Farm Forestry New ZealandCladding Grades
Cladding includes weatherboards, base battens and fascia, barge and coverboards.
These grades meet or exceed the durability performance requirements set out in NZS 3602:2003 for cladding.
Species
Redwood, larch, Western red cedar, cypress (macrocarpa, lusitanica, Lawsons or Leyland cypress)
All grades
Cladding timber shall be heartwood only (unless sapwood preservative treated to H3.1 as agreed or specified by customer).
Decay and incipient decay not allowed.
At least 80% of the overall volume shall comprise lengths of over 1.8 m and all lengths shall be over 90 cm.
Distortion
- Bow maximum 40/1
- Crook maximum 200/1
- Twist minimal
- Cup 75/1
Splits not allowed. Shakes not allowed.
Timber must be dried to 18% moisture or less (i.e. fully air dried).
Clears grade
Not allowed: Knots, holes, resin pockets, bark pockets, bark inclusion, skip, wane, want, pith.
Minimal surface checks allowed.
Standard Cladding grade
Allowable defects:
Unlimited tight (intergrown and partially intergown) knots allowed provided they do not exceed 50 mm width, or 25 mm width for spike knots. Knot checks allowed provided they do not exceed 2 mm width on the best face.
Bark encased knots allowed where tight and no larger than 15 mm wide.
Wane and want allowed only on the back face and edges. These should not exceed 5mm from the back edge and 10 mm wide on the back face.
Minimal skip allowed on the profiled surface, not sufficient to affect the appearance of the product.
Surface checks are allowed provided they are not longer than 100 mm and are not wider than 1 mm.
Pith allowed only on the back face, provided it is not wider than 5 mm.
Minimal resin streaks allowed.
Defects not allowed:
Loose knots, holes, voids, resin pockets, bark pockets.
Bark inclusion on the better face.
General and Responsibilities
At least 95% of the consignment of graded timber shall meet the grade specifications above upon despatch.
For tallying volumes call dimensions shall be used.
| Call sizes (mm) | 25 | 40 | 50 | 75 | 100 | 125 | 150 | 200 | 225 | 250 | 300 |
| Actual dressed dry size (mm) | 19 | 35 | 45 | 70 | 90 | 115 | 140 | 180 | 205 | 230 | 280 |
Once despatched the seller shall not be responsible for any subsequent deterioration of condition of the timber or defects arising from further processing.
Farm Forestry Timbers reserve the right to revise our grading rules without notice. Grade revision 1.1 October 2013.
See Glossary for explanation of terms.
Disclaimer: While every effort is made to ensure the accuracy of the information provided on this site, Farm Forestry Timbers Society do not accept liability for any consequences arising from reliance on the information published. If readers have any doubts about acting on any articles they should seek confirming, professional advice.
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