Yes, the initial costs of factory graded battens do cost more than standard sawn battens. The grade of timber required to meet BS5534 is high. The defect allowance, especially for 25×38, is small. This results in either higher grade timber being used or a large quantity of non compliant material being produced from lower grade material.
This is off set though by:
- Lower waste. The quantity of waste does vary significantly according to the initial quality of the batten. In ALL cases there will be waste when using battens. Even with BS5534 graded battens there is the need to trim back to the nearest rafter and to ensure joints are staggered as specified in BS8000;Pt6. It has been suggested that this process of trimming back to the next rafter acts as a grading mechanism in cutting out the defects. This is only the case if the defect is in the last section of batten. Defects can be randomly distributed and it is just as possible to end up with 100% waste if there are, say, 2 defects about 1.2m in from each end. This would result in batten that was too short to use!
- Reduced time in grading and marking; correct timber visual grading is time consuming and writing or marking every batten “BS5534” would be slow.
- Quicker to fix.
- Importantly it is also a safer product.