Board to death - health and safety for timber scaffolding boards
An important use of timber is in scaffolding boards for construction workers. Jim Coulson, Director of Technology For Timber Ltd, in Ripon, UK, highlights the grading problems compromising health and safety.
The trouble with scaffold boards is that they can break unexpectedly and people get hurt, sometimes killed, as a consequence. One solution would be to specify them correctly, to the British Standard, BS2482: 2009.
Unfortunately, most of the scaffolding industry in the UK – and the timber trade who sell boards – just uses planks of wood, cut to approximately the right size, with a metal band on each end. These are known, misleadingly and dangerously, as ‘Grade A’ boards, although they are neither ‘A’ quality (implying the best available), nor have they been genuinely graded by anybody. So why does the scaffolding industry use them? It is down to price – they are cheaper than ‘full British Standard (BS)’ boards.
Technology for Timber Ltd, in Ripon, UK, might get five or six broken boards delivered for examination and an opinion on the cause of failure. But in the first four months of 2010, the company received 10 such boards, from sites all over the UK. This prompted the question of why do they fail?
All except one of the broken boards was Grade A, and the nature of the breakages concerning one or more major defects in the board – often found at a critical point, such as in the middle of the span, which had not been discovered because the boards had never been looked at in the first place. The one BS board that the firm examined had broken because of the combination of a permissible defect, although it was one at the extreme upper end of the grading limit, coupled with severe decay in the same area, which had developed in the board due to poor storage.
The cause of so many failures in a short space of time may be market conditions. The construction industry is beginning to come out of the downturn, and the scaffolding industry is leading the way in this – conversely, it felt the downturn coming before the rest of the sector. There is a huge surge in demand for new boards in the UK and simultaneously, most of the old boards – taken from a stockpile that has been at the bottom of a heap for over a year – are quickly being put into service again. Hence the mixed bag of breakages that have been seen in the early part of 2010, with some new boards containing excessive defects, and also some old boards suffering from rot.
All shapes and sizes
Grade A boards are cut to approximately the right size for scaffold boards. The correct size for BS2482 boards is 225mm wide, by either 38mm or 63mm thick. There are tolerances on these dimensions of ± five millimetres on the width, ± two millimetres on 38mm thickness and ± three millimetres on 63mm thickness. But, in keeping the price as low as possible, Grade A boards are always sawn to the minus tolerances.
Even this is not the whole picture. The boards are sawn to these minimum dimensions as ‘green’ lumber in the sawmill, at moisture contents well in excess of fibre saturation point. They then shrink afterwards, so that boards may finish at around 220mm x 34mm, or 219mm by 59mm, which is both under tolerance and under-size from a load-bearing point of view.
Frequently it is assumed that ‘it must be a scaffold board, because it’s got bands on the ends’. It is strange that in such a health and safety-dominated industry as construction, where scaffolders can often require a ‘tag’ to be allowed into scaffolded zones that are ‘safe’, and a supervisor checks the proper erection of the poles and the tightness of the brackets and clamps, that nobody will look at the adequacy of the timber, when it is the wood that the workers have to stand on.
Unless the number of the Standard – BS 2482:2009 – is stamped on each band, then the board is not a BS board. It does not need to have a Kitemark, or some other third-party assurance mark on it, although that would be desirable. But, unless it claims compliance with the British Standard and it has been graded by a competent person or a correctly-calibrated machine, then it should not be put onto a scaffolding.
Why not ban Grade A boards altogether? This is a heretical view, because both the timber trade and the construction industry seem to hate paying a fair price for wood. The only reason that Grade A boards still occupy the majority of the market is because they are much cheaper than BS boards.
Yet if, as has been the situation with structural timbers for over 20 years, it could be made compulsory to have every piece of wood graded and marked before it could be used, then there would be no place for Grade A boards, or for the cheaper end of the market that supplies them. Then the scaffolding Iindustry would all be on a level playing field, and those who are trying to use better quality boards will no longer be penalised on price when tendering for work.