IS 1331:1971 is the Indian Standard (BIS) for cut sizes of timber. This standard specifies the preferred cut sizes of timber for use in structural framing, doors, windows, and general construction purposes. It establishes standardized dimensions and permissible tolerances to rationalize the timber trade, ensure interoperability, and minimize wastage during milling and construction.
cut sizes 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 |
|---|---|---|---|
| Standard Thickness Range | 12, 19, 25, 30, 40, 50, 65, 75, 100 mm... | 16, 19, 22, 25, 32, 38, 50, 63, 75, 100 mm... | BS EN 1313-1:2010 |
| Standard Width Range | 75, 100, 125, 150, 175, 200, 225, 250 mm... | 75, 100, 125, 150, 175, 200, 225, 250 mm... | BS EN 1313-1:2010 |
| Sizing System | Direct metric 'cut sizes' | Nominal sizes with standardized actual (surfaced) dimensions | PS 20-21 |
| Example Scantling Size (Nominal vs. Actual) | 50 x 50 mm (Cut size) | Nominal 2x2 inch (Actual 38 x 38 mm) | PS 20-21 |
| Tolerance on Thickness/Width (up to 100 mm) | +3 mm / -1 mm | ±1.0 mm (Tolerance Class 1) or +3/-1mm for some sizes | BS EN 1313-1:2010 |
| Tolerance on Length | +25 mm / -0 mm | Generally +50 mm / +25 mm (allows for end trimming) | BS EN 1313-1:2010 |
| Reference State for Dimensions | Not explicitly defined in relation to moisture content | Defined at a reference moisture content of 20% | BS EN 1313-1:2010 |