Fire rated
Fire-rated walls and ceilings built as a whole tested system
A rated wall is not a sheet of special board. It is a complete assembly, tested as one, and it performs only if every part is built the way the specification sets out.
People ask for fire rated board. What actually carries a rating is the system around it: a named board at a named thickness, on framing of a stated type and spacing, with stated fixings at stated centres, joints and junctions treated a particular way, and every penetration through it dealt with. Change one of those and the tested result no longer describes what is in the building.
This page covers what installing a rated wall or ceiling involves, why nothing in it gets substituted, how garage walls, party walls and service penetrations are handled, and what the work has to leave behind on paper. Where a rating is required, the specification governs and the job is built to it.
- Built to the specified system
- No substituted components
- Recorded before it closes up
The system is the product
Board, framing, fixings, joints and penetrations are one tested assembly, not a shopping list.
Nothing is improvised
If the specified detail is not available, the wall waits. Guessing at a rated junction is not a saving.
Penetrations are part of the wall
Every hole through a rated lining has to be dealt with, or the rating stops at that hole.
Recorded as installed
Product and system references, fixing details and photographs taken before anything is closed up.
Start here
What a fire rating actually describes
Nearly every misunderstanding on a rated job comes from treating the rating as a property of the board. It is worth getting these straight before anyone orders a sheet.
- A fire resistance level applies to a building element, not to a material, and it is set by the code for that element
- Where your project needs one, it is nominated in the drawings, the specification or the construction certificate
- It is established by testing or assessment of a complete assembly, from one face through to the other
- The board grade and thickness, the framing type and spacing, the fixing type and centres and the joint treatment are all part of that assembly
- Substituting any one of them takes the wall outside the thing that was tested, however similar the substitute looks
- Layers matter: where two layers are specified, the second is not optional and the joints between layers are offset deliberately
- Both faces usually matter, so a rated wall is rarely finished by lining one side of it
- The head, the base and the junctions at each end are details in the system, not site decisions
- Every service penetration is a designed part of the wall and has to be treated as the system requires
- Damage and later cutting into a rated lining undoes it, which is why access has to be planned rather than cut in
Scope
What rated lining work covers, and who does what
This page is the installation of specified fire-rated wall and ceiling linings. Our part is building the nominated system correctly and recording it. The items on the right belong to other people in the same job, and saying so clearly is part of doing it properly.
Our part of a rated job
- Reading the specification, the drawings and the system reference before anything is ordered
- Framing set out to the type and spacing the nominated system calls for
- Board of the specified grade and thickness, in the specified number of layers, both faces where required
- Fixings of the specified type at the specified centres, with layers offset as the system sets out
- Joints, junctions, head and base details built as the system requires rather than as general practice
- Openings, bulkheads and shaft linings within a rated wall or ceiling, built to the same system
- Coordinating with the trades whose services pass through the lining, so penetrations are formed rather than cut later
- Rated access panels fitted where the documentation calls for access into a rated element
- Setting, beading and sanding the finished surfaces so a rated wall looks like any other wall
- Photographs and product records of what was installed, handed over with the job
Not our part
- Deciding what rating your building needs, which is the certifier, the engineer or the designer
- Certification, inspection or sign-off of the completed element, which is not a plasterer's document to issue
- Fire stopping and sealing systems installed by a specialist, including collars, wraps, mortars and dampers
- Repairing or restoring plaster after a fire, which is assessed damage and goes through insurance plaster repairs
- Sound rating, which is a separately tested system: acoustic plastering
- An ordinary internal wall with no rating attached, which is partition walls
- Plain lining and setting with no system requirement, which is gyprock and plasterboard
- Sprinklers, detection, doors, door hardware and the services themselves, which stay with those trades
Where a rating is required and no system has been given to us, we ask for one rather than choose something that looks equivalent. An element built to an assumed detail is very hard to defend later, and it is your building that carries it.
How it runs
Documents, frame, board, junctions, penetrations, record
A rated job has the same shape as any lining job with two differences: it starts in the paperwork, and nothing about it is finished until it has been recorded.
- 01
Read the documents first
The drawings say which walls and ceilings are rated. The specification says how they are built. We go through both before ordering, and where something is missing or contradictory we ask the builder or the certifier rather than fill the gap ourselves.
- 02
Frame to the system
Stud or furring type, gauge, spacing and the head and base detail come from the system rather than from habit. Where the wall meets a slab, a beam or a roof, the junction is built as the documents show, because that is where a rated wall is usually weakest.
- 03
Fix the board as specified
The right grade and thickness, the right number of layers, the right fixings at the right centres, with the second layer offset so its joints do not land over the first. Offcuts get used where the system allows them, not wherever they happen to fit.
- 04
Build the junctions and openings
Ends, heads, corners, control joints, openings and any bulkhead or shaft within the element. These look like trim work and are not, and they are the first thing an inspector looks at.
- 05
Deal with every penetration
Outlets, lights, ducts, pipes and access panels are coordinated with the relevant trade so they are formed and treated as the system requires. Where a rated collar or fire stopping product is called for, it is installed by whoever holds that scope and we build the lining around it.
- 06
Photograph and hand over
Framing, fixings and penetrations photographed before they are covered, product and system details recorded, and handed over with the job. If anyone asks in three years what is in that wall, the answer should not depend on memory.
Documents and frame Board, penetrations, records
Where they turn up
The rated elements people actually ask about
Most enquiries here are one of a few familiar situations. Whether a rating applies to yours is a question for the certifier, but it is useful to know which conversation you are in.
The garage is the most common by a distance. Where a garage sits under or beside habitable rooms, the wall and the ceiling between them are often required to be rated, and the ceiling is the part people forget. A garage ceiling patched over the years, or cut into for storage or a hoist, may no longer be what was built.
Party walls between townhouses, duplexes and terraces are next. These are usually designed as a complete separating system between two occupancies, and often they carry a sound requirement as well, which is why a single wall can appear in two specifications. Anything touching the neighbour's side of it stops being a simple job.
After that it is stairwells, corridors and shafts, secondary dwellings and granny flats, plant rooms, and walls separating a tenancy from common property in strata buildings. In fit-outs the wall usually has to be taken to the underside of the slab rather than stopping at the ceiling, which changes the coordination with everything in the void.
In all of them the plastering question is the same and the answer comes from the documents: which element, which system, and how it is built at the head, the base and every penetration.
The quote
What shapes the cost of a rated element
A rated wall costs more than an ordinary one for reasons that are worth understanding, because most of them are in the detail rather than the board price.
The system itself
Board grade, thickness and the number of layers, plus the framing the system calls for. A two layer system on both faces is four times the board of a plain wall.
Fixing and jointing requirements
More fixings at closer centres, layers offset, and joint and junction details that take longer than standard taping and setting.
The junctions
Heads, bases, corners and abutments to slabs, beams and roofs are the slowest parts, and a wall with many of them costs more per metre than a long straight run.
Penetrations and coordination
Every service through the element is a detail and a conversation. A wall with a switchboard, ducting and a dozen outlets is a different job from a blank one.
Working around other trades
Rated work has to be done in sequence and cannot be caught up later, so it often means more visits and waiting on others.
Existing construction
Adding to or altering an existing rated element means finding out what is there first, and older linings have to be assessed before they are disturbed.
Records and inspections
Photographing, recording products and being available for inspection at the right stage all take time.
Access and the building
Height, staging, lift bookings and restricted hours apply here as anywhere, and they bite harder when the work cannot be rushed.
Where it fails
The details that quietly undo a rating
A rated element rarely fails because of the board. It fails in the parts that look like finishing, or months later when another trade needs to get through it.
| The detail | What goes wrong | What the system asks for |
|---|---|---|
| Board and thickness | A similar looking sheet substituted because it was on the truck, or one layer used where two were drawn | The nominated board at the nominated thickness and layer count, on both faces where the system says so |
| Fixing pattern | Fixings run out at standard spacing, the wrong type used, or the second layer fixed through into the first as if it were one | The specified fixing type and centres for each layer, with the layers offset as the system sets out |
| Framing type and spacing | Studs or furring at a convenient spacing, or a different gauge to the one tested, because the wall looked the same afterwards | Framing as nominated, at the nominated spacing, with noggings and support where the system calls for them |
| Head and base junctions | The gap at the head packed with offcuts or left, or a base detail treated as skirting work | The junction built exactly as detailed, including how movement at the head is allowed for |
| Service penetrations | A downlight, an outlet or a duct cut through after sheeting with nothing done about it | Penetrations located, formed and treated as the system requires, with rated products installed by the trade that holds that scope |
| Later alterations | An access hole cut in years afterwards, or a section removed for a renovation and patched with whatever was handy | Any opening into a rated element reinstated to the same system, or a rated access panel fitted where access is needed |
Before sheeting
Straightforward rated work, and what to settle first
The left column is the ordinary version of this job. The right column is what we will ask about, and none of it means trouble.
Ordinary rated lining work
- A nominated system on the drawings, with the board, framing and fixings clearly stated
- A new garage wall and ceiling being lined as part of a build or a renovation
- A party wall between two new dwellings, built from one side while the frame is open
- Corridor, stairwell and tenancy walls in a fit-out, taken to the underside of the slab
- Penetrations known early, so they are formed as the wall goes up rather than cut afterwards
- A rated access panel fitted where something behind the lining has to be reached
Settle these before anything is sheeted
- Which elements are rated and to what level, which comes from the certifier, the engineer or the designer
- The system reference or specification, because without one there is nothing to build to
- Who holds the fire stopping scope for collars, wraps, mortars and dampers through the element
- What the existing wall or ceiling is actually made of, where we are altering rather than building new
- Whether an older lining might contain asbestos, which is assessed and handled by a licensed party before anything is disturbed
- How access into the element will be provided later, so nobody has to cut into it
- When inspection is expected, so the work is not closed up before it can be seen
We build it, we do not certify it
Installing a rated system and certifying a rated element are two different jobs held by two different people. We build the nominated system correctly, keep to the specified components, and hand over records and photographs of what went in. The document that says the element complies comes from a certifier, and it should.
That split matters when somebody offers you a fire rated wall with no system named, no records and a price that looks good. There is nothing to check and nothing to hand a certifier, and the only way to find out what is really in the wall is to open it again.
Questions
Fire-rated lining questions we get asked
The questions that come up on nearly every rated job, answered plainly.
Is fire rated plasterboard the same thing as a fire rated wall?
No, and the difference matters. Fire rated board is one component. A rated wall is the whole assembly: that board, in the right thickness and number of layers, on the right framing at the right spacing, with the right fixings, the specified joint treatment and every penetration dealt with.
You can build a wall out of rated board and have it perform nothing like the tested system, simply by changing the stud spacing or leaving the head junction as a gap. That is why the system reference is worth more than the product name.
Can you tell me what rating my wall needs?
No, and you should be wary of anyone who says yes off a phone call. The required level for a particular element comes from the building code applied to your building, its class, its height and its layout, and it is nominated by the certifier, the designer or the engineer on your project.
What we can do is read what has been nominated, tell you plainly what it means for the build-up, the thickness and the sequencing, and flag where the documents are silent on a detail we need. On a domestic renovation, the builder or the certifier is the person to ask first.
What happens where a downlight or a power point goes through a rated ceiling?
It gets treated as part of the system rather than as a hole. Depending on what the documentation calls for, that can mean the fitting sitting in a specified enclosure, a rated collar or wrap installed by the trade that holds that scope, or the penetration being relocated so it does not pass through the element at all.
What it never means is cutting the opening afterwards and moving on. If a light position matters to you, raise it before the ceiling is sheeted, because a rated ceiling is one of the worst surfaces on which to change your mind later.
Can a rating be added to a wall that already exists?
Sometimes, and it starts with finding out what the existing wall actually is: the framing, the cavity, what is already on each face and whether both faces can be reached. From there a system can be nominated that suits what is there, usually by adding specified layers.
Two things commonly get in the way. One is access to the far face, particularly on a boundary or party wall. The other is not knowing what is in the wall, which on older buildings includes the possibility of material that has to be assessed before anything is disturbed. Both are answerable, and both are cheaper to answer before the work is priced.
Will two layers of ordinary plasterboard give me a rating?
Not by themselves, no. Two layers of standard board make a heavier and more solid wall, which has its uses, and a rating is a tested performance rather than a general improvement. Without a system that has been tested or assessed in that configuration, there is nothing to claim.
If what you actually want is a wall that feels more solid and passes less noise, that is a reasonable goal and it is covered on acoustic plastering. If you need a rating, the system comes first and the layers follow from it.
What paperwork do I get at the end?
Records of what was installed: the system reference we built to, the board and framing products used, the fixing details, and photographs of the framing and penetrations taken before they were covered. On a commercial job that usually goes into the builder's handover package.
What we do not issue is a certificate of compliance for the element, because that is the certifier's document. Our records exist so the certifier, the owner or whoever is looking at it in ten years can see what is actually in there without opening it up.
Send the documents
Send the drawings and the specified system
The marked up plan, the nominated system or specification, and what services pass through the element. With those we can price it properly, and without them we will ask before we quote.