This code establishes the general principles for the structural design of timber in buildings. It covers the classification of timber species, defines safe working stresses based on standard moisture content, and provides detailed design procedures for flexural and compression members.
Specifies permissible stresses for various types of timber used in structural applications.
Quick Reference Values
Standard Moisture Content12%
Group A Timber Min Modulus of Elasticity (E)12.6 x 10^3 N/mm2
Group B Timber Min Modulus of Elasticity (E)9.8 x 10^3 N/mm2
Group C Timber Min Modulus of Elasticity (E)5.6 x 10^3 N/mm2
Max Slenderness Ratio for Solid Columns50
Max Deflection (with brittle finishes)Span / 360
Max Deflection (general/other beams)Span / 240
Key Formulas
S = l / d — Slenderness ratio for solid columns
fc = (pi^2 * E) / (U * S^2) — Permissible compressive stress for long columns
Practical Notes
Permissible stresses provided in the code assume a standard moisture content of 12%. Appropriate modification factors must be applied if the environmental working conditions differ.
Natural defects like knots, shakes, and sloping grain severely reduce timber strength and must be accounted for by using location-specific modification factors or culling during visual grading.
For outdoor or exposed structures, adequate chemical preservation as per IS 401 must be ensured before calculating structural load capacities, as decay alters physical properties.