Open stairways are widely used in commercial interiors to maintain visibility between levels, connect floors, and support the overall design intent. They also create a vertical opening that can allow smoke and heat to spread between floors in a fire. If that opening is left unprotected, smoke can rise quickly beyond the floor where the fire began, interrupting egress, reducing visibility, increasing risk to occupants, and complicating smoke control strategies designed around separated floor plates.
These stair openings require careful review when they pass through rated floor assemblies or need to comply with the building’s life safety strategy. Many projects rely on the openings to maintain daylight, openness, and circulation between floors, so adding full-height walls can change how the space works, while significantly altering the design intent. When a permanent enclosure is not part of the plan, the main question becomes how to protect the opening while keeping the stairway open during normal use without sacrificing the building’s overall design.
Why Open Stairways Create a Fire+Smoke Concern
An open stairway creates a direct path for vertical smoke movement. Hot gases rise, and that upward movement can carry smoke to upper levels before occupants have adequate time to react.
A large opening changes how smoke moves through the building and may require added protection at the floor penetration. Because of that, open stairs are scrutinized to confirm the opening is properly protected and continuity and safety are maintained at the floor penetration.
Options for Protecting Large Floor Openings
When open stairways need protection, the solution is not always a full enclosure. In some projects, that may be the right answer. However, in many others, the design calls for the stair to remain open during normal use. In those cases, design teams may consider deployable opening protective systems that work with the building’s smoke-control strategy while preserving the space’s openness and design intent.
One highly effective and proven protective system is the Smoke Guard M4000 perimeter curtain, which is used at large floor openings such as open stairs and atriums. The system remains concealed above the ceiling during normal conditions and deploys upon activation to form a continuous barrier around the opening.
The M4000 (fire-resistance rated to UL 10B and smoke tested to UL 1784) is designed to address both fire resistance and smoke migration in a deployable assembly. That can help teams protect the opening while preserving the open design. The M4000 is a perfect solution in hospitals, in particular, where considerations have to include the separation of smoke compartments.
What to Evaluate During Design and Coordination
For architects, fire protection engineers, code consultants, and contractors, the bigger issue is not just product selection. It is coordination. Large opening protection needs to be evaluated early so teams can address a variety of important items, including:
- Opening size and geometry
- Ceiling space and support conditions
- Fire alarm and control integration
- Smoke control strategy
- AHJ review and acceptance
When these conditions are addressed early, teams are better positioned to protect the opening without disrupting the design later in the project.
Keeping the Design Open Without Leaving the Opening Unprotected
Open stairs can improve circulation and strengthen a space’s design; they also may create a critical condition that must be addressed as part of the fire and smoke protection strategy.
For projects where a full enclosure is not part of the design, deployable opening protective systems can offer a functional and effective path. The goal is to protect the opening, support code compliance, and preserve the openness that made the stair part of the design in the first place.
If you are planning an open stairway, atrium, or other large floor opening, Smoke Guard can help you evaluate protection options that align with the design and code strategy.