Metal stud, timber stud or demountable: choosing by use
Choose the frame by the building and the duty, not by price. Metal stud is the default where fire performance is critical, where runs are long and must stay dead straight, or where the structure is concrete or steel. Timber stud suits short runs in domestic settings where fixings for heavy loads are needed. Demountable systems suit offices where layouts change.
Metal stud partitions use galvanised C-studs in a floor and head track, typically at 600mm or 400mm centres depending on board thickness and the performance required. The advantages are dimensional stability, non-combustibility of the frame itself, and the fact that the great majority of published fire and acoustic test data is based on metal stud systems, so the specification you are working to actually matches something that has been tested.
Timber stud remains the sensible choice for a short domestic partition dividing a bedroom or forming a hallway, and it takes heavy fixings, such as wall-hung sanitaryware or a large TV bracket, more readily than a light-gauge metal stud without additional pattressing. Its weakness is movement: timber shrinks and twists as it dries, and a long run of timber stud in a heated London flat is where hairline cracking at board joints tends to appear a year later.
Demountable partitions, solid or glazed, are a different product: an engineered kit designed to be taken down and reconfigured. Where an office tenant expects to change the layout inside the lease term, reconfiguration becomes a day's work rather than a strip-out. Where a wall will not move for twenty years, the demountable premium buys nothing.
Fire rating: what EI 30 and EI 60 actually certify
A fire rating belongs to a complete tested system, not to a board. EI 30 means the wall maintained integrity and insulation for 30 minutes in a standard test to BS EN 1364-1, classified under BS EN 13501-2; the equivalent older British Standard test is BS 476 Part 22. The certificate covers the specific frame, stud centres, board type, board thickness, layer count, fixing pattern, joint treatment and insulation that were tested together.
That is why substitution is the single most common way a fire-rated partition ends up unrated. Swapping a 15mm fire-rated board for two layers of 12.5mm standard board, opening stud centres from 400mm to 600mm, changing screw spacing, or leaving out the cavity insulation the tested build-up included, all take the wall outside the scope of the certificate. The wall may still perform, but nobody can demonstrate it, and a building control officer or fire risk assessor is entitled to treat an undemonstrable rating as no rating.
The two letters matter separately. E is integrity, meaning the wall resists the passage of flame and hot gases. I is insulation, meaning the unexposed face does not rise in temperature beyond defined limits. A glazed screen may achieve E 60 but only EI 30, or E 60 with no I classification at all, which changes where it can be used relative to an escape route. Asking a supplier for "a 60 minute screen" without asking which classification is how the wrong product gets ordered.
The rating must also be continuous. A partition rated EI 60 that stops at a suspended ceiling, with a plenum above it open to the adjoining room, provides an EI 60 barrier for the height of the wall and nothing above it. Where the partition is a compartment wall it has to run to the underside of the structural slab, and the fire performance of anything crossing that line has to be dealt with deliberately.
Acoustic performance and the London flat conversion
Where a partition separates two dwellings, it is a separating wall and falls under Part E of the Building Regulations. Approved Document E sets a minimum airborne sound insulation of 45 dB DnT,w + Ctr for walls in new-build dwellings and 43 dB DnT,w + Ctr for dwellings formed by a material change of use, which is what a converted London terrace or a flat subdivision is.
Those figures are performance standards, verified by pre-completion sound testing on the finished wall, not by the specification on the drawing. Robust Details, the route that avoids pre-completion testing, applies to new-build separating walls rather than conversions, so on a conversion the test is generally unavoidable and the wall has to be built to pass it rather than to look adequate.
The build-up that reaches those numbers is not a single-boarded stud wall. It is typically an independent or twin-frame construction, double-boarded with staggered joints, with mineral wool in the cavity, and with the two leaves isolated from one another so that structure-borne sound is not simply carried across. Resilient bars are a partial substitute for a genuinely independent frame and are less forgiving of poor workmanship, because a single screw that is long enough to reach the stud behind the bar short-circuits the isolation across the whole wall.
Flanking transmission is what actually fails conversion tests in London stock. Sound travelling through a continuous floor screed, a shared joist running through the new wall line, a continuous ceiling void, or back-to-back service penetrations, bypasses a perfectly good wall. On a Victorian conversion the flanking paths usually cost more to deal with than the partition itself, and a contractor who quotes the wall without mentioning them has not looked at the job.
Not every partition is a separating wall. A wall between two rooms in the same flat carries no Part E requirement, and building it to that standard is money spent on a rule that does not apply.
Services in the wall: sockets, data and the fire-stopping that gets missed
Every penetration through a rated partition has to be sealed with a system tested for that wall and that service. Cables, conduit, pipes, ductwork and socket boxes all breach the line, and a proprietary firestop, collar or sealant carrying its own test evidence is what restores it. Expanding foam is not fire-stopping and should not appear anywhere near a rated wall.
Socket boxes are the classic failure. Two boxes fitted back to back in the same stud void, which is the tidiest thing to do on site, create a straight path through both leaves of board for fire and for sound. The correct approach is to offset boxes into different voids, and to use fire-rated putty pads or intumescent box liners where the wall is rated. Both fixes take minutes and both are routinely omitted.
The same discipline applies to acoustic walls even where there is no fire rating. A pair of back-to-back sockets, a recessed media plate, or a poorly sealed pipe sleeve will cost several decibels on a wall that was otherwise going to pass, and decibels lost this way are extremely expensive to recover afterwards because the fix means opening the wall again.
Sequencing is what makes this achievable. First-fix electrical and data have to be complete and inspected before the second face is boarded, because once the wall is closed the only way to verify the fire-stopping is to cut it open. On a job where the wall matters, photographing the open stud void before boarding is worth the five minutes it takes and goes straight into the building file.
Head details, deflection and why long runs crack
A partition fixed hard to a structure that moves will crack, and in London that most often means a timber floor above deflecting under load or a concrete slab creeping over its first year or two. The answer is a deflection head: the studs sit loose in a deep head track so the structure can move without loading the partition, with the gap closed by a compressible seal or, on a rated wall, by a tested deflection head detail.
Where the wall is fire rated, that gap has to be fire-stopped with a system tested for the movement it is expected to accommodate. A rigid mortar fillet in a moving joint cracks and then the compartment line is open, so a proprietary flexible firestop is the correct product rather than a convenient one. The base and the vertical junctions need the same attention: a continuous bead of acoustic sealant under the floor track and behind the wall track is missed more often than any other single detail, because it disappears the moment the boards go on.
When a partition needs building control approval
A non-loadbearing partition that simply subdivides an existing room generally does not need building control approval in its own right. Approval is engaged where the work affects something the regulations control: means of escape and fire compartmentation under Part B, ventilation and daylight to a room under Part F, sound insulation between dwellings under Part E, or where the work forms a new dwelling and therefore a material change of use.
The commonest trap in a London flat is a partition that creates an inner room, where the only way out is through another room. Subdividing a through-lounge to form a bedroom, so that the new bedroom's escape passes through the remaining living space, is a Part B question rather than a plastering question, and it is the reason a straightforward-looking partition sometimes cannot be built as drawn.
The second trap is a partition that leaves a habitable room with no openable window or no adequate ventilation, or that halves the natural light to a room that then no longer functions as a bedroom for building control purposes. Both are resolved at design stage cheaply and after construction expensively.
Where a partition affects a party wall, or is built up to or off one, the Party Wall etc. Act 1996 may also be engaged. That is a separate process from building control, it sits with the property owner rather than the contractor, and it needs starting well before the programme assumes the wall goes up.
What to ask a partition contractor before you book
Four questions separate a contractor who is pricing a wall from one who is pricing your wall. Which tested system are you building to, and can I see the certificate. Is this a separating wall under Part E, and if so who is arranging the sound test. How are service penetrations being fire-stopped, and when can I see the void before it is boarded. What is the head detail, and what movement does it allow.
A contractor who answers those without hesitation is working from a specification. One who answers with a price per linear metre and a brand of plasterboard is quoting a wall shape, and the difference only becomes visible at inspection, when the rating cannot be evidenced and the test cannot be passed.
Ask also what is excluded. Flanking works on a conversion, pattressing for heavy fixings, first-fix electrical, and the acoustic sealant at the perimeter are the four items most often outside a partition quotation and most often assumed to be inside it.
Lian Construction build metal stud, timber stud and fire-rated partitions across London for landlords, managing agents and commercial occupiers, working to a named tested system with the fire-stopping recorded before the wall is closed.