When people think about fire safety, they often picture alarms, extinguishers, or sprinkler systems. But in the majority of fire-related incidents, it isn’t the flames that pose the greatest threat – it’s the smoke.
Smoke spreads faster than fire, significantly reduces visibility, and contains toxic gases that make evacuation difficult and dangerous. That’s why smoke ventilation, also known as smoke control, is a critical part of any building’s fire protection strategy and a key component of a thorough Fire Risk Assessment (FRA).
At FireRiskAssessments.com, we regularly support landlords, building owners, and responsible persons in ensuring their properties meet the highest standards of fire safety. In this blog, we’re breaking down what smoke ventilation is, how it works, and why it must be properly reviewed in every fire risk assessment.
What Is Smoke Ventilation?
Smoke ventilation systems are designed to remove smoke, heat, and toxic gases from a building during a fire. Their main purpose is to:
- Keep escape routes (like stairwells and corridors) free from smoke
- Improve visibility for occupants during evacuation
- Reduce heat levels to slow fire spread
- Assist firefighters in conducting safe and effective rescue operations
There are two primary types of smoke ventilation systems:
1. Natural Smoke Ventilation
These systems use Automatic Opening Vents (AOVs), windows, or smoke shafts that open when smoke is detected. They rely on natural air movement, buoyancy, and wind pressure to remove smoke.
Natural ventilation is common in residential blocks, stairwells, corridors, and atriums.
2. Mechanical Smoke Ventilation
These systems use powered smoke extract fans and ductwork to actively remove smoke from the building.
Mechanical systems offer more control and are often used in larger or more complex buildings, such as commercial properties, underground car parks, and high-rise developments.
Why Smoke Ventilation Is Essential in a Fire
During a fire, smoke can spread incredibly quickly. Within just a few minutes, escape routes can become impassable if smoke isn’t properly controlled.
Here’s why smoke ventilation saves lives:
✔ It preserves clear escape routes
Keeping stairwells, lobbies, and corridors smoke-free allows occupants to exit safely and quickly.
✔ It reduces smoke inhalation risks
Most fire deaths result from smoke inhalation, not burns. Smoke control significantly reduces exposure to toxic gases.
✔ It lowers temperatures
Removing hot gases and heat slows fire growth, helping prevent flashover.
✔ It supports firefighting
Smoke-free routes allow fire crews to enter the building, access the fire source, and conduct rescues more effectively.
Smoke Ventilation & Fire Risk Assessments: What Must Be Reviewed
A fire risk assessment should always evaluate the effectiveness, condition, and compliance of any smoke ventilation system in the building. Here’s what a competent assessor will look at:
1. System Type and Design
Your assessor will confirm:
- What smoke control system is installed
- Whether it is appropriate for the building type
- If it complies with relevant standards (BS 9991, BS 9999, BS EN 12101 series)
- Whether AOVs or smoke shafts are correctly sized and positioned
Incorrectly designed systems can make smoke spread worse — not better — so a design review is essential.
2. Operation and Activation
Assessors will check how the system activates:
- Smoke detectors
- Fire alarm signals
- Manual override controls
- Control panels and wiring
They also confirm that activation is reliable, consistent, and aligned with a clear cause and effect plan.
3. Maintenance and Testing
Smoke ventilation systems must be:
- Tested weekly or monthly (depending on system type)
- Serviced by a competent engineer at least annually
- Documented in maintenance logs
An FRA will check maintenance records, physical system condition, and any outstanding defects.
4. Power Supplies and Fail-Safes
Because smoke vents must work even if the building loses power, your assessor will also review:
- Backup power supplies
- Battery health
- Failsafe mechanisms (e.g., spring-loaded AOVs)
- Fire-resistant cables and automated releases
A smoke ventilation system that fails during a fire can be catastrophic — so redundancy is critical.
5. Escape Route Effectiveness
An FRA evaluates whether:
- Stairwells remain naturally ventilated
- Corridors stay clear of hot smoke
- Pressurisation systems maintain correct airflow
- Vent openings allow enough fresh air to replace extracted smoke
The ultimate test is simple: Does the smoke ventilation strategy enable safe evacuation?
Common Smoke Ventilation Issues Identified in Fire Risk Assessments
Many buildings — particularly older or converted ones — have inadequate, outdated, or poorly maintained smoke control systems. Some issues we regularly encounter include:
Vents that fail to open
Caused by poor maintenance, wiring issues, corrosion, or actuator failure.
Obstructed vents or smoke shafts
Debris, paint, or structural changes can block vents over time.
Non-compliant AOV sizes
Undersized vents can’t remove enough smoke to keep routes safe.
Inadequate natural ventilation
Buildings with sealed windows or modern airtight construction require mechanical systems.
Lack of maintenance logs
Missing or incomplete documentation can lead to enforcement action.
Unclear or missing “cause & effect” plans
Without proper activation strategies, systems may not respond correctly in a fire.
These issues can severely compromise life safety and must be addressed promptly.
Smoke Ventilation Regulations & Standards in the UK
Smoke control systems in the UK must comply with several regulations and British Standards, including:
• Regulatory Reform (Fire Safety) Order 2005
Requires responsible persons to maintain all fire-safety systems and include them in FRAs.
• Building Regulations: Approved Document B
Sets requirements for smoke ventilation in both residential and non-residential buildings.
• BS EN 12101 series
Covers smoke and heat control system components such as AOVs, fans, control panels, and ducts.
• BS 7346-8
Guidance on design, installation, commissioning, and maintenance of smoke ventilation systems.
• BS 9999 & BS 9991
Fire safety codes of practice for non-residential and residential buildings.
Non-compliance can lead to enforcement notices, penalties, or — most importantly — significant life-safety risks.
Best Practices for Building Owners & Responsible Persons
If you’re responsible for a building, here’s how to ensure your smoke ventilation system remains compliant and effective:
1. Schedule regular testing and maintenance
Weekly or monthly tests should be carried out, plus annual servicing by specialist engineers.
2. Keep detailed records
Maintenance logs, activation tests, and engineering inspections must be documented.
3. Ensure systems are unobstructed
AOVs, smoke shafts, and vents should remain clear and functional at all times.
4. Review your FRA annually
Or sooner if building use, layout, or occupancy changes.
5. Train staff
Caretakers and facilities teams should know how the smoke ventilation system works and what to do in a fire.
How We Can Help
At FireRiskAssessments.com, we provide comprehensive fire risk assessments that fully evaluate your building’s smoke ventilation strategy.
Our assessors:
- Inspect the condition and operation of smoke control systems
- Identify compliance issues against UK fire safety standards
- Review maintenance logs and servicing schedules
- Provide clear, actionable recommendations
- Help building owners prioritise corrective actions
- Ensure your building remains safe — and legally compliant
A well-functioning smoke ventilation system can be the difference between a safe evacuation and a life-threatening disaster. Our assessments ensure it performs when it matters most.
Ready to Improve Your Fire Safety? Get a free quote today
Smoke ventilation is one of the most critical elements of fire safety. In a fire, a well-designed, properly maintained smoke control system:
- Allows safe evacuation
- Reduces smoke inhalation risks
- Helps firefighters access the building
- Slows fire growth
- May prevent serious injuries or fatalities
That’s why it’s essential that smoke ventilation is always evaluated as part of your fire risk assessment.
If you’re unsure whether your building’s smoke ventilation system is compliant, effective, or up to date, we can help. Get a free quote.