As Timber Systems Estimators and Designers, we rely on the engineering software to do it all for us, but there are a number of times that we really don’t need to fire up the computer and information knowledge should be at our finger tips.

Also, what governs the design of a beam or lintel from the software?

With the use of software when the design certificate is produced, we can see that it lists all the relevant Australian Standards used to produce the design. Hence the reason for using such software as it can become very complex, and it also takes out part of the human factor.

As designers we should be aware of the different standards that are used in our industry, but there are a couple that should be on our shelf in the office and be conversant with as they are handy documents to assist with and justify designs that we produce on a daily basis.

Let’s take AS1684.2 and (AS1684.3 for those that experience the cyclones), predominately AS1684.2 is used to cover what we need to design for residential timber-framed construction. This comprehensive document provides you information on but not limited to: terminology and definitions, how to determine the size and grade of components used in the: substructure, floor framing, wall framing and roof framing (stick built) complete with bracings, fixings and tie down. The 270 odd pages provide you with a wealth of knowledge that includes building practices for engineered wood products, durability etc. it is then complimented with it’s comprehensive span tables for a huge range of timber species and grades.

AS4440-2004 installation of nailplated timber roof trusses.

WOW has this got me out of the hot seat a few times, as designers and suppliers of timber roof trusses we can only but provide an engineered product BUT! For it to perform as per its design, it must be installed in accordance with AS4440-2004 or it will surely cause some issues. This document must be read and understood by all timber roof truss designers, it’s not as bad as reading the phone directory but it will be of a lot more use. It contains bracing, connection details, tolerances, storage and handling and a recommended practice for truss installation.

These two Australian Standards should be on the shelf within reach in every frame and truss plant, providing all timber systems estimators and timber systems designers the tools to perform their role accurately and confidently.

As people that are a part of this timber systems industry, we need to be aware that there are many Australian Standards that have a part or an effect of what we do on a daily basis.

There are Australian Standards for most components that are supported by or, connected to what we supply. Hence, they rely on what we do to make their part work.

Whilst we don’t need to know the standards, we need to be aware that there probably is a standard for it.

I strongly suggest that if it outside AS1684 or AS4440-2004 that you contact your software supplier engineer, and they will point you in the right direction.

Quick Mention

AS1720.5-2015 Timber Structures Part 5: Nailplated timber roof trusses. This relatively new Australian Standard is more for the engineers and not so much for the fabricator.

Guide to standards and tolerances is a free download, and can be handy for many things including squeaking floor, springy floors etc.

The National Construction Code (NCC) Volume 1 & 2 these are also a free download and a great resource.

We can’t remember every thing in life, but we need to remember where to look if we need to.



This edition of Biz Buzz was written by Phil Ladson of Ladson Consulting.