Natural Smoke Ventilation Systems

The Main Purpose of the System.

Natural Smoke Ventilation Systems from FDS FireSmart are a code compliant passive ventilation solution that are assisted by thermal buoyancy and stack effect.


In the event of a fire, smoke detectors will activate the natural smoke ventilation system.


The venting systems are designed to create natural ventilation to the common corridor on the effected fire floor.


The effect of the natural air flow allows smoke to exit from the building and exhaust out to the atmosphere.


Offering a safe means of escape for occupants, providing visibility and access for the fire fighters.

System Overview

Approved Document B: Fire Safety of the Building Regulations provides guidance on choosing the most appropriate system based on several key factors. This includes the height of the building, internal layout of the property and the distance of each dwelling from the staircase for evacuation.

Building Height

There is no limit to building height for a 1.5m2 natural smoke shaft, however, for a naturally ventilated corridor that is vented by a 1.5m2 AOV, the maximum building height is 30m.


The requirement for a natural system is either a 1.5m2 smoke shaft where the corridor is land locked or alternatively a 1.5m2 AOV to the façade.


Sympathetic to the Architects vision.

Travel Distance

NSVS is a suitable option when there is travel distances of 7.5m or below in un-sprinklered buildings or 15m in sprinkled buildings.

Wind Conditions

If the building is subject to turbulent wind conditions, an NSVS would not be the best solution. MSVS’ are not affected by wind conditions and would therefore be more suitable.

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Technical Data

NSVS are a code compliant solution that provides a reliable and cost-effective method of meeting the requirements of Approved Document B.

Shaft Size

A minimum cross-sectional area of 1.5m2 is required.

Shaft Width

A minimum dimension of 0.85m is required.

Shaft Height

The shaft must extend 2.5m above the highest ceiling served by the shaft and terminate at least 0.5m above the surrounding structure.

Shaft Damper Size

A minimum free area of 1.0m2 is required for openings into the shaft. BS EN 12101-8 certified dampers are required for use in the shaft.

Head of Stair Vent

The free area of the opening at the head of the shaft should be a minimum of 1.0m2.


For AOV’s a 1.5m2 free area is required. They must also be certified and certificated to BS EN 12101-2.

Guidance Legislation

SCA Guide

Common Escape Routes in Apartments - Jul 20

SCA White Paper

Specification of Products and Systems for Smoke Shafts

Approved Document B

Fire Safety Approved B Vol 1: Dwellings

BS EN 12101-8:2011

Smoke and Heat Control Systems

Relevant Case Studies

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