Sliding doors - double or triple glazed?

[Tresco]

Shortly starting an extension and will be fitting an 8m run of sliding glass doors made up of four panels. Room size is 30sq m and will have a couple of big skylights.

The triple glazed option is much more thermally efficient - passive house spec but the frames are bulky, the double glazed units have minimal framing which is preferable but I'm concerned that as it's a lot of glass we'll lose a lot of heat, I'm putting in a rad, underfloor and a woodburner.

I know all the U values but wondered if anybody has a room with a lot of glass and whether the view is to go double or triple glazed?

[Tresco]

Thanks Jim, that's very helpful.

Wasn't that clear in my initial post but my layout will be the same as yours and you're right in that the two fixed side panels are virtually frameless. Surprisingly the triple glazed units, made by Internorm in ali clad timber, are easier to slide than the all aluminium double glazed system despite being significantly heavier.

Who did you use?

[Tresco]

Had buildings regs approval so don't think the glass area is an issue, doors face North West.

Spoke with Reynaers, their requirement is max 2mm beam deflection which on a 9m steel is some challenge and would mean almost doubling the size of the planned steel, plus their longest frame extrusion is around 7m.

I'm leaning towards doubled glazed although I can just picture 'er indoors next year huddled around the woodburner scowling at me as I extol the virtue of minimal frames...

[Tresco]

iphonedyou said:

OP, you could try Cantifix for Sky-Frame (more £ than you can imagine but excellent) or IQ Glass also.

With Sky-Frame you can get down to around .3 G and 1.0 U. That's with triple but to be honest their double has similar G and 1.5 U so not too bad. And you don't get the slightly greenish tinge either due to glazing thickness of course.

Thanks for that, I spoke to Cantifix, great system but as you say they are serious money. Fineline also minimal framing but again over budget.

I've visited IQ glass and like their system although only two shoot bolts as security which is a concern but it's probably between them and Internorm.