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Glazing system for Listed and Conservation jobs...

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#1 joiner


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Posted 02 March 2010 - 08:07 PM

Whilst searching for information on double glazing performance I came across this company and sent away for a sample and more gen…


The sample came this morning and I’m impressed. The system is ideal for use on conservation and Listed Building jobs (if you can get past the hidebound, knee-jerk, jobsworth CO’s incapacity for imaginative thinking) and can be used as a direct replacement for single glazing in the existing rebates. It’s a brilliant system.

Relatively expensive though. The sq.m cost is roughly double that of a conventional unit and, because of the way the unit is packed, you can add a significant chunk to the cost. But it does offer a solution to the age-old problem associated with bringing the older building into line with the current requirements of energy saving and introducing a welcome level of human comfort.

#2 temp


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Posted 03 March 2010 - 07:31 AM

We needed some 4-6-4 sealed units for some metal windows on our place. Wish I'd known about a 5mm wide seal back then. We could only find wider seals and they show above the putty in one or two places.

#3 joiner


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Posted 03 March 2010 - 08:25 AM

The sample I got came as a 3 x 4 (gas-filled) x 4 low 'e' with a u-value of 1.9.

Despite the thin section, their spec sheets show a noise reduction of an average 27 dB. I wonder how much of that is down to the different pane thicknesses, which is known to reduce sympathetic resonance? I might just ask them, if only out of curiosity.

I did post the thread on another forum and got the response that the cost is actually 10x that of a conventional unit, to which I answered:

My figures for the basic costs are:

Both types 4mm, low 'e', gas-filled.

Standard unit £40.63 per sq.m + £6.50/sq.m for gas + VAT

Slimlite unit £83.85 per sq.m (inc gas) + VAT

The delivery cost of £130 is a one-off per delivery, so cost per item will reduce with quantity (although still a bit stiff).

It is a possible way around the knee-jerk reaction of some COs against double-glazing per se, especially on Grade 2 listings, and at least makes the point arguable.

As for the conversion of single to double-glazed - when you factor in the cost of machining the existing rebates (or re-making the whole sash) it's not going to work out any different in the long-run and at least makes the process feasible and the retention of original features possible.

It's at least worth considering as another weapon in the arsenal.

#4 paulwood


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Posted 22 September 2010 - 06:58 AM

From a point of view of energy optimizing your aging home, the necessity for using double glazing windows or doors is a foregone conclusion.

Statistics show almost 15% - 25% of heat is lost (or gained as the case may be) through glass doors and windows.
Other useful features of double glazing windows and doors are better safety, energy savings, better acoustic properties,
style & design, attractive glasses & frames of modern material.
For information on Glazing visit http://www.greentech.ie
The last but not the least important feature is that it is easy to install.

#5 joiner


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Posted 22 September 2010 - 08:30 AM

Sorry Paul, but "foregone conclusion" it ain't. This thread is about conservation and I'm surprised you haven't taken on board the distinction.

Things MIGHT change with the introduction of the new Regs next month, but comments on other threads (and forums) would appear to indicate that the discretion allowed on the issue of fenestration in older buildings is anything but as clear-cut as the authors of the new Regs intended, which means that owners of older buildings and the joiners who make the windows for them will find themselves still in a postcode lottery, and one complicated further by the lack of consistent approach between individual BCOs in the same office!

The decision as to what type of glazing to use in an older property has NEVER been made by the owner and rarely by the joiner. So, given the factors outlined in the last paragraph, "foregone conclusion" it ain't.

Perhaps an unfortunate choice of phrase?

But welcome, and stick around mate. One thing that these forums teach you is that contrary opinions are grist to the mill.

(And just realised that you're in Ireland, so you probably won't be too familiar with UK Regs and the idiosyncracies of our local authorities and their officers!)

(Message edited by joiner on September 22, 2010)

#6 sarahsouthwest


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Posted 23 July 2014 - 10:38 AM

We're using Slenderglaze made by the Bath Sash Window Consultancy. http://www.sashconsu...dex.cfm?page=51 We found them via this report http://www.historic-...lazing_2010.pdf Their window performed a teeny bit better than the Slimlite window Dave did the link to - but I expect they're all much of a muchness TBH, and of course, the companies make improvements all the time.

We found them v easy to deal with. We took up one of the original sashes and they have made exact copies, except they are double glazed - luckily our original glazing bars were reasonably wide at 22mm so it didn't cause problems. I've seen a sample they made with 18mm bars and you can just see the double glazing unit at the edges if you look v hard. I don't think you'd notice generally.

We've got a 6mm gap between the panes of glass, using a white spacer bar - for some reason the 4mm spacer bars are only available in black. We've seen them and they're beautifully made - they're currently waiting for installation for when the pointing is done.

And yes, they cost a lot - but only a bit more than we were quoted locally by several companies which only did duplex double glazing - about £1000 extra, ie £200 per window. We think it's been well worth it as the windows were one of the few original features left in the chapel.

#7 joiner


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Posted 23 July 2014 - 02:43 PM

You can go down as low as 13mm with duplex bars. Cost for this window was plus £18 a unit for duplex. The units were Pilkington K, 16mm argon-filled.

Attached File  FRONT BEDROOM WINDOW - DUPLEX BAR 001.jpg   34.02K   2 downloads

(The black marks at the head are from stripping the paint off the old frames. Several layers, judging from the colours probably dating back to when the windows were installed in 1848!!)

Edited by joiner, 23 July 2014 - 02:46 PM.