How the two differ in kind
Around a lift shaft, a stair enclosure or a services riser there is a problem that does not arise on an ordinary partition: there is no far side to work from. The shaft IS the far side, and nobody is standing in it to screw a board on.
A CONVENTIONAL fire-rated partition assumes access to both faces. Studs go up, boards are fixed to one face, services are installed in the cavity, insulation goes in, and the second face is boarded — a sequence that works everywhere two-sided access exists and cannot be performed at all around a shaft.
A SHAFTWALL solves it with a specific arrangement. Its studs are C-H sections: a C on one side and an H-shaped throat on the other, open toward the shaft. Liner panels are slid edgewise into the throats of adjacent studs from the occupied side, so the shaft face of the wall is formed without anybody reaching it. The occupied face is then boarded conventionally. The whole wall is built, and its rating achieved, from one side.
That capability comes with a constraint that matters more than any other: a shaftwall is a TESTED ASSEMBLY. Its fire rating was established by testing a specific combination — that stud profile and gauge at that spacing, that liner panel, that number and type of face boards, that screw type and pattern, that treatment at the joints, that head detail — and the rating belongs to the combination rather than to any component in it. Substituting a board of equal thickness from a different manufacturer, changing a stud gauge, or improvising the head detail does not preserve the rating, because the rating never came from the thicknesses; it came from a furnace test of the whole wall.
The other design item is the HEAD. A shaftwall runs floor to floor in a building whose structure deflects, so the connection at the top has to permit that movement while maintaining the rating — which is a detail with its own tested arrangement, not a gap filled with sealant.
The factors that actually differ
Show
| Shaftwall system | Conventional fire-rated partition | |
|---|---|---|
| Access required | One side only. This is the entire reason it exists. | Both faces. |
| Where it belongs | Lift shafts, stair enclosures, services risers, duct shafts — anywhere the far face is unreachable. | Ordinary rated partitions between accessible spaces. |
| How the far face is formed | Liner panels slid into the open throats of C-H studs from the occupied side. | Boarded from that side by somebody standing there. |
| Rating basis | A tested assembly. The rating belongs to the exact combination, not to the components. | Also a tested assembly, with the same constraint — which is equally often ignored. |
| Substituting components | Voids the rating, even for a board of identical thickness from another manufacturer. | Identically so. |
| Head detail | A tested deflection head that accommodates structural movement while maintaining the rating. | The same requirement wherever the partition meets a deflecting structure. |
| Shaft-side pressure | Designed for it — a lift shaft sees air pressure pulses from the car, which the wall must resist. | Not normally a consideration. |
| Thickness | Typically thinner than an equivalent two-sided rated partition, which on a tight core plan matters. | Thicker for the same rating in many cases. |
| Penetrations | Firestopped to a tested system — and a riser is full of them, which makes this the recurring risk. | The same requirement, usually with fewer penetrations. |
| Cost | Higher per square metre for the system and its components. | Lower, where two-sided access makes it possible at all. |
Which one, and when
Choose shaftwall system when…
- A lift shaft, stair core, services riser or duct shaft where there is no access to the far face.
- A tight core plan, where the shaftwall's smaller thickness for the same rating saves usable area.
- A shaft subject to air pressure from lift movement, which the system is designed for.
- Any enclosure that has to be built progressively as the floors go up, from the occupied side.
Choose conventional fire-rated partition when…
- An ordinary rated partition between two accessible spaces.
- Where both faces can be worked from, which makes the cheaper and more familiar construction available.
- Where services in the cavity need to be installed and inspected from both sides.
- Where the specified tested assembly is a conventional one, which is the case for most rated walls in a building.
Now run your own numbers
This page holds no prices on purpose — a national average is wrong for almost every real project. Quantify both options with your dimensions and your local quotes.
Frequently asked questions
- Why can't a conventional partition be built around a shaft?
- Because the sequence requires somebody on the far side, and there is nobody there. A conventional partition is boarded on one face, has its cavity worked in, and is then boarded on the other — and the second boarding operation has to be performed from the space the wall encloses. Around a lift shaft that space is a void running the height of the building; around a services riser it is a shaft full of pipework with no floor. There is no safe or practical way to stand in either and fix boards. A shaftwall's C-H stud, with an open throat that receives the liner panel's edge, removes the requirement entirely: the liner is fed in from the occupied side and captured by the studs, so the enclosing face is formed by somebody standing outside it.
- What is a C-H stud?
- A metal stud with two different profiles on its two sides: a conventional C on the face toward the occupied space, and an H-shaped section on the shaft side whose open throat receives the edges of liner panels. In assembly, the first stud is set, a liner panel is slid into its throat, the next stud is offered up so its throat takes the panel's other edge, and the sequence repeats — so the liner forms a continuous face held mechanically by the studs rather than screwed to them from behind. The face boards are then fixed conventionally to the C side. The geometry is what makes single-side erection possible, and it is also why the stud profile is a component of the tested assembly rather than an interchangeable piece of metal.
- Why does substituting a board void the rating?
- Because the rating is a property of the tested assembly, not of any part in it. A fire-resistance rating is established by building a specific wall — that stud at that gauge and spacing, that liner, that number of face layers of that specific board, those screws at that pattern, those joints treated that way — and subjecting it to a standardised furnace test. What the certificate records is that this assembly achieved that rating. A board of the same nominal thickness from a different manufacturer has a different core formulation, different glass fibre and additive content, and different behaviour as the gypsum calcines, so it is simply not the wall that was tested. That is why fire-rated construction is specified by the assembly's listing reference, and why a like-for-like substitution needs a listing of its own rather than an argument.
- What is a deflection head and why does it matter?
- The detail where the partition meets the structure above, designed to let that structure move without transferring load into the wall or opening a gap in the fire separation. Floors deflect under load and structures move over time, so a partition rigidly fixed top and bottom either takes load it was not designed for — crushing the studs and cracking the boards — or opens a gap at the head as the structure moves away. A deflection head accommodates the movement, typically with a deep track and studs that are not fixed to it, or a purpose-made head component, and the fire-stopping at that joint has to maintain the rating while permitting the movement. Like everything else in the assembly, it is a tested detail with a specified movement capacity, and the common site failure is a gap packed with whatever came to hand.
- What are the recurring failures on a shaftwall?
- Penetrations, and the head. A services riser is by definition full of things passing through the wall — pipes, cables, ducts, and their supports — and every one is a hole in a fire separation that has to be closed with a firestop system tested for that element, that opening and that penetrating item. In a live building those penetrations keep being added, so the wall degrades over time as each new cable is run through it by somebody who does not treat the riser wall as rated. The head is the other: a deflection head detail improvised on site, or fire-stopped with a general-purpose product rather than the tested one, is a continuous gap along the top of every wall. Both are invisible from the occupied side once the boards are on.
- Does the wall have to resist pressure from inside the shaft?
- In a lift shaft, yes, and it is a load case people do not expect on a partition. A lift car moving in a shaft acts as a piston, pushing air ahead of it and drawing it behind, which produces pressure pulses on the shaft walls — repeatedly, for the life of the building. Shaftwall systems are designed and rated for a pressure as well as for fire, and the permitted stud height depends on the stud's gauge and depth at that pressure, which is why limiting-height tables exist for the system. A wall specified on fire performance alone and built to the height the fire test allows can be inadequate for the pressure, with the symptom appearing as movement, cracking at the joints and eventually a compromised separation. The two requirements are checked together.
- Is a shaftwall thinner than a conventional rated wall?
- Usually, for the same rating, and on a building core that is a meaningful gain. A shaftwall achieves its rating with a liner panel plus face boards on a relatively shallow stud, where a conventional partition of equivalent rating often needs multiple layers on both faces and a deeper stud. Across a core with several shafts and a stair, the difference in wall thickness recovers usable floor area on every storey — which on a tall building is a commercial number rather than a detail. The trade is cost per square metre, since the system's components are proprietary and dearer than generic board and stud, and the labour is specialised. On a core, the area recovered generally justifies it; on an ordinary partition with two-sided access, it does not.
- Can services be run in a shaftwall cavity?
- Within limits, and the limits come from the tested assembly rather than from convenience. The cavity between the liner and the face boards is shallow and it is part of the rated construction, so anything installed in it — services, boxes, supports — has to be compatible with the assembly's listing, and electrical boxes in rated walls have their own restrictions on size, spacing and the treatment behind them. Cutting into the liner panel from the occupied side to run something through is a breach of the shaft-side face and needs a firestop, not a patch. The general position is that a shaftwall is a fire separation first and a convenient chase second, and where services genuinely need to run in that plane the assembly is chosen and detailed to allow it rather than adapted afterwards.