Stair pressurization is a smoke control method that supplies outdoor air into an exit stair so the stair stays at a higher pressure than the floors around it, limiting smoke entry during evacuation. It is part of a wider smoke control strategy designed to NFPA 92, Standard for Smoke Control Systems (2024 edition), or to the adopted building code, and it only counts once acceptance testing proves it works.
Key takeaways
- Smoke control contains smoke with pressure differences or exhausts it; stair pressurization is containment.
- In the 2021 International Building Code (IBC), stairs serving floors more than 75 ft (about 23 m) above fire department vehicle access must be smokeproof enclosures.
- The IBC sets stair pressure between 0.10 and 0.35 in. of water (25 to 87 Pa); the upper limit protects door-opening force.
- Typical requirements include UL 864 (category UUKL) listed controls, a firefighters’ control station, standby power and protected wiring.
- NFPA 92 and the International Fire Code (IFC Sections 909.20.4 and 909.20.5) require dedicated smoke control systems to be tested at least semiannually and non-dedicated systems at least annually, and on standby power where the authority requires it.
- The 2018 Saudi Fire Protection Code (SBC 801) covers smoke control in Section 909; confirm SBC 2024 requirements with Civil Defense.
In this article
- How smoke control and stair pressurization work
- Where smoke control is required in Saudi projects
- Design criteria for stair pressurization
- Controls, power and fire alarm integration
- From design to handover, step by step
- Common site mistakes
- Inspection, testing and maintenance
- What drives cost
- How AZEIDK helps
- FAQ
How smoke control and stair pressurization work
NFPA 92 covers two types of systems. Smoke containment systems, such as stair pressurization, elevator hoistway pressurization and zoned smoke control, use pressure differences across barriers to keep smoke out of protected spaces. Smoke management systems, typical in atria, exhaust smoke to keep the smoke layer above people’s heads.
In a pressurized stair, dedicated fans push outdoor air into the shaft, so air leaks through door gaps into the floor, pushing smoke away. Opening doors drops the pressure; closing them can push it too high unless relief dampers or fan speed control release the excess. As Professor James Milke notes, the aim is to limit smoke entry and keep the stair tenable, not to keep it entirely smoke free.
Other options for smokeproof enclosures
The IBC also allows a ventilated vestibule or an open exterior balcony before the stair; pressurization is the alternative in fully sprinklered buildings. European designs follow EN 12101-13:2022, which took over the design, installation and testing content of EN 12101-6:2005 (EN 12101-6:2022 now covers system kits); it applies to buildings up to 60 m, and taller buildings need additional calculation and verification.
Where smoke control is required in Saudi projects
The 2024 Saudi Building Code has been mandatory since 30 June 2025, though projects past key approval milestones may continue under the 2018 edition. In the 2018 Saudi Fire Protection Code, Section 909 covers smoke control systems and Section 910 smoke and heat removal, per its published table of contents. The General Building Code (SBC 201) was developed from the IBC, so these IBC triggers are a useful guide; the adopted Saudi text and Civil Defense decide.
| Space | Typical IBC requirement | Note |
|---|---|---|
| High-rise exit stairs | Smokeproof enclosures where stairs serve floors more than 75 ft above the lowest level of fire department vehicle access | Pressurization is one permitted design |
| Atria | Engineered smoke control keeping the smoke layer at least 6 ft (about 1.8 m) above the highest walking surface | Atrium: two or more connected stories in Groups I-2 and I-3, three or more elsewhere |
| Underground buildings | Smoke control where a floor is more than 30 ft (about 9 m) below the lowest level of exit discharge | Check the adopted text |
| Car parks and large enclosures | Smoke ventilation or smoke control, depending on the code path | Confusing the two causes redesign |
See our hospital fire and life safety guide for smoke compartments and our car park fire protection guide.
Design criteria for stair pressurization
| Item | Value or rule | Note |
|---|---|---|
| Minimum pressure difference | 0.10 in. of water (25 Pa) above adjacent spaces, stair doors closed | IBC Section 909.20.5, 2021 edition |
| Maximum pressure difference | 0.35 in. of water (87 Pa) | Protects door-opening force |
| Door-opening force | 30 pounds-force (lbf), about 133 N, to set the door in motion | IBC Section 1010.1.3; NFPA 92 also derives its maximum from door force |
| Fans | Dedicated to stair pressurization, not part of the heating, ventilation and air conditioning (HVAC) system | At top or bottom, several fans, or supply via an adjacent rated shaft |
| Open doors | NFPA 92 assumes doors closed unless opened by automatic devices; local codes may require open doors | Open-door designs need much larger fans |
Stack effect, caused by the inside-outside temperature difference, varies over the stair height, so in tall stairs one injection point may not meet both limits on every floor. In a Saudi summer, the outdoor air is hotter than the air-conditioned interior, which reverses stack effect, so local temperatures and leakage should be modeled.
Leakage and air intakes
Unsealed penetrations, poorly fitted doors and missing closers bleed air and weaken pressurization. Air intakes should sit away from smoke and car park exhausts.
Controls, power and fire alarm integration
- Activation: the system normally starts automatically on a fire alarm signal from any initiating device.
- Control equipment must be listed to UL 864 under category UUKL.
- NFPA 92 and the IBC require a firefighters’ smoke control station (FSCS) for status and manual control.
- Smoke dampers must be listed to UL 555S.
- The IBC requires standby power for stair pressurization equipment and its detection, and the 2024 IBC requires control wiring outside the building, within the exit enclosure, or in 2-hour rated construction; see our fire alarm cables guide.
- It is good practice to document fan, damper, HVAC shutdown, door release and elevator recall sequences in one cause and effect matrix and test them together; see our building management system (BMS) integration guide.
From design to handover, step by step
- Confirm the code path with the designer and Civil Defense.
- Set the design basis: pressure limits, doors assumed open, outdoor design temperatures, wind and leakage.
- Model the stair, using network modeling for tall or complex stairs.
- Select dedicated fans, a relief or speed control method, listed dampers and UUKL-listed controls with an FSCS.
- Coordinate standby power, wiring protection and air intakes.
- Program fire alarm and smoke control interfaces from the cause and effect matrix.
- Seal the stair and check doors, closers and seals before testing.
- Run acceptance tests: pressures on every level with doors closed and with design doors open, plus door-opening forces. Under the IBC, a special inspector performs the tests, witnessed by the building official where required.
- Keep the final acceptance test report in the building, as the IBC requires, and hand over documents and training.
Common site mistakes
- Over-pressurized stairs where doors near the fan cannot be opened.
- Relief dampers missing, blocked or wrongly set.
- Fans shared with general HVAC, or controlled by a building automation system not listed for smoke control.
- Testing only with all doors closed when the design assumes some open.
- New doors or openings after handover without retesting.
Inspection, testing and maintenance
NFPA 92 and IFC Sections 909.20.4 and 909.20.5 require dedicated smoke control systems to be tested at least semiannually and non-dedicated systems at least annually, and on standby power where the authority requires it. NFPA 92 makes the building owner responsible for system testing, and complete records are good practice.
Under NFPA 80 (fire dampers) and NFPA 105 (smoke dampers), each damper is tested one year after installation, then every four years, or every six years in buildings containing a hospital. Visible smoke bombs do not reproduce a real fire’s heat and buoyancy; measured pressures, airflows and door forces are the evidence. Our annual maintenance contracts schedule inspections, functional tests and reports within the agreed scope.
What drives cost
- Building height and the number of stairs and injection points.
- Fan capacity: Consulting-Specifying Engineer (CSE) notes one open exterior door can double or triple fan size.
- Relief and smoke dampers, actuators and wiring.
- UUKL-listed controls, the FSCS and system integration.
- Standby power, protected wiring and rated shafts or ducts.
- Modeling, air balancing, special inspection and acceptance testing.
How AZEIDK helps
AZEIDK’s smoke extraction and emergency ventilation solutions cover site assessment, supply and installation of smoke extraction fans, ducting coordination with HVAC and mechanical, electrical and plumbing (MEP) works, control components, fire alarm integration, testing and maintenance. Our engineering design and calculations service prepares criteria, calculations and specifications within the project scope, and our programming and systems integration team configures and tests cause and effect sequences.
We also provide Civil Defense approval support, drawing on 16+ years in the Saudi market and 17+ branches and service regions.
FAQ
What pressure is required in a pressurized stair?
In the 2021 IBC, a pressurized stair must be at least 0.10 in. of water (25 Pa) above adjacent spaces and no more than 0.35 in. of water (87 Pa), with doors closed. The maximum keeps door-opening force within 30 lbf. On Saudi projects, confirm the values with the adopted SBC edition and Civil Defense.
Is stair pressurization required in every building?
No. In IBC-based codes it is mainly used for smokeproof enclosures in high-rise buildings, where stairs serve floors more than 75 ft above fire department vehicle access, and even there it is one permitted option. The adopted code, the occupancy and the Civil Defense review decide each case.
What is the difference between smoke control and smoke ventilation?
Smoke control, in NFPA 92 terms, contains smoke with pressure differences or manages it by exhaust to keep escape routes tenable. Smoke ventilation in car parks and large enclosures, and smoke and heat removal under Section 910 of the 2018 SBC 801, mainly support firefighting.
Why are stair doors hard to open when the fans run?
Because stair pressure has exceeded the design limit, often after other doors close or because relief dampers are faulty. Extra pressure adds force on the door until it exceeds the allowed opening force, which can trap children and older occupants. Measure pressure and door force on every level and adjust relief or fan speed.
How often should a smoke control system be tested?
NFPA 92 and IFC Sections 909.20.4 and 909.20.5 require dedicated smoke control systems to be tested at least semiannually and non-dedicated systems at least annually, and on standby power where the authority requires it. Under NFPA 80 (fire dampers) and NFPA 105 (smoke dampers), each damper is tested one year after installation, then every four years, or every six years in buildings containing a hospital. The adopted code and Civil Defense set the final requirements.
Does NFPA 92 apply in Saudi Arabia?
NFPA 92 can serve as the design standard for engineered smoke control where the adopted code and the authority having jurisdiction (AHJ), usually Civil Defense, accept it. Agree on the standard and its edition, the latest being 2024, before calculations start, because pressure limits and test criteria follow it.
Planning smoke extraction or smoke control? Share your drawings and code path, and our team will review them with you and define what our smoke extraction and engineering services can cover. Contact the AZEIDK team
