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?

[Jimnic007]

Tresco,

I have a new build house with triple glazing throughout, but for the 7.5m slider at the rear I went with double glazing. However, instead of having a full sliding opening I went with two fixed frameless glazed pieces (with a black sealant between them which disappears to the eye) and a slider that slides in front of them. This only gives me one reasonably bulky frame around the sliding aperture and the rest disappears into the wall/floor and ceiling, which gives it a great feel.

When you go triple glazed, the glazing pieces get incredibly heavy and require a crane to lift in, whereas with double glazing and a relatively manageable piece (3m long by 2.4m high say) it can be man handled into position. Also a triple glazed slider would be heavy to move.

Don't get me wrong, you can feel the difference in this room of an evening, when everywhere else is toasty, it is a tad cooler, but that is also down to the size of this room (12m long x 4.2m wide).

Whereabouts are you in the country?

Cheers,
Jim

[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?

[PugwasHDJ80]

Depends on budget,

Very finest doors here http://www.finelinealuminium.co.uk

[Jimnic007]

I used Internorm triple glazed Ali clad windows throughout the house, but not for the slider as i found the profile of it a bit chunky and they couldn't go a slider wide enough for the single aperture.

I used a Reynaars system that was built for the aperture. That and the Internorm windows wee supplied and fitted by a company called Anglezarke from Chorley.

[WindyMills]

Sounds like you might be aware of this, but you're limited to a maximum window/glazed area of 25% of new floor area + openings lost due to extension. Any more glazing requires justification through area-weighted u-value calc.

Back on topic, which way do the windows face?

[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...

[NorthDave]

I dont have an opening that large but do have a glass roof (maybe 6m2) and double glazed bifolds (spanning 5mish) on a room 30m2. I just have underfloor heating in the area and the room is toasty. The external walls are 100m block - 100mm insulation - 100mm block and the extension is warmer than the rest of the victorian house.

The underfloor is set up as a separate zone of the heating so temp can be different than the rest of the house.

[iphonedyou]

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.

[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.

[blade runner]

PugwasHDJ80 said:

Depends on budget,

Very finest doors here http://www.finelinealuminium.co.uk

I've got those across the back of my extension. They are pricey but great quality and very minimal frames to interrupt the view.

[PugwasHDJ80]

blade runner said:

PugwasHDJ80 said:

Depends on budget,

Very finest doors here http://www.finelinealuminium.co.uk

I've got those across the back of my extension. They are pricey but great quality and very minimal frames to interrupt the view.

The quality is amazing- I was lucky enough to have a look round the factory and see the quality control on the glass which was just phenomenal; they had a roughly 3x x 3m double glazed panel (one piece of glass was 12mm thick iirc) and It had a minute blemish in the top right hand corner- honestly I could only barely see it, but it failed quality control.

expensive, but expensive for a good reason

The folding doors they do are a work of art.

They also have an associated company making some very interesting lantern roofs which looks really nice as a half way house between an orangery and a kitchen extension. http://www.atlasroofsolutions.co.uk/appearance/con...