What is Wood

What is Wood or Timber?

Understanding basic information about timber and wood for interior design and decorating. We find out what is wood and timber?

What is Timber and Wood?

Which word to use? Timber or wood? I was taught that the easy way to remember was that you put wood on the fire to burn and keep you warm and you use timber to build things from.  But I know that some people use the word wood for wooden blinds, wooden floors, wooden furniture. So perhaps my definition is incorrect. Here we will explain what wood and timber are.

There are over 6000 common names for various timbers worldwide and approximately 2000 in everyday use. These are made up of 60 species of Pine, 20 species of Oak, and 40-50 species of Mahogany. We class timber as:
Indigenous – meaning native to a country.
Exotic – native to a country but grown in another and imported, a timber which is imported into a country in board form.


Timber comes from trees. There are three main parts to a tree:

The Crown

The crown holds the leaves.

The Trunk

The trunk supports the crown and the roots, which support the trunk and the crown. Carbon dioxide passes from the air into the leaves and with the aid of sunlight and chlorophyll in the leaves combines with compounds in the leaf cells to build up food substances. These are sugar and starch.

The Roots

The roots absorb water and mineral salts from the soil.

The Characteristics of Softwoods and Hardwoods

These trees are non-porous; they are usually evergreen conifers. They have needle like leaves and uncovered seeds.


These trees are porous, and usually deciduous. They have broad leaves and covered seeds.

Parts of a Tree


The centre of tree growth. The pith is prominent in Pines but hardly visible in other varieties.


This is the fully developed mature section in the centre of the tree. Due to the gum or resin contained in the wood cells it is usually darker in colour than sapwood. Its main function is to support the tree as it is inactive (ceased growing).


This is newly formed wood that surrounds the heartwood. It is lighter in colour and softer than the heartwood. Water and dissolved minerals are conducted to the leaves through the cells of the sapwood. The sapwood gradually matures and hardens into heartwood as the tree grows. Sapwood is less resilient to decay and insect attack.

Cambium Layer

Surrounding the sapwood is a layer of cells, just under the inner bark. This is where the growth of the tree takes place through the division of cells. The cambium layer creates new sapwood on the inside of the previous years growth and new inner bark on the outside.

Bark (or Cortex) – Outer Bark

This is the rough corky layer on the outside of the tree. It acts as a layer of protection against the cold, extreme heat or insect attack.

Inner Bark (Phloem or Bast)

On the inside of the outer bark is a thin green layer that carries the plant food or sap from the leaves to the cambrian layer throughout the tree. This is the inner bark.

Annual Growth Rings

These represent one season’s growth in a tree from spring to autumn; they are made up of cells. These are clearly divided into two layers.

Spring (or early) Wood

This is formed during spring or early summer when the tree growth is rapid, the timber is lighter in colour and softer than summer (late) wood.

Summer (or late) Wood

This is formed in summer to early autumn when the tree growth is slower; the timber is usually darker and harder than spring (or early) wood.

Medullary Rays

These are thin plate like layers of special cells reaching from the pith to the Cambrian layer. They transport food horizontally in the tree from the bark to the pith. They also store food and are very predominantly visible in some trees for example oak and barely visible in other trees for example Pinus.

More Articles Interior Finishes – Timber or Wood next page is Properties of Wood

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