Timbers come in various forms, ages and sizes, colours and structural properties. Depending upon these parameters and a few others, timbers are graded and professional deck builders in Brisbane like any other place will take into account this gradation while suggesting timbers for decking at the behest of their customers. Thus, if you are looking forward to having a timber deck built at your Brisbane property, you need to know about this gradation.
In other words, grading is simply sorting of timbers and clubbing them in various categories depending upon their age and physical properties. This sorting of timber is done by following a specific process to give the process a somewhat uniformity. Many of the timbers are Australian standards while some others are industry-based standards.
Here is a quick look at the gradation.
The Methods that are used to grade the timber
Timbers are graded to predict the strength and the durability of the timbers and these gradations are either machine based or are visually based and each gradation is done under the set Australian standard. Let us know what is visual grading and machine grading that is needed for building timber decks in Brisbane or elsewhere.
Visual Grading: This is basically a stress grade, which is determined by the inherent strength or the strength group of the timber species along with its visual qualities and structural properties. Some other characters like the knots and the sloping grains are also taken into account. Knots and sloping grains generally reduce the strength and hence are considered detrimental.
Machine Grading: This is a method in which the stress grades are determined mechanically. In this method, a technique that correlates strength with stiffness is used.
These Stress Grades are generally allocated to the timbers using strength groups classification along with the grade quality descriptions from the relevant Australian Standards pertinent to the structural timbers.
What are stress grades?
Stress grades for a particular species of timber of a species group can be allocated using several methods. They are namely,
Determination by full size and in-grade strength and stiffness evaluation, evaluation of the associated parts with the use of several methods.
Confirmation of the traditional ‘F’ grades, based on the strength group or the visual grade relationship, with the use of full-size in-grade testing.
Allocation of traditional ‘F’ grades based solely on strength group or visual grade relationship, which is determined from the small and clear property testing.
Traditional Stress Grades adjusted or confirmed by the in-grade testing
There are certain species or species groups, which are stress graded traditionally. They include the northeastern hardwoods that include spotted gums and blackbutt, Australian-grown Pinus, which include maritime, slash, Caribbean, Radiana and the likes.
Branding and Marking of Graded Timber
Stress Grades that are applicable to the mechanically graded timber are recorded by colour coding or branding following the set Australian Standards.
The F grades on the other hand, are applicable to the seasoned structural timbers, and are applied only and only when the average moisture content does not go beyond 15%. Timbers that are seasoned to not in excess of 20% have to be allocated in F grade.
One of the most noted advantages of hiring premium deck builders in Brisbane is they know everything about this gradation, and hence will be able to help you with the right kind of timber.
In Brisbane, the best name to turn to is BB Decking as we have highly experienced decking specialists with in depth knowledge about timber grading. Call us now to have a detailed discussion and get a free quote from our end.