divorcingjack

3G glass supplier for fixed rooflight

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Morning all, 

 

So, our architect has specified two large fixed rooflights in the house. He has recommended a detail that he has used numerous times before which involves creating an upstand in the roof, fitting a metal angle into it and flashing the glazing in. This means that we have to source two panels of 3G glazing without a frame that can be fitted into the opening. I have a recommended spec from internorm that I have been punting around local glazing firms, creating a lot of teeth-sucking and slow shaking of heads. 

 

Does anyone have any recommendations as to an online supplier (or someone that will deliver to scotland) where I can source 3G panels suitable for rooflights? I finally found a local firm, but they are looking at 8-12 weeks lead! 

 

Before you all say, yes, I KNOW I should have ordered it earlier...... 

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What size and spec ..?? I have two that I use - both will deliver if it’s not too big. 

 

Don’t forget to make you curb tilt 1-2 degrees so water doesn’t sit on the roof light. 

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@PeterW - can you say who the suppliers are?  I also need to source 3G roof lights.

 

Thanks.

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1 minute ago, vivienz said:

@PeterW - can you say who the suppliers are?  I also need to source 3G roof lights.

 

Thanks.

 

This is just for panels - not roof lights - although the design is dead simple for them anyway and it just needs some black anodised aluminium profile and a couple of tubes of CT1 assuming they don’t need to be walked on..!

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You could look at velux commercial rooflights. Not the rooflights for houses but their modular skylights system. They have single fixed rooflights up to 1000 x 3000mm. The advantage is you get all the flashings, glazings, curbs, upstands, everything from one company so you get a full guarantee for everything.

 

https://www.velux.ie/professional/products/rooflights-roof-glazing

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Thanks, chaps.  I think I've used the wrong terminology - the 'windows' in our roof, AFAIK, are just fixed windows.  I don't intend them to be openers.

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@PeterW I'll look up the spec and size - I have them in an email "somewhere". They are quite big, one is 2400 x 1200 ish IIRC - nope, even bigger than I thought!

 

I'll update later, cheers. 

 

Sizes are: 

 

2500 x 1850

 

and 1300 x 1850

 

Spec that I was advised from Internorm is as follows: 

Glass: 8ESG SunGuard 70/41-16arg-8-16arg-55.2VSG TF+TGI , Ug value: 0,6 W/(m²K)

 

Edited by divorcingjack
add spec and sizes

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Mine came from http://toughenedglasssystems.co.uk/. Cheap and cheerful, but the units seem to be good quality and delivery and comms were good. They are extensively on eBay too.

I have 3G units and the outer pane of glass is 100mm larger all round to sit on top of an upstand. The two inner panes are smaller to fit inside the upstand. Can take a pic later when I get home if that helps.

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If you just need some sealed units try local glass merchants. Might save money if you can collect as delivery can be expensive.

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I got quotes for 3g fixed units (frame in RAL colour if required). u value inc frame 0.9 circa £800 each ex vat delivery and fitting. That was for fixed 1000 x1000 units. 

 

 Very nice but we dropped them out in the end.

 

Company was great, very helpful.  they do good drawings with quotes too.

 

 duplus.co.uk

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Thanks for replies everyone, I have tried the two companies mentioned above, but unfortunately duplus don't do rooflights without frames and toughenedglasssystems don't deliver to Scotland.

 

@PeterW could you share your suppliers or drop me a message? Thanks 

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So, just to update - we have asked Internorm directly for a quote. They are supplying some other replacement glass for a door panel, so thought I might as well ask. They are on a long lead as well, unfortunately. I'll update when I have numbers (and probably after a cuppa to recover). 

 

I have another question though - forming the upstand for the skylight has meant a lot of solid timber and it looks like a pretty bad thermal bridge through to the house to me. Is there any way to mitigate this? Should we be thinking about some PIR on the inside, underneath the plasterboard? The rest of the house will be pumped with cellulose, but there's no cavity around the skylights for this and we would lose a lot of depth, trying to get a decent U-value. 

 

Seems a shame to have this weak point, when the rest of the house is pretty good thermally, and MBC have put a lot of thought into the details to avoid cold bridging. I've uploaded the detail we are using. Rooflight details.pdf

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One thing to watch for is that if the glass is coming from abroad and there is an issue, you start from scratch. I say that because on our order they got the wrong glass for the very biggest opening (2.3x2.3) and it needed to be reordered. They couldn't source the glass in the UK and it took 8 weeks to arrive. And when it did, the unit was blown...at which point it would have been another 8 weeks. At least with a more local supplier you can cut a chunk out of any lead time as there is less of a dependency on transport. I might sound pessimistic but given that they screwed it up twice with us...! lol

 

 

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My formwork is made up of a frame of 50mmx50mm timber, skinned on the outside with 12mm ply. The PIR on the flat roof covers the lower 150mm, so it's effectively insulated from the outside. The inside of the formwork will have 50mm PIR between the 50mm square timber. I'm going to see what it looks like before deciding whether to add 25mm PIR over the top of that, or some of the 'foil bubble-wrap' stuff under the plasterboard.

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53 minutes ago, divorcingjack said:

I've uploaded the detail we are using. Rooflight details.pdf

 

Is that detail complete? What's fixing the glass down? is it the metal angle on 3 sides?

 

For me, this needs a re-think... Not just a weak point, but condensation will be running down the inside of the up-stand, I would have thought... It also looks a difficult detail to get airtight - the corners will be especially difficult.

 

Are you specifying a black-out around edge of the glass. If not I wonder if the "normal" compressive sealants are UV resistant

 

Personally, I'd go with a framed glazing unit as it gives you a chance of breaking the thermal bridge between glazing and upstand, and somewhere that get's covered to hide the airtight tape. Then I'd insulate the up-stand inside and out. I used insulated plasterboard internally and celotex externally.

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20 minutes ago, IanR said:

 

1 hour ago, divorcingjack said:

I've uploaded the detail we are using. Rooflight details.pdf

 

Is that detail complete? What's fixing the glass down? is it the metal angle on 3 sides?

 

 

 

Thats a pretty standard detail on this sort of flat rooflight. They are bonded down using high strength sealant and short of breaking the glass you will not remove them. The frame is then bonded to the glass too - usually 3 sides if it’s got a glass lip - and that overhangs the unit and the top of the upstand to stop someone cutting the sealant or  the unit being split. 

 

Other ones I’ve used have the top layer of glass 60-70mm larger than the other layers as that allows the removal of the cold bridge with the inner layer getting cold at its edges. 

 

First time I’ve seen galvanised steel for the edging though - normal detail is powder coated or anodised aluminium angle that is sealed to the glass after fitting. 

 

Airtightness is as simple as taping the airtight layer up into the top of the upstand and then bonding to the top of this. 

 

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I went through a lot of anxst on roof window, which was originally going to be a larger oblique quadrilateral with simple insulated timber upstands;

but advised to use a commercial system, which meant a simpler rectangle.

Fakro DXF-DV6 was the eventual outcome, and my builder's quote was not that much more than Roofing Superstore price.

Velux and Sunlux have similar offerings, but Fakro seemed a reputable system.

IIRC there were issues about delivery of larger items from RS too.

My note says U=0.76W/m2

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would it not be possible to replace the solid timber with jji's and pump the cavity with cellulose?

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11 hours ago, Simplysimon said:

would it not be possible to replace the solid timber with jji's and pump the cavity with cellulose?

 

 not now! MBC were too quick and openings are formed and have EPDM roofing on the outside of them. The potential problems just didn't pop up onto our radar till now. 

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