IS 3731:1985 is the Indian Standard (BIS) for teak squares. This standard prescribes the requirements, dimensions, tolerances, and grading rules for teak squares (Tectona grandis) used in construction, joinery, and general carpentry. It categorizes teak squares into grades based on the presence and extent of natural defects like knots, splits, and sapwood.
teak squares
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Moisture Content (Max) | Shall not exceed 12% unless otherwise agreed. | Varies by end-use; e.g., 8-12% for interior use in centrally heated buildings. | BS EN 942:2019 |
| Sapwood Allowance (Highest Grade) | Grade 1: Permitted on one edge, not exceeding 1/10th of the face width. | Prime Grade: Generally specified as 'Free of Sapwood' (FOS). | Malaysian Grading Rules (MGR) |
| Knots (Highest Grade) | Grade 1: Sound knots up to 15 mm diameter, max two per metre length. | Prime Grade: One face must be practically clear of all defects; reverse face has limited small knots. | Malaysian Grading Rules (MGR) |
| End Splits | Permissible if total length at each end does not exceed 50 mm. | Generally limited, often to a length not exceeding the width of the timber piece. | Malaysian Grading Rules (MGR) |
| Dimensional Tolerance (Thickness > 100mm) | Oversize tolerance of +6 mm, no undersize tolerance (-0 mm). | Tolerance Class 1: +4 mm / -2 mm. | BS EN 1313-2 |
| Warp (Bow) | Not to exceed 6 mm in a length of 2 m. | Permitted up to 10 mm per 2 m length for pieces over 20 mm thick. | BS EN 942:2019 |