Extended Corridor System - Exhaust shaft ventilation

Approved Document B (Fire safety) recommends that where there is a dead-end corridor, the travel distance from the dwelling door to the staircase is limited to 7.5 metres. The Extended Corridor System allows safe escape conditions to be maintained in the corridor, even when the travel distance is extended by a factor of 2 or 3 in one direction. It is designed for both evacuation and fire-fighting. The system is generally unaffected by external wind pressure.

The system comprises a supply and extract system with shafts at each end of the corridor. Vertical builders' ducts are required at each end of the corridor which will supply fresh air and provide smoke extraction to fans mounted at roof level, providing a smoke dilution system to the fire floor. The ductwork is nominally only 0.6 m² in cross sectional area, enabling a much reduced footprint compared to alternative solutions.

The Extended Corridor System is a LABC Registered System because of its superior performance as proven by CFD and full scale physical testing, witnessed and approved by independent consultants including the London Fire and Emergency Planning Authority.

Features and benefits:

• Space saving - The Extended Corridor System requires a shaft with a cross sectional area which can be as small as only 0.6 m² compared with 3 m² for the BRE shaft or 1.5 m² for a natural residential (ADB) shaft. This represents up to 80% reduction in the floor space required.
• Enhanced performance - The Extended Corridor System can perform better than a BRE Shaft since it extracts at a defined rate - this means that it is unaffected by external wind pressures. It is also less susceptible to obstructions to the airflow within the duct. Its design has been proven by extensive CFD analysis and by empirical tests.