1. Timber - the Material Timber grows on Trees Properties of Timber Grading sawn timber Durability of timber Specifying and handling timber Application of timber in buildings Manufactured wood products

2. Timber Grows on Trees! Environmental Issues Growth of trees Classification of Timber Processing timber Sawing logs to give timber Seasoning Treatment Other processing

3. CO 2 CO 2 emitted as rotting occurs CO 2 Large trees die by losing leaves then falling over CO 2 Growing trees absorb lots of CO 2 Untouched/native forest Over long term Carbon in ~ carbon out

4. New trees plantedGrowing trees Managed Native Forest Plantation CO 2 Growing trees Harvesting trees removes carbon CO 2 New trees planted Harvesting removes Carbon Environmental Considerations Over long term Carbon removed from atmosphere > carbon released into atmosphere

5. Hardwoods and Softwoods Hardwoods broad leaf generally higher densities often dark in colour Softwoods needle-like leaves generally lower densities often light in colour Native Australian h’wds include mountain ash brown box spotted gum jarrah Native Australian h’wds include mountain ash brown box spotted gum jarrah common Australian s’wds include radiata pine cypress pine hoop pine douglas fir common Australian s’wds include radiata pine cypress pine hoop pine douglas fir

6. Tree Growth New wood on outside of tree oldest wood on inside of tree youngest wood on outside diameter largest at base one ring (layer) per year Tree in forest grows towards light trunk straight lower branches die leaving small knots in wood Bark protects wood from damage tree sheds bark each year

7. Production of Wood Sapling - fibrous juvenile wood becomes pith Cambium - growth cells wood cells created on inside bark cells created on outside Bark - protects wood new bark made continually bark falls off each year Wood - new wood cells on outside newest wood takes nutrients to leaves Pith - the start of growth in the tree the original sapling Cambium - growth cells wood cells created on inside bark cells created on outside Sapwood - newest wood on outside of tree (~ 1-3 cm) takes nutrients from root to leaves Heartwood - older wood cells closed - can’t pass nutrients storage for waste - extractives Pith - the start of growth in the tree the original sapling Cambium - growth cells wood cells created on inside bark cells created on outside Sapwood - newest wood new wood has thin cell walls sapwood most effective on outside Heartwood - older wood oldest sapwood becomes clogged new heartwood added on outside Pith - the start of growth in the tree the original sapling

8. Growth Rings Early wood rapid growth at beginning of growing season thin, large cells - lighter colour Late wood slower growth, often limited by lack of water thick small cells - darker colour gives the growth ring Generally one ring per year some climates may have more than one growth season per year fires or disease may produce an extra ring Growth rings give texture and figure to wood

9. Conversion 1 - Logs Tree trunk (wood with bark) De-barked log (sapwood & heartwood) Shaped log (some sapwood removed) Log preparation often in forest

10. Conversion 2 - Log breakdown De-barked log Splits Winged split Wings Splits - pith always on edge

11. Conversion 3 - green sawn Sawing patterns Back sawn or quarter sawn Optimising sizes  cut more pieces in most popular sizes Unseasoned timberStock for seasoned or milled products Further processing Further processing

12. Green sawing - Quarter sawn Growth rings parallel to short edge Advantages best grain shows on face good wearing surface for floors, furniture radial face preferred for coatings lower width shrinkage on drying less cupping and warp than other cuts can be successfully reconditioned Less common in structural timber Unseasoned Product Unseasoned Product or - on to further processing Disadvantages slower seasoning nailing on face more prone to splitting

13. Green sawing - Back sawn Rings parallel to long edge of piece Advantages season more rapidly good figure on face less prone to splitting when nailing wide sections possible few knots on edge More common in structural timber Unseasoned Product Unseasoned Product or - on to further processing Disadvantages shrink more across width when drying more likely to warp and cup collapsed timber more difficult to recondition

14. Conversion 5 - Dry Milling Sized, Planed, Profiled Products Rough-sawn and seasoned product passed though planer to produce  controlled dimensions  smooth surfaces  prepared edges  specific cross sectional shapes Docking  removes potential problems from lengths of products  potential weakness eg splits  appearance eg large knots  utility eg holes