these ventilation rates and requirements are stated below for all garage conversions:-

VENTILATION REQUIREMENTS - GENERALLY

HABITABLE ROOMS.

1. Opening windows to have 1/20th floor area for rapid ventilation.

2. 8000mm2 controllable trickle vents located in the head of the window frames for background

ventilation.

3. No requirement for mechanical or passive stack ventilation.

KITCHENS.

1. Opening windows of no min. size for rapid ventilation.

2. 4000mm2 controllable trickle vents located in the head of the window frames for background ventilation.

3. Mechanical extraction from fans to external air consisting of 30 litres/sec adjacent to a hob or 60 litres per sec. if fan located elsewhere in kitchen.

UTILITY ROOM

1. Opening windows of no min. size for rapid ventilation.

2. 4000mm2 controllable trickle vents located in the head of the window frames for background ventilation.

3. Mechanical extraction from fans to external air consisting of 30 litres/sec.

SANITARY ACCOMMODATION EXCLUDING BATHROOMS and SHOWER ROOMS.

1. Opening windows to have 1/20th floor area for rapid ventilation or mechanical extraction as

stated in '3' below.

2. 4000mm2 controllable trickle vents located in the head of the window frames for background ventilation.

3. Mechanical extraction from fan to external air consisting of 6 litres/sec if no windows are in the room.

BATHROOM and SHOWER ROOM.

1. Opening windows of no min. size for rapid ventilation.

2. 4000mm2 controllable trickle vents located in the head of the window frames for background ventilation.

3. Mechanical extraction from fan to external air consisting of 15 litres/sec.

NEW EXTRACT FANS - GENERALLY

Requirements:- Provide and install mechanical extract fans as indicated on plans. Duct fans to outside air and flash to external surfaces accordingly. Ducting of fans to outside air can be either through the roof / ceilings or via walls.

All fans must be tested and adjusted as required for commissioning and a certificate of testing must be provided to the Building Control Dept. by the main contractor.

Also, all new mechanical; ventilations systems installed for new dwellings, the air flow rates shall be measured on site and a notice given to the Building Control Body. This applies to intermittently used extract fans as well as complete systems.

The property owner must be given sufficient information about the system and maintenance requirements at completion.

Fans are to provide the following min. extract rates:-

Kitchen - 30 litres per sec. if a cooker hood extractor or:-

60 litres per sec. if an adjacent fan.

Bathrooms and Shower rooms - 15 litres per sec.

Sanitary rooms - 6 litres per sec. if the room has no window.

Fan operation: For rooms with windows, the fan is to be operated by an adjacent pull cord isolator switch for intermittent use by the owner.

For rooms without windows, the fan is to operate in conjunction with light switch.

All fans are to have an adjustable overrun period of 15 mins. minimum.

TESTING and CERTIFICATION:-

Main contractor to arrange for pre-completion testing of each installed extractor appliance and issue a formal certificate of testing confirming that the fan achieves the required level of air extract rate. The certificate must be issued to the Building Inspector and a copy supplied to the client.