This document discusses different types of basic construction materials, including softwood, hardwood, and sheet materials like plywood. Softwood comes from coniferous trees and makes up most timber production, though it is not always softer than hardwood. Softwood is lighter, more resinous, and easier to work with than hardwood. Hardwood comes from broad-leaved trees and has a more complex structure with pores. Hardwood is denser and stronger in resisting shear stresses. Sheet materials like plywood and laminate are manufactured by gluing together veneers or plies of wood in alternating directions to reduce warping and increase strength. Plywood is widely used in construction, furniture, and other applications.

1. Basic Construction Skills
Timber Vocation
Basic Material
 Softwood
 Hardwood
 Sheet Material
Softwood
 Wood from coniferous trees are terminated softwood. Conifers are evergreen trees such as
Spruce, Deodar and Walnut etc.
 Softwood forms 80% of the world's timber production.
 Softwoods are not necessarily softer than hardwoods. In both groups there is an enormous
variation in actual wood hardness.
 Some hardwoods (e.g. balsa) are softer than most softwoods.
 There are about a hundred times as many hardwoods as there are softwood. The woods
of longleaf pine, douglas fir, and yew are much harder in the mechanical sense than
several hardwoods.
Properties of Softwood
 Softwood is light in weight and color
 Annual rings are very distinct
 Comparatively weaker and split easily
 Has straight fiber
 Is resinous, contains resins and turpentine with a peculiar fragrance
 Very strong is resisting tensile forces
 Weak in bearing loads across grain
 Has soft and regular texture
Use of Softwood
 Many American homes are built of Canadian softwood lumber
 In general softwood is easy to work. It forms the bulk of wood use by humans
 Extensively use as material for structural components
 Used in the manufacture of furniture, decorative timber items, machined items
 As raw material for pulp in the production of paper and paper board

2. Hardwood
 Hardwood is wood from dicotyledonous trees
 These are usually broad-leaved trees are mostly deciduous, but
in tropics and subtropics mostly evergreen.
 Hardwood should not be confused with the term 'heartwood', which means mature wood in the heart of
exogenous tress.
 Hardwoods are not necessarily harder than softwoods. There are many hardwoods which are softer
Structure of Hardwood
 Hardwoods have a more complex structure than softwoods.
 The dominant feature separating "hardwoods" from softwoods is the presence of pores, or vessels.
 Annual rings are not distinct.
 The wood is hard and difficult to work with.
 Contain large percentage of acid.
 Strong in resisting, shearing stress.
 Close grained and strong
 No resinous
 Teak, Ork and Mahogany are some examples.
Applications
Hardwoods are employed in a large range of applications including:
 Construction, furniture and flooring
 Solid hardwood products are more expensive compared to softwood
 Countries with cold climates used to import hardwood such as Burma Teak, and Mahogany
 Therefore cheaper "hardwood" doors, for instance, now consist of a thin veneer bonded to a core
of softwood, plywood or medium-density fibreboard (MDF).
Hardwoods can also be used in a variety of objects but mainly for furniture or musical instruments because of
their density.
Sheet Timber
 Also called manufactured timber
 Sheet timber is used with the intention of reducing tree cutting by manufacturing wood material from waster or
cheap (inferior) timber
Veneers
 Thin sheet of wood peeled off, sliced or swan from a log
 Manufactured by rotary veneer cutters or slicing machines
 Thicknesses of veneers are from 4mm to 6mm
 Veneers of expensive timber are glued to inferior timber to improve appearance and from decorative designs
 Veneers are used in the manufacture of Plywood, Lamin board and Batten board ect.

3. Plywood
 Veneers used for making plywood are called piles
 Plies are glued in odd numbers to form plywood. Gluing is done under pressure
 Direction of grain of adjacent plies is crossed to give more strength and to prevent shrinkage and wrapping of
plywood
 The two external plies are called face plies and can be of rich grained expensive timber
 Standers size of the plywood board is 2.4m x 1.2m
Advantageof Plywood
 Givesbetterappearance
 Strongera three plywoodboardisthree timesstrongerthana solidboardof same thickness
 Can be easilybent
 Shrinkage andexpansionisnegligible due tocrossgrainedstructure
 Givesuniformtensile strengthinall directions
 Available inlarge sizesthatare not possible withsolidboard
 Doesnot splitwhennailednearthe edge
Uses of Plywood
Plywoodisusedfor;
 Wall paneling
 Doors
 Furniture
 Form workinconcrete
Cheapervarietiesare usedinpackaging
Laminboard