Posted By Ken Taylor I think the problem with this one is that, whereas new build has to follow Approved Document N to the Building Regulations, existing glazing is a matter for assessment under the Workplace (Health, Safety and Welfare) Regs - which require safety material or protection against breakage 'where necessary for reasons of health and safety'. This is inevitably a matter of judgement by the employer, local EHOs and ultimately the Courts. I suspect that much shop-front glass meets the standards when thickness is compared with area but, where not, my own inclination is to 'err on the side of caution' where reasonably practicable.