Lecture 09
- 1. COURSE NO: ARCH 2101 COURSE TITLE: Construction II: Finish Materials NS Lecture 09 TIMBER
- 3. MECHANICAL PROPERTIES OF TIMBER: Durability Depends on- Natural and artificial defects Thickness, length and straightness Regular annual ring Uniform and dense Well seasoned “Any wood used in engineering construction is termed as timber.” Strength 1. Tensile strength 2. Compressive strength Main stress Depends on anatomical structure and moisture content 3. Flexural strength Found in timber beams A Text Book of Engineering Materials- by Dr. M. A. Aziz
- 4. •Easy to work •Comparatively stronger than other common materials compared in proportion to weight •Both load bearing and non-load bearing •Very economic and low wastage •Low thermal conductivity •High electrical resistance •Good sound proofing property •Unquestionably durable when properly treated •Contemporary timber products can add lightness and beauty •Great resale value ADVANTAGES (Using Timber as a building material) A Text Book of Engineering Materials- by Dr. M. A. Aziz
- 5. Annual growth rings Rapid growth in spring and slow in summer, no wood added during winter Spring wood and Summer wood Pith The center Sapwood and Heartwood SOME IMPORTANT TERMS (About Timber/ Timber processing) A Text Book of Engineering Materials- by Dr. M. A. Aziz
- 6. Principal methods of sawing logs are- 1. Ordinary or cross sawing 2. Radial or Rift sawing 3. Quarter sawing 4. Tangential or Slash sawing SAWING OF TIMBER A Text Book of Engineering Materials- by Dr. M. A. Aziz “The conversion of logs into various market forms of timber is generally done by sawing.”
- 7. Natural defects Knots Twisted fiber Shakes •Radial shake •Through shake •Ring shake •Cup shake Upsets Foxiness Rind galls DEFECTS IN TIMBER A Text Book of Engineering Materials- by Dr. M. A. Aziz Knots Twisted Fiber Shakes Foxiness Rind galls Upsets
- 8. Artificial defects Warping Splitting and cracking Fungal infections Insects and worms DEFECTS IN TIMBER A Text Book of Engineering Materials- by Dr. M. A. Aziz
- 9. SEASONING IN TIMBER • As fresh timber contains about 30 to 40 % sap or moisture. • This sap is very harmful for the life of a timber • All those methods which are used for removing the sap from timber are collectively termed as seasoning of timber. A Text Book of Engineering Materials- by Dr. M. A. Aziz Methods of Seasoning of Timber 1. Natural (air seasoning ) • Long outdoor exposure to air • Staked on dry elevated platform, covered from rain • Turned frequently for equal drying • Very slow process, takes 2 to 3 years
- 10. Methods of Seasoning of Timber 2. Natural (water seasoning ) • Immerged in water and stands for couple of days • Then dried in natural air • Well suited for timber, containing lots of sap A Text Book of Engineering Materials- by Dr. M. A. Aziz
- 11. Methods of Seasoning of Timber 2. Artificial seasoning Kiln seasoning • Temperature 70 to 82 degree Celsius • Requires 4-6 days or 3-6 months for first shrinkage. Then exposed to higher temperature for 6-12 days • Two types of kiln…Compartment kiln and Progressive kiln • Used in Bangladesh Chemical seasoning • Also known as “salt seasoning” • Before placed in the kiln, timber is soaked into salt bath (generally Urea) • Uniform and fast drying A Text Book of Engineering Materials- by Dr. M. A. Aziz Kiln seasoning
- 12. Methods of Seasoning of Timber 2. Artificial seasoning Electrical seasoning • High frequency alternative currents are passed through timber • Quick process but not used in Bangladesh Steaming • Takes 4-6 hours • Reduces elasticity and strength of timber Boiling • Emerged in boiling water for certain period of time A Text Book of Engineering Materials- by Dr. M. A. Aziz Smoke seasoning • Used in boat making industry
- 13. • Strong, stiff, tough, durable • Free from both natural and artificial defects • Regular, uniform annual growth ring • Uniform and lustrous color • When struck with hammer, timber should give a clear sound • Being obtained from the heart of a full grown tree • High density • Good workability • Should be elastic • Resistance to compression • Should be fire resistant, thus dense not light and porous. • It should retain the shape during the period of use CHARACTERISTICS of Good Timber A Text Book of Engineering Materials- by Dr. M. A. Aziz
- 14. Juri Troy Architects' passive House Under The Oaks in Austria
- 15. Wood Products Following are the few products of wood which are widely used for furniture, partitions, etc.: 1. Veneer 2. Plywood 3. Particle board 4. Laminated wood
- 16. Veneer • Veneer refers to thin slices of wood, usually thinner than 3 mm (1/8 inch), that typically are glued onto core panels (typically, wood, particle board or medium- density fibreboard) to produce flat panels such as doors etc. • Walnut is a very suitable wood for veneering. Plywood • Plywood is a manufactured wood panel made from thin sheets of wood veneer. It is one of the most widely used wood products. • Plywood is commercially available in thickness ranging from 4mm 25mm
- 17. Particle Board • Particleboard is a composite product of wood manufactured from wood particles, such as wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder. • it is rarely used outdoors or places that have high levels of moisture. Laminated Board- • Laminated wood is an engineered wood product composed of thin layers of wood, or veneers, that are glued together to make a stronger wood product. • The inner core consists of wooden strips of thickness not exceeding 7mm.
- 18. Furniture • Whether this is buying in or creating from scratch, furniture is a fundamental aspect of interior design. From chairs and tables, to sideboards and bookcases, the furniture a homeowner chooses is very much a of their personality. Walls/Ceilings • Decorating the walls and ceilings of a home can be as simple as a quick paint job, or as complicated as altering the layout of a property via the creation and demolition of said walls and ceilings. In this case, you may find that timber is an ideal material for strengthening structural integrity, as well as being aesthetically pleasing.
- 19. Flooring • This is definitely an area of design that's especially suited to wood. Whilst carpeted rooms are still very much in use, many people are having wooden floors installed to increase the value of their homes. Solid wooden floors are aesthetically pleasing, offering the best of modern chic combined with a timeless beauty. They are also easy maintain and complement most (if not all) design choices. • Another great advantage is that, when properly maintained, they can potentially last a very long time.
- 20. Paneling • Ideal for both external and internal design, panelling (also known as cladding) provides a professional and visually stimulating way to add on to the exterior of fixtures. • The benefits extend beyond how it looks. Wooden panelling is renewable, consumes less energy and any carbon retained by the tree's growth is locked into the timber - making it an ideal choice for the environmentally- homeowner.
- 21. Decking With more and more people staying at home, the garden is becoming a place to be. is proving very popular as terraces, roof gardens and balconies are being incorporated into home design. Softwood is a very common material in decking.
- 22. Wooden house in Holland from Onix Architects Wooden house in Austria
- 23. RECOMENDED REFERENCES Aziz. M. A: Engineering Materials. Smith, R. C: Material of construction. Andres, C. K: Manufactures manuals and brochures,