What is the maximum height for a standard plasterboard partition?

The maximum height depends on the stud size, spacing, and number of board layers. A typical 70mm C-stud (CW75) at 600mm centres with single-layer boarding each side achieves approximately 2.9m — just above standard ceiling height. For taller partitions (3.5m+), you need wider studs (92mm or 146mm), closer spacing (300-400mm), or multiple board layers. All heights are based on BS 5234 with L/240 deflection limits.

What is BS 5234 and why does it matter?

BS 5234 is the British Standard for internal non-loadbearing partitions. Part 1 covers code of practice for design and installation, while Part 2 covers specification for performance requirements. It sets the deflection limit at L/240 (height/240) under a lateral load of 0.25 kPa (typical office loading). This means a 3m partition must not deflect more than 12.5mm under load. Compliance is expected under Building Regulations.

What is a deflection head and when do I need one?

A deflection head allows the partition to accommodate structural movement (floor deflection, thermal expansion) without transferring loads to the partition. It is essential in all steel-frame and concrete-frame buildings where slab deflection can be 10-25mm. The stud sits in a deep track at the head with a compressible material allowing vertical movement. Without a deflection head, structural movement can crack the partition or buckle the studs.

How does board thickness affect partition height?

Adding more layers of plasterboard significantly increases the stiffness of the partition (by the cube of the total thickness). A double-boarded partition can be 10-15% taller than single-boarded with the same studs. Triple boarding adds a further 5-10%. This is because the boards contribute to the composite stiffness of the stud — they act as flanges in a composite beam section.

Can I use timber studs for tall partitions?

Timber studs (typically 38mm × 89mm or 38mm × 140mm) can be used for partitions, but their maximum heights are generally lower than steel C-studs of equivalent depth. Timber also has more variable properties and can twist, warp, or shrink. For partitions over 3m, steel C-studs are strongly recommended. BS 5234 covers both steel and timber stud systems.

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Partition Height Calculator — Max Height by Stud Size per BS 5234

Calculate maximum partition height by stud size, spacing, and board layers per BS 5234. Includes deflection head detail.

Required Partition Height

Floor to underside of slab/ceiling

Stud Size

Deeper studs allow taller partitions

Stud Spacing

Closer spacing = taller partitions

Board Layers (per side)

More layers = stiffer = taller

Head Detail

Deflection head for steel/concrete frame buildings

How We Calculate This

This calculator determines the maximum achievable height for a metal stud plasterboard partition based on stud depth, spacing, and board layers. It uses limiting heights from BS 5234-1 and manufacturer data (British Gypsum White Book, Knauf partition tables).

The design criteria

Maximum deflection = Partition height ÷ 240 (L/240 limit)

The partition height is limited by the deflection of the steel stud under a lateral load of 0.25 kPa (the standard design load for internal partitions per BS 5234). The stud acts as a simply-supported beam between floor and head tracks, with the plasterboard providing composite stiffness.

Deflection heads add usable height by allowing the stud to be shorter than the floor-to-soffit dimension — the movement gap (25-50mm) is filled with compressible mineral wool and sealed with a flexible acoustic sealant.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.