Minimising Oil Canning

Good design and installation can minimise oil canning.


  • Use thicker material.
  • Use low gloss paints or embossed surfaces.
  • Use natural weathering materials that dull over time.


  • Limit flashing width to 300 mm.
  • Limit the joined length of fixed flashings to 12 m.
  • Attach wide flashings with brackets that allow independent thermal expansion.
  • Manufacture a stiffening swage into flashings that have a face width greater than 200 mm.
  • Do not fix flashings to timber with a moisture content greater than 18%.


  • Limit cladding length.
  • Ensure the purlin alignment avoids convex curving.
  • Inspect for flatness before installation.
  • Avoid thin materials.
Draft Clause: