Double or triple glazed

I just posted this in another thread - I'm currently looking at putting in a few new windows and have had three companies out to me so far.

All three companies have stated to go double instead of triple, saying the triple is only worth it if you live in a noisy area. All three, on three seperate occasions have said this to me.

Curious as to why they would say this as the triple is more expensive.

BryanF wrote: »

Chance is same, double or triple. As Mick says above, the better quality triple all day long.

Mod note: deleted duplicate post. as regards the ‘go the double’ they sound like cowboys. They must be selling inferior frames, can’t think why else they wouldn’t want to sell you triple glazing.

NP on double post.

Regards cowboys, this is three separate fitters who've all said the same thing. Two of which are good reputable companies, I can PM you their details if you wish.

One uses Camden windows/frames, the other who we are leaning towards uses Spectus Frames & Windows from Buncrana I believe.

Cal04 wrote: »

Whole unit

So its not this then?

Cal04 wrote: »

Adding a 3 m slider to an extension, obviously want to keep heat in but have heard of some that middle pane of glass shattered..so double or triple glazed in your opinion please

Naos wrote: »

Rang yesterday and they've advise it's a 1.1 uvalue for Frame & Window combined. They said a triple glaze would get you to 0.8 but in their opinion, it would be overkill for our order.

FYI they sell & install both.

This is daft. 1.1 u-value in today's world is very poor and the way windows work is most of the heat is lost through the frame.

In windows the glass itself is generally a better insulator than the frame. Standard triple glazing has a u-value of about 0.6 with a frame of about 1.1. You combine these to get the overall window. As it's a 3 meter wide slider and I'm presuming 2.1 meters high you've a huge area of glass and a tiny area of frame. In comparison having a window 1 meter x 1 meter would have a lot more frame to glass.

Due to the slider having a huge amount of glass to frame ratio it will be one of the best performing windows in the house by a long distance in terms of u-value per sqm. If standard triple glazing is 0.6 and good triple glazing is 0.5 for just the glass then I'm guessing this guy is using the same frame for his double and triple glazed units. Let's say he has in the double glazing 8mm inner, a 20mm gap and 8mm outer that's a total of 36mm. For the tripple he probably has 8mm inner, 7mm gap, 6mm middle glass, 7mm gap and 8mm outer which also adds up to the 36mm total. When you fit more pieces of glass into the same distance you loose performance as the gaps between the glass get smaller. The total thickness for the triple glazzing should be up around the 50mm for triple glazing if you want to keep the same gap between the glass as in the double glazing. The other issue with putting three layers of glass into a frame designed for two is the frame wouldn't be designed for the extra weight. This is critical for such a large heavy unit which has to slide and won't move as smoothly as it should. If the frame distorted a fraction it will start to catch and get stuck.

If the above is a bit complicated in summary I think he's selling very poor quality triple glazing which is why he's pushing the double. Can you ask for a data sheet for each? You can remove any info that identifies you and the supplier if you want as it's not what we're interested in.

BryanF wrote: »

Fitters?!?

Do you think they like lifting double or triple glazed windows?

Wrong choice of word I guess, what would you call a company that supplies & fits windows?

I've a Nordan 3.2m wide, 2.4m high triple glazed Aluclad slider. It's been installed 2+ years and have had no issues with it. Seals are great and the slider is not too heavy to push, my 5 year old can manage it easily.