What are the grades of timber specified in IS 5966?

The standard specifies three grades: Grade I, Grade II, and Grade III, based on the nature and extent of permissible defects (Clause 6).

What is the required moisture content for timber used in a coastal area like Chennai?

Chennai falls in Climatic Zone IV (>67% average humidity). The required moisture content is 14% ± 2% for sections up to 50 mm thick (Clause 4.1 & Table 1).

What is the acceptable tolerance on the thickness of a 50mm thick timber plank?

For dimensions up to 100mm, the tolerance on thickness and width is ± 3.0 mm. So a 50mm plank can be between 47mm and 53mm thick (Clause 7.1).

Does this standard cover plywood?

No, this standard is for sawn or converted solid timber. Plywood is covered by other standards like IS 303.

IS 5966

: 1993

Non-coniferous timber in converted form for general purposes

CurrentSpecializedSpecificationBIMMaterials Science · Timber and Timber Stores

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This standard specifies the requirements for non-coniferous (hardwood) timber that has been sawn or converted for general purposes. It covers aspects like suitable timber species, moisture content requirements for different climatic zones, permissible defects, grading, and dimensional tolerances.

Non-coniferous timber in converted form for general purposes

Quick Reference Values

Moisture Content for Zone I (<40% humidity)8% ± 2%

Moisture Content for Zone II (40-50% humidity)10% ± 2%

Moisture Content for Zone III (50-67% humidity)12% ± 2%

Moisture Content for Zone IV (>67% humidity)14% ± 2%

Tolerance on specified thickness and width (up to 100mm)± 3.0 mm

Tolerance on specified thickness and width (>100mm)± 6.0 mm

Tolerance on specified length+ 25 mm

Practical Notes

Ensure the specified moisture content corresponds to the climatic zone of the project site as defined in Table 1.

The choice of timber species from Appendix A should consider local availability, cost, and specific end-use requirements like durability and strength.

Visual inspection for defects like knots, cracks, and warp is critical for confirming the grade of timber supplied at the site.