Nickel sulphide inclusions and consequent shattering of glass have reduced as a source of problems, due to such factors as changes in sand for manufacture. There is some use of heat soaking, though this is a costly process. A Euro-standard on heat soaking is due out soon.
Risk assessment may be the first step for overhead glazing. For example, the forthcoming cwct document on sloped glazing will have separate recommendations for glass below 5m high, 5-13m and over 13m.
Other causes of overhead glazing failure can include:
- inaccurate cutting of glass or edge-damage to glass in transit and on site, all leading to local stress build-ups
- cad drawing especially can help in creating complex geometries with small tolerances that are difficult to build
- triangular glazing panels may slip under their own weight down into the 'V' shape of the framing, jamming against setting blocks, negating the freedom of movement that setting blocks in rectangular openings provides.