Timber

Associated Learning Outcome:

At the end of this module, learners will be able to:

• Describe the pros and cons of using Timber as the main structural material in new building design
• Identify the pros and cons of timber as a construction material

Introduction to Timber

Timber, also commonly known as wood or lumber, has been an ideal material to utilize in construction for thousands of years. In recent years, timber has regained popularity as we discover new ways of manufacturing and processing lumber to upgrade desired properties. Lumber offers many advantages including its natural aesthetic appeal, versatility, sustainability [11], and relatively low carbon footprint especially when it is sourced locally. Generally, in its natural state, timber is classified as either softwood or hardwood. Softwood, such as pine, spruce, and fir are commonly used due to their abundance, fast growth, and affordability. Hardwoods, like Oak, mahogany, and teak are more durable and more often sued in higher-quality finishes, furniture, or other specialty applications.

In regards to its structural use, timber is used in framing, roof trusses, beams, columns, and joists. Recently, engineered wood products (EWP) such as glulam (glue laminated timber) and LVL (laminated veneer lumber) have become more abundantly used because they offer enhanced strength and dimensional stability, which allow for larger spans and more structural versatility. It was previously thought that a timber-framed building could not exceed 10 stories in height; however, with modern EWP, these limits are being pushed further (and higher) as innovation continues.

Other common applications for timber include cladding and facades, interior finishing, fire safety, and modular construction. This course however will focus on timber as the structural skeleton for buildings.

Time to test your understanding!

Advantages of Using Timber [10]

1. Sustainability: Timber is a renewable resource, and its use in construction promotes sustainable practices. It can be harvested from responsibly managed forests and helps reduce reliance on non-renewable materials.
2. Low carbon footprint: Timber has a lower carbon footprint compared to materials like steel and concrete. Trees absorb carbon dioxide during their growth, acting as a carbon sink, which helps mitigate climate change.
3. Design flexibility: Timber offers great design versatility. It can be easily shaped, cut, and joined, allowing for complex and innovative architectural designs. Timber structures can be customized to fit specific project requirements.
4. Construction speed: Timber construction can be faster than traditional construction methods. Off-site prefabrication is possible, where components are manufactured in controlled environments, reducing construction time on-site.
5. Energy efficiency: Timber has excellent thermal insulation properties, which can contribute to energy-efficient buildings. It helps retain heat during the winter and keeps the interior cool during the summer, reducing heating and cooling demands.
6. Aesthetics: Timber structures can provide a warm and natural aesthetic appeal, creating a cozy and inviting atmosphere. The use of exposed timber beams or columns can add visual interest and architectural character to a building.

Disadvantages of Using Timber [10]

1. Fire susceptibility: One of the main concerns with timber is its combustibility. Wood is flammable, and timber structures require appropriate fire protection measures to meet safety codes and regulations. Fire-resistant treatments and sprinkler systems may be necessary.
2. Durability and maintenance: Timber is susceptible to rot, decay, insect infestations, and moisture-related issues. Proper maintenance, regular inspections, and protective finishes are required to ensure its longevity and prevent deterioration.
3. Limited span lengths: Compared to materials like steel and concrete, timber has relatively limited span lengths. Large open spaces may require additional support columns or beams, which can impact the design and layout of a building.
4. Shrinkage and expansion: Timber can experience dimensional changes due to moisture variations. It may shrink or expand, potentially causing structural issues, such as warping or cracking. Proper design and detailing are necessary to accommodate these movements.
5. Material sourcing and availability: The availability of suitable timber resources can vary by region. Certain types of high-quality timber may be limited or more expensive in some areas, affecting the cost and feasibility of timber construction.
6. Perceptions and misconceptions: Some people have concerns about the structural integrity of the timber and its susceptibility to damage. Overcoming these perceptions and addressing misconceptions about timber construction can be a challenge in certain markets.

Suitability of Timber for Particular Applications

Determining whether timber is suitable for particular buildings depends on a few factors. Some of these are structural requirements, environmental implications and objectives, aesthetics, cost, and availability. Evaluating the structural capabilities is very important when considering timber and consultation with an engineer should be done to analyze building height and load paths that could affect material choice. The environmental implication could consist of conditions the structure will be exposed to during its regular life, temperature fluctuations, and the potential for decay or insect infestation. Additionally, it is common nowadays for building codes to have a quantitative carbon footprint limit or goal that needs to be met. Environmental regulations like these need to be taken into account before deciding on a material. People like the way wood looks, and this is where aesthetics come into play. If the architect has a certain image or design in mind, timber could be the key to achieving the desired look. Cost is a big one and depending on where the budling is being made and what resources are available, timber could be the cheaper alternative to concrete or steel. Like concrete and steel, timber is in fact a finite material and its availability hinges on manufacturing lines, shipping routes and ports, and trucking. If any of these aspects of the production and deliverance of the material are put on hold, then availability can pose a threat.

The video below is something I find fascinating. Timber has often been overlooked due to its strength, durability, or flammability. Society is pushing more and more towards timber construction and the video below explains how it could even be used in high-rise buildings in the near future! Watch the video below to learn more about the capabilities of timber.

Module Quiz