This is a guest article by Saveheat Group MD Colin Torley
You recently raised the question about whether the glazing industry is corrupt. I have been in the window and door industry for over 30 years now and I have seen a lot of change over the years and most of it good. As most of that 30 years was spent in the pvc industry I have had my eyes opened by moving across into other materials and Timber Windows.
At the Saveheat group, we manufacture PVCu, Aluminium, IGU’s and Timber in 4 separate manufacturing companies. The one that not only frustrates me, but infuriates me, is the Timber window industry. Having never come across the term “low sightline units” before I’m just amazed at what the glazing and the timber window industry is doing.
The “big” issue with the Heritage market is that planners and specifiers are looking to replace old timber Sash and Case (mainly) windows and to make them look the same as when they were fitted over 100 years ago. The difference is that they want to replace these windows with double glazing rather than single glazing, which makes sense. Where the problems arise is when they want to use through astragal bars, which is in keeping with the old style, and these tend to be approx. 20mm wide on the face.
For these windows to comply they really need to be manufactured to the following dimensions:
IGU sightline – the minimum that these can be to comply with BS1279 is 8.5mm. So, with a through astragal you have two units – 17mm.
We have been advised by our sealant supplier and the GGF that these units must have a 3mm edge clearance either side of the unit, or they won’t guarantee their product = 6mm.
The Aluminium spacer bar must sit 2mm below the sightline = 4mm.
We have been told that with the weight of the double-glazed unit then these should sit on an astragal feather of 6mm.
Add all that up and for the glazing specification to comply with BS1279 and CPR then the glazing astragal needs to be 33mm. So how come companies are fitting windows to astragals no more than 20mm? Why? because they are manufacturing glazing products that do not comply with legislation and are therefore illegal.
While you might think that this is done on the “odd” contract, this is widespread to an extent where we are now starting to get unit failures on a regular basis.
As a leading Timber window and IGU manufacturer, there isn’t a day goes by where, myself or another member of staff is having to deal with the issue of “low sightline” heritage glazing and to try and explain that what they are asking for, just doesn’t comply with the CPR. We are usually told that, AN Other company will do it, so why won’t you, The Planning department are telling us that’s what we must have etc, and we are losing out to unscrupulous companies, planners, specifiers who are either, totally ignoring the regulations, don’t understand the regulations, or both.
We follow, and have always done so, the GGF guidelines which clearly state the situation regarding “low sightline” heritage units, but these guidelines are being totally ignored by other companies within our industry, which leads to the situation that is now starting to be highlighted.
Excerpt from the GGF Guidelines
This article cannot be used to avoid the preparation of a Declaration of Performance and compliance with a harmonised Product Standard for the following reasons:
(a) IGUs are manufactured in a series production and therefore this derogation does not apply. Also, the IGU manufacturer is not responsible for the incorporation of the IGU into the construction works;
(b) IGUs are not manufactured on a construction site;
(c) IGUs are not manufactured in a traditional manner and are not manufactured in a non-industrial process.
It doesn’t have to be this way. We can manufacture replacement Sash and Case windows that will replicate and maintain the look of old historic buildings and the glass will perform and comply with all the necessary regulations.
We use standard timber window construction detail along with a structural grid system to give the window that authentic look. We have recently supplied windows to a Grade A listed building in St Vincent Place in Glasgow with windows that matched the appearance of the windows that they replaced and allowed the building to retain the character and look that the specifier set out to achieve. No, non-compliant products were used to achieve the performance and the required appearance so why do planners and specifiers continue to look for something that is not only non- compliant, but illegal.
We are actively campaigning to have the practice of using non-compliant double-glazed units banned, but some people are turning a deaf ear to the situation. We have enlisted the help of the GGF, who accept our stance and will campaign to have the use of these illegal units and windows banned and companies who continue to flout the law, brought to court and fined, if not jailed.
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