DEEPTASHREE SAHA

INTERIOR DESIGN

4th SEMESTER

CONSTRUCTION

MATERIALS

edexcel logo sourcewww.colossaltraining.co.ukarch logo source : www.sholay.in

WOOD

What is construction material?•Construction material is any material which is

used for construction purposes.

•Many naturally occurring substances have been

used to construct buildings :

oClay

oRocks

oSand

oWood

oTwigs

oLeaves

Clay

Stone

Sand Twig

What is wood ?•Wood is a porous and

fibrous structural tissue

found in the stems and

roots of trees and

other woody plants

• It has been used for

thousands of years for

both fuel and as a

construction material.

• It is an organic

material, a natural

composite of cellulose fi

bers (which are strong in

tension) embedded in

a matrix of lignin which

resists compression.

Classification of wood

WOOD

NATURAL WOOD

ENGINEERED WOOD

NATURAL WOOD

Where do we generally find

wood ?

fuel

flooring

furniture

fuel

utensils musical

instruments

sports equipments

Wood processing

Physical Properties

Wood rings Water content Colour

Grains Knots

Classification of natural

wood

NATURAL WOOD

HARD WOOD

SOFT WOOD

Hard wood•Hardwood is wood from dicot angiosperm trees•The term may also be used for the trees from which the wood is derived; these are usually broad-leaved.•In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen• Hardwoods are not necessarily harder than softwoods

Hard woodCharacteristics •Hardwoods have a more complex structure than softwoods•Dark in colour

•Expensive

•Slower growth rate

•Higher density

•Heavy in weight

•More fire resistant than soft wood

•Strong in compression and

tension

Hard woodExamples - Oak •Light in colour

•Heavy

•Ring porous

•Open grain

•Hard to work with.

•When treated it looks classy and

elegant

Hard woodExamples - Oak products

Hard woodExamples - Maple• Maple is so hard and resistant to

shocks that it is often used for

bowling alley floors.

• Its diffuse evenly sized pores

give the wood a fine texture and

even grain.

•Maple that has a curly grain is

often used for violin backs.

•Burls, leaf figure, and birds-eye

figures found in maple are used

extensively for veneers.

Hard woodExamples - Maple products

Hard woodExamples - Mahogany• An easy to work wood

•reddish brown in colour

•Expensive

•Strong

• poorly defined annual rings

•may display stripe, ribbon,

broken stripe, rope, ripple, mottle,

fiddle back or blister figures

•excellent carving wood and

finishes well

Hard woodExamples - Mahogany products

Hard woodExamples - Cherry• hard

•Strong

•Light to red-brown wood

•Resists warping and checking

•Easy to carve and polish

Hard woodExamples – Cherry products

Hard woodExamples – Rubber wood• light colour

•Medium density

•Usually from the tree of rubber

plantation

•Advertised as eco-friendly wood

oBecause It is not grown

specially for timber but instead

have timber as by product

Hard woodExamples – Rubber wood products

Soft wood•Softwood is wood from gymnospermtrees such as conifers• Softwood is the source of about 80% of the world's production of timber• Softwoods are not necessarily softer than hardwoods•The woods of long leaf pine, douglasfir, and yew are much harder in the mechanical sense than several hardwoods

Soft woodCharacteristics •Cheap comparative to hard wood•Faster rate of growth

•Lower density

•Softer than hardwood

•Light in colour

•Light in weight

•Poor fire resistant

•Strength in tension but week in

sheer

Soft woodExamples - Ash •Hardwoods have a more complex structure than softwoods•Dark in colour

•Expensive

•Slower growth rate

•Higher density

•Heavy in weight

•More fire resistant than soft wood

•Strong in compression and

tension

Soft woodExamples – Ash wood products

Soft woodExamples - Pine• soft

•White or pale yellow in colour

•Light weight

•Straight grains

•Lack figures

•Resists shrinking and swelling

•knotty

Soft woodExamples – pine wood products

Soft woodExamples -Cedar• Knotty soft wood

•Red brown colour with light

steaks

•Aromatic and moth repellant•Popular wood for lining drawers, chests and boxes• Brittle wood

Soft woodExamples – cedar wood products

Soft woodExamples –Red wood• The best quality redwood comes from the heartwood which is resistant to deterioration due to sunlight, moisture and insects•Redwood burls have a "cluster of eyes" figure. •They are rare and valuable.

Soft woodExamples – redwood products

NATURAL WOOD

seasoning

•Reduces moisture content of wood

•There are two main reasons :i. Woodworking: when wood is used as a construction material,

whether as a structural support in a building or in wood working objects, it will absorb or desorb moisture until it is in equilibrium with its surroundings. Equilibration (usually drying) causes unequal shrinkage in the wood, and can cause damage to the wood if equilibration occurs too rapidly. The equilibration must be controlled to prevent damage to the wood.

ii. Wood burning: when wood is burned, it is usually best to dry it first.

Over exploitation of natural

wood on nature•Deforestation•Desertification

•Extinction of species

•Forced migration

•Soil erosion

•Ozone depletion

•Greenhouse gas increase

•Natural hazard and desert

So Need for

engineered wood

arises

ENGINEERED

WOOD

• Also called composite

wood, man-made wood,

or manufactured board

•Includes a range of

derivative wood products which

are manufactured by binding

or fixing the strands,

particles, fibers, or veneers or

boards of wood, together with

adhesives, or other methods of

fixation to form composite

materials

• Engineered wood products are

used in a variety of applications,

from home construction to

commercial buildings to

industrial products.

Engineered woodPlywood• Plywood is a sheet material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another•This alternation of the grain is called cross-graining and has several important benefits: o it reduces the tendency of wood to split when nailed at the edgeso It reduces expansion and shrinkage, providing improved dimensional stabilityoIt makes the strength of the panel consistent across all directions.

Engineered woodBlock board• Blockboard is a wood based panel, made up of a core of softwood strips glued together• The strips may be up to about 28mm wide and are placed edge to edge and sandwiched between veneers of softwood, hardwood or thin MDF or particleboard, glued under high pressure•The internal strips are generally made of light weight poplar wood or spruce•To achieve maximum strength, it is important to ensure that the core runs lengthways•has very good screw holding•it has a good resistance to warping.

Engineered woodVeneers • veneer refers to thin slices of wood,

usually thinner than 3 mm (1/8 inch),

that typically are glued onto core

panels

•Veneer is obtained either by "peeling"

the trunk of a tree or by slicing large

rectangular blocks of wood known as

flitches

• The appearance of

the grain and figure in wood comes

from slicing through the growth rings of

a tree and depends upon the angle at which the wood is sliced

Engineered woodLaminates • Lamination is the technique of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance or other properties from the use of differing materials•A laminate is usually permanently assembled by heat, pressure, welding, or adhesives

• also known as chipboard•manufactured from wood chips, sawmill shavings, or even sawdust, and a synthetic resin or other suitable binder, which is pressed and extruded•It is a composite material

Engineered woodParticle board

• made by breaking down hardwood or softwood residuals into wood fibres, often in a delibrator, combining it with wax and a resin binder, and forming panels by applying high temperature and pressure• MDF is generally denser than plywood•It is made up of separated fibres• stronger and much denser than particle board

Engineered woodMedium Density Fiber board

• also called hardboard• made out of exploded wood fibres that have been highly compressed• It differs from particle board in that the bonding of the wood fibres requires no additional materials,although resin is often added•Unlike particle board, it will not split or crack

Engineered woodHigh Density Fiber board