What are stairwell smoke vents?

A stairwell smoke ventilator is an automatic opening ventilator (AOV) which provides at least 1.0mof free area when open. There are two main stairwell smoke vent types – louvred vents and hatch vents. Both types of vents can perform the expectations of an AOV, however, each has its individual benefits which influence the selection process. Both smoke vent types usually serve one of two purposes:

  • To evacuate any smoke that gets in the stairwell of small buildings
  • To provide replacement air for a lobby smoke extract system in large buildings

Smoke Vent TypesStairwell Smoke Vent Types

Louvred Vent

  • Louvred ventilators can be used for daily ventilation, either by adding a rain sensor to the control system, or by selecting a louvre with separate side mounted daily ventilation louvres to allow fresh air input without opening the whole louvre. This means that daily ventilation can be provided even in wet weather.
  • Louvred vents have a low profile when installed, which means the vent is less likely to incur wind damage when open. This is a frequent cause of damage to hatch ventilators which are opened in high winds.
  • Even when open, intruders will not be able to gain access to the building through the vent.


Hatch vent

  • Smoke Vent Types

    The lid opens to over 120° to ensure smoke exhaust benefits from cross winds and has no obstructions.

  • The free area of a hatch vent is maximised as there are no obstructions to airflow therefore the roof opening size is slightly smaller than the equivalent louvre.
  • An insulated hatch vent will have a better u value than the equivalent louvre giving a better insulation performance.
  • Hatch vents may also be used for roof access.
  • Using hatch vents for roof access will require the opening mechanism to be designed in such a way that it doesn’t obstruct access through the hatch. In addition, manual controls to facilitate the opening and closing both from inside and from the roof can be installed.  Explore Group SCS’s range of hatch and louvred vents our download one of our AOV guides to find out more about our products.

Under the Construction Products Regulations (CPR) it is a legal requirement to use only certified products for smoke ventilation. It is the responsibility of the installer to ensure installations meet the relevant standards. For more information see SCS Group’s Technical Bulletin here.


Share this post: