Glazing - what to go for....

[Anonymous]

I've just been speaking to our local double glazing specialist.
He can make us winodws with a 14mm width, which should mean we can make a smallish bar between the units. If we have it argon filled and use the Future N glass coating which is clear and has a better U-value than Pilkington K, we can get the U Value of the windows down to 1.9, which fits nicely under the BR's 2.5 value.
At 16mm it would be about 1.7 and at 20mm it would go down to about 1.2, which apparently is closest to the best you can get of 1.1 presently.

Anybody - Hi Biff!!!!! - had any experience of working with this sort of size (14mm) unit? This type of glass? Got anything at all to say on the matter.

Graham

 

[Anonymous]

I am probably bing a bit stupid, but why does unit thickness necessarily dictate glazing bar thickness.

I can see it would need to be DEEP enough to enclose the unit, but surely as it gets deeper it gains a little extra strength meaning you could actually make it a little thinner?

G.

 

[Anonymous]

Building Regs Part L requires no higher than U=2, not 2.5

Planitherm Future N is the soft coat low-e glass made by St Gobain, a French company that has a large factory at Eggborough, Yorkshire. The glass is clearer than Pilkington K (see previous thread) and gives U-values that are slightly lower. Handling during manufacture of dg units is more difficult so many firms won’t supply it. I’m not sure, Graham, that the figures you quoted are correct. They certainly conflict with the indicative table in the appendix to the Part L from the ODPM.

A 14mm unit, with two sheets of 4mm glass has a gap of only 6mm. Even with Future N, that will not give a U value below 2. The most usual thickness for a dg unit is 24mm, i.e. a gap of 16mm This is the ideal space for thermal insulation. The very lowest value quoted on the Part-L table is 1.3 and that is for a triple glazed window. Perhaps you should ask your double glazing specialist to check those figures.

Not stupid at all, George, the unit thickness does not affect the glazing bar width.

 

[Anonymous]

Biff,
Another couple of questions.
Unless I'm reading your site wrong then it says that the thicker the D/G the larger the glazing bar will have to be? Also in another posters thread you asked how he could get away with a thin glazing bar when using D/G?
Yet here you say that D/G width makes no difference to glazing bar thickness?

I was under the impression that the thinner the D/G the thinner the glazing bar could be, can you put me straight? I understand that the larger the gap the more efficient it will be, but if we are replacing totally inneficient windows, ones with gaps, that don't seal properly, some single glazing, some blown units, window frames that don't fit properly then anything that fits properly and is of good quality will be more efficient anyway?

My expert D/G manufacfturer, who sounded very knowledgable and was very helpful on the phone, spent 1/2 hour with me, is obviously not that good!!! If he is saying U value has to be below 2.5 to meet current regs and you say it is 2 or less.

I've searched for Building Regs, but I can only find sites quoting some sections, which seem to suggest U2 is the limit, but to get the regs I need to pay £10. Does anyone have a link through to the proper regs - or proper free ones <IMG SRC="http://www.periodproperty.co.uk/discussing/smileys/smile.gif" BORDER=0 ALT="">

I also spoke in another post about my plumber saying we'd need to update all our water system to meet current regs adn someone here said it was baloney, but in my search for windows help, I found the plumbing one, which says what the plumber was saying
http://www.plumbingpages.com/featurepages/PartL.cfm

I've got to go and do some work, so I can't do any more searching today.

Thanks all.

Graham

 

[Anonymous]

Oh dear, this is getting a bit muddled. The glazing bar for a normal dg unit has to have a rebate of at least 12mm to cover up the mastic that holds it all together. Two rebates and a bit down the middle adds up to at least 30mm. This has got nothing whatsoever to do with the air/argon gap between the glass sheets and hence the thickness of the unit. Somebody did claim a few days ago that they could get dg units with thinner bars and I did ask how this was done and who the manufacturer was. Unfortunately the poster did not reply so I’m left thinking it can’t be done. I’d love to be proved wrong. Thermal insulation improves with increasing space up to a limit of around 20mm when convection currents set in spoiling the insulting properties of the gas. Hence the ideal gap is regarded at around 16 to 18mm. As you say, anything may be better than nothing but that doesn’t mean that it complies with the Building Regs. All the Regs and much more are downloadable for free from the ODPM website.
The ODPM website is not the easiest to navigate. Here’s a little game:
Start with
http://www.odpm.gov.uk/
and see how many clicks it takes you to get to
http://www.odpm.gov.uk/index.asp?id=1130727
No cheating now.
Now you can download the pdf Approved document L
The table is on page 35 or thereabouts.

 

[Anonymous]

It's getting clearer Biff, if you'll excuse the pun. I remember that post, I was hoping for an answer to.
So, I can have a 20mm D/G unit and still have the same glazing bar size.
Can you tell I don't know what I'm talking about!!!! Unfortunately my Father in Law's wife's Son died last week and he's not working at the moment, so not bothering him with details like this.
Point taken about the regs.
I'll do the ODPM tomorrow, as I'm just off to work. I have though been using it a lot lately, as we have a planning application for a park and ride ( about 2 miles away) going through and this has meant a lot of trawling the ODPM site. That's a totally different story, as apparently their are no guidleines to what constitutes a park and ride so say the ODPM.

Did you get my email Biff?

Graham

 

[Anonymous]

re: glazing bars, am I correct in thinking that the spacers between the glass panes are square? That would mean that the minimum rebate to hide the spacer would be dependent upon the thickness of the glass.

Someone did say that they made up a fake wooden bar and stuck it on with a bit of silicone, so a single dg unit per sash frame, then you can have as thin as you like.

 

[Anonymous]

Did you get my email Biff?
Graham
Not recently, did you send one in the last couple of days?

 

[Anonymous]

4 clicks, but two days reading to try to get to grips with it..... It does say for the elemental method of calculation that 2.0 is the value for windows, but then goes on about whole house values, which could mean any figure for any item so long as the whole house meets the regs.... now where was my scientific calulator, and my measuring stick <IMG SRC="http://www.periodproperty.co.uk/discussing/smileys/smile.gif" BORDER=0 ALT=""> some of those permutations look interesting!!!!!!!