Glass:
Safety glass

Identifying safety glass
All installed safety glass should be clearly marked with the British Standard test reference BS6206, with the letter L for laminated or T for toughened, together with the company registration number of the supplier. If you want to identify (older) safety glass that may not have been marked at the time there are some tests that will give an indication but which, I would stress, should not be relied upon as being definite. To test for toughened glass: look at the glass carefully side on and you should notice a distortion, not too dissimilar to the way sheet glass looks, where the glass has been heated and cooled. Also, if you look at toughened glass through polarised sunglasses (ordinary sunglasses will NOT do), you should be able to see the gas marks.

With laminated, the only real test is an accurate measurement, which should show up a thickness of 6.4mm and not 6mm as with ordinary float glass. A calliper-type measuring device is really not accurate enough for this. I use a laser measure, which is held to the glass and which, even on a double-glazed sealed unit, can tell me the exact thickness of each pane, the air gap between and the overall thickness - all by one push of a button! Find out some more interesting stuff about it at merlinlazer.co.uk.

Location of safety glass in the home
In 1972 a new code of practice, number CP152, was introduced in the glazing industry. It said, more or less, that in doors you should use 6mm glass instead of 4mm glass, on the basis that thicker glass is harder to break. In fully glazed doors such as patio doors, toughened (tempered) glass was recommended, but all too often not used because of the extra cost to the seller. As a result, people were still having some very nasty accidents.

Safety glass has now been mandatory in the home since 1992 when Building Regulations Part N, covering glazing materials and their locations for all building work, was first introduced. I believe this was also updated in 1995 and the Regulations apply not only to new but also to replacement glass. Briefly, then, all glass changed since 1992 should have been done with safety glass in areas most at risk (called critical locations).

This means most doors and all glazing in windows where the glass is within 2ft 7in (800mm) of the floor or ground, where particularly toddlers and the elderly are most at risk.

Most conservatories should be fitted with safety glass throughout, except in the fanlights where it is not really necessary. Buying on price could mean sacrificing safety - is penny-pinching worth it?

The 'law' on safety glass
There is no 'law' as such, although the industry has to comply with British Standards, and we would in effect be breaking the law by not complying with the relevant Standards. This is because the Consumer Protection Act 1987 states that ‘it is an offence to supply goods which fail to comply with the general safety requirement’. In effect this means that BS6262 Part 4 should be regarded, for all practical purposes, as a legal requirement for any glass sold, supplied or fitted directly to the public knowingly for use in critical locations.

See all about a new and clever laser device that can detect if glass has been toughened: http://www.merlinlazer.com 

All about 'misted-up' sealed units
Do sealed units have a vacuum?
Types of glass
Sealed units - manufacturing techniques
Air gaps and insulation
Why did my sealed unit explode?
Brewster's Fringes