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Types of Wood
Basically, there are two types of wood, namely;
- Hardwood and,
- Softwood
Hardwoods:
Hardwoods are produced by broad leaved trees whose seeds are enclosed in fruit. They have a variety of grains and a multitude of colors.
Types of Hardwood
- Evergreen hardwoods: are trees that keep their leaves all year round. they are found in tropical or sub-tropical countries.
Examples include: mahogany, teak, African walnut, ebony and balsa.
- Deciduous hardwoods: are trees that lose their leaves in winter. They generally grow in temperate climates. examples include: oak, ash, elm, beech, birch, walnut, sycamore, chestnut, lime, maple and popla
- Softwoods: softwoods are produced by the cone bearing trees (conifers). They have needle-like leaves. They generally grow much quicker than hardwoods and are cheaper, softer and easier to work with. their seeds are held in cones. e.g. pine, fir, spruce, larch, cedar and the giant redwood, balsam, tamarack.
Comparison between soft wood and hard wood
|
Soft wood |
Hard wood |
|
Annual rings are distinct, |
Annual rings are not distinct |
|
medullar rays are not distinct |
medullar rays are distinct |
|
Resinous structure |
Close grained structure |
|
Light in colour |
Dark in colour |
|
Light in weight |
Heavy |
|
Strong in resisting direct tension but weak in resisting compression or shear |
Equally strong in resisting tension, compression and shear |
Properties of Good Timber
A good timber has the following properties:
- It is free from serious defects like knots, shakesand
- It has uniform
- Its texture is fine and
- It has close
- It has pleasant odor when freshly cut.
- It has higher
- It is hard.
- It has higher strength.
- It has higher modulus of
- Its fire resistance is high.
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