What is the main difference between Class I and Class II timber?

Class I timber has a higher natural durability (average life > 120 months) and is more resistant to decay. Class II has moderate durability (60-120 months) and may require preservative treatment for longevity (Clause 4).

Is Mango wood suitable for window frames?

Mango (Mangifera indica) is listed as a Class II timber, making it suitable, but it falls under treatability class 'd', meaning it requires preservative treatment (Table 1 and IS 401).

Which code should I refer to for the strength group of a timber?

The strength group classification (A, B, or C) for various timber species is given in IS 399.

Does this standard apply to plywood doors?

No, this standard is for solid timber. Plywood and other engineered wood products for doors are covered by different standards, such as IS 2202.

IS 12896

: 1990

Indian timbers for door and window shutters and frames- Classification

CurrentFrequently UsedSpecificationBIMMaterials Science · Timber and Timber Stores

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This standard classifies Indian timber species into Class I and Class II for use in door and window shutters and frames. The classification is based on key properties like natural durability, treatability, and strength, guiding the selection of suitable wood for different quality and exposure requirements.

Indian timbers for door and window shutters and frames- Classification

Quick Reference Values

Natural durability for Class I timber (graveyard test)> 120 months

Natural durability for Class II timber (graveyard test)60 to 120 months

Strength requirement for Class I timberBelongs to Strength Group A, B or C as per IS 399

Treatability requirement for Class I timberHeartwood treatability class (a), (b) or (c) as per IS 401

Strength requirement for Class II timberBelongs to Strength Group A, B or C as per IS 399

Treatability requirement for Class II timberHeartwood treatability class (a), (b), (c) or (d) as per IS 401

Practical Notes

Class I timbers (e.g., Teak, Sal) are recommended for exterior use or high-quality applications due to high natural durability. Class II timbers are suitable for interior use, often requiring preservative treatment.

This code classifies the species, but for actual use, the timber must also be properly seasoned as per IS 1141 (for frames) or IS 2202 (for shutters).

Always verify the regional availability of a specified timber species before finalizing the design.