Residential smoke shafts and common-corridor ventilation systems are intended to help control smoke in shared escape routes and protect access to stairs. Their arrangement may be natural or mechanical, but the correct solution must come from the project fire strategy and a competent smoke-control designer.
This guide explains the principal system types, the ductwork and damper interfaces that require coordination, and the information that should be agreed before equipment is selected or ductwork is manufactured. It is not a design method and does not replace project-specific calculations, product evidence, commissioning or approval.
What is the system intended to achieve?
A fire in a dwelling can allow smoke to enter the common corridor or lobby when the dwelling door opens or leaks. A correctly designed ventilation system can help remove or control that smoke and provide additional protection to the common stair, firefighting access route or evacuation route.
The required objective must be defined by the fire strategy. Depending on the building, the system may be intended to support escape, protect a staircase or lobby, assist firefighting operations, provide post-fire smoke clearance, or combine more than one objective. Those purposes should not be treated as interchangeable.
Common residential smoke-control arrangements
| Arrangement | Typical principle | Important coordination points |
|---|---|---|
| Natural smoke shaft | Smoke is discharged through a vertical shaft using buoyancy, with a vent opening from the affected corridor or lobby and an outlet at high level. | Shaft geometry, aerodynamic free area, ventilator performance, fire-floor selection, replacement air and weather effects. |
| Mechanical smoke shaft | A powered fan extracts smoke from the affected corridor or lobby through a dedicated shaft or ducted system. | Fan duty and temperature rating, system pressure, leakage, replacement air, standby arrangements, power supply and controls. |
| Direct natural vent | A high-level vent discharges directly to outside rather than through a common shaft. | Available free area, location, external wind effects, opening mechanism and fire-alarm interface. |
| Pressure differential system | Air-pressure differences are used to resist smoke movement into a protected stair, lobby or firefighting space. | Air paths, pressure relief, door forces, open-door conditions, fan control and acceptance testing. See BS EN 12101-13. |
A building may incorporate a combination of these principles. The description “smoke shaft” alone is not enough to establish the required performance or scope.
How does a zoned smoke-shaft system typically operate?
In a typical zoned arrangement, smoke detection identifies the affected corridor, lobby or storey. Subject to the approved cause-and-effect matrix, the ventilator or smoke-control damper serving that level opens, the shaft outlet opens or the extract fan starts, and the necessary replacement-air path is established.
Openings serving unaffected storeys are normally kept closed so the system concentrates its available duty on the fire floor and limits the movement of smoke into other areas. This is a general operating principle, not a universal rule. The actual sequence, including stair vents, inlet air, fan changeover and firefighter controls, must be confirmed by the fire strategy and cause-and-effect matrix.
Which standards and guidance may be relevant?
| Subject | Relevant route | Why it matters |
|---|---|---|
| Building fire-safety provisions | Approved Document B or the applicable national guidance | Provides statutory guidance for common building situations. The applicable edition and UK jurisdiction must be confirmed. |
| Pressure differential systems | BS EN 12101-13 | Covers design and calculation methods, installation, acceptance testing, routine testing and maintenance. |
| Natural smoke ventilators | BS EN 12101-2 | Product performance for natural smoke and heat exhaust ventilators. |
| Powered smoke extract fans | BS EN 12101-3 | Product performance for powered smoke and heat control ventilators. |
| Smoke-control duct sections | BS EN 12101-7 | Product standard for smoke-control duct sections. |
| Smoke-control dampers | BS EN 12101-8 and testing to BS EN 1366-10 | Relevant to dampers operating as part of a smoke-control system. |
| Multi-compartment smoke extract ductwork | BS EN 1366-8 and BS EN 13501-4 | Potentially relevant where smoke-extract ductwork passes through another fire compartment. |
| Whole-system planning and commissioning | BS 7346-8 | Recommendations for planning, installation, commissioning and maintenance of smoke-control systems. |
This list is a coordination guide rather than a complete specification. A smoke shaft is not automatically an EN 1366-8 duct, and a shaft formed from building construction is not automatically equivalent to a tested metal smoke-extract duct system. The proposed construction, route, exposure, pressure and interfaces must be checked against the applicable design and supporting evidence.
Ductwork, shaft and damper interfaces
The system should be coordinated as a complete airflow path. Important interfaces may include:
- The construction and fire resistance of the shaft or smoke-extract ductwork.
- The tested installation position and supporting construction for each smoke-control damper or ventilator.
- Connections between builders’ work shafts, metal ductwork, dampers and fans.
- Required E, I and S criteria, duration, pressure and leakage performance.
- Fire stopping at wall and floor penetrations.
- Fire-rated supports, anchors and access for inspection or replacement.
- Any insulation or protection forming part of the tested or assessed construction.
- Fan connections, flexible connectors and vibration isolation suitable for the required duty.
- Replacement-air paths and the effect of doors opening during escape or firefighting.
Information needed before pricing or manufacture
- Current fire strategy and smoke-control design report.
- Approved cause-and-effect matrix and system schematic.
- Plans, sections, shaft dimensions and coordinated duct routes.
- System objective and the areas or storeys served.
- Fan duty, operating temperature, pressure and standby philosophy.
- Damper and ventilator schedule, classifications and installation details.
- Duct or shaft classification, duration, orientation and fire-exposure requirements.
- Wall, floor, penetration, fire-stopping and support details.
- Power-supply, control, override and fire-alarm interfaces.
- Inspection, leakage testing, commissioning and handover requirements.
Who is responsible for what?
- Fire strategy author: establishes the life-safety objectives and required protection of escape and firefighting routes.
- Smoke-control designer: develops the airflow strategy, calculations, equipment duty and operating method.
- Mechanical consultant: coordinates fans, shafts, ductwork, dampers, controls and replacement air.
- Ductwork specialist: manufactures and installs the agreed ductwork construction within its tested or assessed scope.
- Controls and fire-alarm specialists: implement the approved cause-and-effect requirements.
- Commissioning team: tests the completed system and records whether the required sequence and performance have been achieved.
Commissioning and ongoing maintenance
Completion is not demonstrated by fan operation alone. Commissioning should verify the defined operating sequence, damper and ventilator positions, fan changeover, airflow or pressure performance, door interaction, alarms, controls, overrides and failure responses required by the approved design.
Access for inspection, testing, cleaning, repair and replacement should be planned before shafts and ceilings are closed. The building’s responsible person should receive suitable records and a maintenance regime for the installed system.
Common coordination mistakes
- Using “smoke shaft” as the complete performance specification.
- Assuming a non-combustible shaft or duct is automatically fire resisting.
- Selecting a fan before the system pressure and fire-temperature duty are established.
- Omitting a defined replacement-air route.
- Using dampers outside their tested supporting construction or installation position.
- Assuming vents or dampers on every floor should open simultaneously.
- Failing to coordinate penetrations, supports or access before the shaft is closed.
- Treating smoke clearance, escape protection and firefighting support as the same design objective.
- Commissioning individual components without proving the complete cause-and-effect sequence.
Request a ductwork scope review
Send the fire strategy, smoke-control report, drawings, ductwork classification and damper schedule for an initial review of the ductwork scope. This can help identify missing information and establish an appropriate basis for manufacture, insulation and installation.
Commercial manufacture and installation enquiries submitted through EN1366.co.uk are handled by DuctFix.
Important guidance note
This page provides general coordination guidance only. Residential smoke-control systems must be designed by competent specialists using the project fire strategy, applicable legislation and guidance, current standards, product evidence, calculations and an approved cause-and-effect matrix. EN1366.co.uk does not replace the fire engineer, smoke-control designer, building-control body, approving authority or project consultant.
Source basis: Approved Document B for England, BS EN 12101-2, BS EN 12101-3, BS EN 12101-7, BS EN 12101-8, BS EN 12101-13, BS EN 1366-8, BS EN 1366-10 and BS 7346-8. Requirements differ by UK jurisdiction and project. Always check the current applicable documents. This page is an original practical summary and does not reproduce or replace those publications.
Guidance review: September 2026. This is an original practical summary and does not reproduce or replace the relevant standards or project evidence. How this guidance is reviewed.