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57問 • 2年前

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may have a variety of noticeable grain patterns •Tends to twist and cup, and wears unevenly •Tends to have raised grain •Shrinks and swells less in thickness, more in width

PLAINS SAW LUMBER

Wears more evenly with less raised grain and warping •shrinks and swells less in width, more in thickness

QUATER SAW LUMBER

come from the conifers (evergreens) which have needles instead of leaves, e.g. pine

SOFTWOOD

come from the broad-leaved or deciduous trees. Most Philippine timber are of this latter kind

HARDWOOD

isthesofter,youngerouterportion of a tree that lies between the cambium (formative layer just under the bark) and the heartwood. - Itismorepermeable,lessdurable and usually lighter in color than the heartwood.

SNAPWOOD

theolder,hardercentral portion of a tree. - usuallycontainsdeposits of various materials that frequently give it a darker color than sapwood. - isdenser,lesspermeable and more durable than the surrounding sapwood. - Thecentralcoreofthe log, it is composed of inactive cells and serves only as a mechanical support

HEARTWOOD

This is measured by the compression which a piece of timber undergoes when a weight is applied to it.

HARDNES

The amount of piece will bend before breaking . Softwoods are generally brittle while most hardwoods are flexible

FLEXIBILITY

PROPERTIES OF WOOD

HARDNES FLEXIBILITY DURABILITY STRENGTH

Caused by the attack of fungi.

DECAY

Cracks or lengthwise separation across the annual rings of growth caused by irregular shrinkage during drying. Checks are formed when the circumference shrinks more than the interior section of the log.

CHECKS

These are cracks between and parallel to the annual rings of the growth.

SHAKES

These are irregular growths in the body of a tree which interrupt the smooth curve of the grain. The fibers of the tree are turned from their normal course and grow around the knot at that point of the tree

KNOTS

These are well- defined openings between annual rings containing solid or liquid pitch.

PITCHPOCKET

This is the lack of wood on the edge or corner of a piece.

WANE

- Any variation with the plane surface of the piece caused by unequal shrinkage of the board. There are several forms of warp:

WRAPPING

a distortion of the board in which the edge is convex or concave longitudinal.

CROOKS

a distortion of the board in which the face is convex or concave longitudinal.

bow

a distortion of the board in which the face is convex or concave across the bo

CUP

a distortion of the board in which one corner is raised.

TWIST

refers to lumber cut tangent to the annual rings or growth or, in commercial practice, cut with annual rings at an angle 0 to 45. Plainsawn lumber is preferable when a pleasing pattern is required, as in wall paneling.

PLAIN SAWING

refers to wood cut radially to the annual rings of growth parallel to the rays or, in commercial practice, cut with the annual growth rings at an angle 45 to 90. Quartersawn lumber is desirable because it has less shrinkage than plainsawn lumber, and this is important where joints must be kept tig

QUATER SAWING

Lumber less than 2” thick and less than 8”

STRIPS

Pieces less than 2” thick and at least 8” wide.

BOAR LUMBER

Pieces more than 2” and less than 5” in any dimension.

DIMENSION LUMBER

Pieces 5” or more on the smallest dimension

TIMBERS

which the lumber is exposed to the air.

AIR DRYING

which warm moist air or superheated steam is used to heat the wood and drive out moisture. The ideal condition in seasoning is for the moisture from the interior of the wood to replace the surface moisture which vaporizes. When the moisture from the

KILN DRYING

all

producing treated wood that is highly leach-resistant and safe to use in applications with regular human contact.

FIXATION

Consists in placing the wood in cylinders into which the preservative is pumped under pressur

PRESSURE TREATMENT

Thisconsists first in 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

HOT AND COLD BATH METHOD

the most common wood composite. It gets its name from its construction: it is 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.

PLY WOOD

all

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.

HARDBOARD

light brown in color and has a fairly hard, smooth surface on one side and a screened impression on the other. It is flexible and easy to bend. It is suitable for interior use only and where it is not subject to moisture.

STANDARD HARDBOARD

somewhat denser than the Standard but not as dense as Tempere

PANEL HARDBOARD

the densest type, made by impregnating standard board with tempering compound of oils and resins and baking it to polymerize the tempering materials. 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

TEMPERED HARDBOARD

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 glu

CHIP BOARD

This is a non-combustible building board with a gypsum core enclosed in tough, smooth paper. It is designed to be used without addition of plaster for walls, ceilings or partitions. It is extensively used in “dry-wall” construction, where plaster is eliminated

GYPSUM BOARD

This type is used for surface layer on interior walls and ceilings. The regular wallboard comes with grey liner paper backing and special paper finish on the facing and edges suitable for decoration. The foil-backed gypsum board has aluminum foil bonded to the liner paper to serve as vapor barrier and thermal insulation. Predecorated gypsum board comes with a decorative vinyl or paper sheet on its fac

WALL BOARD

This is used 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

BACKING 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, 1⁄2 “ thick layers of backing board

CORE 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 materia

TYPE X GYPSUM BOARD

This type comes with water-resistant gypsum core and water-repellant face paper. It maybe used as base for walls of bathrooms, showers, and other areas exposed to wetting.

WATER RESISTANT BACKING GYPSUM BOARD

This type is used as fire protection and bracing of exterior frame walls. It must be protected from the weather by an exterior facing.

GYPSUM SHEATHING

This type is used as a permanent form in the casting of gypsum concrete roof decks.

GYPSUM FORMBOARD

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 togethe

PARTICLE BOARD

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.

MILLWORKS

Are used to fisnish the joint between the cieling

CONICES

conceal and finish the joint between the wall and flooring

BASE BOARD

Popular brands are “LUCITE” and “PLEXIGLASS”, this material combines the transparency of glass (but not scratch-proof quality) with plastics’ shatterproof quality. Used principally for skylights, skydomes, safety glass, paints, adhesive

ACRYLIC

In spite of its sensitivity to solvent action, its is one of most important thermoplastics because of its excellent transparency and rigidity and its easy moldability. It is non-water absorbent, it is found in colorful, but brittle wall tiles. It is one of several plastics used in lighting fixture diffusers. In foam form, it has become an important thermal insulator. Also found in paint for concrete.

POLYSTYRENE

a largely amorphous, rigid, tough, solvent- resistant, flame-resistant thermoplastic. Used for resilient floor tile, films, pipes, and for paint lacquers, adhesives and safety gl

PVC

family of linear polyesters, is a white, substantially amorphous, very tough and strong material with good heat resistance up to 150 deg C and excellent dimensional stability. It is injection-molded to produce plates, rods, gears, and other shaped parts that advantageously replace die-cast metal parts. Used for skyli

POLYCARBONATE

The term nylon refers to a family of polymers called linear polyamides. It is desired for the following properties: exceptionally strong, elastic, abrasion resistant, easy to wash, resistant to damage from oil and many chemicals, can be precolored or dyed in wide range of colors, and resilient

NYLONS

used in buildings for its remarkable adhesive qualities. It may also be used for special paints that are chemically resistant and for special caulking compounds.

EPOXY

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