FAQ: The abbreviation FENSA stands for FENESTRATION - SELF ASSESSMENT.
The uk dictionary definition of the word fenestral or fenestrate is " belonging to or like a window" The word fenestration is "the arrangement of windows in a building". FENSA is used by double glazing uk trade companies to certify that their replacement windows and doors installed comply with Building Regulations Document L (and more), actually checking av. 1% of all replacement windows installations.
Did You Know?
There are two main types of safety glass used in the home:
Toughened (tempered) glass
Four to five times harder to break than ordinary annealed glass, and if it breaks it does so safely by disintegrating into thousands of very small pieces with dulled edges (like car windscreens used to). In a normal thickness of 4mm (unless you get a 'cheap and nasty' door which might have 3mm thickness), this is what is commonly used in most sliding patio doors and front and back doors in the replacement industry today.
The other type of safety glass is Laminated, which looks much like ordinary glass but has an almost indiscernible tint, which some customers think makes them look as if their net curtains are dirty! The slight tint is the result of the sandwich structure of laminated glass where two layers of 3mm glass are used with a tough plastic interlayer called polyvinyl butyrain (pvb). The combination of the extra thickness , now 6.4mm overall, and the plastic interlayer is what gives it the slight tint. Although laminated glass uses ordinary non toughened annealed glass, when hit hard enough the outer layer of glass may crack, but the broken pieces will adhere firmly to the interlayer, and so stop splinters of glass flying off.
Laminated glass is a combination of two or more glass sheets with one or more interlayer of plastic (PVB) or resin. In case of breakage, the interlayer holds the fragments together and continues to provide resistance to the passage of persons or objects. This glass is particularly suitable where it is important to ensure the resistance of the whole sheet after breakage such as: shop-fronts, balconies, stair-railings, roof glazing. Production
Identifying safety glass:
All installed safety glass should be clearly marked with the British Standard test reference BS6206, with the letter L for laminated, and 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 which will give an indication, but I would stress should not be relied upon as being definite, and these are: Toughened - look at the glass carefully side on, a distortion, not too dissimilar in looks to sheet glass, should be noticeable where the glass has been heated and cooled.
Also with toughed glass the gas marks will be noticeable when looked at through polarised sunglasses NOT ordinary sunglasses). 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, and I use a laser measure which is held to the glass, and even on a double glazed sealed unit it can tell me the exact thickness of each pane, the air gap between, and the overall thickness - all by one push on a button! Find out some more interesting stuff about it at: merlinlazer.co.uk
Location of Safety glass in the home:
1972 saw the introduction in the glazing industry of a new 'code of practice' number CP152 which more or less said that in doors use 6mm glass instead of 4mm glass on the basis that is is thicker and therefore 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, and because firms selling on price had to keep their costs down, people were still having some very nasty accidents.
'Safety' glass is now mandatory in the home since 1992 when Building Regulations part N, covering glazing materials and their locations for all building work was very first introduced. I believe this was also updated in 1995 and the regulations apply to not only new, but also replacement glass. Briefly then, all glass changed since 1992 should have been done so with the use of 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 - or 800mm, of the floor or ground, where particularly toddlers and the elderly are most at risk.
All glass in the blue shaded area should be safety.
Most Conservatories should be fitted with safety glass everywhere, except in the fanlights where it is not really necessary. Buying on price could mean sacrificing safety- is penny pinching worth it!
The 'law' about safety glass:
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 either sold, or supplied and 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: