ARB PART2

woods and plastic

uses of wood in architecture

natural warmth

workability

infinite variety

flexibility

fire protection

color

Decay

Caused by the attack of fungi.

Checks

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.

Shakes

– These are cracks

between and parallel to the

annual rings of the growth.

Knots

– 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.

Pitchpockets

– These are

well-defined openings between

annual rings containing solid or

liquid pitch.

Wane

– This is the 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. There are

several forms of warp:

Crook

–a distortion of the board

in which the edge is convex or

concave longitudinal.

Bow

–a distortion of the

board in which the face is

convex or concave

longitudinal.

Cup

–a distortion of the board in

which the face is convex or

concave across the board.

Twist

–a distortion of the board

in which one corner is raised.

Plain sawing and Quartersawing

methods of sawing wood

Plainsawing

efers to lumber cut tangent to the annual rings or growth

or, in commercial practice, cut with annual rings at an angle

0° to 45°. for pleasing pattern

Quartersawing

efers 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 tight.

Strips

Board lumber

Dimension Lumber

Timbers

Four available classification of lumber

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. The finished size is

therefore smaller.

Strip LUmber

Dimension Lumber

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.

Board Feet formula

Thickness (in.) x Width (in.) x Length (ft.) over

12

Moisture

has a big influence on the behavior and

properties of wood. While water has been in wood

since its formation, yet after a tree is cut, water

becomes detrimental to it. It makes wood liable to the

attack of insects and fungi and unfit for use.

Shrinkage of Wood

---

_____wood occurs at moisture content

percentages below the fiber saturation point.

“fiber-saturation point”

When all free water is removed but all absorbed water

remains,____ is reached

“equilibrium moisture content”

This condition of dryness of the wood

seasoning.

The process of removing moisture from green wood

(wood from freshly-cut logs)

Air drying

which the lumber is exposed to the air.

KILN-DRYING

in which warm moist air or superheated

steam is used to heat the wood and drive out moisture.

Advantages of Seasoned

Lessen the liabilty of wood from being attacked by a fungi

Reduction of weight

increased strength

minimum shrinkage

reduced checking and warping

increase nail holding power

improvement of the wood for the application of paint

Advantages of Klin drying

Greater reduction in weight.

Control of moisture content to any desired value.

Reduction in drying time.

Killing of any fungi or insects.

Setting the resins in resinous wood.

Less degrade (Degrade is the loss in quality during

seasoning of the lumber through unequal shrinkage

which causes checks and loosening of knots,

warping).

Decay

Molds, stains and decay in

wood are caused by fungi. Their

growth depends on mild

temperatures and dampness.

Subterranean termites

which live in the ground and

build earthen tubes to reach their food– cellulose

which includes wood primarily but also paper and

pulp products. The channels formed as they eat all

the wood substance tends to follow the grain.

Non-Subterranean termites

only relatively permanent method of arresting

attack is to use lumber that has been given

full-length termite proofing with wood preservatives.

Attention to structural features and sanitation are

also important.

Carpenter Ants and Powder-Pest Beetles

use wood for shelter rather than for food, but if they are not found and are left undisturbed they can do extensive damage.

They convert wood to powder, shredded fibers or pellets. Their channels

are likely to cut across the grain. The damage to wood by the various marine organisms, mollusks and crustaceans in salt water or brackish water is best arrested by heavy, thorough treatment with coal-tar creosote or creosote-coal tar solutions.

Perservation of Wood

Oil type wood

water borne wood

Coal-tar creosotes.

Black or brownish oil made from distilling coal tar.

Advantages are: highly toxicity to wood-destroying organisms; insolubility in water; ease of application.

Disadvantages are its strong,unpleasant odor, cannot be painted, easily ignited when first applied .

Creosotes derived from wood, oil, and water gas.

Has same advantages as coal-tar creosote but is less effective .

Pentachlorophenol

a mixture of petroleum oils and 5% pentachlorophenol.

Has high protection against decay fungi and termites; can be painted; has no unpleasant odor; is less easily ignited than coal-tar creosotes.

Chromated Zinc Chloride (CZC)

Gives protection against decay, insects and fire; can be painted on; has no objectionable odor.

Chromated Zinc Chloride (CZC) and Ammoniacal Copper Arsenate (ACA)

are dissolved in water for

pressure treating, producing a product that is clean

and odorless.

Both preservatives bond with the wood after

pressure treating in a chemical process known as

fixation, producing treated wood that is highly

leach-resistant and safe to use in applications with

regular human contact.

Provides good protection against decay and

insects; can painted on; has no objectionable odor.

Wood can be used in contact with the ground but

generally recommended for contact with water.

Methods of applying perservatives

Pressure treatment

Hot and Cold Bath method

Dipping or immersing the wood in a hot preservative for a short time

Brushing

Methods of treating wood to increase its fire resistance

Covering the wood with a compound or material.

Impregnating the wood with a chemical

Covering the wood with a compound or material.

Such superficial coatings or layers protective materials

retard the normal increases in temperature under fire

conditions and thereby decrease the rate of flame

spread.

Impregnating the wood with a chemical

which the

wood itself not support combustion. The chemicals

commonly used for impregnation are:

- monobasic ammonium phosphate

- dibasic ammonium phosphate

- ammonium sulfate

- borax, boric acid and

- zinc chloride

WOOD COMPOSITES

are those products made from a

mixture of wood and other materials. Most wood

composites are produced in large sheets, usually

1220mm (4’) x 2440mm (8’).

PLYWOOD

the most common nwood 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.

Standard sizes of Plywood

3’ x 6’ (900mm x 1800mm) and

4’ x 8’ (1220mm x 2440mm)

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

Types of Plywood:

Ordinary Plywood

Form Plywood

Marine Plywood – waterproofed

Fancy Plywood:

HARDBOARD

is a paneling material made by reducing and refining wood chips intosmall, threadlike fibers, and then pressing them under heat in hydraulic pressure into dense, smooth, and very rigid panels.

Standard hardboard

is 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.

Panel hardboard

is somewhat denser than the Standard but not as

dense as Tempered.

Tempered hard board

is 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

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.

FIBERBOARDS and MEDIUM DENSITY FIBERBOARDS

is a type of fiberboard which is made from wood fibers glued under heat and pressure. has many qualities that make it an ideal alternative to plywood orchipboard.

Acoustic Fiber boards

is manufactured from wood, straw,

bagasse pulp pressed into boards with or without holes or

slots. Thicknesses of acoustic fiber board vary from ½ “ to

2” (12 to 50mm) in ½” (12mm) increments.

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.

GYPSUM BOARDS

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

Square and Tapered

Wall 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.

Backing 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.

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 .

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

Water-Resistant Backing 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.

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.

Gypsum Formboard

This type is used as a permanent form in the casting of

gypsum concrete roof decks.

FIBERCEMENT BOARDS

______ cement board is comprised of 72%

Portland Cement, 20% mineralized cellulose fibers

derived from recycled materials, and 8% calcium

carbonate.

PARTICLE BOARD

_____ 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.

MILLWORK

_____ consists of finished lumber which is further cut

and processed at a lumber mill. _____ includes doors,

windows, mouldings, trim and other ornamental forms of

wood.

Types of Wood Mouldings

Types of wood mouldings are:

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 Wood Mouldings

Plastics

It is used to describe a product of synthetic origin

which is capable of being shaped at some stage of its

manufacture, but is not rubber, wood, leather or metal.

It is made from a number of common substances such as

coal, salt, natural gas, cotton, wood and water, from

which relatively simple chemicals known as monomers

are built up into chainlike molecules of high molecular

weight called polymers.

can be hard, soft, clear, opaque, light, heavy,

heat resistant or easily softened by hot water.

CLASSIFICATION OF PLASTICS

Cellulose plastics

- Synthetic resin plastics

- Plastics derived from proteins and natural

resins

Two classes of Synthetic resin plastics

Thermoplastics

Thermosetting plastics

Thermoplastics

soften when heated and harden when cooled

regardless of the number of times the process is

repeated. They have a molecular structure which is

essentially linear or threadlike in form.

Thermosetting plastics

sometimes called

thermocuring plastics, set into shape permanently when

heat and pressure are applied during the forming stage.

They have a molecular structure in a 3-dimensional

arrangement

Examples of Thermaplastics

Acrylic

CELLULOSICS

POLYETHYLINE (PE)

POLYSTYRENE

POLYVINYL CHLORIDE (PVC)\

POLYCARBONATES

POLYPROPYLENE

NYLONS

FLUOROPLASTICS

ACRYLONITRILE BUTADIENE STYRENE (ABS)

Examples of Thermosetting plastics

MELAMINE and UREA

EPOXY

ALKYDS

PHENOLICS

POLYESTER

URETHANES

SILICONES

Sheets

Usually made of acrylate, polyester, or polystyrene

plastics, either plain or reinforced with glass-fiber, are

available in flat or corrugated sheets and various

deformed shapes.

can be used to replace glass in any

type of windows or doors, skylights, shower enclosures,

or in any area where a translucent, transparent or

opaque material in

FILM SHEETS

As water barrier or dampproofing material, it is

generally made of polyethylene and polyvinyl and

come in thicknesses ranging from 1 to 10 mils

(0.001 to 0.01 inch) and in rolls of 50’ length and 3’

to 40’ width.

FOAM

Used as flotation material, thermal insulators, and

shock-resistant mountings. Offers possibilities for

lightweight materials of high strength

LAMINATES

is the process applied to paper or fabric

impregnated with thermosetting resins.

Cotton cloth and paper

_____ and _____ are used as filler materials,

usually in sheet forms, that are bonded together by

heat and pressure to form an integral body.

HARDWARE

Metal products used in construction, such

as: bolts, nails, screws (as in rough

hardware); and fittings, such as, catches,

hinges, locks, etc. (finish hardware); and

tools.

Classifications of Hardware

Rough and Finish

ROUGH HARDWARE

Hardware meant to be concealed, such as bolts, nails, screws, spikes, and other metal fittings.

FINISH HARDWARE

also called Architectural Hardware, Builders’ Finish Hardware, Finish Builders’ Hardware. Hardware, such as hinges, locks, catches, etc., that has a finished appearance as well as a function esp. that used with doors, window, and cabinets;

Decorative treatment

TYPES OF NAIL CONSTRUCTION

Face Nailing

Blind-nailing

Toe-nailing –

Face-nailing

– nailing in which

the nails are driven

perpendicular to the face of the

material.

Blind-nailing

also called

concealed or secret nailing.

Nailing in such a way that the

nail heads are not visible on

the face of the work. In

finished roofing, the use of

nails that are not exposed to

the weather.

Toe-nailing

– also called skew

or tusk nailing. Nailing

obliquely to the surfaces being

joined.

Screws –

– are externally threaded fasteners.

Wood screw

– a helically threaded metal

fastener having a pointed end; forms its

own mating thread when driven into wood

or other resilient material.

Metal screw

– fastened by screwing into metal.

Lag screw, lag bolt, coach screw

– a bolt having a square head and a thin, coarse-pitched thread.

Screw anchors

– an anchor (similar to an

expansion bolt) having a metal shell with

a screw along its central axis; when the

shell is placed in a hole and the screw is

driven in, the shell expands, tightly

securing the anchor in the hole. Locally

called a tux screw with a plastic shell.

Tekscrew

– a screw used to fasten metal

roofing sheets to the purlins.

Bolts

– A metallic pin or rod

having a head on one end and

an external thread on the other

for screwing up a nut[1]; used for

holding members or parts of

members together.

Machine bolt

t – a threaded bolt having a

straight shank and a conventional head such

as a square, hexagonal, button, or

countersunk type.

Carriage bolt

– a threaded bolt having a

circular head, an oval or flat bearing surface,

and a means (such as a square shoulder

under the head) of preventing rotation of the

bolt.