Wall and ceiling linings are required to meet different specified performances for different building types, location within the building and whether or not it is sprinkled. Material used for wall and ceiling linings is required to have a Group Number of 1, 2 or 3 and buildings not fitted with sprinklers are required to have a Smoke Development Rate of not more than 100, or an average extinction area less than 250m2/kg.
Generally speaking, Group 3 materials refer to timber products, Group 2 materials are predominately fire retardant timber and Group 1 materials are non-combustible or near non-combustible. All materials are required to be assessed in order to assign the appropriate Group Number. Table 3 provides a summary of group numbers for common solid timber species.
| Common Name | Group Number | Average Extinction Area |
|---|---|---|
| Ash, Alpine | 3 | Less than 250m2/kg |
| Ash, Mountain | 3 | Less than 250m2/kg |
| Ash, mountain (Tasmanian oak) | 3 | Less than 250m2/kg |
| Ash, Silvertop | 3 | Less than 250m2/kg |
| Beech, Myrtle | 3 | Less than 250m2/kg |
| Blackbutt | 3 | Less than 250m2/kg |
| Blackbutt, New England | 3 | Less than 250m2/kg |
| Blackbutt, WA * | 3 | Less than 250m2/kg |
| Blackwood | 3 | Less than 250m2/kg |
| Bloodwood, Red | 3 | Less than 250m2/kg |
| Box, Brush | 3 | Less than 250m2/kg |
| Box, Grey | 3 | Less than 250m2/kg |
| Brownbarrel | 3 | Less than 250m2/kg |
| Cedar, western red | 3 | Less than 250m2/kg |
| Cypress pine, northern (white cypress pine) | 3 | Less than 250m2/kg |
| Gum, Blue, Southern | 3 | Less than 250m2/kg |
| Gum, Blue, Sydney | 3 | Less than 250m2/kg |
| Gum, Manna | 3 | Less than 250m2/kg |
| Gum, River Red | 3 | Less than 250m2/kg |
| Gum, Rose | 3 | Less than 250m2/kg |
| Gum, Shining | 3 | Less than 250m2/kg |
| Gum, Spotted | 3 | Less than 250m2/kg |
| Gum, Sugar | 3 | Less than 250m2/kg |
| Gum, Yellow | 3 | Less than 250m2/kg |
| Ironbark, Grey | 3 | Less than 250m2/kg |
| Ironbark, Red | 3 | Less than 250m2/kg |
| Jarrah | 3 | Less than 250m2/kg |
| Karri | 3 | Less than 250m2/kg |
| Kwila (merbau) | 3 | Less than 250m2/kg |
| Mahogany, Red | 3 | Less than 250m2/kg |
| Messmate | 3 | Less than 250m2/kg |
| Oak, red, American | 3 | Less than 250m2/kg |
| Pine, Celery-top | 3 | Less than 250m2/kg |
| Pine, Radiata | 3 | Less than 250m2/kg |
| Rosewood, Papua New Guinea | 3 | Less than 250m2/kg |
| Stringybark, Yellow | 3 | Less than 250m2/kg |
| Tallowwood | 3 | Less than 250m2/kg |
| Turpentine | 3 | Less than 250m2/kg |
| Walnut, black (American walnut) | 3 | Less than 250m2/kg |
| Wattle, Silver | 3 | Less than 250m2/kg |
* Note: All data are for a timber thickness of 9 mm or greater