Timber Construction : Beam grading rules - QPA and QP1


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Oak Beam Visual Grading Rules

QPA Grading (Highest quality)

  • Sawn timber with sharp arrises (edges); in case of pieces longer than 3m, wane less than 10% of the face width is permitted across no more than 25% of the length.
  • Sound sapwood permitted on two arrises if the total width is less than 15% of the face width.
  • Fully or partly intergrown sound knots are permitted if the diameter is less than one third of the face width.
  • Dead knots, permitted where equivalent to two dead knots with a diameter less than 15mm per linear metre.
  • Boxed heart permitted, as well as slight traces of heartwood on two faces. Slope of the grain less than 7%, not exceeding 12% locally.
  • Also known as D30 Construction Grade
Excluded: unsound knots, end shake, frost crack, ring shake, star shake, curly grain, bark pocket, unsound sapwood, brown pith, brown streak, rot, holes.

QP1 Grading (Second highest quality)

  • Sawn timber with practically sharp arrises, permitting wane less than 10% of the face width across no more than 30% of the length.
  • This width tolerance is increased to 15% for sections above 250 x 250mm.
  • Sound sapwood permitted on two arrises if the total width is less than 15% of the face width.
  • Fully or partly intergrown sound knots are permitted if the diameter is less than half the face width.
  • Boxed heart permitted, as well as traces of heartwood on both faces. Slope of the grain less than 12%, not exceeding 20% locally.
  • Also known as D24 Construction Grade
Permitted on a limited number of pieces: brown streak, black holes, brown pith. Excluded: unsound knots, frost crack, ring shake, star shake, curly grain, bark pocket, unsound sapwood, rot, white holes.