Timber
Contents
Recall the cross-section of Exogenous Tree 3
Recall the Seasoning of Timber 5
Recall the Conversion of Timber 6
Recall the Preservation of Timber 7
Recall different market forms of Timber 10
Recall different uses of Plywood 12
Define the term Timber
The term “timber” refers to wood that is used as a construction material. It is a natural, renewable resource that is extracted from trees and processed into various forms for use in construction, furniture, and other applications.
Timber is made up of cellulose, hemicellulose, and lignin fibres, which give it its strength and flexibility. These fibres are arranged in a parallel manner in the tree trunk, which gives the wood its characteristic grain. The density, strength, and durability of the wood depend on the type of tree it comes from and the way it is processed.
Timber is harvested from forests, either by felling mature trees or by thinning out overgrown areas. The harvested wood is then processed into a variety of forms, such as logs, planks, and beams. The processing of timber can include sawing, planing, and kiln-drying. These processes are used to create different sizes and shapes of timber to suit specific construction and design needs.
Timber has been used as a building material for centuries and continues to be a popular choice for many types of construction, such as framing, flooring, and roofing. Because of its insulating properties, wood-framed buildings are energy efficient and have a low carbon footprint, which makes it an eco-friendly choice. Additionally, wood products store carbon, which helps in reducing carbon emissions.
In summary, Timber is a natural and renewable resource made from wood that is used as a construction material. It is extracted from trees, processed and used in a wide range of applications such as framing, flooring, roofing, furniture and many more. Timber is made up of cellulose, hemicellulose, and lignin fibres, which give it its strength and flexibility. Timber has been used as a building material for centuries and continues to be popular, this is due to its low-carbon footprint, energy efficiency, and the ability to store carbon.
Classify Tree
Classification of Trees
These trees grow outward and have distinct consecutive annular rings in their horizontal section. They can be further divided into two types :
a) Soft wood – Chair, Deodar, fir, koil, pine, spruce, etc.
b) HardWood – Babul, Mahogany, oak, sat, teak, etc.
Lumber mostly used for engineering purposes comes from Exogenous Trees.
These trees grow inwards and fibrous mass can be seen in the longitudinal sections. Eg : Bamboo, Cane, Palm etc. These trees have limited engineering applications.
Recall the cross-section of Exogenous Tree
The cross-section of an exogenous tree, also known as an angiosperm tree, refers to the internal structure of the tree when viewed as a cut perpendicular to its longitudinal axis. The main parts of an exogenous tree cross-section include the bark, cambium, xylem, and phloem.
- Bark: The bark is the outermost layer of the tree and protects the tree from damage and pests. It is made up of dead cells and serves as a barrier between the tree’s internal structures and the external environment.
- Cambium: The cambium is a thin layer of actively dividing cells that is found just beneath the bark. It is responsible for the tree’s growth in girth, and it gives rise to new layers of phloem and xylem.
- Xylem: The xylem is a complex tissue that conducts water and dissolved minerals from the roots to the leaves of the tree. It is made up of several types of cells, including tracheids and vessel elements, that are arranged in a network to transport water and dissolved minerals throughout the tree.
- Phloem: The phloem is a complex tissue that conducts sugars and other organic compounds produced by the leaves to the rest of the tree. It is made up of several types of cells, including sieve elements and companion cells, that are arranged in a network to transport sugars and other organic compounds throughout the tree.
In summary, The cross-section of an exogenous tree is the internal structure of the tree viewed as a cut perpendicular to its longitudinal axis, it is composed of four main parts. The Bark which is the outermost layer of the tree, Cambium which is responsible for the tree’s growth in girth, Xylem, a complex tissue that conducts water and dissolved minerals from the roots to the leaves of the tree, and Phloem, a complex tissue that conducts sugars and other organic compounds produced by the leaves to the rest of the tree.
Recall the felling of Tree
Felling of trees is nothing but cutting of trees which are suitable for engineering purposes. Felling should be done when the tree is matured. Then only it contains more heart wood than sapwood. The perfect age of trees for felling varies from 50 to 100 years. The best season for felling of trees is Mid-winter for plain areas and Mid-Summer for hilly areas. Firstly a cut is made at the lowermost part of the trunk on a side where the tree is expected to fall. The cut should be beyond the center of gravity of the tree. Then provide a parallel cut which is exactly opposite to the first cut. Then tie up the tree top with 4 ropes on 4 sides. Now pull the rope on the first cut side and loosen the rope on the opposite side. Using the other two ropes, swing the tree slowly. Then the tree starts breaking along the cuts and gently falls on the ground. The branches are chopped off, bark is removed and is cut into required size
Recall the Seasoning of Timber
Seasoning of timber refers to the process of drying freshly cut wood so that it is suitable for use as a construction material. Freshly cut wood contains a significant amount of water, which can cause problems such as warping, splitting, and rot if not removed. The process of seasoning reduces the moisture content of the wood to an appropriate level, making it stable and suitable for use in construction and furniture-making.
The process of seasoning can be broken down into several stages:
- Stacking: Freshly cut timber is stacked in a well-ventilated area, with space between each piece of wood to allow air to circulate. The stack is covered with a tarp or plastic sheet to protect the wood from rain and direct sunlight.
- Drying: As the wood dries, it will naturally lose moisture through evaporation. Depending on the species of tree, and the humidity and temperature of the environment, this process can take anywhere from several months to several years.
- Monitoring: During the drying process, the moisture content of the wood is monitored using moisture metres. The moisture content of the wood needs to be reduced to an appropriate level for the intended use, which can vary depending on the specific application.
- Storing: Once the moisture content of the wood reaches the appropriate level, it can be stored in a dry place. The wood must be protected from rain and direct sunlight, to avoid re-absorption of moisture.In summary, Seasoning of timber refers to the process of drying freshly cut wood to make it suitable for use as a construction material. This process involves stacking the wood in a well
Recall the Conversion of Timber
Conversion of timber refers to the process of transforming raw timber logs into a variety of finished products that can be used for construction, furniture-making, and other applications. The process of converting timber typically includes several stages, such as sawing, planing, and shaping.
- Sawing: The first step in converting timber is sawing the logs into rough-cut boards of various dimensions. The most common sawing methods are band saws and circular saws. Once the logs are sawed, they are then inspected for defects, such as knots and splits.
- Planing: The rough-cut boards are then passed through a machine known as a planer, which smoothes one or both faces of the board. The board is cut to a specific thickness and width.
- Dressing: This is an optional step that involves cutting the board to specific lengths and shaping it as per requirement using different cutting tools like chisels, knives, and so on.
- Sanding: This step is also an optional step which smoothens the surface of the board even further. It is done using different grits of sandpapers, starting with coarse and progressing to finer grits.
- Finishing: This is the final step in converting timber, in which a finish, such as paint or varnish, is applied to the surface of the board to protect it from moisture and other external elements.
In summary, Conversion of Timber is the process of transforming raw logs into finished products such as planks, beams, and lumber. It is done by sawing the logs, planing the rough-cut boards, dressing, sanding and finishing them to make them suitable for the intended use. Sawing and planing
Recall the Preservation of Timber
The preservation of timber refers to the process of treating wood with chemicals or other agents in order to protect it from decay and insects. The main purpose of preservation is to extend the life of the wood and make it suitable for use in various applications, such as construction, decking, and fencing.
There are several methods of preserving timber, which can be broadly grouped into two categories: natural preservation and chemical preservation.
Natural preservation methods include the use of heat and pressure to create solid, durable lumber from wood. Kiln drying is a common method of natural preservation in which the wood is placed in a large, heated chamber and dried to a specific moisture content. The heat and pressure used during this process help to remove any remaining moisture from the wood and make it less attractive to insects and fungi.
Chemical preservation methods use various chemicals and preservatives to protect the wood from decay and insects. These methods are typically used for outdoor applications, where the wood will be exposed to the elements. There are several types of chemical preservatives that can be used to treat wood, including:
- Creosote: This is a tar-like substance that is commonly used to protect wood used in railroad ties and utility poles.
- Copper chromium arsenic (CCA): This is a common wood preservative that contains copper, chromium, and arsenic. It is often used to protect wood used in decks, fences, and other outdoor structures.
- Alkaline Copper Quaternary (ACQ): It is a type of water-based preservative that contains copper and quaternary ammonium compounds.
- Boron: Boron is another common wood preservative, it uses boron compounds which are effective against many species of wood-destroying insects and also helps to prevent decay.
It’s important to note that these chemical preservatives are highly toxic and can be harmful to human health if not handled properly, thus it should be done by a professional and must follow the manufacturer’s instructions for safe use.
In conclusion, the preservation of timber is a process of treating wood to protect it from decay and insects and prolong the life of the wood. There are several methods of preserving timber, including natural preservation and chemical preservation. Both of these methods have their advantages and disadvantages, and the choice of preservation method will depend on the intended use of the wood and the local climate.
Recall the following defects in Timber: i. Defects due to Seasoning ii. Defects due to Conversion iii. Defects due to Fungi and Insects iv. Defects due to Natural forces
Timber, like all natural materials, can be subject to various defects that can affect its structural integrity and usability. The following are four common types of defects that can occur in timber, each with its own causes and characteristics:
- Defects due to Seasoning: Seasoning is the process of drying wood to reduce its moisture content to a level that is suitable for use. During the seasoning process, a number of defects can occur, including:
- Checks: These are diagonal cracks that occur in the end grain of the wood, typically as a result of uneven drying.
- Warp: This is a general term that refers to any deviation from a straight line or flat surface in the wood. Warp can include cupping, bowing, crooking, and twisting.
- Case Hardening: This is a condition that occurs when the surface of the wood dries out faster than the interior, resulting in an outer layer that is harder and more brittle than the interior.
- Defects due to Conversion: Conversion refers to the process of converting raw wood into usable products, such as lumber. During this process, a number of defects can occur, including:
- Knots: Knots are formed when branches are cut off a tree and remain in the wood. They can weaken the structural integrity of the wood and are often considered a defect.
- Slope of grain: Slope of grain is a condition in which the direction of the wood fibres deviates from the longitudinal axis of the board. It can result in splitting and twisting of the board.
- Shake: Shakes are splits in the wood that occur along the grain and can weaken the structural integrity of the wood.
- Defects due to Fungi and Insects: Fungi and insects can both cause damage to wood, resulting in a variety of defects, including:
- Rot: Rot is caused by fungi that decompose the wood, weakening its structural integrity.
- Insect infestation: Wood-destroying insects such as termites, beetles, and carpenter ants can bore into the wood, causing damage and weakening its structural integrity.
- Defects due to Natural forces: Wood can also be affected by natural forces, such as weather and sun exposure, resulting in a variety of defects, including:
- Weathering: Exposure to sun, wind, and rain can cause the wood to lose its colour, split and crack.
- UV Damage: Exposure to UV radiation can cause wood to lose its strength, become brittle, and change colour.
It’s important to note that not all defects are visible on the surface and some can be internal and can only be detected by special testing and inspection. And it is important to identify these defects and address them to ensure that the timber is suitable for its intended use, and to avoid any potential safety hazards.
Recall different market forms of Timber
Timber, also known as lumber, is a versatile natural resource that is used in a wide range of products, from construction materials to furniture and decorative items. As a result, there are various market forms of timber, each with its own characteristics and uses. The following are some of the most common market forms of timber:
- Roundwood: This is the most basic form of timber, consisting of logs that have been cut directly from the tree. Roundwood is typically used in construction, such as for house logs, poles, and piles.
- Sawnwood: Sawnwood is roundwood that has been cut into planks or boards of a specific thickness and width. Sawnwood is the most common form of timber and is used in a wide range of applications, including construction, furniture, and flooring.
- Veneer: Veneer is a thin layer of wood that is cut from the face of a log using a rotary or slicing process. Veneer is used to create decorative panelling and veneered furniture and can be glued to other woods.
- Plywood: Plywood is made from thin layers of wood, called veneers, that are glued together with their grain running at right angles to each other. It’s very strong, durable and commonly used in construction, flooring, and furniture.
- Laminated Timber: Laminated Timber is a type of engineered wood that is made by glueing together several layers of lumber. It’s strong, stable, and has a consistent colour and grain pattern, and used in construction, flooring, and furniture.
- Particleboard and Chipboard: These are engineered wood products made from wood particles and fibres that are pressed and glued together, often used in furniture and flooring.
- Oriented Strand Board (OSB): OSB is a type of engineered wood made by pressing and glueing together thin layers of wood strands. It’s often used in construction as a substitute for plywood.
- Wood-plastic composites: These are composite materials made from wood fibres and thermoplastic materials. They are often used as an alternative to natural wood products, and can be found in decking, fencing, and other outdoor applications.
Each of these market forms has its own unique properties and characteristics, making them suitable for different applications. For example, roundwood is used for construction purposes, whereas sawnwood and plywood are used for furniture and cabinetry. The choice of market form of timber will depend on the specific needs of the project, including the intended use, budget, and desired aesthetic.
Define the term Plywood
Plywood is a type of engineered wood product that is made from thin layers, or plies, of wood veneer. The plies are typically made from softwood or hardwood and are glued together with their grain running at right angles to each other. This cross-graining pattern helps to create a strong and stable panel that is less likely to warp or twist over time.
One of the main benefits of plywood is that it is much stronger than solid wood of the same thickness. This is because the multiple layers of wood are able to counteract the natural tendency of wood to warp or bend. Additionally, because the grain of each layer runs in a different direction, plywood is less likely to split or crack when nailed or screwed.
There are two main types of plywood: softwood and hardwood. Softwood plywood is made from softwoods such as pine or spruce, and is typically used in construction, flooring, and furniture. Hardwood plywood, on the other hand, is made from hardwoods such as oak or maple and is often used in furniture, cabinetry, and decorative panelling.
Plywood is produced by peeling the log into veneers using a rotary lathe or a slicing machine. The veneers are then dried and glued together in a press. The glue used is usually a urea-formaldehyde adhesive, but there are also other options such as phenol-formaldehyde and melamine-formaldehyde.
Plywood can come in many different sizes and thicknesses, and is rated based on the number of plies and the type of wood used. For example, an interior grade plywood would have a lower number of plies and a lower quality wood, while marine grade plywood would have a higher number of plies and a higher quality wood.
In conclusion, Plywood is a type of engineered wood that is made from thin layers of wood veneer, glued together with their grains running at right angles. It is strong, stable and can be made from both softwoods and hardwoods, depending on the intended use. It’s commonly used in construction, flooring and furniture, and can come in different thicknesses and sizes.
Recall different uses of Plywood
Plywood is a versatile engineered wood product that is used in a wide range of applications. Some of the most common uses of plywood include:
- Construction: Plywood is widely used in construction as a structural material. It is often used as sheathing for walls and roofs, as well as in flooring, formwork, and bracing. Its strength and stability make it ideal for use in framing, subflooring, and roof decking.
- Furniture and cabinetry: Plywood is a popular choice for use in furniture and cabinetry, both as a structural material and as a decorative surface. Its smooth, stable surface and consistent thickness make it ideal for use in cabinets, desks, and tables.
- Decorative panelling: Plywood can also be used as a decorative panelling material. Its smooth surface and consistent thickness make it easy to paint or stain, and it can be used to create a wide range of patterns and designs.
- Transport and packaging: Plywood is widely used in the transport and packaging industry, as it is strong and lightweight. Plywood boxes and crates can be used to transport and store a wide variety of goods.
- Industrial and commercial: Plywood can also be used in various industrial and commercial applications, such as in signboards, hoardings, and as a base for laminates.
- Marine Applications: Marine grade plywood is specially treated to withstand harsh marine environments and is often used in boat building, ships and other marine applications.
- Exterior application: Plywood can be treated with preservatives to protect it from rot and decay, making it suitable for exterior uses such as roofing, siding, and decking.
- DIY projects: due to its versatility and easy availability, plywood is widely used in DIY projects, from simple shelves to elaborate structures such as sheds and cabins
It’s important to note that not all plywood is suitable for all applications, so it’s important to choose the right type of plywood for the specific use. For example, marine grade plywood is treated to withstand harsh marine environments and is suitable for boat-building, whereas furniture grade plywood is for indoor use, where a smooth finish and fewer knots are desired.
In conclusion, plywood is a versatile engineered wood product that is used in a wide range of applications. Some of the most common uses of plywood include construction, furniture and cabinetry, decorative panelling, transport and packaging, marine and exterior application, and DIY projects. The specific use and requirements of the project determine which type of plywood is the most appropriate to use.
Recall the following Qualities of Timber: i. Appearance ii. Colour , iii. Durability, iv. Elasticity, v. Fire Resistance
Timber, or wood, is a natural material that is valued for its beauty, strength, and versatility. There are several qualities of timber that are important to consider when selecting wood for a particular application. These include:
- Appearance: The appearance of a wood refers to its visual characteristics such as its colour, grain, and figure. The natural variations in colour, grain, and figure can make each piece of wood unique, making it an attractive option for use in furniture, flooring, and decorative items.
- Colour: The colour of a wood can vary widely depending on the species and the age of the tree. Some woods, such as pine, have a light yellow colour, while others, such as mahogany, have a reddish-brown colour. The colour of a wood can also be affected by the way it is finished, such as by staining or painting.
- Durability: Durability refers to a wood’s resistance to decay and insects. Some woods, such as cedar and redwood, are naturally resistant to decay and insects, while others, such as pine, are more susceptible. The durability of a wood can also be affected by the way it is finished, such as by treating it with a preservative.
- Elasticity: Elasticity refers to a wood’s ability to bend or flex without breaking. Some woods, such as ash and oak, are known for their high elasticity, making them suitable for use in applications where flexibility is important, such as in furniture and flooring.
- Fire resistance: Fire resistance refers to a wood’s ability to resist burning and charring. Some woods, such as cedar and redwood, have natural resistance to fire, while others, such as pine, are more flammable.
It’s important to note that different types of wood have different qualities and characteristics, and it’s important to choose the right type of wood for the specific use and application. For example, woods that are known for their durability and fire resistance are more suitable for outdoor use and in construction, while woods that are known for their appearance and elasticity are more suitable for furniture and decorative items.
In conclusion, Timber is a natural material that has several qualities that are important to consider when selecting wood for a particular application. These qualities include appearance, colour, durability, elasticity, and fire resistance. Each species of wood has unique characteristics, thus careful consideration should be given to the specific requirements of the project when selecting the most appropriate type of wood.