A discussion paper by Chris Polaczuk, CHASNZ and Brett Francis, Window & Glass Association NZ
In 2014 a research project was carried out with 61 experienced Residential Builders in New Zealand who were asked for practical ways that musculoskeletal disorders (MSDs aka strains and sprains) could be prevented in their industry. One of the most popular recommendations (made by 26 of the 61 Builders) was to install windows unglazed. The researchers at the time rated this intervention as having a high potential to reduce MSDs risk.
This straightforward measure presents an obvious means of reducing the amount of weight handled by both the builder and manufacturer. The thresholds above which windows would be delivered unglazed do not seem clear, making it difficult to know or control the conditions in which windows arrive at a building site. To save costs, builders reported installing windows glazed unless they were exceptionally heavy. Cost seemed to be the main barrier to windows being delivered unglazed.
Even when unglazed, builders commented that they could still be awkward and difficult to handle, which was often made harder by the presence of scaffolding. Builders referred to a trend of larger and therefore heavier windows where their increased weight precluded them from being installed when glazed, and Glaziers and Framers were reported to be increasingly aware of the handling difficulties encountered.
Over time the size (and weight) of windows and doors has continued to increase. This is expected to increase as window design accommodates increasing thermal requirements (eg addition of thermal breaks, triple glazing).
Although it is well known that lifting can be a hazard for workers, there is no 'magic number' in health and safety regulations worldwide describing a safe weight for lifting. The maximum acceptable amount of weight a worker can handle depends on the worker's build and fitness, the height lifted from and to, the distance from the body, the frequency of lifting and many other factors.
The NZ Manual Handling Code of Practice 2001 states that: It is unhelpful to prescribe specific weight limits (because of the complexity of the way the different risk factors combine), but the risk of harm increases with increasing weight or force.
The Health and Safety at Work Act (2015) specify The manufacture must, so far as is reasonably practicable, ensure that the plant, substance, or structure is manufactured to be without risks to the health and safety of persons. Good design includes supplying comprehensive information to the appropriate parties or users. Information should identify the manual handling hazards that remain in the plant, and how to use, maintain, operate, clean, transport and dispose of the plant without the risk of harm from manual handling.
In summary, the question of how heavy a window should be delivered glazed or unglazed to a building site is a grey area and the risk is that windows will mainly end up being delivered glazed which will contribute to the injury toll in builders. Manufacturers will face the same quandary and this could pose risk to their workforce especially if they are to realise their aim of increasing diversity in the workplace. A weight limit may at least provide direction for these industries giving them some sense of certainty that they have so far, as is reasonably taken all steps to reduce the risk for both parties.
Builders have the highest rates of back injury in construction and the reduction in weight of windows being installed could offer a small but significant step in reducing this risk.
Questions for discussion and feedback:
Chris and Brett invite you to feedback on these questions by the 30th August 2021. We also welcome assistance and ongoing input into this project so let us know if you are interested. You can submit your feedback online at:
email your feedback to email@example.com
write to CHASNZ, Delivering and Installing windows as an injury prevention initiative feedback, PO Box 106 302, Customs Street, Auckland 1143.