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The problem with slimline double-glazing

There are many fine woodworking businesses offering sash window services, but, regrettably, few of them appear to know much about double-glazing. The use of solid-bedded ultra-slim sealed-unit double glazing is fine if you don't mind seeing the headlines that we saw back in the early 1980s.

Here's one I recall from the Sunday Mercury, a midlands regional newspaper of the time.

                             TROUBLE GLAZING"

Most of those advocating the dodgy glazing techniques that brought double-glazing of wood windows into disrepute more than thirty years ago are too young to remember the problems, but those who prosecute cases through the courts remember them well, and are licking their lips at the prospect of more easy business. 

Being a fine joiner is simply not enough in this technological era. Take care to do your research and establish the facts BEFORE you spend your hard-earned money.

The fact is, to be certain it will last, double-glazing MUST be installed in such a way that the edge seal is in contact with nothing but fresh air.  If water does get in to the frame, it MUST be provided with a way out.  This is called "Dry Glazed, Drained and Vented".  Aluminium and PVC windows have been built like this from the start, but many wood window makers - fine joiners though they may be - simply either don't know this, or don't believe it.

Remember to ask:
Is it dry glazed, drained and vented to GGF Best Practice?

If it's not SupaSash, it probably isn't.

Specify SupaSash for peace of mind.

Here are more links for the full story:

o    more on ultra slim sealed unit double glazing

o    Expertexpert forum discussion: Ultra slim sealed units

o   Expertexpert forum discussion: Does anyone know anything good about ultra slim sealed units?

Editor's NOTE:
Sadly, the prime-movers of the Fenestration Associates have all passed away, so the website links have been removed. It's a measure of just how long these matters have been discussed, still with no wide industry agreement. It seems that, for some people, making money is more important than telling the truth.

However, here's an interesting development in support of everything you've just read...

5th Oct 2017
an email from Colin Torley, past Sales Director of VEKA UK

Hi Keith,
Thanks for your E-Mail.
I am new to the Glass and Timber side of the Industry having worked in pvc for the last 30 years and I find it incredible that non-compliant glass is being used quite freely.
The last straw was a few weeks ago when we were given a contract for approx. £30K and then had the contract taken from us because it had to be Slimlite glass, which we refused to supply. It didn’t matter what we said or did they wouldn’t accept it so I have gone on a campaign,
The letter has been published in Fenestration News, The Glass Times have put it in page three of their magazine which came out yesterday and are using it as a headline on their web site. The Glazing Blogger with an audience of 10,000 on Twitter has also highlighted it as well. I am talking to the other magazines to get them to use it and some have asked for more information before they do etc. 
The problem is, I, maybe a bit like yourself, am hitting some brick walls as some of the glass industry people do not want to know, so I have said I want a round table discussion with Industry people to put a stop to this in particular The GGF, BSI and Edgetech. Please find details of what I have sent to the trade press along with the letter.
There is story to be told here. There is a lot of noise just now about the use of non-compliant products in the construction industry.
The industry, especially glass manufacturing companies are aware of this, but have tended to turn a blind eye. I can’t do anything about this other than highlight the problem, but it needs to be taken up with...
1       The GGF, They are aware that this is going on, but are they turning a blind eye to it because some of their members are actually supplying these “illegal" units? Should they not be policing this? If it isn’t them, then who is? The GGF saw a copy of this before it was sent to the press.
2        BSI –
We are aware that companies are sending out copies of their EN 1279 certificate and passing it off as including these heritage units. What are they doing   about the misrepresentation of their Kite-Mark?
3         The spacer bar company (Edgetech) who know what this is being used for and know that the way it is being used is for non-compliant glazing units, but continue to sell it. Why? Because it is too easy to say that they sell a component and what people use it for has nothing to do with them!!!
I believe that there is a story here to be told and it will be interesting to see who, if anyone, replies to what has already been sent out and used by other mags.


Colin Torley

updated June 2018

REMEMBER  Slim double-glazed units fail to meet the Building Regs, so you'll only find them on jobs that can be classified as "refurbishment" rather than "new installation".

Something to bear in mind.

Tel 07831 194655


to email .... Click HERE