The three numbers on a partition tag
A partition type on a wall schedule normally carries three numbers, and every one of them is priced differently. Read them in this order.
- Depth. How deep the stud is, commonly 64, 92, 152 mm, or the imperial equivalents. Depth is driven by height, services inside the wall, and acoustic performance.
- Gauge. How thick the steel is. Lower number means thicker steel. Gauge is driven by wall height, the load on the wall, and whether the wall is structural or non load bearing.
- Spacing. How far apart the studs sit, usually 400 or 600 mm on centre. Spacing is driven by board thickness, the finish, and anything hanging on the wall.
Changing any one of these changes the price, and changing depth or gauge on a tall wall can change whether the wall passes at all.
Gauge, and the limiting height problem
The single most common source of field trouble is a partition specified at a gauge that does not carry its own height. Non structural interior studs are typically supplied in 25, 22, 20 and 18 gauge, and every manufacturer publishes a limiting height table for each combination of depth, gauge and spacing at a given deflection criterion.
That deflection criterion matters as much as the steel. The same stud that is fine at L over 240 behind a corridor wall may not qualify at L over 360 behind a wall carrying tile or a rigid finish, because a stiffer surface cracks at deflections a painted wall tolerates. If the drawings do not state the deflection limit, that is a question to ask before the wall is priced rather than after it is framed.
| Situation | Typical direction | Note |
|---|---|---|
| Standard office partition to underside of ceiling | 25 gauge | Short walls, light finishes |
| Full height partition on a normal floor to floor | 20 gauge | The common commercial default |
| Tall wall, atrium, or a high warehouse partition | 18 gauge or heavier | Check limiting height at the stated deflection |
| Wall carrying tile, stone or a rigid finish | Heavier gauge, tighter spacing | Deflection limit drives this, not the wall height |
| Wall supporting cabinetry, grab bars or equipment | In-wall backing, gauge unchanged | Blocking solves this, not a heavier stud |
| Shaft wall around an elevator or a service riser | Proprietary shaft wall studs | A rated system, do not substitute components |
Spacing, and why 600 is not always the saving it looks like
Six hundred millimetre spacing uses fewer studs, so it looks like the cheaper option on a takeoff. It often is. But it puts more span between supports, which means the board carries more of the work.
- Single layer 12.7 mm board at 600 on centre can telegraph the framing under critical light, particularly on a wall taking a gloss
- Ceilings are a different case entirely and normally want tighter spacing than a wall
- Fire-rated assemblies specify their own spacing, and that is not adjustable
- Acoustic assemblies tested at a given spacing lose their rating if the spacing changes
On anything with a Level 5 finish or a demanding acoustic target, 400 on centre is usually worth the extra steel. On a back of house corridor at Level 4, 600 is fine.
Head of wall, the detail that gets missed
The top of a full height partition has to let the structure above it move without loading the wall. On a concrete or steel frame the slab deflects under live load, and a wall framed tight to the underside becomes a column nobody designed.
- Slip track, sometimes called deflection track, with a deeper leg so the stud can move inside it
- Deflection clips fixed to the stud web, leaving the stud free of the track
- A double track arrangement where one track slides inside the other
Which one is right depends on the expected movement, whether the wall is fire-rated, and whether it is also an acoustic separation. On a rated wall the head of wall joint has to be a tested and listed detail, because an untested gap at the top of a rated partition is a hole in the assembly no matter how neatly it is framed. That is a firestopping scope question as much as a framing one, and it needs an answer before the wall closes.
What to put on the drawings
A wall schedule that answers these questions prices cleanly and builds without an RFI.
- Depth, gauge and spacing for every partition type
- The deflection criterion the studs were selected against
- Whether each type runs to the ceiling or to the underside of the structure
- The head of wall detail, keyed to a listed assembly on rated walls
- Board type, layers and finish level per side
- Insulation type and whether it is thermal or acoustic
- Backing locations and heights
We self perform steel stud framing and boarding, so when a partition type is ambiguous we raise it at bid stage rather than framing to an assumption. Send a wall schedule and we will tell you which types need a decision before they can be priced.