This is what I did when insulating the "slopey bits" of the ceilings in my house. However due to the inconsistent width from top to bottom I opted to use fibre glass at 65mm thick to maintain a 50mm air gap rather than kingspan type product. Worked a treat and made a big difference. I also insulated the vertical plasterboard walls at the same time with 75mm cavity wall pads and a small bit of ceiling from the rooms below. I finished it off with an extra 40mm of insulation on the sides of the dormer windows, that being the maximum I could do due to the window.
Cold bedrooms, condensation on curved ceilings.
- Thread starter Millhouse
- Start date
This is what I did when insulating the "slopey bits" of the ceilings in my house. However due to the inconsistent width from top to bottom I opted to use fibre glass at 65mm thick to maintain a 50mm air gap rather than kingspan type product. Worked a treat and made a big difference. I also insulated the vertical plasterboard walls at the same time with 75mm cavity wall pads and a small bit of ceiling from the rooms below. I finished it off with an extra 40mm of insulation on the sides of the dormer windows, that being the maximum I could do due to the window.
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No you cut a hole in the plasterboard to access the void behind it, by crawling in you can then install the insulation. There is no need to remove tiles. My roof is slated so it would all have had to been taken off to gain access, and being in Scotland it has sarking on as well making coming in roof side completely impractical.
Once finished I stuck some fresh plasterboard over the hole and plastered up. My plastering is not very good, but the hole is sufficiently small that it was feasible to sand it down and I would defy anyone to tell me where the hole was. If you have a radiator on the wall you could always take that off, and cut the hole behind that.
It was something of an unpleasant job as the space under the dorma window was very right, and I did it during the summer so it got roasting hot in their. In retrospect it would have been easier just to have pulled all the plasterboard off and installed the insulation though more expensive.
It was however worth it as last winter you could see the difference between my house and the rest of the street by how long the snow remained on the roof. The room is of course much warmer.
Oh I see. My void is only about 10 inches. Having thought and thought, I think that I will remove the raked part of the ceiling in one room and just see what is there. I plan to use 50 mm Celotex between the rafters and 25mm Celotex across the whole area. Then use 60mm screws to fix 12mm plasterboard over the top, thus sandwiching the 25mm between the rafters and the plasterboard (as suggested by Noseall last year.)
Thanks for all your suggestions and advice.
Thanks for all your suggestions and advice.
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Surely you can reach or see into the void from the loft ?
Or at least access the void from there.
If so, you could at least put some insulation between the rafters from there.
Simon.
Hi Simon, I think that you are right! I have so much insulation in my loft that I could not get right in to see, but I just had a look and I can get to it, though the roof is very low there. Am going to investigate now and will let you know how I get on. Thanks!
Charlie.
Charlie.
Well, thanks to Simon I have managed to get some Celotex sheets down the back of my raked ceilings. I was sure that the loft area was boxed so that I could not get to the sloping area. I was wrong. As it turned out, and as noseall had said, there was only 100mm between rafter and plaster. I was quite glad that I did'nt remove the ceiling as the max. insulation was 50mm anyway, though I could'nt insulate between the plaster/rafter. But I hope that I have made some improvement.
Thanks to everyone for their contributions!
Thanks to everyone for their contributions!
Useful thread as I have the same and decided to search here for a solution. 2" Kingspan was what I had in mind, glad to see that was successfully used. Thanks to you all for your comments and suggestions.
The simplest way bob is to overboard your ceiling with insulated plasterboard, the thicker the better and then get the ceiling re skimmed.
Yes that could be simpler, although I have to get a plasterer in and pay them. No doubt have to clear the room and deal with all the debris as well.
Kingspan I can do myself, wont be an easy job, will be very messy and itchy with the loft insulation, but the labour will be free!
Some of my ceilings have already been over boarded, so they don't suffer as much as other ceilings. I'm currently decorating one room and the emulsion paint wont dry on some parts of the ceiling slope! Having to warm the room well to get it to go off!
My main concern at the moment (without getting into the loft to look properly) is that the original ceiling will be lath and plaster. So the back of this in the loft area where I want to put the kingspan will not be flat as where the original plaster pushed through the laths it is likely to be ridged. Will have a good look at the weekend and see how it looks.
Just measure the gaps between the rafters, which should be roughly the same, cut a load of kingspan to size and then just get in the loft and fit. That's the plan anyway, time will tell.
Kingspan I can do myself, wont be an easy job, will be very messy and itchy with the loft insulation, but the labour will be free!
Some of my ceilings have already been over boarded, so they don't suffer as much as other ceilings. I'm currently decorating one room and the emulsion paint wont dry on some parts of the ceiling slope! Having to warm the room well to get it to go off!
My main concern at the moment (without getting into the loft to look properly) is that the original ceiling will be lath and plaster. So the back of this in the loft area where I want to put the kingspan will not be flat as where the original plaster pushed through the laths it is likely to be ridged. Will have a good look at the weekend and see how it looks.
Just measure the gaps between the rafters, which should be roughly the same, cut a load of kingspan to size and then just get in the loft and fit. That's the plan anyway, time will tell.
It's something I have "in the plans" as well. I'm assuming that the ceiling joists will be nailed to the side of the rafters - which means the insulation slabs will need a corner cut out. And unless fed in from the bottom, will need to be fed in in two pieces - an L shape to go down and then sideways, followed by a parallel slab to fill the rest of the gap.
Is it worth trying to foam in the gaps - or is that generally just impossible, and very messy ?
Pity it wasn't done when the house was re-roofed a few years ago
As to why they did ceilings like that, my assumption was to reduce the overall height of the house - which in turn would remove around a foot of height from all the external (brick) walls. Whether it was for cost or practical considerations I've no idea, or perhaps it was just an aesthetics thing. For a narrow house, it may make the proportions "look right".
Is it worth trying to foam in the gaps - or is that generally just impossible, and very messy ?
Pity it wasn't done when the house was re-roofed a few years ago
As to why they did ceilings like that, my assumption was to reduce the overall height of the house - which in turn would remove around a foot of height from all the external (brick) walls. Whether it was for cost or practical considerations I've no idea, or perhaps it was just an aesthetics thing. For a narrow house, it may make the proportions "look right".
Good thought about the corner requiring to be cut out, hadent thought about that!
When I did my sloped edges I cut the boards in half so they could be wedged in place in two halves.
Some screws teased in place from underneath help keep the boards flat in place in strong winds, and I retain a 2" air gap.
View media item 51865 View media item 51866
Some screws teased in place from underneath help keep the boards flat in place in strong winds, and I retain a 2" air gap.
View media item 51865 View media item 51866
At our last house I did this in two room as I did a load of "catch up" work. At first it caused a certain amount of domestic friction - SWMBO was thinking 2 or 3 days and sime paint, it took my a year/room. She was happy with the result in the end - esoecially the storage cuoboard I made by opening up the wasted soace above the stairs.
I pulled the sloping section of ceiling off, battened the rafters so the insulation I already had would fit, put 100mm between the rafters (foamed the gaps all round), put another 100mm underneath, re-boarded and had it skimned (both rooms needed major work on the plastering anyway).
200mm of "Celotex" made a huge difference
Then just after I'd git the second room finished, a few things came together and we moved. So some time I'll get to do it all again in this house
I pulled the sloping section of ceiling off, battened the rafters so the insulation I already had would fit, put 100mm between the rafters (foamed the gaps all round), put another 100mm underneath, re-boarded and had it skimned (both rooms needed major work on the plastering anyway).
200mm of "Celotex" made a huge difference
Then just after I'd git the second room finished, a few things came together and we moved. So some time I'll get to do it all again in this house
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