Plastering Beads: Stop Beads, Angle Beads, Arch Beads — Types & Fixing Methods

Summary

Beads are the unsung component of quality plastering. Without them, external corners chip, edges crack, and reveals lack definition. With them, a skilled plasterer produces sharp, straight lines that define the quality of the finish. Most experienced plasterers have a strong preference for bead manufacturer and type — Expamet, Renderplas, and TrimTex are among the leading UK suppliers, and each offers a wide range of profiles for different applications.

The fundamentals are simple: bead goes on first, plaster goes on around it. The bead's exposed nose gives the trowel a level to run against, and the mesh or perforated wings key into the plaster. But the selection of the right bead for the location and the correct fixing method are frequently underestimated.

Key Facts

• Angle bead — Protects and defines external (salient) corners. Standard: 3mm nose radius. Thicknesses: 10mm, 13mm, 16mm
• Stop bead — Creates a clean termination line where plaster meets a surface that will not be plastered (sills, reveals, frames, ceilings)
• Movement bead — Two-part bead with a compressible infill. Used at construction joints and changes of substrate
• Arch bead — Flexible bead that can be bent to the radius of an arch without kinking
• External angle (drip bead) — For external render: has a larger nose and drip groove to shed water. Do not use internal angle bead outside
• Soffit bead — Stop bead with one wing extended, used at ceiling-to-wall junction
• Thin coat bead — For 3–6mm skim applications. Do not mix bead gauge with plaster thickness — a 13mm bead in a 6mm skim creates a raised ridge
• Material selection — Galvanised steel (general internal use), stainless steel (wet areas, shower enclosures), PVCu (shower rooms, humid areas)
• Fixing method — Plaster dabs: quick, accurate, does not require additional fixings. Mechanical: use in external render or where movement is expected
• Bead plumb and level — Every bead must be checked with a spirit level before the plaster is applied. Re-setting a bead after plaster has set requires breaking out and re-starting

Quick Reference Table

Detailed Guidance

Selecting the Right Bead

Match thickness to plaster depth. The bead nose must project at the finished plaster face — not be buried by the plaster. Standard two-coat plaster (bonding + skim) totals 11–13mm, so a 13mm angle bead is appropriate. A skim-only coat over plasterboard is 2–3mm, so a thin-coat bead (3mm) is required. Using a 13mm bead in a skim coat produces a permanent ridge at every corner.

External vs internal. Never use internal galvanised steel beads on external render — they corrode within 3–5 years, causing rust staining and bead failure. External applications require hot-dip galvanised or stainless steel beads. In coastal or industrial areas, use stainless steel as minimum.

Wet rooms. All beads in shower enclosures, wetrooms, and wet room adjacent walls must be stainless steel or PVCu. Galvanised beads corrode in high moisture environments even with tile coverage — the tile grout is not impermeable.

Movement locations. At the junction between plasterboard and masonry, or between different ceiling heights, use a movement bead — not a standard stop bead. Movement beads have a compressible centre section that accommodates differential movement without cracking the plaster.

Fixing Methods

Plaster dabs (most common for internal work):

1. Mix a small quantity of board finish or multi-finish to a firm consistency
2. Apply 3–4 dabs per metre to the wall at the bead position
3. Press the bead into the dabs and check immediately with a spirit level — vertically for angle beads, horizontally for horizontal stop beads
4. Adjust by pressing or easing the bead. Alignment must be perfect now — you cannot move a bead once the dabs have set
5. Leave dabs to set (minimum 30 minutes) before floating up the surrounding plaster

Mechanical fixing (for external render or high-impact areas): Use 19mm galvanised nails or screws through the pre-punched holes in the bead wings. Fix at 300mm centres on external render, 450mm internally. Ensure fastener heads are countersunk flush — protruding heads create bumps in the render.

Staples (specialist tool): A plasterer's staple gun can drive U-staples through bead wings at high speed. Faster than nails for experienced plasterers. Ensure staples are galvanised or stainless for external use.

External Render Beads

External angle beads for render have larger noses (typically 10–15mm radius) and are heavier gauge. They are always fixed mechanically — plaster dabs are insufficient for the weight and exposure.

Drip bead at window cills: The render must terminate cleanly at the top of the window cill. A drip bead (or bellcast bead) provides this termination and includes a groove that causes water to drip free of the wall face rather than tracking back. Fix with screws through the wing into the masonry, pitched slightly downward at 5–10° toward the face.

Render depth at reveals: Window and door reveals are often the weakest points in external render. Fix angle beads at all reveals before rendering. The bead must be plumb (reveals go into the wall vertically) and square to the wall face.

Installing Arch Beads

Arch beads have one rigid wing and one flexible wing. The flexible wing can be cut at intervals (every 50mm) to allow the bead to curve tightly. Score the wing and bend. For very tight radii, use a purpose-made arch mould to pre-form the bead to the correct curvature before fixing.

Fix the arch bead to the substrate with dabs or staples, following the arch profile. The bead must run smoothly — any kinks or bumps will show in the finished plaster. Check the arc with a batten cut to the radius.

Common Mistakes

• Using the wrong bead gauge (too thick or too thin for the plaster depth)
• Using galvanised bead in wet areas
• Fixing beads out of plumb or not checking level until after the plaster has dried
• Failing to cut bead to length cleanly (use tin snips — do not attempt to break it)
• Missing movement beads at substrate change junctions

Frequently Asked Questions

Do I need beads on internal corners?

No — internal corners (arrises that go into the wall) do not need angle beads. The plaster is worked into the corner with a trowel. Beads are for external (salient) corners only. However, some plasterers use an internal bead profile (an internal corner bead or angle tool) as a guide to produce consistently sharp right-angle internal corners.

Can I plaster without beads?

Technically yes, but it requires a high skill level to produce clean corner lines without them. For commercial and residential work of reasonable quality, beads are standard practice and expected by building inspectors, architects, and clients. Not using beads is a sign of a corner-cutting installation.

My beads are rusting through the plaster. How do I fix this?

Galvanised beads in wet or damp conditions will rust through the plaster within 3–10 years. The fix requires: cut out plaster around the bead, remove the old bead, allow to dry, install stainless steel or PVCu replacement bead, replaster. There is no surface-treatment fix that works long-term — the bead must come out.

Can PVCu beads be used externally?

Yes, for moderate exposure. PVCu does not corrode but can become brittle over many years in UV exposure. In sheltered locations, PVCu external beads are fine. In highly exposed south-west-facing or coastal locations, hot-dip galvanised steel or stainless steel is more durable.

Regulations & Standards

• BS 8481:2006 — Specification for materials for internal plastering (includes reference to bead types)

• BS 5492:1990 — Code of practice for internal plastering (superseded but still referenced)

• BS 8000-10:1995 — Workmanship on building sites: Code of practice for plastering and rendering

• Approved Document B (Fire safety) — Fire-rated plasterboard systems: beads must not interrupt the fire rating at joints

• Expamet Technical Guide — Plaster Beads and Accessories — Comprehensive bead specification guide

• Renderplas Product Range — PVCu bead ranges for internal and external use

• British Gypsum White Book — System specifications including bead locations in Gypsum systems

• skim coat — Applying skim plaster around beads

• sand cement render — External render bead requirements

• skirting architrave — Interface between plastering and carpentry finishes