IS 6534:1971 is the Indian Standard (BIS) for guiding principles for grading and inspection of timber. This standard lays down the guiding principles for the grading and inspection of timber. It defines common defects and establishes a framework for creating specific grading rules based on the intended end-use of the wood.
Guiding principles for grading and inspection of timber
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Number of Structural Grades (Cut Timber) | 3 grades (Grade 1, Grade 2, Grade 3) | 2 primary grades (SS - Special Structural, GS - General Structural) | BS 4978:2007+A2:2017 |
| Slope of Grain Limit (Highest Grade) | Not steeper than 1 in 15 | Not steeper than 1 in 10 | BS 4978:2007+A2:2017 (SS Grade) |
| Slope of Grain Limit (Second Grade) | Not steeper than 1 in 12 | Not steeper than 1 in 6 | BS 4978:2007+A2:2017 (GS Grade) |
| Wane Limit (Highest Grade) | Permitted up to 1/8 of the width of face or edge. | Permitted up to 1/3 of the width of face or edge. | BS 4978:2007+A2:2017 (SS Grade) |
| Knot Size Limit (Highest Grade, Margin Knot) | Not to exceed 1/4 of the width of the face. | Not to exceed 1/3 of the width of the edge. | BS 4978:2007+A2:2017 (SS Grade) |
| Through Checks/Shakes (Highest Grade) | Not permissible. | Not permitted. Other fissures are limited in length and depth. | BS 4978:2007+A2:2017 (SS Grade) |