Attaching GIB plasterboard to a curved wall frame is a satisfying challenge that most competent DIYers can tackle with the right preparation. The key is understanding that standard 10 mm or 13 mm GIB board can be coaxed into gentle curves, while tighter radii call for specialist flexible board or a different approach altogether. Getting the framing right before you touch a sheet of board is the most important step.
Understanding the Curve Radius
Before choosing your method, measure the radius of your curved wall. This single measurement determines everything else:
- Large radius (over ~2.5 m): Standard 10 mm GIB board can often be bent dry with close stud spacing.
- Medium radius (roughly 1–2.5 m): Flex-scoring or wetting the board is usually needed.
- Tight radius (under ~1 m): You'll need flexible plasterboard (sometimes called "bendy board") or multiple thin layers.
Always check the board manufacturer's minimum bending radius specifications before you start. GIB's technical literature provides guidance on what their products can handle.
Getting the Framing Right
A curved wall frame is typically built from closely spaced timber or steel studs bent or cut to follow the curve. For timber framing, this usually means:
- Reducing stud spacing to 200–300 mm centres (compared to the standard 600 mm for flat walls) to support the board as it bends and prevent flat spots.
- Using kerfed or laminated timber top and bottom plates to follow the curve, or purpose-bent steel track for steel framing.
- Ensuring all studs are plumb and sit on the curve line — any stud that's out of alignment will create a flat spot or a hump in your finished wall.
Framing for internal non-loadbearing curved walls is generally covered under Schedule 1 of the Building Act as exempt work, but always confirm with your local council before starting, as exemptions depend on the specific scope of work. Visit MBIE Building Performance for guidance on building consents and exemptions.
Method 1 — Dry Bending (Large Radii)
For gentle curves, standard 10 mm GIB board can often be fixed dry:
- Orient the board with the long edge running horizontally (perpendicular to the studs) — this is the direction the board bends most easily.
- Fix one end to a stud, then carefully flex the sheet around the curve, fixing to each stud as you go.
- Use GIB-brand plasterboard screws at the recommended spacing — typically 200 mm along studs.
- Work slowly and have a helper hold the sheet to avoid cracking.
Method 2 — Flex-Scoring (Medium Radii)
For tighter curves, flex-scoring the back of the board allows it to bend more readily:
- Lay the board face-down on a flat surface.
- Using a straight edge and scoring knife, make a series of parallel cuts through the paper backing and into (but not through) the plaster core — typically every 25–50 mm, running parallel to the short edge of the board.
- Carefully flex the board — the scored side opens up as it bends.
- Fix to studs as above, working from one end to the other.
Method 3 — Wetting the Board (Medium to Tight Radii)
Wetting temporarily softens the gypsum core, allowing tighter bends:
- Lay the board face-down and use a damp roller or sponge to thoroughly wet the back paper and core.
- Allow the water to soak in for 15–30 minutes — the board will become noticeably more flexible.
- Carefully bend it around a former (a curved jig or the frame itself) and allow it to dry in position before fixing permanently.
- Only fix the board once it has dried and held its shape — fixing wet board can cause fastener pull-through.
Method 4 — Flexible Plasterboard
For radii under about 1 m, purpose-made flexible plasterboard is the most reliable solution. This product has a fibreglass-reinforced core that allows it to bend to much tighter curves without scoring or wetting. It is available through specialist plasterboard suppliers and some larger trade outlets such as PlaceMakers. Check availability and minimum order quantities, as it may need to be ordered in.
Fixing and Fastener Tips
| Board Type | Minimum Stud Spacing | Fixing Method |
|---|---|---|
| 10 mm standard (dry) | 200–300 mm | Screws at 200 mm |
| 10 mm standard (wet/scored) | 150–200 mm | Screws at 150–200 mm |
| Flexible board | Per manufacturer spec | Screws or adhesive + screws |
- Use corrosion-resistant GIB screws of the correct length — typically 25 mm for 10 mm board into timber.
- Plasterboard adhesive (such as products from Sika or Ardex) used in conjunction with screws can help pull the board tight to the frame and reduce fastener count on flexible installations.
- Avoid overdriving screws — the head should sit just below the surface without breaking the face paper.
Stopping and Finishing Curved Walls
Finishing a curved wall requires flexible stopping tape (fibreglass mesh or paper tape both work) and careful feathering of the compound. Internal and external curved corners will need flexible corner bead rather than standard rigid metal bead. Apply stopping compound in thin coats, allowing each to dry fully before sanding. Refer to GIB's stopping and finishing guides for recommended coat thicknesses and drying times.
When to Call a Professional
While attaching GIB to a curved wall is not restricted work under NZ law, it is a skill that takes practice. Consider hiring a qualified plasterer if:
- The curve is complex or the radius is very tight.
- The wall is loadbearing or forms part of a fire-rated or bracing system — these situations may require a building consent and Licensed Building Practitioner (LBP) involvement. Check LBP requirements at lbp.govt.nz.
- You want a high-quality finish for a prominent feature wall.
- You're unsure about the framing specification.
A skilled local plasterer can save you time and costly mistakes. You can find qualified tradespeople in your area on tradedirectory.co.nz.
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