Glulam quality description
| Characteristics | Quality class | ||
| A | B | C | |
| Gluing | Surfaces glued absolutely tight, tight joints along the narrow side and wide side | Surface closed along the wide side and narrow side | |
| Appearance, surface | Uniform appearance, balanced colour | Some colour tolerance permissible as regards play of colours. | Up to 25% firm healthy brown heartwood permissible |
| Texture | Texture typical of the type of wood permissible, but texture must be even | Coarser texture permissible | No requirement |
| Brown, wet, figure | Not permissible | Not permissible; in places in beech | Permissible up to 25% of the area, unlimited in beech |
| Rays | Medullary rays, end stains not permissible; minerals 1 mm wide and up to 50 mm long permissible | Medullary rays, end stains permissible; minerals permissible without limit | Permissible |
| Sapwood | Not permissible | Permissible | Permissible |
| Wavy grain | Permissible | ||
| Dormant buds | Permissible | ||
| Pin knots | Up to 3 mm thick knots in wood colour, up to 3 pcs. per m² | Up to 8 mm thick in wood colour | Permissible |
| Healthy tightly adhering knots | Not permissible | Diameter up to 15 mm permissible, but no more than 4 pcs. per m2 | |
| Black knots | Not permissible | Up to 8 mm, no plugs | Permissible, but closed surface, filling in wood colour Holzfarbe |
| Cracks | Not permissible | Permissible surface closed and filled | |
| Bark pocket | Not permissible | Permissible | |
| Feeding tunnel infestation | Not permissible | ||
| Discoloration, fungal attack | Not permissible | Slight discoloration permissible, no rot | Rot not permissible |
| Open joints | Not permissible | ||
| A Brown heartwood in ash and beech, including steamed, in Class B max. 5% of surface permissible B Sapwood is not permissible in Class A in oak, cherry, elm, chestnut or robinia C Not permissible in Class B in oak or chestnut | |||