How to tackle a clear problem
Phil Brown, European regulatory marketing manager at Pilkington UK, discusses the requirements for glass manifestation, and how they’re needed to help prevent injuries.
Many of us remember watching those old black-and-white slapstick comedies and chuckling at the two hapless heroes carrying a large pane of glass, knowing that an unsuspecting passer-by was about to walk into it. And, dare I say, many of us have probably been the unfortunate person that walks into a glass wall, door or partition, much to the amusement of those in our company.
While it can initially seem like a funny incident, accidentally walking into glass can result in people getting injured or damage to the glazed area.
Glass is a unique construction material, not least due to its high transparency, but it can pose a danger to people coming into contact with it. So, to reduce risk, designs or patterns known as ‘manifestation’ are applied onto vertically glazed areas to make its presence more apparent.
It’s questionable whether the regulatory requirements for manifestations are widely understood in the glass and glazing sector. They are arguably less well known than regulations for marking of safety glass, for example, which helps with identification and traceability when safety glass is installed in critical locations like doors, door side panels and at low level. So, what do you need to know about manifestation?
In Part 4 of BS 6262, the British Standard Code of Practice for safety related to human impact, manifestation is defined as a technique for enhancing a person’s awareness of the presence of transparent glazed areas. This part of BS 6262, which is undergoing revision, gives safety recommendations for the vertical use of glass in locations likely to be subject to accidental human impact.
Glass doors and glazed screens, including those alongside a corridor, need to provide manifestation at two levels, between 850mm and 1,000mm and between 1,400mm and 1,600mm above floor level, to cater for people of all heights, ages, and for those in wheelchairs. There also needs to be a visual contrast between the manifestation and the background in all lighting conditions to ensure its visibility.
Manifestation can take many forms. For example, broken or solid lines, patterns, company logos and straplines. If a logo or sign is deployed, then it must be a minimum of 150mm high and repeated at regular intervals, whereas lines or bands need to be at least 50mm high. For any glazed doors used as part of a screen, then they need to be clearly marked with a high-contrast strip at the top and on both sides.
In England, glass manifestation is addressed in Approved Document K. This has been effective since April 2013 and now incorporates the former Approved Document N (Glazing – safety in relation to impact, opening and cleaning). The requirement in Section 5.2 of Approved Document K is that transparent glazing that people are likely to become into contact with should be apparent, and applies to all buildings except for homes. Permanent manifestation is required to avoid people walking into large uninterrupted areas of transparent glazing. Alternatively, indications of glazing, such as mullions, transoms or large pull and push handles, should be installed.
Manifestation is not necessary in other cases too, particularly where it is obvious to the building users that there must be glass present. For example, glazing that doesn’t require manifestation includes when the distance between frames is less than 400mm, a single pane glazed into a door with a substantial frame, and a frameless glass door with large handles. On some projects, there may be other areas where it is not a clear-cut case, which would need to be discussed with building control.
While there is sometimes comedy value in someone walking into a glass wall, a legal challenge to a building owner by an injured person wouldn’t be amusing. Neither would the cost be of replacing a damaged window, which could have been prevented if manifestations were present.
There are applications in which we need to make it obvious to building users that the glass is present through manifestation. Failure to do so could cause harm to people or create legal headaches for building managers.