IS 3629:1986 is the Indian Standard (BIS) for structural timber - use in buildings - code of practice. Specifies the requirements for structural timber used in buildings, including its classification, grading, permissible defects, seasoning, and preservation. It acts as the primary material specification standard before conducting structural design.
Provides recommendations for the selection, grading, and use of structural timber members in different parts of buildings.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Design Philosophy | Permissible Stress Design (Working Stress Method) | Limit State Design (LSD) / Load and Resistance Factor Design (LRFD) | EN 1995-1-1 |
| Load Duration Factor (Permanent Load) | 1.0 (Basic stresses are defined for long-term/permanent loading) | k_mod = 0.60 (for solid timber, permanent load). Characteristic strength is short-term, so it's reduced for permanent load. | EN 1995-1-1 |
| Load Duration Factor (Short Term, e.g., wind) | 1.5 (as per Clause 5.2.1.2 for short term loading) | C_D = 1.6 (Load Duration Factor for wind/seismic load in ASD) | ANSI/AWC NDS |
| Strength Modification for Wet Location (Bending) | 0.80 (Modification factor for 'wet' location from Table 2) | C_M = 0.85 (Wet Service Factor for bending stress, Fb, for lumber ≥ 5 in. thick) | ANSI/AWC NDS |
| Column Slenderness Limit (l/d) | Slenderness ratio shall not exceed 50 for a solid column (Clause 9.5.1). | Slenderness ratio (Le/d) for compression members should preferably not exceed 50. | ANSI/AWC NDS |
| Notched Beam Shear Strength | Shear stress calculated using effective depth at the notch (Clause 8.4.2). | Shear stress is increased by a factor depending on notch geometry and location (e.g., Eurocode 5, Eq. 6.55). | EN 1995-1-1 |
| Bearing Stress (Perpendicular to Grain) | A single permissible compressive stress perpendicular to grain is provided. | A modification factor (k_c,⟂) is applied to account for the length and position of the bearing area. | EN 1995-1-1 |