Metal Stud Sizes UK: 48mm, 70mm, 92mm and 146mm – Which to Specify and When
Metal stud sizes in the UK range from 48mm up to 146mm width, with each size suited to different partition heights, acoustic requirements, and structural conditions. The stud width determines the maximum height the partition can reach without additional bracing, the depth of cavity available for services and acoustic fill, and to a degree the acoustic performance of the finished wall. Choosing the wrong size is rarely catastrophic but it does create problems – a partition that exceeds its maximum height for the stud specified will need remedial work, and a cavity that’s too shallow for the acoustic spec will mean the system falls short of its target.
How Metal Stud Sizing Works
Metal studs are C-shaped cold-rolled steel sections that slot into U-shaped floor and ceiling tracks. The size refers to the width of the stud web – the flat back face of the C section. A 70mm stud has a 70mm web, which means the cavity between two faces of plasterboard on a standard single-frame partition is 70mm plus board thickness on each side.
Studs are typically available in a standard flange depth of 50mm with a 0.5mm or 0.6mm steel gauge for standard partitions, with heavier gauge options for structural or tall partition applications. The stud length is usually cut to suit the floor-to-ceiling height on site, with standard stock lengths available from 2400mm up to 4800mm or beyond from specialist suppliers.
Track is specified to match the stud width – a 70mm stud requires 70mm track. The track forms the head and floor channels into which the studs locate. On most partition applications, the head track is fitted with a deflection detail to allow for structural movement in the floor above without transferring load into the partition.
48mm Stud: Low-Height Partitions and Space-Constrained Applications
The 48mm stud is the smallest standard size and is suitable for partitions up to around 2700mm in height under standard conditions. It’s most commonly used in domestic applications where ceiling heights are low and acoustic or fire performance requirements are modest – non-habitable room dividers, cupboard walls, and secondary partitions where the primary goal is simply to divide space.
At 48mm, the cavity depth is limited. There’s enough room for a single layer of 25mm acoustic mineral wool slab, but not much more. This restricts the acoustic performance available from the system and means 48mm is rarely the right choice where Part E compliance or meaningful sound reduction is needed.
For commercial applications, 48mm is generally considered too narrow for most fit-out work. It does appear in some office partition systems where height and acoustic requirements are both low, but it’s not a common specification on projects of any meaningful scale.
70mm Stud: The Standard Domestic and Light Commercial Specification
The 70mm stud is the workhorse of the UK drylining industry. It covers the majority of domestic partition applications, standard office fit-outs, and light commercial work where ceiling heights run to around 3600mm. Maximum partition height under standard conditions is typically in the range of 3600-4000mm depending on the stud gauge and board configuration – single or double board affects the lateral stiffness of the finished partition.
The 70mm cavity comfortably accommodates 50mm acoustic mineral wool slab, leaving clearance for services runs if needed. This makes it the default choice for most acoustic partition specifications in the 40-45dB Rw range, which covers the majority of domestic separating wall requirements.
For most UK contractors working on residential and light commercial projects, 70mm is the size to default to unless there’s a specific reason to go wider or narrower. It’s widely stocked, competitively priced, and supported by published tested system data across the main manufacturers.
92mm Stud: Taller Partitions and Improved Acoustic Performance
The 92mm stud extends the maximum partition height to around 4500-5000mm under standard conditions, making it the standard choice for commercial spaces with higher floor-to-ceiling heights – open plan offices, retail fit-outs, and public buildings where 70mm would be at or near its height limit.
The wider cavity also improves acoustic performance. A 92mm cavity can accommodate 75mm acoustic mineral wool, and the additional air space between board faces increases the system’s ability to attenuate low-frequency sound. For partitions targeting Rw 45-50dB, 92mm is often the appropriate starting point before considering additional board layers or specialist acoustic products.
Services integration is also easier in a 92mm cavity. Where mechanical and electrical runs need to pass through partition walls – a common requirement in commercial fit-outs – the additional width provides meaningful working space without requiring chasing or surface-mounted conduit.
146mm Stud: Maximum Height and High Acoustic Performance
The 146mm stud is specified where partition heights exceed what 92mm can handle, or where acoustic performance targets push into the upper range of what standard stud partition systems can achieve. Maximum heights with 146mm studs can reach 6000mm or above depending on gauge and configuration, covering the full range of commercial and industrial applications.
The 146mm cavity allows for 100mm or thicker acoustic mineral wool, and the mass-air-mass relationship between the two board faces at this separation distance improves low-frequency attenuation meaningfully. For partitions targeting Rw 50dB and above, 146mm with appropriate board specification is the standard route.
In practice, 146mm stud is less commonly held in local merchant stock than 70mm or 92mm. For projects requiring it, ordering through a specialist metal stud and track supplier rather than a general builders merchant is usually the more reliable route for availability and lead times.
Metal Stud Size Comparison Table
| Stud Width | Max Height (approx) | Cavity Depth | Typical Acoustic Range | Primary Applications |
| 48mm | ~2700mm | 25mm usable | Rw 35-40dB | Domestic non-habitable, low partitions |
| 70mm | ~3600-4000mm | 50mm usable | Rw 40-45dB | Domestic, light commercial, standard fit-out |
| 92mm | ~4500-5000mm | 75mm usable | Rw 45-50dB | Commercial, taller partitions, higher acoustic spec |
| 146mm | ~6000mm+ | 100mm+ usable | Rw 50dB+ | High-rise, industrial, maximum acoustic performance |
Maximum heights are indicative under standard single-board conditions. Double boarding, heavier gauge studs, and intermediate noggins all affect the achievable height. Always check the manufacturer’s published height tables for the specific product and configuration being used.
Specifying the Right Size for Your Project
The starting point is always the partition height. If the ceiling is above 3600mm, 70mm is likely borderline and 92mm is the safer choice. If it’s above 4500mm, 146mm is the appropriate size. Height is the non-negotiable constraint – acoustic performance can often be improved by adding board layers or denser mineral wool within a given stud width, but a partition that exceeds its maximum height for the stud size is a structural and compliance problem that can’t be fixed with extra plasterboard.
Once height is confirmed, acoustic requirements drive the cavity specification. For most domestic work, 70mm with 50mm mineral wool and two layers of board will hit Part E targets comfortably. For commercial work with higher performance requirements, 92mm or 146mm with appropriate fill and board spec is the standard approach.The full metal stud and track range is available at Online Insulation across all standard sizes. For complete acoustic system builds, the resilient bars range covers decoupled wall and ceiling applications, and the wall lining system range is available where a metal frame lining against an existing masonry wall is needed rather than a freestanding partition.
