Timber the Material

The Materials teaching resource package is an introduction to timber. This resource covers a variety of topics and is suitable for inclusion in Civil Engineering, Architecture and Building courses at university level, and a large number of courses in the Building and construction streams at Trade Training level. In this section are downloadable PowerPoint files that can be edited and used in your lectures. Each file covers just one topic, so that you can choose the topics that are most relevant to your unit.

This section covers 3 main areas:

Properties

Performance is simply satisfying expectations, and there are many expectations of timber elements in buildings.  An understanding of the properties and behaviour of timber will mean that all who use timber will be able to make decisions that will mean the timber used is able to deliver the required performance. This section of the course starts by looking at the way trees lay down the wood that becomes timber as it is milled.  This is important, as the growth of the wood fibres gives them unique characteristics that underpin their behaviour.  The remainder of the section explores the properties of timber.  An understanding of the basic properties is needed by all who work with timber.  This is especially true of the moisture effects on timber.

 

Introduction to Timber and Timber Products

This module provides a general introduction to timber and covers the main types of timber products:  round logs, sawn logs, engineered wood products.  It also discusses the environmental credentials of timber products.  There are two accompanying videos that can be downloaded and run through the powerpoint presentation, providing you save all the files into the one folder.

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Growth

This module examines timber as an integral part of a tree. It looks at how the tree lays down the cells that become timber in the standing trunk and how a trunk gets bigger. The oldest part of the tree is right at the centre at the base of the trunk. The module also looks at the cell structure of timber and the origin of growth rings.

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Environmental Benefits of Growing and Harvesting Timber

A simple overview of some of the environmental benefits growing and harvesting timber provides.
Presentation to come.

 

Processing

This module examines the processes in sawing timber to give the shapes required. It examines the strategies of cutting timber from round trunks and gives a number of different cutting patterns for producing sawn timber. It also follows the other saw mill processes in limited detail. More information is given on seasoning in the next module, and more on grading can be found in the section on grading.

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Seasoning

This module focuses on the very important task of removing moisture from the wood structure so that the timber is close to the moisture content in equilibrium with the air in indoor applications. A number of different methods are explored.

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Characteristics

This module looks at the characteristics of timber that come from its growth as part of a tree. Knots, sap, and growth rings are all part of the natural character of each individual piece of timber. There are many others as well. They contribute to the appearance of timber products and also affect the way it behaves under load.

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Moisture and shrinkage

This module is very important for all students. It outlines the way timber reacts with different moisture environments. In a tree, the timber is saturated with moisture, and in service, it can have less than 10% of its original moisture left. As well timber absorbs moisture from the air under humid conditions and gives it back again under dry atmospheric conditions. The module also gives details on the way timber shrinks or swells in response to moisture movement

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Unique Properties

This module looks at the unique properties of timber that come from its micro-structure. It really helps students develop an intuitive understanding of the way timber responds to everything from – loads, shrinkage, even the application of paint. A bundle of drinking straws will help with demonstrations for this material.

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Utility

This module gives information on many practical aspects of timber. In order for it to be easy to use in construction, timber must be straight and have appropriate dimensions. There are production limits on tolerances for timber dimensions and out-of-straightness. It is useful for students to understand the terms used to describe straightness of timber and understand the implications of each utility requirement.

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Specification of Timber

Everyone in the building industry needs to know how to specify timber correctly. Specification is the essential link between what the designer envisaged and the timber that is supplied to site to do the job.  This is quite a small section, though it contains some valuable information:
The module contains the detail on how to specify timber or call it up on an order list. It gives the information needed and some hints as to how to make the decisions required to select the material that will best fit the design brief.

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Transport and Delivery of Timber

This module covers the vital issue of ensuring that the performance of the material is not compromised by problems during transport, unloading or in storage on site. Specification of these issues can be almost as important in achieving good results as the specification of the timber itself.

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Grading

Grading is the process of sorting a production of timber into groups that have similar attributes. It is applied to all timber products, appearance products, structural sawn timber and even manufactured timber products such as plywood and glulam.
This section helps students understand how timber is graded so that they can select types of products and grades that will deliver appropriate performance in service.
The modules include:

Appearance Grading

This module examines all of the issues and processes in determining the grade of timber to be used in an appearance role. It covers the methods of classification of the appearance grades, and indicates the extra information that may be required in some cases to achieve the desired effects.

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Structural Grading

Structural grading is the process of sorting timber on the basis of expected structural properties such as strength or stiffness. This module simply explains stress grades, the Australian systems for allocating properties to groups of timber. It then is supported by the remaining three modules in this section. Visual stress grading, machine stress grading and quality control.

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Further information on structural grading

Visual Stress Grading

Visual grading is a structural grading process. It is quite different to appearance grading, but uses trained operators to discern between pieces that are likely to have high strength and stiffness and those that are likely to be weaker on the basis of the features that can be seen in the piece. This module explains the processes.

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Further information on visual stress grading

Machine Stress Grading

Structural machine stress grading is another structural grading process, but this one uses a machine to measure some structural properties along the length of the piece. Other properties are inferred from the measured ones. This module focuses on the method used for the stress-grading of the majority of sawn structural timber in Australia.

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Further information on machine stress grading

Machine Proof Grading

Machine proof grading is not as widely used as visual and machine stress-grading methods but is used in limited applications for grading of some Australian hardwoods and cypress pine and radiata pine underpurlins. It may also find application in the grading of treated timber.

Further information  on machine proof grading

Grading and Quality Control

This module refers to a number of processes for ensuring that graded timber products have the properties claimed by the grade classification. There are different levels of quality assurance; some aimed at providing feedback to production for day-to-day control of the production processes, and others that give customers the assurance that the products have the claimed properties.

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Durability

An important aspect of any material study is its durability; its ability to continue to deliver a performance over a long period of time. Timber has been a building material for thousands of years, and in Europe, there are timber buildings that are 100 years old or more. This whole section explores durability of timber in a systematic way; by looking at hazards for timber, examining natural durability of timber in resisting those hazards, then seeing what preservatives can be used to enhance durability of timber, and finally examining some good detailing practice that will give timber the best chance of resisting its in-service hazards..
The durability section has seven modules:

Further information on durability can be found on the WoodSolutions website.

The Timber Service Life Design Guide provides information to assist timber industry employees, timber users and specifiers of timber to select members and structures with respect to their service life requirements.

The information provided has been derived from historical performance and field and laboratory research and experience.

Making Timber Durable

This module provides and overview to timber durability covering hot the natural environment affects timber and choosing timbers to suit environments.  It also introduces naturally durable timers, treated timbers and the concept of design for protection of timber.

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Durability Hazards

The durability hazards module examines the agents that may compromise durability of timber. It looks at all timber; appearance products and structural products. The module introduces the H-classification that can be used to describe the severity of the hazards that timber is likely to experience in service. The module uses pictures to illustrate not only the hazards themselves, but also the environments that are likely to characterise the hazards.

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Natural Durability

The natural durability module looks at timber species in terms of their resistance to degradation under attack from the hazards described in the previous module. It details the way in which the natural durability of a species is measured and what the implications are of each natural durability class.

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Durability Treatments

The Treatments module summarises some of the more common treatments, their limitations and their success in improving the durability of timber. It is a handy introduction to the field of timber treatments, but it is a rapidly changing field, and it is recommended you check this information with other sources.

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Further information:

Treated Roundwood

Treated Plywood

Design for Durability Protection

This module looks at many inexpensive, common sense approaches to detailing that can significantly improve the response of timber to hazards. It contains diagrams and tips for designers that will enable exposed timber to fare better. Again it is not exhaustive, but it does present the principles that can be applied to many design situations

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Design for durability tutorial

Timber durability and exterior wood finishes – Video

Fire Resistance

The fire resistance module looks at the way timber can be configured so that it fares as well as possible in a fire. Large section and protected timber elements have survived hot building fires and continue to serve their structural function (although charred) in the building. A number of methods of enhancing performance in fires are examined.

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Further information on fire performance of timber

Termite Management

The termite management module outlines how the managed approach is best identifying what is at risk of attack and the priorities of a termite management system.  The module also discusses common barrier systems and ongoing inspections.

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