A flex corner is a flexible corner profile — usually a self-adhesive strip or a double corner bead with a hinging fold line — used in plaster, render and tiling work to finish internal and external corners cleanly and crack-free. The flex corner combines the rigidity of a traditional corner bead with the adaptability of mesh tape.
Build-up
A flex corner typically consists of:
- Two plastic or metal strips — as the base
- Central fold line (hinge) — adjustable from 0 to 180 degrees
- Fibreglass mesh or fleece — on both sides for plaster adhesion
- Self-adhesive strip — for positioning during application
Application
Flex corners are used wherever two surfaces meet at an angle:
| Location | Benefit of flex corner |
|---|---|
| Wall–ceiling internal corner | Prevents shrinkage cracks |
| Dormer internal corner | Crisp 90° finish |
| Sloped roof wall | Any angle adjustable |
| Knee wall on attic | Conforms to pitch |
| Stair niche or recess | Follows any angle |
How to use a flex corner
Application proceeds in four steps:
- Measure the corner — cut the flex corner to length
- Set the angle — fold along the hinge to the correct angle
- Fix — peel the self-adhesive strip or press into a thin plaster bed
- Finish — plaster or fill over the profile
A well-applied flex corner is fully hidden in the plaster; only the plastic edge forms the final outer corner.
Pros and cons
Pros
- Adjustable angle — suitable for any non-standard angle
- Prevents cracking — dampens movement between materials
- Easy to install — no screws or bolts
- Compatible with all plasters — gypsum, lime, cement
- Available on rolls — quick on length
Cons
- Single use — not reusable after removal
- Cost — more expensive than fixed corner beads
- Needs clean substrate — otherwise relief shows through
Difference from related products
- Classic corner bead — only for fixed 90° corners
- Plaster corner bead — steel or aluminium, not flexible
- Plain corner trim — without mesh, only visual finish
- Fibreglass scrim tape — for joints only, no corner stiffness
In new builds with many sloping ceilings (attic rooms, dormers), the flex corner has become standard among plasterers and drylining contractors.
Related terms
- Plaster
- Corner bead
- Plasterboard
- Plaster coat
- Mesh
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