Applies to all quality classes
Wane (bark edges) is permitted in non-visible parts of the timber, where it does not affect the visual appearance, such as on the underside or within tongue-and-groove areas.
Other timber defects and quality-related parameters not described above are considered acceptable or may be agreed upon individually.
- Non-through cracks up to 50 mm in length are permitted.
- For pine timber, minor resin pockets up to 10 mm in length are permitted.
Class I
Slightly lower quality grade.
- Wood moisture content: 8–12%.
- Knots are permitted — size of live knots is not limited.
- Black knots permitted up to 15 mm.
- Fallen knots permitted up to 8 mm.
- Non-through cracks are permitted.
- For pine timber, resin pockets up to 25 mm are permitted.
Class II
Lowest quality grade.
- Wood moisture content: 8–12%.
- Knots are permitted without size limitation.
- May include black knots and fallen knots.
- Non-through cracks are permitted.
- Through cracks up to 300 mm are permitted.
- For pine timber, resin pockets are permitted without size limitation.
Exterior Timber Products
For exterior cladding boards and other timber products intended for outdoor use, two main quality classes are defined.
AB Quality
- Wood moisture content: 18–20%.
- Knots are permitted — size of live knots is not limited.
- Black knots permitted up to 20 mm.
- Fallen knots permitted up to 10 mm.
- Non-through cracks are permitted.
- Resin pockets permitted up to 50 mm.
C Quality
- Wood moisture content: 18–20%.
- Knots are permitted without size limitation.
- May include black knots and fallen knots.
- Non-through cracks are permitted.
- Through cracks up to 300 mm are permitted.
- Resin pockets permitted without size limitation.