CLASSIFICATION OF WOOD a. Softwoods come from the conifers (evergreens) which have needles instead of leaves
b. Hardwoods come from the broad-leaved or deciduous trees. (Philippine timber)
STRUCTURE OF WOOD
a. Sapwood - softer, younger outer portion of a tree that lies between the cambium (formative layer just under the bark) and the heartwood. b. Heartwood
- the older, harder central portion of a tree.
PROPERTIES OF WOOD a. Hardness. measured by the compression b. Flexibility. The amount of piece will bend before breaking . Softwoods are generally brittle while most hardwoods are flexible.
DEFECTS OF WOOD a. Decay – attack of fungi. b. Checks –Cracks or lengthwise separation across the annual rings of growth caused by irregular shrinkage during drying.
c. Shakes – cracks between and parallel to the annual rings of the growth.
d. Knots –irregular growths in the body of a tree which interrupt the smooth curve of the grain.
e. PITCHPOCKETS- well-defined openings between annual rings containing solid or liquid pitch.
f. Wane –lack of wood on the edge or corner of a piece.
Warping - Any variation with the plane surface of the piece caused by unequal shrinkage of the board.
Crook – edge is convex or concave longitudinal. Bow –face is convex or concave longitudinal.
Cup –face is convex or concave across the board.
Twist –one corner is raised.
METHODS OF SAWING WOOD
a. Plain sawing • cut tangent to the annual rings or growth (angle 0 to 45). • preferable when a pleasing pattern is required, as in wall paneling.
b. Quarter sawing • cut radially to the annual rings of growth parallel to the rays (angle 45 to 90). • it has less shrinkage, important where joints must be kept tight.
LUMBER • Wood that is used in construction • classified by its size or dimensions measured in inches • Generally available in even-numbered widths: 4, 6, 8, 10,12 inches. CLASSIFICATION OF LUMBER a. Strips. Lumber less than 2” b. Board Lumber. Pieces less thick and less than 8” wide. than 2” thick and at least 8” wide.
c. Dimension Lumber. Pieces more than 2” and less than 5” in any dimension.
d. Timbers. Pieces 5” or more on the smallest dimension
Nominal size is the size of lumber when it is cut from the log. After cutting, the lumber is dried and then planed on all four sides to achieve smoothness.
NOMINAL SIZE 2 x 4 ACTUAL SIZE 1½ x 3½
2 x 6
2 x 8 2 x 10 2 x 12 1 x 4
1½ x 5½
1½ x 7½ 1½ x 8½ 1½ x 11½ ¾ x 3½
1 x 6
1 x 8 1 x 10 1 x 12
¾ x 5½
¾ x 7½ ¾ x 9½ ¾ x 11½
MEASUREMENT OF LUMBER Lumber is sold in lengths from 6’ up to 20’ in increments of 2’. Special lengths greater than 20’ are also available but cost more per board foot than the standard lengths. Lumber measure is the board foot which may be described as the measure of a piece of wood 1” thick, 12” (or 1’) wide and 12” (or 1’) long. Board Feet = Thickness (in.) x Width (in.) x Length (ft.) 12
Compute the number of board feet in
(a) a piece of ¾” x 8” x 10’ (b) 10 pcs. of 2” x 6” x 14’
(c) 5 pcs. of 1” x 4” x 10’
1 x 3/4 x 8 x 10 12 10 x 2 x 6 x 14 12 5 x 1 x 4 x 10 12 = 5 bd. ft.
140 bd. ft.
16 – 2/3 or 17 bd. ft.
SEASONING OF LUMBER The process of removing moisture from green wood a. AIR-DRYING - lumber is exposed to the air.
b. KILN-DRYING warm moist air or superheated steam is used to heat the wood and drive out moisture.
Seasoned lumber has many advantages over green lumber: a. It lessens the liability of the wood to be attacked by the fungi b. Reduction of weight. c. Increased strength. d. Minimum shrinkage after the lumber is in place e. Reduced checking and warping. f. Increased nail-holding power of the wood g. Improvement of the wood for the application of paint and to receive wood preservatives, fire retardants.
The advantages of kiln-drying over air-drying are: a. Greater reduction in weight. b. Control of moisture content to any desired value. c. Reduction in drying time. d. Killing of any fungi or insects. e. Setting the resins in resinous wood. f. Less degrade
DETERIORATION OF LUMBER a. Decay - molds, stains and decay in wood are caused by fungi.
• Non-Subterranean termites live solely in the wood that they feed on
• Carpenter Ants and Powder-Pest Beetles
use wood for shelter rather than for food. • Subterranean termites which live in the They convert wood to powder, shredded ground and build earthen tubes to reach fibers or pellets. their food – cellulose.
installing a shield made of metal or special termite-proof materials.
Termite proofing the wood used for construction close to earth.
Poisoning the soil adjacent to the building.
Preservative Creosote Pentachlorophenol ACA CCA
Applications Railway ties, mine timbers, poles, foundation piles, marine piles and bulkheads Utility poles, cross arms, bridge timbers and ties Piles, utility poles, marine timbers, construction lumber Guide rail posts, utility poles, bridge timbers, piles, structural glued-laminated timbers, landscape timbers, posts, boardwalks, permanent wood foundations and residential construction, decking and fencing
The methods of applying preservatives are: a. Pressure treatment. placing the wood in cylinders into which the preservative is pumped under pressure b. Hot and Cold Bath Method. placing the wood in a bath of hot preservative for an hour or more. It is then withdrawn and quickly placed in a bath of cold preservative. This is generally used for creosote preservative c. Dipping or immersing the wood in a hot preservative for a short time d. Brushing
There are two methods of treating wood to increase its fire-resistance: a. Covering the wood with a compound or material. coatings or layers protective materials retard the normal increases in temperature under fire conditions and thereby decrease the rate of flame spread . b. Impregnating the wood with a chemical which the wood itself not support combustion.
WOOD COMPOSITES • products made from a mixture of wood and other materials.
1. PLYWOOD made of several thin plies, or veneers, of wood that have been glued together. Each ply or veneer is glued so that its grain is at right angles to the grain of the previous ply.
a. Standard Sizes of Plywood:
Standard thicknesses are: 3/16” (4.5mm) for double wall partitions and ceilings ¼” (6.0mm) for double wall partitions 3/8” (10.0mm) for drawers and shelves ½” (12.0mm) for drawers and shelves ¾” (19.0mm) for drawers, shelves, cabinet and closet doors 1” (25.0mm) for cabinet and closet doors, and sub-floors
Plywood is commonly available in: 3’ x 6’ (900mm x 1800mm) and 4’ x 8’ (1220mm x 2440mm) b. Advantages of Plywood: • the approximate equalization of strength properties along its length and width; • greater resistance to checking and splitting; and • less change in dimension due to moisture content c. Types of Plywood: • Ordinary Plywood • Form Plywood • Marine Plywood • Fancy Plywood:
2. HARDBOARD • This is a paneling material made by reducing and refining wood chips into small, threadlike fibers, and then pressing them under heat in hydraulic pressure into dense, smooth, and very rigid panels.
• Hardboards are a cheaper option than plywood where strength is not required.
• Hardboard has a smooth surface on one side and a screened surface on the other. It is sometimes known as Masonite, after the man who invented it.
There are three types of hard board: a. • Standard hardboard light brown in color and has a fairly hard, smooth surface on one side and a screened impression on the other. flexible and easy to bend. suitable for interior use only and where it is not subject to moisture.
b. Panel hardboard • denser than the Standard but not as dense as Tempered.
c. Tempered hard board
• densest type
• It is dark brown in color, brittle and stiff, with improved machining qualities and greater resistance to moisture and water penetration, making it ideal for exterior use
Hardboard is usually in panel size of 4’x8’ (1220mm x 2440mm) with thicknesses of 1/8” (3mm), 3/16” (4.5mm) or ¼” (6mm), and is obtainable either with a plain, textured, or perforated surface.
Brand names of Hardboard: LAWANIT standard and tempered boards LAWANEX panel boards MASONITE standard, panel and tempered hard board
3. CHIPBOARD Chipboard is made by bonding together wood particles with an adhesive under heat and pressure to form a rigid board with a relatively smooth surface, often faced with veneer. It is made by binding phenolic resin or urea formaldehyde glue.
Chipboard is available in a number of densities; normal, medium and highdensity.
- Normal density is fairly soft and 'flaky‘
- High-density is very solid and hard (often used for worktops and fire doors) - Medium density is somewhere in between
FIBERBOARDS and MEDIUM DENSITY FIBERBOARDS • finishing materials made from vegetable fibers such as corn or sugarcane stalks pressed into sheets. • It is not very strong, but has good insulating properties.
• It is generally 4’x8’ (1220mm x 2440mm) panel size, in thicknesses of 3/16” (4.5mm) or ¼” (6mm), ½” (12mm) and ¾ “ (19 mm).. Brand names of Fiberboard: CELOTEX, CANEX, HOMASOTE, PHILTEX, BONOTEX
MDF is a type of fiberboard which is made from wood fibers glued under heat and pressure. MDF has many qualities that make it an ideal alternative to plywood or chipboard. It is dense, flat, stiff, has no knots and is easily machined. Its fine particles provide a material without a recognizable "grain". Unlike plywood, MDF contains no internal voids, and will produce better edges providing that it is correctly machined.
PARTICLE BOARD Particleboard is made of small wood chips and base materials including cotton stalk, rice straw, bagasse, conventional wood chips and sawdust that have been pressed and glued together.
GYPSUM BOARDS • This is a non-combustible building board with a gypsum core enclosed in tough, smooth paper • extensively used in “dry-wall” construction, where plaster is eliminated
ADVANTAGES • Light weight • Fire resistance • Water resistance • Sound insulation • Easy assemblage • Convenience for decorating on the surface Brand Names: BORAL ELEPHANT
Square Edge (S.E.)
for coverstrip jointing; visible butt jointed panelling with clamp fixing and free suspension.
Tapered Edge (T.E.) for smooth seamless jointing; jointless wall and ceiling panelling
The types of Gypsum Board are:
a. Wall Board
for surface layer on interior walls and ceilings. Pre-decorated gypsum board comes with a decorative vinyl or paper sheet on its face. The foil-backed gypsum board serve as vapor barrier and thermal insulation.
b. Backing Board
as base layer in multi-ply construction, where several layers of gypsum boards are desired for high fire resistance, sound control and strength in walls.
c. Core Board To save space, this type is used as a base in a multi-ply construction of self-supporting (studless) gypsum walls. It comes in 1” (25mm) thickness or 2- factory-laminated, ½ “ thick layers of backing board .
d. Type X Gypsum Board
For use in fire-rated assemblies, this may be wallboard, backing board, or coreboard made more fire-resistant by addition of glass-fiber or other reinforcing materials
e. Water-Resistant Backing Gypsum Board This type comes with waterresistant gypsum core and water-repellant face paper. It maybe used as base for walls of bathrooms, showers, and other areas exposed to wetting.
f. Gypsum Formboard
This type is used as a permanent form in the casting of gypsum concrete roof decks.
g. Gypsum Sheathing
This type is used as fire protection and bracing of exterior frame walls. It must be protected from the weather by an exterior facing.
FIBERCEMENT BOARDS Fiber-reinforced cement board is comprised of 72% Portland Cement, 20% mineralized cellulose fibers derived from recycled materials, and 8% calcium carbonate.
Millwork consists of finished lumber which is further cut and processed at a lumber mill. Millwork includes doors, windows, mouldings, trim and other ornamental forms of wood.
TYPES OF WOOD MOULDINGS a. crown b. bed c. cove d. quarter-round e. half-round f. nose and cove g. stop h. astragal i. Screen moulding j. panel strip k. picture moulding
Types of Architectural Mouldings Crown moulding used where the wall meets the ceiling and it hides any imperfections as well as creating a decorative element.
Chair rail moulding used in order to stop chairs from marking walls when they are pulled out or purely decorative feature.
Base moulding used where the wall meets the floor and it hides imperfections and is attractive. Consider door trim when selecting base moulding, the two to complement each other.
Shoe moulding used in conjunction with base moulding in order to protect the base moulding from scuffs, vacuum cleaners, and so forth.