Fire-Rated Ductwork in KSA: Using Fire-Boards for HVAC & Smoke Ducts
- murtaza
- November 9, 2025
- Uncategorized
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In a fire, an unprotected HVAC (air conditioning) system is a superhighway for fire, smoke, and toxic gases. It can spread a fire from one compartment to another in seconds. The Saudi Building Code (SBC) mandates that ducts passing through fire-rated walls or floors must be protected. While mechanical fire dampers are one solution, an increasingly common and robust solution is to use Fire-Boards to create fire-rated ductwork.
This method involves either wrapping existing sheet-metal ducts or building “self-supporting” ducts made entirely from fire-boards. This creates a passive, failsafe barrier that contains the fire and maintains the integrity of the fire compartment.
In This Article:
The Danger of Unprotected Ducts
A standard metal duct has zero fire resistance. It will rapidly transfer heat, igniting materials in the adjacent compartment. Worse, the duct itself will deform and collapse, leaving a large, open hole in a 2-hour fire-rated wall. Fire-rated ductwork solves this by providing a robust, 1-hour or 2-hour barrier *around* or *as* the duct itself.
Two Types of Fire-Rated Ducts: Encasement vs. Self-Supporting
As a specialist passive fire protection contractor, we install both main systems, which are typically made from high-performance calcium silicate or high-density mineral wool Fire-Boards.
| System Type | Description | Common Use |
|---|---|---|
| Duct Encasement | A standard sheet-metal duct is wrapped in one or two layers of fire-board (often a flexible, foil-backed mineral wool board). | The most common application. Used for standard HVAC ducts that need to pass through a rated wall or floor. |
| Self-Supporting Ducts | The duct is built *entirely* from rigid, high-strength fire-boards. There is no internal metal duct. | Used for critical smoke extraction and kitchen exhaust systems, or where a metal duct is not practical. |
Critical Applications: Smoke Extraction vs. Kitchen Ducts
Not all ducts are the same. Fire-board systems are critical for:
- Smoke Extraction Ducts: In a fire, these ducts must *remain open and functional* to extract smoke from escape routes. A self-supporting fire-board duct is engineered to withstand high temperatures and continue working, a key SBC requirement.
- Kitchen Exhaust Ducts: These ducts carry grease and are a high fire risk themselves (a fire can start *inside* the duct). They must be encased in a 2-hour rated system to prevent a duct fire from spreading to the rest of the building.
Why Specialist Installation is Essential
Installing fire-rated ductwork is a high-stakes, zero-error job. The integrity of the system, demonstrated in our past projects, depends on specialist knowledge:
- Support Systems: The duct must be supported by specialized, fire-rated hangers and supports. Standard supports will fail, causing the duct to collapse.
- Joints & Penetrations: All board joints, seams, and the point where the duct passes through the wall must be sealed perfectly according to the tested system.
- Access Doors: Any access doors for cleaning or maintenance must be of an equivalent fire-rating to the duct itself.
“A fire damper is an active system that can fail. A fire-rated duct is a passive, ‘always on’ solution. It is the most robust way to ensure compartmentation is never breached by the HVAC system.”
Conclusion: A Failsafe Solution for Air Distribution
Fire-Board systems for ductwork are a critical and increasingly specified part of modern fire safety design in KSA. They provide a passive, un-bypassable solution that ensures the building’s HVAC system does not become a liability in a fire. This specialist work requires a certified contractor who understands the tested systems for both the boards and their support structures.
Need to specify or install fire-rated ductwork for your KSA project?
