Smoke Control for Metal Stairwell Enclosures: Design Considerations

Why the Enclosure Matters for Smoke Control

A stairwell is often the main escape route in a building, and smoke that enters it can quickly make the exit unusable. The enclosure around the stair, whether steel framed glazing, perforated metal panels or solid sheet, determines how well smoke is kept out and how it is vented if a system is planned. For architects, the metalwork is not only a visual element but part of the fire strategy.

Early discussion with the fire engineer helps set the performance targets before the design is fixed, so the metal elements are not changed late in the project.

Choosing Materials and Panel Types

Steel and stainless steel are generally stable under heat and suitable for enclosure panels. Aluminum is lighter but softens at lower temperatures, so its use in fire-related enclosures should be confirmed with the engineer. Solid panels, glazed infill and perforated sheet each behave differently in smoke and heat.

• Solid steel panels for smoke-resisting walls
• Glazed infill with suitable fire-rated glass
• Perforated sheet only where the engineer confirms it is acceptable

Doors, Gaps and Sealing Details

Smoke rarely passes through a wall alone. It leaks through gaps around doors, at panel joints and where the enclosure meets the structure. Door frames, leaves and threshold details should be designed to close tightly, and perimeter gaps should be kept to what the specification allows.

Self-closing mechanisms and smoke seals need to be specified clearly, and the door hardware should be checked against the escape route requirements.

Vents and Smoke Extraction Openings

Where a smoke extraction or ventilation strategy is part of the design, the openings in the enclosure must be sized and located by the engineer. Metal louvres, vents and actuated dampers are common, but their free area and position affect how the system performs. Their operation, access for maintenance and weather protection all need attention.

Exact opening sizes should come from the calculations and standards for your project, not from general assumptions.

Coordinating With the Smoke Control System

Smoke control usually involves detectors, fans, dampers and controls supplied by other trades. The metal enclosure must leave room for these, including cable routes, mounting points and access panels. Late changes to openings or fixings can compromise the system, so the metalwork drawings should show these items clearly.

A coordinated drawing set shared with the engineer and the installer reduces conflicts on site.

Detailing for Durability and Inspection

A smoke control enclosure must stay effective for the life of the building. Finishes such as hot-dip galvanizing or powder coating protect steel from corrosion, and fixings should be chosen to suit the environment. Panels and doors should be detailed so that inspection, testing and maintenance are practical without damaging the seals.

Access for periodic checks should be considered from the design stage.

Frequently asked questions

Can any metal be used for a stairwell enclosure?

Steel and stainless steel are commonly used for fire-related enclosures. Aluminum and other materials should only be used after the fire engineer confirms their performance for your project.

Do perforated metal panels work for smoke control?

Perforations allow smoke and air to pass, so they are usually not suitable where smoke resistance is required. Their use should be confirmed with the engineer for each location.

Who decides the required smoke control performance?

The fire engineer, in line with the applicable standards and the building authority's requirements, sets the performance criteria. The metal fabricator then details the enclosure to meet them.

When should the metalwork supplier be involved?

Involve the fabricator early, ideally during design development, so that openings, fixings and seals are coordinated before drawings are finalised.

Common mistakes to avoid

Designers often leave gaps, vents or fixings to be decided late, which creates leakage paths and conflicts with the smoke control equipment. Choosing finishes or panel types without confirming their fire performance is another common error.

Our recommendation

Share your fire engineer's smoke control requirements with the metal fabricator at the start, and request shop drawings that show all openings, seals and service penetrations before fabrication begins.

Summary

Smoke control for metal stairwell enclosures depends on material choice, sealing, openings and coordination with the smoke control system, all agreed with the fire engineer early.

Related guides

• Protected Escape Routes: Metalwork Requirements Overview
• Fire-Rated Metal Door Frames: Key Design Principles
• Access Control Hardware Compatible with Emergency Egress
• Door Closer and Self-Closing Mechanisms for Fire-Rated Doors
• Security Gates for Residential Entrances: Design Options
• Emergency Exit Signage Integration with Metal Doors
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