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Building Regulations

The design of natural smoke ventilation systems for buildings is governed by Building Regulation Approved Document B.

For Residential buildings the basic requirements of Approved Document B state that a smoke ventilation system must be provided if the travel distance between an apartment door and the nearest escape exit is greater than 7.5 metres.

Approved Document B identifies a number of situations where AOVs to provide natural ventilation are
appropreate, including:

  • Small single stair block of flats.
  • Common escape routes in larger blocks of flats.
  • Basement areas.
  • Enclosed car parks.
  • Vertical smoke shafts, as part of a smoke control design.
140 Smoke Vent
In several cases, Approved Document B specifies the minimum 'free area' of ventilation - Generally either 1 square metre or 1.5 square metres.

The information within this website is to be used as a guide only and is subject to change without prior notice. Whilst we endeavour to keep the information up-to-date and correct, we make no representations or warranties of any kind about the accuracy or suitability of the information provided. If you would like assistance at any time, please don't hesitate to call us on 01276 451555 or you may e-mail us at To see the full range of rooflights available including the smoke vents listed on this website, please visit our main rooflight website at