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Stud centres — the distance between the centre lines of adjacent studs — is one of the most important variables in an SFS wall. It affects strength, cost, acoustic performance, fire rating and installation speed. Getting it right matters. This guide explains what stud centres are, why 600mm is the default, when to tighten to 400mm or 300mm, and why tighter isn't always better.

What are stud centres?

Stud centres is the distance from the centre line of one stud to the centre line of the next. It's measured in millimetres. Common values are 600mm, 400mm, and 300mm. Occasionally 450mm is used, but it's less common in UK practice.

Why "centre to centre" and not "gap between studs"? Because the centre spacing is what matters structurally. A 70mm stud at 600mm centres has a 530mm gap between studs, but the structural spacing is 600mm. The centre measurement is consistent regardless of stud width.

600mm centres — the standard

600mm is the default in most SFS applications. Why?

• Board sheets are 1200mm wide — 600mm centres means every board joint falls on a stud, and the mid-sheet is also supported. Two boards cover three studs perfectly.
• Standard span tables are built around 600mm — most manufacturers publish their maximum heights for 600mm centres, because that's what most projects use.
• Cost-effective — fewer studs per metre than 400mm or 300mm centres means lower material cost.
• Adequate for most applications — with the right stud width and gauge, 600mm centres handles most walls up to their maximum span.

Use 600mm centres when:

• The wall is a standard partition or infill
• The wall height is within the span table for 600mm centres at the stud size you're using
• Wind loading is standard (not exposed or coastal)
• Acoustic performance is Rw 50 or lower
• Fire rating is up to 90 minutes (with the tested board build-up)

400mm centres — when to tighten

400mm centres is the first step up in density. It's used where 600mm isn't enough. Common reasons:

• Taller walls — if a stud at 600mm centres would deflect too much for the wall height, tightening to 400mm centres reduces the span between supports and reduces deflection.
• Higher wind loading — exposed locations, coastal sites, mid-rise buildings. Tighter centres share the load across more studs.
• Higher acoustic performance — Rw 50–55 often needs 400mm centres to reduce flanking through the stud line.
• Heavy items being fixed — a wall carrying radiators, TVs, or heavy shelving benefits from tighter centres so fixings always land near a stud.
• Larger openings — around large windows or doors, tighter centres help transfer loads around the opening.

Use 400mm centres when:

• The span table for 600mm centres doesn't quite work, but the next stud size up would be overkill
• Wind loading is above standard
• Acoustic target is Rw 50–55
• Wall will carry heavy fixtures

300mm centres — heavy duty

300mm centres is the tightest standard spacing. It's used where the loads or performance requirements push past what 400mm can handle. Common reasons:

• Very tall walls — over 6m in exposed conditions, 300mm centres may be needed to keep deflection within limits.
• Very high wind loading — high-rise, coastal, or exposed sites where wind pressure exceeds 1.5 kN/m².
• High acoustic target — Rw 55+ walls often use 300mm centres, or twin-frame construction at 600mm centres.
• Loadbearing walls — where the wall carries significant structural loads.
• Sport halls and industrial buildings — where impact loading or abuse is expected.
• Board deflection limits — some board types (especially fire-rated boards) specify tighter centres for higher fire ratings.

Use 300mm centres when:

• The span table for 400mm centres doesn't work
• Wind loading is severe
• Acoustic target is Rw 55+
• Wall is loadbearing or heavy-duty
• Board manufacturer specifies 300mm for fire or impact resistance

Effect on strength

Reducing stud centres increases the strength of the wall because:

• More studs share the load — a 600mm spacing has 1.67 studs per metre of wall; 400mm has 2.5 per metre; 300mm has 3.33 per metre.
• Each stud spans a shorter distance — the span between supports (the tracks) is the same, but the tributary load per stud is reduced, so deflection is lower.
• The board is supported more closely — reducing centres from 600mm to 400mm means board spans between supports drop by 33%, which dramatically reduces board deflection under load.

Rough effect on deflection (assuming all other factors equal):

So going from 600mm to 400mm reduces the deflection to roughly two-thirds. Going to 300mm halves it.

Effect on acoustics

Tighter stud centres can improve acoustic performance because:

• The stud line is a "hard" path for sound — more studs means more potential sound paths, which sounds like it would be worse. But tighter centres also mean the board between studs is more constrained, which reduces the board's ability to resonate.
• The wall is stiffer, which reduces low-frequency transmission through panel movement.
• Insulation fills better — with fewer gaps between studs, the insulation fits more snugly, which improves acoustic performance.

In practice, tighter centres give roughly 2–4 dB improvement, similar to adding a layer of board or upgrading insulation. If you're aiming for Rw 55+, tighter centres plus better board plus better insulation is a common combination.

Effect on cost

Tighter centres cost more. Going from 600mm to 400mm increases the stud count by 50%, which increases the metal cost by roughly 30–40% (studs cost more than the saved track, and the labour to install them costs more too).

Going from 400mm to 300mm adds another 33% stud count, and another 25–35% on metal cost.

So a 600mm-centre wall that costs £100 in metal becomes roughly £140 at 400mm, or £190 at 300mm. On a large project, that's a meaningful cost difference — don't tighten centres without a genuine reason.

Stud centres at openings

At openings (doors, windows), the framing gets denser regardless of the general wall centres. Standard practice:

• Doubled studs at each side of every opening — two studs side by side on each side of the opening, regardless of whether the wall is at 600mm, 400mm, or 300mm centres.
• Lintel or head above the opening — a horizontal track spanning the top of the opening.
• Sill track below the opening — where applicable, especially for windows.
• Trimmer studs sometimes — extra vertical studs to take the load from the lintel down to the base.

The result is that openings always have framing at tighter effective centres than the general wall, even if the wall itself is at 600mm centres. This is normal — openings carry extra load and need extra framing.

How to choose

Start with 600mm. Then work through this checklist:

1. Does the span table allow 600mm centres for the wall height and wind loading at the stud width you're using? If yes, use 600mm.
2. Does the acoustic target demand tighter centres? If Rw 50+, consider 400mm.
3. Does the fire rating demand tighter centres? Check the tested build-up — some fire-rated systems specify 400mm centres.
4. Does the wall carry heavy items? If yes, consider 400mm for reliable fixing.
5. Is the wall unusually tall or heavily loaded? If yes, drop to 400mm or 300mm, or go up in stud width/gauge.

If you're unsure, get quotes for 600mm and 400mm at the stud size you need. If 600mm meets the requirement, use it. If it doesn't, 400mm is usually the right next step — 300mm is rarely needed unless the wall is heavy-duty or high-rise.

Summary

Stud centres is a balance between strength, cost, acoustic performance and fire rating. The standard is 600mm. Tighter centres (400mm, 300mm) are used when the wall needs more strength, better acoustics, or is subject to higher loads.

• 600mm — standard for most partitions and infill walls
• 400mm — taller walls, higher wind loading, Rw 50–55 acoustic, heavy fixtures
• 300mm — very tall walls, high-rise, Rw 55+ acoustic, loadbearing, heavy-duty

For most projects, 600mm is sufficient. Tighten only when the performance requires it — tighter centres add significant cost for benefits you may not need.