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?

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

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

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.

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

Absolutely, the case for warm deck is clear and convincing. However, a cold deck van work perfectly well with adequate ventilation.

Interesting. I know some of the pro-warm deck arguments, and they all seem sensible (I'd have gone warm deck myself under different circumstances) but am not familiar with such anti-cold deck arguments that would make the good folk of Scotland ban them. Is it a different reading of the same technical pros and cons, or is it that parts of Scotland literally have a different climate to England that results in such a divergence in the regs? I'm currently getting my head around the apparent conflict between my cold deck and a vapour barrier, by the way!

I'm very close to other houses so went for the lowest height I could. How do you mean you're not allowed to use a cold deck? Who forbids it, and on what basis?

Yes it is.

I'm sure I've seen board lifters that double up as trolleys to help get boards where needed. I shouldn't think they can climb stairs of course...

A Labour exchange is an excellent idea. It could also be an opportunity to learn a bit from each other on site. Unfortunately you're too far away from me, but good luck.

Some interesting ideas here, thanks. The idea is to fix the ply deck in place, and get the epdm up and at least resting in place all as one operation if possible, so as to minimise the time the ply is exposed to the risk of rain. I'll have at least one other person with me when I do all this, so I reckon I'll hire a genie for the day, and possibly a block tackle kit, then work my way through the various options. My concern about using the joists to winch the roll up, especially if I use a counter weight, is the amount of stress I'm placing on the joists. The whole of the joists are resting on a wall plate at one end (only on the inside leaf), but at the other end (above the steel) only the top chord of the joist is resting, and I may be taking a risk relying on that to take the weight.

Leaving aside whether the joist can take being used in the ways suggested above, the ply boards that will sit under the rubber need to be installed to some extent or I'll have nothing to rest the rubber on when I get it up to roof height. The normal way is to have all the boards fixed in place before getting the rubber up there, but I can look into winching or pulleying it up. Thanks

If the EPDM comes on a central cardboard roll, I could run a scaffold pole through the centre of the roll, then (having placed the roll adjacent to the wall) place something under each end of the pole, allowing it to rotate. I then take the end of the rubber and feed it up onto the roof (as per my sketch), like unrolling a giant toilet roll, except upwards. That could work?

Ha! The SB is adjacent to our current house, and the whole place is accessible only by footpaths. Once, as part of renovating our current house I moved a 300kg 4m long, 40cm depp, 50cm wide green Oak Beam down a 80m long, 1m wide footpath using timber rollers like something from ancient times. Then I used a genie to lift it up near the opening it was to span. Then I realised I couldn't get it across from the genie to its destination. Then I rested the beam on two piles of blocks at either end while, underneath the resting beam, I built a platform of scaffold boards across the threshold. Then I heaved the genie up onto the scaffold board platform. Then I lifted the beam, from its centre, up to the required height (each turn of the genie handle made the beam see-saw precariously). Then, once the beam was up at the right height and perched on the genie above head height, I (and this is the best bit) unlocked the genie wheels in the hope I could roll the genie, with 300kg beam balanced on top, gently forward into position. The laws of physics had other ideas, but I just about got away with it. I could have made a grand at least out of You've Been Framed that day!