Similar International Standards
BS 8417:2011+A1:2014BSI (British Standards Institution), United Kingdom
HighCurrent
Preservation of wood. Code of practice
Provides a comprehensive code of practice for wood preservation based on a formal 'Use Class' system.
AWPA U1-22AWPA (American Wood Protection Association), USA
HighCurrent
Use Category System: User Specification for Treated Wood
Defines treatment requirements based on a 'Use Category System' that links end-use exposure to preservative retention and penetration.
AS/NZS 1604.1:2021Standards Australia / Standards New Zealand
HighCurrent
Specification for preservative treatment - Part 1: Sawn and round timber
Specifies requirements for preservative-treated timber using a 'Hazard Class' (H1-H6) system for different service conditions.
EN 335:2013CEN (European Committee for Standardization), Europe
MediumCurrent
Durability of wood and wood-based products - Use classes: definitions, application to solid wood and wood-based products
Defines the 'Use Class' system for exposure conditions, which underpins all other European timber preservation standards.
Key Differences
≠IS 401 uses descriptive categories for end-use (e.g., 'timber in contact with ground'), whereas modern international standards (BS 8417, AWPA U1, EN 335) use a more structured numerical 'Use Class' or 'Hazard Category' system (e.g., Use Class 4 for ground contact).
≠IS 401 prominently features and specifies Copper Chrome Arsenic (CCA) preservatives for a wide range of applications. Many international standards heavily restrict or ban CCA for residential and consumer applications due to health and environmental concerns, promoting alternatives like ACQ (Alkaline Copper Quaternary) and Copper Azole.
≠While IS 401 focuses primarily on the net retention of preservatives (kg/m³), international standards like EN 351-1 and BS 8417 place equal or greater emphasis on specifying and classifying the depth of preservative penetration into the sapwood.
≠International standards are often more explicit in their requirements for quality control schemes, third-party verification, and branding/marking of treated timber to ensure traceability and compliance.
Key Similarities
≈All standards share the fundamental objective of extending the service life of timber by protecting it from biodegradation by fungi, insects, and marine borers.
≈The primary methods of treatment, including non-pressure (brushing, dipping) and pressure processes (Full-cell, Empty-cell), are described in a similar manner across IS 401 and international standards.
≈A core principle in all standards is the requirement for timber to be properly seasoned to a suitable moisture content before pressure treatment to ensure effective preservative uptake.
≈All standards categorize preservatives into basic types, such as oil-borne (e.g., Creosote) and water-borne (e.g., CCA and its alternatives), and specify them based on the exposure risk.
≈The principle of increasing preservative retention and penetration requirements with increasing biological hazard (e.g., interior dry vs. ground contact vs. marine use) is a common thread throughout all the codes.