Fire ratings and fire separation in a fitout
What an FRL actually means, which walls need one, and why the cheapest way to fail an inspection is a hole somebody drilled after the wall was signed off.
The short answer
Fire separation is the part of a fitout that is invisible when it is right, expensive when it is wrong, and almost always discovered late, because the wall looked finished for weeks before anyone asked what was inside it.
Key points
- An FRL is three numbers in minutes: structural adequacy, integrity, insulation.
- Which elements need one comes from the NCC, and depends on your building's class and type.
- Every service that passes through a fire-rated wall has to be sealed with a tested system.
- A fire-rated ceiling is not the same as a wall to the slab, and they are not interchangeable.
Fire separation is the part of a fitout that is invisible when it is right, expensive when it is wrong, and almost always discovered late, because the wall looked finished for weeks before anyone asked what was inside it.
What an FRL actually is
A Fire Resistance Level is written as three numbers separated by slashes, in minutes. 60/60/60 means sixty minutes of each of three things, in this order.
- Structural adequacy. How long the element keeps carrying its load.
- Integrity. How long it stops flames and hot gases passing through.
- Insulation. How long it stops the far side getting hot enough to ignite what is touching it.
A dash means that criterion does not apply. So –/60/60 is a non loadbearing wall that still has to hold back fire and heat, which is most tenancy walls.
The number is a test result, not an opinion. A wall achieves an FRL because a specific construction, with specific studs, specific board, specific screw spacing and specific insulation, was tested as a system. Substitute any part of it and you no longer have the result, which is why the board type on a fire wall is not a place to make a saving.
Which walls need one
This comes from the National Construction Code and depends on your building's class and its type of construction, which in turn depends on rise in storeys and use. It is a determination the certifier or building surveyor makes, not a rule of thumb, but the patterns repeat.
- Tenancy separation. The walls between you and the tenancy either side, usually running to the underside of the slab rather than to your ceiling.
- Exit paths. Walls bounding a required exit, a fire-isolated stair or a corridor serving as a path of travel.
- Service risers and shafts. Anything vertical that passes between floors.
- Plant and hazard rooms. Depending on what is in them.
- Boundary walls close to a fire source feature, which is a defined term rather than a description.
A tenancy that changes classification is the one to watch. If your fitout moves a Class 5 or Class 6 tenancy into Class 9a, the fire separation requirements change with it, and the classification question therefore has to be settled before anything is drawn rather than after.
Penetrations, which is where it goes wrong
Every fire-rated wall in a working building has holes in it. Data, power, hydraulic, mechanical and sprinkler pipework all have to get through, and each of those holes destroys the tested system unless it is made good with a fire stopping system that was itself tested for that substrate, that service and that FRL.
That is the actual compliance issue. Not the wall, the holes. In a clinical fitout there are a great many of them, because a practice has more services than an office: suction and compressed air in dental, medical gas in a procedure room, extra hydraulic for every basin, and additional mechanical for consulting room ventilation.
The failure mode is mundane. A trade returns after the wall is signed off, needs one more cable through, drills it, pulls the cable and moves on. Nobody records it and nobody seals it. Six weeks later the certifier is asked to sign a wall that no longer performs, and opening it up to prove otherwise is the only way forward.
Ask your builder how penetrations are recorded and who signs them off. On a well-run job there is a register with photographs of each one before it was closed.
Ceilings, and a distinction that costs money
A fire-rated ceiling and a wall carried to the underside of the slab do different jobs and are not alternatives to each other.
Walls to the slab give you separation between tenancies or rooms, and incidentally solve the acoustic problem that a ceiling-height wall creates, since a shared ceiling void is an acoustic connection between two rooms. Fire-rated ceilings protect what is above the ceiling, typically the floor structure, and are a different specification entirely.
Where the base building relies on a rated ceiling and your fitout wants to cut into it for lighting, speakers or air outlets, each of those is a penetration in a rated element, and the same tested-system logic applies. This is a common and expensive surprise in older buildings.
When the code cannot be met
Sometimes the deemed-to-satisfy provisions cannot be achieved in a tenancy that already exists. An exit travel distance is too long, a wall cannot practically be rated, an opening is in the wrong place.
The pathway then is a performance solution: a fire engineer demonstrates that an alternative achieves the performance requirement, documented in a report the certifier accepts. It is a legitimate route and it is used constantly. It also costs money, takes time, and needs to be started early, because a performance solution discovered during construction is a program problem rather than a design one.
Sources and further reading
The National Construction Code on fire resistance and separation, and Standards Australia for the test standards behind an FRL. Which elements need rating on a specific tenancy is a determination for your certifier or building surveyor.
The National Construction Code: building classification, fire separation, egress, sanitary provisions and access.
Source for AS/NZS 4815 and 4187 reprocessing, AS 1428.1 access and AS 1668.2 ventilation. The standards themselves are purchased, not free.
Room-by-room design guidance and standard components used across Australian health projects, including consulting, treatment and sterilising rooms.
Questions
What does FRL 60/60/60 mean?
Sixty minutes of structural adequacy, sixty of integrity and sixty of insulation, in that order. Structural adequacy is how long the element keeps carrying load, integrity is how long it stops flames and hot gases passing through, and insulation is how long it stops the far side getting hot enough to ignite something touching it. A dash means that criterion does not apply.
Which walls in a fitout need to be fire rated?
Typically tenancy separation walls, walls bounding required exits and fire-isolated stairs, service shafts, some plant rooms, and boundary walls near a fire source feature. Exactly which, and to what level, comes from the National Construction Code via your building's class and type of construction, and is determined by the certifier or building surveyor.
Can I drill through a fire rated wall?
Only if the penetration is sealed with a fire stopping system tested for that substrate, that service and that FRL. A fire wall achieves its rating as a tested system, so an unsealed hole voids it. This is the most common fire compliance failure on a fitout, and it usually happens after the wall has already been signed off.
Is a fire rated ceiling the same as a wall going to the slab?
No, and they are not interchangeable. A wall carried to the underside of the slab separates one space from another, and solves the acoustic problem a ceiling-height wall creates. A fire-rated ceiling protects the structure above it and is a different specification. Cutting lights or air outlets into a rated ceiling is a penetration in a rated element.
What is a performance solution?
An alternative way of meeting the Code's performance requirements where the deemed-to-satisfy provisions cannot be achieved, demonstrated by a fire engineer in a report the certifier accepts. Common in existing buildings with long travel distances or awkward openings. Start it early: discovered during construction it becomes a program problem rather than a design one.
Send us the floor plan
A site assessment tells you what the tenancy can take and what it will cost to get there, ideally before you have signed for it.