Importance Of Structural Grading

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TASK 5 GRADED TIMBER Structural grading of timber is the process by which it is assigned into different stress grades (groups), the timbers within each group should have similar properties. However due to the nature of timber there is inevitably a substantial range of properties within each grade and also an overlap in properties between grades, graded timber is stamped in accordance with The Timber Research and Development Association (TRADA) guidelines. Structural grading can be performed in numerous ways including the following; Visual Stress-grading This is the traditional method of determining stress grades, during this process a grader who is highly trained examines each piece of timber produced in accordance with the European Standard EN 14018. Once visually inspected each piece of timber is assigned to one of the following groups; • Special structural (SS) – this has 50 – 60 per cent strength of ‘Perfect timber’; • General structural (GS) – this has 30 – 50 per cent strength of ‘Perfect timber’; • Reject – not suitable for structural use. Machine stress-grading This process uses a machine to bend the timber, the machine measures the stiffness and uses a correlation between stiffness and strength to assign a stress grade. USING TIMBER FOR STRUCTURAL PURPOSES …show more content…

Factors such as building size, location (is it subject to adverse weather conditions or in a hot climate) and use would all inform the decision making process and have a bearing on the outcome of the final materials chosen. For example in an area with more woodland you may choose to use timber to blend in better with the environment whereas in a built up urban area you may choose to use a combination of concrete and steel for speed and ease of build and also the lower maintenance

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