Updated August 4th, 2017
Timber is one of the most important building material in construction world. This exceptionally versatile material is extensively used to build house, making furniture and home decoring. In this epic article I’ll describe the wood from construction professional’s point of view.
What is Timber?
Most of the time we call this wood. Sometimes it is also called Lumber. Whatever it is called, from general point of view we always call it wood. But there are some confusion around it. Let me clear that.
Lumber is a piece of wood which is smaller than 5″ wide by 5″ thick regardless of its length.
A piece of wood which is bigger than 5″ wide by 5″ thick regardless of its length is called timber.
Okay. Lumber and Timber confusion are now gone! But there is another thing, that is Beam.
What is Beam?
As we are engineer, we always have a mind problem that is to ask “Why and How”.
Why Wood is So Popular in Construction World?
Wood is very much popular in construction world. Because
* Wood is a natural resource.
* It is economical.
* It is strong relation to its weight.
* It provides insulation from cold.
* It can be shaped and sized as needed.
* It is environment friendly.
As we all know, whatever it is called timber or lumber or wood or beam, we get it from trees.
But wood from all trees can’t be used as construction material. Then wood from which trees are useable?
Classification of Trees
Depending on the mode of growth of trees it can be divided into two categories as below –
1. Endogenous trees, and
2. Exogenous trees
1. Endogenous trees: Bamboo, cane, palm are the example of this trees. This type of trees don’t have any major application in construction world except some centering purpose of horizontal structure or making door and window frame.
I’m going direct to the point by not wasting valuable time of engineers (you).
2. Exogenous trees: These are the trees we used mostly in our construction world. This type of trees can further be categorised into two sub-category.
Conifers and Deciduous.
This is not a tree classification class. So I won’t go to in-depth discussion about this. I just briefly describe about this for your easy understanding.
Most of the wood we get for our construction world from the last group of trees. That is Deciduous trees. Eamaple of this trees are oak, sal, teak, etc. Most of the woods we get from this trees are hard whereas wood from conifer trees are soft.
Here, one thing should be noted that we get some hardwood from conifers group and some softwood from Deciduous group.
Depending on these, wood can be Two types.
Types of Wood
* Softwood, and
Softwood: Softwood are commonly used for making furniture, doors and window frames. Some example of most popular softwoods include pine, hickory, ash, cedar, birch, beach.
Hardwood: Hardwood are commonly used in construction ofceilings, walls and floors. Commonly used hardwoods include maple, oak, mahogany, cherry, teak and walnut.
Other than these, there is also a type of wood that is Engineered wood.
Engineered wood: This is a fabricated wood in which various wood strands, veneers, fibers or other form of woods are gluedtogether to form a type of composite materials. This type of wood are commonly used in a residential, commercial and industrial projects.
Okay. Enough is enough. Enough said about the types of wood. Now let’s move forward……
By far, We cut down trees and got woods from that. Now lets dosome anatomy of structure of that wood.
Anatomy of Wood Structure
Tree structure can be classified into two categories from visibility aspect.
* Micro Structure
* Macro structure
Micro Structure: The micro structure of wood can only be visible under microscope. So we won’t talk much about this structure as we don’t have microscope. Let’s jump to macro structure.
Macro Structure: This type of wood structure can be visible to naked eye or at a small magnification. From the above image we got following terms.
- Heart wood
- Sap wood
- Cambium layer
- Inner bark
- Outer bark, and
- Medullary rays
Pith: It is the innermost portion of the tree. It is also called medulla.
Heart wood: The inner annual ring which is surrounding the pith is called heart wood.
Sap wood: sap wood the cutter annual ring between heart wood and cambium layer.
Cambium Layer: It is the layer between sap wood and inner bark
Inner Bark: The inner skin that is covering cambium layer is called Inner bark.
Outer bark: This is the outer skin of the tree.
Medullary Rays: The thin radial rays which are extending from pith to cambium layer are called Medullary Rays.
After all of these things like type of trees, type of woods and anatomy of wood, we should know how we can be benefitted from wood as a construction professional.
Benefits of Wood in Construction
Wood has several benefits that make it an extra ordinary building material to use in a variety of construction project. Some of them are given below –
- Thermal property – unlike steel, which can expand and collapse in high heat, wood dries out and become stronger as heat increases. In addition, Wood also has the heat conductivity which is relatively low in comparison to aluminum, steel, glass or marble. That is why it is widely used as wall covering celingand hardware equipments handle.
- Acoustic property: wood has the highly sought after acoustic properties. It can absorb sound and echo. That is why it became popular material for concert hall, where proper acoustics is important.
- Another important property of wood is, its resistance to electrical current, which makes it an important materials for electrical insulation.
- Tensile strength of wood is the main factor to choose it as a building material. Such as structural beam.
Hummmm. Take a breathe. So much benefit of wood here.
But to get the optimal benefit from the wood we should know about the defects of wood also. Let’s give a hand to it.
Defects in Wood
Defects in timber can happen due to natural reason and artificial reasons. I have summarize the reasons of defects in wood below –
- Due to Conversion
- Due to Fungi
- Due to Insects
- Due to Natural Forces
Due to Conversion: During converting wood to commercial form this type of defects occur. Below are the defects in wood due to conversion –
Due to Fungi: Following defects are found on wood due to fungi
Due to Insect: Due to insect following defects are found on wood –
Due to Natural Forces: For abnormal growth and rapture of tissues in timber this type of defects happen –
Upset or ruptures
So far we are familiar with the defects in wood. But it is not a good human behaviour to see only defects. We should also look for quality. Now we will see what is a good quality wood?
Characteristics of Good Quality Wood
A good quality wood should have the following characteristics –
Appearance: A freshly cut wood should have the shining appearance.
Color: A good quality wood’ color should be deep.
Defects: it is free from defects.
Durability: It should be durable enough.
Elasticity: A good quality should have the good elastic characteristic, that is it should be return to its original form after removing imposed load from it.
Fibers: A good quality wood should have straight fiber.
Fire resistance: Good quality wood should be dense enough to resistant fire.
Hardness: Good quality wood should be hard.
Abrasion: a good quality wood should not deteriorate easily due to abrasion.
Shape: A good quality wood should be capable to retain its shape during seasoning.
Smell: It should have pleasant smell.
Sound: When struck, a good quality wood should give a clear ringing sound.
Strength: It should have enough strength to carry the imposed load when used as beam or joist.
Structure: The structure of a good quality wood should beuniform.
Toughness: A good quality wood should be tough enough to resist shake due to vibration.
Water permeability: The quantity of water filtered through a unit surface area should be low.
Weathering effect: A good quality wood should be capable to withstand against weathering effect.
Weight: A good quality wood should be heavy.
Working condition: A good quality wood should be easily workable.
That’s it for now.
I tried to write this post as simple as possible to make you reading enjoyable. If you like this post please share your opinion in the comments below….