ARCH 113 Week 2 Wood Building Materials PDF

ARCH 113: BUILDING MATERIALS yeditepe university | architecture department | fall 2024 | week 2 wood bahar aktuna wood “It is the most humanly intimate of all materials. Man loves his association with it, likes to feel it under his hand, s...

ARCH 113: BUILDING MATERIALS yeditepe university | architecture department | fall 2024 | week 2 wood bahar aktuna wood “It is the most humanly intimate of all materials. Man loves his association with it, likes to feel it under his hand, sympathetic to his touch and to his eye. Wood is universally beautiful to Man.” In the Cause of Architecture - Frank Lloyd Wright Experiential qualities of wood: ➔ colour ➔ lustre ➔ smell/fragrance ➔ taste ➔ texture ➔ grain ➔ figure ➔ weight ➔ natural ➔ linear ➔ repetitive ➔ organic ➔ lightweight ➔ strong ➔ simple to work with wood from a value chain perspective “A ‘supply chain’ refers to the system and resources required to move a product or service from supplier to customer.” “The value chain describes the full range of activities which are required to bring a product or service from conception, through the different phases of production (involving a combination of physical transformation and the input of various producer services), delivery to final consumers, and final disposal after use.” primary processing of wood sourcing The process of obtaining raw wood materials, typically from forests or plantations, for further processing into timber products. Sourcing sustainable wood without harming forests is a critical practice aimed at balancing human needs with environmental conservation. Sustainably sourced wood minimizes the impact of logging on forests and the surrounding wildlife and communities. This approach involves adopting forestry practices that ensure the long-term health and productivity of forest ecosystems. logging The practice of felling and removing trees or the removal of dead or damaged trees from an area. Logging involves cutting trees for sale as timber (to build homes, furniture) or pulp (to make paper and paper products). Logging is generally categorized into two categories: ➔ Selective logging: loggers choose only wood that is highly valued, such as mahogany. ➔ Clear-cutting: loggers are interested in all types of wood and therefore cut all of the trees down, thus clearing the forest. primary processing of wood saw milling Saw mill or lumber mill is a facility where logs are cut into lumber. regular lumber primary processing of wood seasoning Seasoning of timber is the process of correctly drying timber and reducing the moisture content of timber so as to enhance the engineering properties of timber and make it more suitable for use in engineering applications. natural seasoning/air drying: timber is seasoned by placing it in the open air, with a provision of ventilation between the individual timber logs. Long duration of time is required for this method. kiln drying: Uses circulating heated air to more rapidly remove the excess moisture from the wood. In this method, hot air is passed through timber placed in a chamber. This air circulates between the timber logs and reduces the moisture content. Quick but energy intensive process. primary processing of wood mill plaining After the wood has reached the correct moisture level for that species, it is sent through the planer and planed to its final dimensions. A planing mill is a facility that takes cut and seasoned boards from a sawmill and turns them into finished dimensional lumber. properties of wood anatomic structure of wood ➔ The outer "skin" or bark ➔ Cambium ➔ Sapwood (Xylem) ➔ Heartwood (naturally has less moisture and thus is more easily kiln dried / more durable and resistant to microorganisms and insects than sapwood) ➔ Knots ➔ Annual rings properties of wood anisotropy Grain is the direction and orientation of the fibers in the wood produced as the cells grow. Inherent qualities of wood depend on the direction of the grain, which refers to its anisotropy: having a physical property which has a different value when measured in different directions. properties of wood composition of wood Cellulose: makes up the cell walls and fibers of plants; linear polymer Lignin: binder for cellulose fibers Hemicellulose: cross-linked polymer properties of wood decay & insect infestation Wood structures are susceptible to damage by fungi, insects, and fire. The threat of insects and fungi both increase due to the level of moisture content of wood and duration of time in which the wood is exposed to moisture. The best protection against both of these damaging elements is to use dry wood products and ensure that the wood is kept dry during construction and thereafter. Preservatives help to protect wood from termites, fungi, bacteria, and rot. Two types preservation of preservatives: water-based and oil-based preservation pressure treatment Pressure-treatment a process that forces wood preservatives or fire-retardants into the wood. It is a process that uses high pressure to inject a preservative into the wood. It extends the longevity of the wood considerably, adding decades to the life of the material. properties of wood hygroscopicity The tendency of a solid substance to absorb moisture from the surrounding atmosphere. Wood can absorb water as a liquid, if in contact with it, or as vapour from the surrounding atmosphere. Thus, wood may undergo shrinkage & swelling. This property has significant implications for the dimensional stability, strength, and durability of wood. Wood expands/shrinks more across the grained and less along the length (longitudinally) properties of wood ➔ Faster to produce & more ➔ Less likely to cup, twist & ➔ The most dimensionally stable affordable but more like to warp cut of lumber available twist & warp ➔ Ideal for custom furniture makers to use for table, chair and other straight pieces properties of wood density The density of wood can affect its stability in changing environmental conditions. Denser wood is less prone to warping, twisting, and shrinking or expanding in response to changes in temperature and humidity. This stability is important for maintaining the structural integrity of wooden products. Denser wood often has tighter grain patterns and fewer voids, making it less susceptible to moisture infiltration and decay-causing organisms like fungi and insects. Dense woods are typically more resistant to rot and decay, which contributes to their longevity, especially in outdoor or humid environments. Dense wood can withstand wear and abrasion better than less dense wood. This makes it suitable for flooring, decks, and other applications where it will be subjected to foot traffic or other forms of abrasion. Denser woods can accept paints, stains, and finishes more uniformly, leading to better long-term appearance and protection. The smoother surface of dense wood allows for better adhesion of coatings. types of wood hardwoods softwoods ➔ Broad-leaved trees / deciduous ➔ Trees that produce cones / trees (shed their leaves during coniferous (evergreens) winter) ➔ have scalelike or needlelike ➔ Contain flowers and bear fruit leaves and nut- and fruit-seed seeds ➔ Primarily employed in building ➔ Denser, stronger and more structurally durable than softwoods ➔ Can be used for doors and ➔ Used for constructing furniture furniture ➔ More expensive than softwoods ➔ Dimensional Lumber: wood fiber that is cut to a specific size ➔ Examples: ash (dişbudak), elm, (thickness/width/length) based beech (kayın), birch (huş), on predefined, standardized mahogany (maun), maple sizes. Common examples of (akçaağaç), oak (meşe), teak dimensional lumber sizes include (tik), walnut, cherry, two-by-fours (2x4s) and four-by- cottonwood, balsa, basswood fours (4x4s). (ıhlamur), hickory, poplar (kavak) ➔ Examples: cedar (sedir), cypress (selvi), fir (köknar), pine (çam), spruce (alaçam), redwood (kızılağaç), hemlock (katran ağacı), larch (karaçam) hardwoods softwoods types of wood softwoods based on species based on stress grading the classification of a timber for structural used in structural applications, which specify the stress limits that apply to timbers used for structural applications / a method used to evaluate the strength and structural performance of wood, and it involves classifying lumber based on its mechanical properties, such as bending, shear, tension, and compression. ➔ stress-graded: used as beams, posts, studs, rafters, and joists ➔ nonstress-graded: (aka common lumber) used in siding, shelving, panelling, sheathing, subflooring, moulds ➔ appearance lumber: used to make softwood furniture, cabinetry, trimming, paneling and other decorative elements types of wood Engineered Wood and Manufactured boards Manufactured boards are processed timber. They have new and useful properties. types of wood cross-laminated timber (clt) ➔ used structurally ➔ formed by stacking and gluing together successive perpendicular layers of kiln-dried lumber ➔ Panels typically consist of three, five, seven or nine alternating layers of dimensional lumber. ➔ The alternating directions provide high dimensional stability types of wood glulam ➔ made up of several layers of structural timber that have been bonded together using adhesives in order to form a bigger, potentially enormous piece of wood. ➔ produces a lighter weight structure with a lesser carbon footprint that is much stronger, pound-for-pound. ➔ A variety of structural components can be formed using glulam including parallel beams, pre-cambered beams, sloped beams, curved beams, flight beams and trusses. types of wood plywood ➔ Plywood boards are made of overlapping wood sheets glued perpendicularly and heat pressed. ➔ Cross-directional fibers in plywood allow the board to withstand greater stress. ➔ It can be used for furniture, floors, ceilings, doors, and countertops among others. types of wood MDF (Medium Density Fiberboard) MDF boards are made of wood fibers bonded by synthetic resin and compressed through pressure and heat, resulting in a solid and very uniform board with good finish and durability. Because the fibers are randomly oriented, the machine can cut them in any direction, delivering a smooth surface to the touch. Naturally, the board does not resist water well, but there do exist options on the market that are more resistant to moisture and sometimes even fire. HDF (High Density Fiberboard) very similar to the MDF, though their manufacturing processes differ. Being compressed under higher pressure, these boards are more resistant, support more weight, and can cover larger extensions. types of wood MDP (Medium Density Particleboard) MDP boards are made of wood particles compressed with synthetic resin and heat pressed, with the difference that the fine particles are deposited on the face of the board and the thickest particles in the core. This distribution allows a better finish, a better adjustability, and more possibilities of application for claddings. It is not very resistant to moisture and may have some imperfections. The resulting panels are widely used in the production of simple furniture. types of wood Chipboard Chipboard is created by pressing wood debris, such as sawdust and dust, with resin and glue. Uses similar to MDF Low cost types of wood OSB (Oriented Strand Board) These boards are made of wood chips pressed in perpendicular layers and bonded with resin applied at high pressure and temperature. They have good mechanical strength and rigidity. In addition to their good sound insulation, they have no empty spaces inside them, and no knots or cracks, so they are very uniform. They are also ecological and durable against the outdoors and the action of rain, humidity, wind, and heat. The main applications of OSB occur in walls and ceilings (sheathing), floor bases for the application of carpets, wood floors, bricks, cladding and construction sheds, packaging, and furniture structure among others. traditional timber construction methods log construction one of the oldest building construction methods in history and was used not only for dwellings but also for other structures such as churches, towers, and bridges. Log walls are either stacked with solid logs or spaced and filled with other insulating materials such as mud or plaster chinking. The log itself can either be left as a round shape or can be edge-sawed for a more solid stacking connection. Log construction is characterized by its corner joints, which interlock with either a dovetail or cross-lap connection. traditional timber construction methods timber framing A timber frame structure uses heavy timber and relies on tight-fitting joinery held together using wood pegs or wedges. structural elements of timber framing ➔ posts ➔ tie beams ➔ plates ➔ braces ➔ girts ➔ bents ➔ floor joists ➔ roof rafters ➔ collar ties connections ➔ mortise and tenons ➔ half-laps The timber frame sections are assembled on the ground (bents) and then erected individually until the traditional timber construction methods timber framing ➔ post vertical structural element ➔ beam horizontal structural element ➔ plate horizontal structural element ➔ joist horizontal structural element ➔ girt horizontal element which stabilizes the frame ➔ brace diagonal element which stabilizes the frame traditional timber construction methods balloon framing platform framing ➔ continuous wood members ➔ formed with story-height studs that throughout stories are joined together with a sole plate ➔ roof and floor members attach at the bottom and double wall to studs running from ground to plates above, and then covered on roof. both sides to stiffen the frame ➔ The length of studs makes them ➔ shorter, standardized pieces of difficult to erect efficiently lumber as more available, less ➔ Increased risk of more rapidly expensive, and easier to handle spreading fire to upper floors ➔ simple nailing connections ➔ Found in older structures - not common today. stick frame traditional timber construction methods modern timber construction methods panel frame construction consists of planar wall and slab elements, which simultaneously form an enclosed space An off-site construction method in which panels (as structural elements) are produced in a factory and delivered to the site and assembled on the site. modern timber construction methods open panel construction closed panel construction Structurally engineered panels made Closed panels arrive ready-insulated from treated softwood timber. and tested for consistent quality of thermal insulation, while open panels Openings formed in panels ready for aren’t pre-insulated. At the extreme onsite installation of windows and end of a closed panel, windows, doors services, plasterboard and even cladding can be factory installed. Panels are delivered to site uninsulated. modern timber construction methods post-and-beam self-supporting structural frame made of heavy timber which carries the weight of the house. The timbers are usually connected with metal fasteners and connectors, which can be hidden or decorative. Post and beam usually use half-lap joinery. The frame is built from the ground up, with the parts being added on top of each other. modern timber construction methods mass timber construction Cross-laminated timber (CLT) is a type of mass timber construction that relies on alternating layers of lumber fastened together to create a solid wood panel. To maximize structural strength, each layer of lumber is laid out perpendicular to the layer beneath it. Clt panel construction below. modern timber construction methods CNC plywood frame Plywood frames use thin sheets of plywood as the material for the entire structural system. Sheets of plywood are run through a CNC router, which cuts the plywood into specially designed shapes. The shapes are then attached together using slots and tabs (helped into place with large mallets) to form a variety of structural elements - walls, box beams, portal frames, columns - which then get assembled (using more slots, tabs, and wedges) to form the superstructure of the building. connectors/fasteners anything used to hold two or more mechanical/threaded mechanical/non-threaded pieces of material together ➔ Screws ➔ Nails ➔ mechanical ➔ Bolts ➔ Nail Plates ➔ adhesives ➔ Toothed Plates ➔ Rivets ➔ Gussets adhesives Commonly called “Glue” / A substance that bonds two or more objects together using surface attraction. Various types according to strength and outdoor/indoor applications. connectors/fasteners designing for disassembly people’s pavilion by arup fire safety Building codes and regulations often require certain components, such as walls, doors, or ceilings, to have specific fire ratings to ensure occupants have a safe evacuation time in the event of a fire. When a wood product in timber construction is described as "fire-rated for 45 minutes," it means that the material has been tested and certified to withstand exposure to a standard fire test for a duration of 45 minutes without significantly losing its structural integrity or fire resistance properties. This rating is important in building construction to meet building code requirements. fire safety The required fire resistance of wood structures can be achieved by: ➔ adding the size of the structure, ➔ adding a protective cladding, ➔ using a non-combustible insulation material ➔ improving the fire resistance of the wood structure with a flame retardant treatment (by pressure or vacuum technology, by spraying, brushing or dipping)