Roof Insulation
Sep. 18th, 2007 06:58 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
armbI've been up in our loft recently, putting more lights in and then some boarding to be able to get to where I have (finally) made a little more progress on the plumbing. And, coincidentally, got a flyer from our District Council about loft insulation (and grants we don't qualify for).
But most of our roof isn't above the loft, it's sloping wall/ceiling on the first floor. So any insulation has to fit in between 200mm rafters. So doubling the existing 150mm fibreglass and 50mm ventilation space can't be done with another 150mm of glass, it needs Kingspan, Celotex, or similar foam (which is twice as insulating at the same thickness - if properly sealed, which might be tricky to do in place). Which I estimate at about £3000 for the whole[1] roof at "buying leftovers and seconds on eBay" prices (it's a big roof). So, not going to happen, at least not now.
[1] Ignoring the fact that the room that would most benefit has no loft over it, so we'd need to take the tiles and felt off from outside to do that.
However, quite a lot of the existing stuff isn't actually "and 50mm ventilation", because the corrugated plastic thing that keeps the air gap clear is missing. Travis Perkins knew what I meant but didn't have any, I haven't tried Ridgeons yet. But if anyone (![[livejournal.com profile]](https://www.dreamwidth.org/img/external/lj-userinfo.gif)
micktim?) knows what it's officially called and/or where I can get some, that would be good. Photo.
(Suggestions on cheaper alternative methods of improving the insulation welcomed too.)
(Much later - apparently it's a "rafter tray" - but finding one which could be retrofitted looks tricky.)
[EDIT: Except thinking about it some more, the whole "roof not over the loft" thing means that between-rafter application notes aimed at warm roofs aren't necessarily relevent, so maybe it's supposed to be that way with only a few ventilation things after all. But is the sloping wall/ceiling really going to be a perfect vapour barrier? The fact that some parts have no insulation down at all is just wrong though. And the (existing) lighting wiring could be a lot neater.]
But most of our roof isn't above the loft, it's sloping wall/ceiling on the first floor. So any insulation has to fit in between 200mm rafters. So doubling the existing 150mm fibreglass and 50mm ventilation space can't be done with another 150mm of glass, it needs Kingspan, Celotex, or similar foam (which is twice as insulating at the same thickness - if properly sealed, which might be tricky to do in place). Which I estimate at about £3000 for the whole[1] roof at "buying leftovers and seconds on eBay" prices (it's a big roof). So, not going to happen, at least not now.
[1] Ignoring the fact that the room that would most benefit has no loft over it, so we'd need to take the tiles and felt off from outside to do that.
However, quite a lot of the existing stuff isn't actually "and 50mm ventilation", because the corrugated plastic thing that keeps the air gap clear is missing. Travis Perkins knew what I meant but didn't have any, I haven't tried Ridgeons yet. But if anyone (
micktim?) knows what it's officially called and/or where I can get some, that would be good. Photo.(Suggestions on cheaper alternative methods of improving the insulation welcomed too.)
(Much later - apparently it's a "rafter tray" - but finding one which could be retrofitted looks tricky.)
[EDIT: Except thinking about it some more, the whole "roof not over the loft" thing means that between-rafter application notes aimed at warm roofs aren't necessarily relevent, so maybe it's supposed to be that way with only a few ventilation things after all. But is the sloping wall/ceiling really going to be a perfect vapour barrier? The fact that some parts have no insulation down at all is just wrong though. And the (existing) lighting wiring could be a lot neater.]