A properly functioning smoke extraction system in a stairwell is vital in the event of a fire—and required by law. This is because the greatest danger in a fire usually comes not from the flames themselves, but from the smoke that develops. Within minutes, smoke can cause impaired vision, disorientation, and a risk of suffocation—especially in escape and rescue routes.
To ensure that a stairwell remains smoke-free in an emergency, the State Building Codes (LBO) of the individual federal states mandate appropriate smoke extractions or smoke and heat exhaust systems (RWA). The exact requirements may vary by state—as do the specifications for interior and exterior stairwells.
Why is an RWA required in a stairwell?
Stairwells serve as the primary escape and rescue routes in the event of a fire. To ensure that people can safely exit the building, these areas must remain smoke-free.
According to the respective state building codes, the following applies: Stairwells must have natural smoke extraction—usually in the form of windows, skylights, or smoke and heat exhaust systems (RWA).
Required smoke extraction areas
To ensure effective smoke extraction, the LBO requires a geometric smoke extraction area of at least 1 m²—or, alternatively, at least 5% of the stairwell’s floor area.
This opening ensures that smoke gases can quickly escape to the outside in the event of a fire and that escape routes remain smoke-free and passable.
Smoke extraction system for interior stairwells
If the stairwell is located inside the building, i.e., without direct contact to the exterior wall, a smoke extraction system (RWA) is mandatory.
In the event of a fire, this system automatically opens designated smoke exhaust openings—usually via the roof or special skylights—and directs the smoke out in a controlled manner.
Advantages of the RWA in an interior stairwell:
- Keeping the escape route smoke-free
- Assistance in rescuing people
- Facilitates firefighting by emergency responders
- Compliance with legal requirements of the state building code
Smoke exhaust system for exterior stairwells
Exterior stairwells—i.e., stairwells that adjoin an exterior wall on at least one side and have an openable window or ventilation element—are also subject to specific requirements.
Above a defined building height or occupancy class, a smoke exhaust system must also be installed here. The exact values—such as the permissible building height or the size of the smoke exhaust area—vary depending on the state building code.
In some states, for example, smoke extraction systems are required starting at three above-ground stories, while others only require them for high-rise buildings or special structures. Early consultation with the relevant building authority or a fire safety expert is therefore essential.
A functioning smoke extraction system in the stairwell is a central component of structural fire protection. It not only protects lives but is also mandatory under virtually all state building codes.
Whether natural or mechanical, internal or external—the right smoke exhaust system ensures that escape and rescue routes remain safely accessible in the event of a fire and that emergency responders can work effectively.
Regular maintenance and functional testing of smoke and heat exhaust systems complement preventive fire protection and are crucial for being optimally prepared in an emergency.
