Is this double glazing?

February 5, 2016 8:23 AM

Help me, AskMe hivemind. Can you identify, from the linked pictures alone, whether the windows shown are single or double glazed? Can you tell me how to demonstrate it to someone else, either way?

I've looked and looked and I can't satisfy myself either way. They look like standard double-glazed units, but at the same time I can't spot definite reflections that would confirm to me that they are.

I am being told different things by different people, and can't work out who is actually right.

posted by howfar to Grab Bag (16 answers total)

Looks single to me. The double glazing in our house has a noticeable gap between the panes approximately 1 cm wide. This is covered with some sort of metal foil with writing on it. From the pictures you've taken it looks like there is a thick rubber seal all around the glass, but there looks to be only one pane there. Easiest way to check would be to just estimate the thickness with your hand, double glazing will mean that your fingers are quite a ways from touching (ie > 1 cm), whereas single glazing they would be much closer (ie < 0.5 cm).
posted by koolkat at 8:33 AM on February 5, 2016 [1 favorite]

Those don't look like it to me. The black band that goes around each window looks like it could be the void between two panes of glass, but upon closer inspection the glass doesn't seem to start until the inside of that black band. I'd guess the black band is some kind of post-hoc weather stripping.
posted by slkinsey at 8:34 AM on February 5, 2016 [3 favorites]

Response by poster: This input is useful to me. To clarify, I am not going to be able to go to the site to confirm things, and have never actually been there myself. The two different groups of people who have been there are telling me directly contradictory things, and there is lots of documentary info supporting the claim that the property is double-glazed.
posted by howfar at 8:37 AM on February 5, 2016

The black rubber gaskets make it very difficult to tell. That said, I think it's unlikely you'd see an intact rubber gasket on a window old enough to be single-glazed.
posted by jon1270 at 8:41 AM on February 5, 2016

In a couple of images, there is a reflection of the exterior frame in the glass. These reflections appear to have a slight halo, suggesting two panes of glass.
posted by yesster at 8:41 AM on February 5, 2016 [2 favorites]

I've never seen a single glazed uPVC framed window, and it looks like the thickness between the inside handle and the surface of the window pane is enough that it'd be double glazed.
posted by ambrosen at 10:20 AM on February 5, 2016 [1 favorite]

Best answer: They look single to me. Every double glazing installation I've seen, its been obvious to look at, there are clearly 2 panes of glass with a significant gap between them.

On the other hand its a new(ish) PVC window, I can't imagine anyone having those installed in the last 20+ years as single glazed although some quick googling suggests they exist for some reason.

Is it an ex-council house?
posted by missmagenta at 10:29 AM on February 5, 2016

I'd be very surprised if those were single pane windows. They are simply too new.

That said, if you can get someone to take a close up picture, looking towards the edge of the window with the camera against the glass, it will be trivially easy to determine this as you will clearly see the space between the panes.
posted by ssg at 10:31 AM on February 5, 2016 [1 favorite]

In my home I can tell there are separate panes of glass because when a light source is on inside I can see it in multiple separate reflections, slightly displaced from one another. I generally notice that from inside but I would think it would work outside, too, if you had a bright source of light to shine on the window and an observer to stand at angle where they can see the reflection.

(It doesn't *have* to be a light source, but in my experience it's easily noticed with a light source; less obvious with other reflections.)
posted by Nerd of the North at 10:41 AM on February 5, 2016

Have a look at this detail from the 6th photo in your series. The doubled reflection of the exterior window frame seems like a dead giveaway that they're double-glazed.
posted by contraption at 11:20 AM on February 5, 2016 [1 favorite]

The reflections of the outdoor objects are very sharp without any "double vision" effect. I see what contraption and yesster are pointing out, but maybe that's caused by a shadow or reflection on the inside? A vertical blind? Curtain? The reflection of the overhead wires and the lines of the cars don't have any blur, making me think they're single panes.

(I'm sure you're also taking into account the motives of the parties telling you conflicting stories...)
posted by sageleaf at 3:24 PM on February 5, 2016

It looks to me like there is definitely a pane of glass sitting in the indentation in the rubber gasket, which makes me wonder where the supposed second pane would be attached.

If you have in writing from someone that it is double glazed, and then you find it is not, I am sure you would have some legal recourse, if this is a property you are planning to buy or rent.

What I would be most concerned about is that they are referring to some sort of removable magnetic retrofit "double glazing" of the sort that is popular here in Australia. I don't think so, though, because that tends to be more obvious.

As far as people saying that the upvc windows are too new to be single glazed, the OP doesn't say their location, and there are places where single glazing is still the norm, even in new buildings (e.g. Australia and New Zealand.)
posted by lollusc at 4:04 PM on February 5, 2016

It's actually surprisingly hard to get a full scale crop of those pictures from Dropbox, but I managed it, and there's very clearly a double reflection of the frame in the window, so I'd very confidently say it's double glazed. Now, whether the seal in between the panes is intact, that's a different question, but there's definitely two panes there.
posted by ambrosen at 5:18 PM on February 5, 2016 [1 favorite]

Looks single-glazed to me. With the depth of the rubber glazing stop on the exterior side, I just don't see any room for there to be two pieces of glass between the exterior and interior frame pieces. The panes would have to be abnormally close together, like a half to a third as much as usual. As others have indicated, there's usually a perforated metal strip that goes between the panes of dual-glazed windows. It's not always there, but pretty typical.

Where the confusion in your sources may be coming from is that it may be laminated glass, which is two panes of glass laminated together, typically with the sort of coating you'd have on a dual-glazed window between them. It's fairly rare, but possible.
posted by LionIndex at 5:50 PM on February 5, 2016

1. Ask a glazier
2. Double glazing with a very small gap has been fitted in the past. If this is double glazing then the gap is miniscule.
3. The supposed double reflection, as seen in this picture, is of the order of the thickness of a pane of glass. My old double glazing has a 6mm gap, but there apparently exists double glazing with even less of a gap.
4. All the double glazing I have seen has a metal lined structure visible between the panes. These pictures do not show that.

If this is double glazing with a minuscule gap then it is not going to provide any thermal advantage over single glazing as the gap is far too small. A 12mm gap is required for insulation.
posted by asok at 5:53 AM on February 9, 2016

Response by poster: It turns out that they were single glazed, but that everyone who had prepared reports in relation to the property had misidentified this, due to the style of the window units. Thanks to everyone who offered input!
posted by howfar at 12:26 PM on March 6, 2016