Skylight Upstands.

[Tony K]

Evening

Does anyone have a decent cross section or detail for timber skylight upstands that show insulation details, please?

 

My SB is single storey, flat roof, EPDM rubber roof, cold deck. 

 

I anticipate making the upstands out of ply sheets for the four faces, and framework inside, like a stud wall.

 

It's really the insulation detail that I'm unclear on. I understand that skylights can be significant cold bridges, so I want to get the insulation right. 

 

Cheers

Edited April 20, 2022 by Tony K

[tonyshouse]

Join insulation seamlessly with insulation in the ceiling, I would use something like 100mm pir outside the ply right up to under the presumed glass.

 

I like a good fall on the glass 3g with top pane over sailing on the low side 

[Dreadnaught]

This is for my flat roofloghts (I have nine in my new build). Hope it helps.

 

[JohnMo]

I have the same roof lights as above, but replaced the upstand shown with, Compacfoam CF200, from Green Building Store.

[Tony K]

Thanks @Dreadnaught that's very useful.

 

Is the upstand shown in the detail a pre-produced one? It doesn't look like something a person would make themselves.

 

I am veering towards making this kind of thing, then adding insulation into the gaps between the beams, and perhaps across the face of the beams too.

 

[Pocster]

9 minutes ago, Tony K said:

Thanks @Dreadnaught that's very useful.

 

Is the upstand shown in the detail a pre-produced one? It doesn't look like something a person would make themselves.

 

I am veering towards making this kind of thing, then adding insulation into the gaps between the beams, and perhaps across the face of the beams too.

 

I used firrings to get my ‘fall ‘ . Plan on using aerogel to insulate upstand internally .

[Tony K]

@pocster, what is the relative benefit of aerogel over PIR?

[Pocster]

2 hours ago, Tony K said:

@pocster, what is the relative benefit of aerogel over PIR?

Much thinner . I didn’t take insulation into account with my upstands . So plasterboard with aerogel is around 6mm I believe .

[Dreadnaught]

3 hours ago, Tony K said:

Is the upstand shown in the detail a pre-produced one?

 

No, not pre-produced by the manufacturer. It is for the customer to make their own up-stand. In my case I entrusted the up-stands (all nine of them, and complete with their 5º fall) to my timber-frame designer and the up-stands were installed along with the rest of the timber frame.

 

All I had to do was plonk the rooflights atop with some glue and screws. It was an easy install. In fact the biggest challenge was not the up-stands or the installation. It was getting the biggest of the rooflights, at 152 kg, on to the roof in the first place. (I am sitting under that rooflight now as I type this.)

[Tony K]

32 minutes ago, Dreadnaught said:

 

No, not pre-produced by the manufacturer. It is for the customer to make their own up-stand. In my case I entrusted the up-stands (all nine of them, and complete with their 5º fall) to my timber-frame designer and the up-stands were installed along with the rest of the timber frame.

 

All I had to do was plonk the rooflights atop with some glue and screws. It was an easy install. In fact the biggest challenge was not the up-stands or the installation. It was getting the biggest of the rooflights, at 152 kg, on to the roof in the first place. (I am sitting under that rooflight now as I type this.)

 

Thanks. What sort of size was the 152kg light?

[Dreadnaught]

2 hours ago, Tony K said:

What sort of size was the 152kg light?

 

2000 x 800, triple glazed, installed directly above the galley of my kitchen. Natural light for chopping the onions.

[Makeitstop]

Cheeky question, but.....

 

Dreadnought, can I ask what other glazing you have in this space, and is there any chance of a daylight picture of how light is transmitted into the room through this rooflight?

 

Also, what is the overall size of the room?

Edited April 21, 2022 by Makeitstop

[Gus Potter]

A few photos of mine.

 

Warm roof. Upstand 150mm, don't skimp on this as in the regs and also you get snow building up round about it, you also can get splashing from the rain.. funnily you can see this in the regs when they say a DPC should be 150mm above ground level.

 

Over kerb size in the photos is 1420 wide x 2855 long.

 

Upstand is framed in 95 x 45, 70mm PIR between and lapped with 200mm of PIR inder the EPDM covering so only 150mm is exposed at the 70mm insulation thickness.

 

Opted not to do insulated plasterboard on top as it was closing in the aperture. Instead accepted that the upstand would be less well insulated and did compensatory U value calc and upgraded the rest of the insulation. Basically the lantern was so expensive that there was no way I was going to shut down the effective opening any more than I had to.

 

Light is fantastic.

 

Still need to do the roof of the main house.. soon!

[Tony K]

Very nice @Gus Potter. I note your comments on the trade off between a smaller aperture and better insulation (although you've hardly scrimped, even in the upstand). I have a cold deck roof, and I feel that I will need to narrow the internal opening by lining the upstand with a little extra PIR to address the tendency for cold bridging. 

 

I am using a flat roof flat skylight, so I have to build a slight fall into the upstand, whereas you (I presume) would build yours flat and level to accept that lantern?

[hotnuts21]

Dont know if it helps, but we purchased our skylight from Vario by Velux and it came with its own upstand, pre insulated, sized etc. All we need is a hole in the roof and the inside drops down into the hole with a vapour barrier.

 

Paul

[Temp]

For comparison..

 

Spacetherm Aerogel - Lambda value: 0.014 W/mK

Typical PIR - Lambda value 0.022 to 0.026

New Kooltherm K100 - Lambda value: 0.018 W/mk

 

So yes Aerogel is better but you still need a decent thickness of it. It's not quite twice as good as standard PIR.

.