Timbers in schedules A, B and C are allocated individual natural durability ratings for above-ground and in-ground situations, in accordance with AS 5604-2005 Timber—natural durability ratings. See the guide: Australian Standards

Natural durability ratings system for heartwood:

• Durability class 1. Above-ground life expectancy >40 years
• Durability class 2. Above-ground life expectancy 15 to 40 years
• Durability class 3. Above-ground life expectancy 7 to 15 years
• Durability class 4. Above-ground life expectancy 0 to 7 years

See the guide: Natural durability ratings