What Are the Structural Properties Of Timber?


No one can deny that timber creates a sense of warmth and brings a sophisticated, contemporary touch to any building. Therefore, it comes as no surprise that there’s such a high demand for timber in the construction industry as a building material.

From engineered oak flooring to building walls, it can be utilized in multiple ways when it comes to constructing houses or any other property.

Due to its appearance, durability, and several other beneficial properties and features, a lot of people like to integrate timber into their homes. However, in order to do so, it is important to determine the quality of timber and ensure it is fit for the intended purpose. The quality can be ensured by checking its various structural properties.

Let’s take a look at some of the most important physical and mechanical structural properties of timber.

Types of Timber

Timber is generally categorized into two types – softwood and hardwood. It is important to understand that the type of wood doesn’t indicate the strength of the sturdiness of wood. Instead, it merely refers to the type of tree that the timber came from.

Hardwood timber comes from deciduous trees that lose leaves during fall and winter. Softwood, on the other hand, is procured from conifers that are evergreen plants. Hardwood generally grows slower as compared to softwood. This is why it is often more dense than softwood.


The color of the timber is the first giveaway of its quality. Generally, light color indicates that the timber is weak. However, that’s not always the case. Trees are often characterized by their color and freshly-cut trees can also be identified by checking out the color of the timber.


The hardness of timber indicates its damage resistance. The hardness of wood is measured by the amount of force or pressure that is required to embed a .444 inch ball of steel to at least half of the total diameter of the wood.

The greater the hardness, the more resistant the timber will be to damage and wear and tear. The Janka scale is used to measure the hardness of timber. The hardest timber comes from Brazilian Walnut which boasts the Janka reading of 3684.

Moisture Content

Wood is hygroscopic in nature which means it absorbs moisture from its surroundings. Absorption or dehydration depends on the humidity in the air. This is why wood often expand when it comes in contact with water or placed in a humid atmosphere. For the same reason, it can contract when the temperature in its surroundings rises up.

The lower the moisture content, the better will be the quality of timber.

Specific Gravity

The specific gravity of timber measures its quality to float. It is measured by measuring the weight of the wood at a certain level of moisture content. So specific gravity indicates the density of timber based on the moisture content. It is important in the construction industry because moisture affects the weight of the wood and its dimensions as cells expand or contract based on its moisture content.


Do you know that timber possesses the property to regain its shape after use? This is called elasticity. It allows the wood to bear and dissipate shock loads. Elasticity plays an important role in determining the strength of the timber. The strength of the wood can be identified as the amount of load that timber can withstand before it reaches its elastic range and breaks.


The strength of wood is perhaps the most important property when it comes to determining its use in construction. The best quality timber has more strength. But what is strength exactly? It is the property of timber to bear load. Since the structure of the wood changes over time, its strength can also change. Therefore, the timber strength is measured on different scales. Some types of strengths include transverse strength (bending strength), compressive strength, and tensile strength.


The workability of timber indicates the ease of transforming it into required shape or items. When the workability of timber is high, it is easy to drag saw through it. Workability is important to convert raw wood into refined timber without degradation or tear out.

Type of Grain

Woodgrain refers to the appearance of patterns, alignment or texture on the timber. Identifying the type of grain is important as every piece grows with a clear and certain grain direction which may appear differently depending on the cutting of the wood. There are four basic types of wood grain.

  • Straight grain: if the grain runs in a single direction across the entire piece of wood, the timber is said to have straight-grain.
  • Cross grain: If you notice that the growth lines in the wood are not parallel as compared to the edge of the piece of timber board, then you have cross grain timber on your hands.
  • Spiral grain: Spiral grain directly affects the commercial value of the wood. Sometimes, the trunk of the tree bends during its development or as it grows. When timber is procured from such trees, it has a distinct grain which is known as the spiral grain.

Keep in mind that the hardwood boards need extra attention during machining. This is because if the wood is machined in the wrong direction, it can lead to lifted grain lines that may separate.

Now that you know all about the different structural properties of wood, make sure you get and use only the best quality timber for the construction of your property. Remember, it is a lifelong investment so it is always better to know all about the type of wood you may be getting!

About Author:-

Simon is an entrepreneur and self-proclaimed jack of all trades. Simon has experience in the building and home renovation industry and he knows what it takes to knock out a successful project whether it be commercial or residential. Currently, he works as a marketing consultant with ASH – a prominent supplier of high quality Australian hardwood. Another niche for Simon is to travel and outdoors leisure, including sporting equipment and bikes. A big kid at heart if it goes fast, bounces, slides or you can climb it Simon has put it to the test.


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