Insulating rafters
Discussion
I've started the process of converting a bathroom into a bedroom and while I'm at it want to add some insulation to the sloped part of the ceiling and the purlin wall in the photo below (above the flat part of the ceiling is a new loft conversion with tonnes of insulation already).
The house is Edwardian and has a boarded roof. The rafters / studs are about 100mm wide. Am I right in thinking that after I've pulled off the plaster I should add 50mm of celotex or similar to that sloped part (leaving a 50mm airflow gap on the roof side) and the full 100mm to the purlin wall?
Do I need to add a vapour barrier before plasterboard and should I be thinking about insulated plasterboard on top or is 50mm decent enough?
The house is Edwardian and has a boarded roof. The rafters / studs are about 100mm wide. Am I right in thinking that after I've pulled off the plaster I should add 50mm of celotex or similar to that sloped part (leaving a 50mm airflow gap on the roof side) and the full 100mm to the purlin wall?
Do I need to add a vapour barrier before plasterboard and should I be thinking about insulated plasterboard on top or is 50mm decent enough?
I think you've got the right idea, 50mmm to the ceiling slopes, leaving a gap over the top for ventilation, 100mm to the walls(might as well you've come this far) vapour barrier over the insulation then plasterboard. You could use an insulated plaster board to stop any cold bridging through the timbers, you can get cheapo 22mm thick ones if you don't want to lose too much room.
In an area like that where space is a premium I would consider Superquilt.
Staple over your studwork/rafter, then batten over the top and attach plasterboard.
One layer of that will give you the same results as 100mm Celotex.
I used it in my conservatory, I nearly didn't as lost of people said "It is snake oil" or "It doesn't work anywhere near as well as Celotex". But just as I was going to go the Celotex route a customer of mine said he was doing all his barn conversions with it and getting great results.
It was covering a pitched roof (polycarbonate sheets) in a room 7m x 7m with a 2.5m ceiling.
It is now the warmest room in the house, never goes above 22ºc in summer and with just a single 2kw electric rad stays at a toasty 21ºc.
I have the rad set to 21ºc to come on at 7am for 1h30mins, then again at 3pm till 11pm. You can see the light come on and off as the thermostat kicks on/off and I would say it is on for approximately 50% of the time, which to me shows the heat loss is minimal.
As we have poly rooffing sheets above the idea was to do the Superquilt first and then add either 50mm or 100mm depending what we felt we needed and go in from above.
Not needed to add any.
I have an attic bedroom and bathroom with nothing but plasterboard between the room and the tiles!
The bathroom is accessible from the other end of the house, it is sort of box in the end of the loft space, I added the Superquilt around the outside of that box, and it has gone from being a room where even with the rad on full it struggled to get above 17-18ºc during winter nights to one that is now often 23ºc when the main 'stat is set to 19ºc in the hallway downstairs, the difference is stunning.
I will do the main bedroom this year too. I am actually thinking about stapling the quilt to the existing walls and ceiling and then battening it out and plaster boarding over the top. Save a whole lot of mess.
I did the superfoil, battens and plasterboard in around 9 hours in the conservatory, oh, and no mess.
Staple over your studwork/rafter, then batten over the top and attach plasterboard.
One layer of that will give you the same results as 100mm Celotex.
I used it in my conservatory, I nearly didn't as lost of people said "It is snake oil" or "It doesn't work anywhere near as well as Celotex". But just as I was going to go the Celotex route a customer of mine said he was doing all his barn conversions with it and getting great results.
It was covering a pitched roof (polycarbonate sheets) in a room 7m x 7m with a 2.5m ceiling.
It is now the warmest room in the house, never goes above 22ºc in summer and with just a single 2kw electric rad stays at a toasty 21ºc.
I have the rad set to 21ºc to come on at 7am for 1h30mins, then again at 3pm till 11pm. You can see the light come on and off as the thermostat kicks on/off and I would say it is on for approximately 50% of the time, which to me shows the heat loss is minimal.
As we have poly rooffing sheets above the idea was to do the Superquilt first and then add either 50mm or 100mm depending what we felt we needed and go in from above.
Not needed to add any.
I have an attic bedroom and bathroom with nothing but plasterboard between the room and the tiles!
The bathroom is accessible from the other end of the house, it is sort of box in the end of the loft space, I added the Superquilt around the outside of that box, and it has gone from being a room where even with the rad on full it struggled to get above 17-18ºc during winter nights to one that is now often 23ºc when the main 'stat is set to 19ºc in the hallway downstairs, the difference is stunning.
I will do the main bedroom this year too. I am actually thinking about stapling the quilt to the existing walls and ceiling and then battening it out and plaster boarding over the top. Save a whole lot of mess.
I did the superfoil, battens and plasterboard in around 9 hours in the conservatory, oh, and no mess.
Thanks, it's only a small area so don't mind the extra cost for insulated PB if we will notice a difference. It's the coldest room in the house
So if we go 50mm in rafters then 1000 gauge polythene then 50mm+12.5 insulated plasterboard we'd be looking pretty good? Is it ok to have the vapour barrier between the two foil surfaces like that?
So if we go 50mm in rafters then 1000 gauge polythene then 50mm+12.5 insulated plasterboard we'd be looking pretty good? Is it ok to have the vapour barrier between the two foil surfaces like that?
gizlaroc said:
In an area like that where space is a premium I would consider Superquilt.
Staple over your studwork/rafter, then batten over the top and attach plasterboard
Our posts crossed - this is very interesting and appealing, especially as it sounds so quick! Off to research it now but I assume no need for any sort of vapour barrier with this stuff? Huge time saving not having to put 50mm battens in to maintain the air gap and then sawing all the celotex etc. Almost sounds too good to be true!Staple over your studwork/rafter, then batten over the top and attach plasterboard
That's what I thought when I used it, but so pleased I did.
I bought 3 rolls of eBay for about £200 which gave me 45 square metres, always people who have over bought on a job.
This was my conservatory once stapled on and battened out...
This should give you an idea on the size of the room...
As I said, the idea was to add hopefully 50mm of Celotex from above, 100mm if the quilt didn't perform as well as we hoped. That was 2 years ago and we use that as our main room now, all year round with absolutely no need for any Celotex. Makes me wonder why the building regs ask for so much insulation?
I fell asleep in there the other night, it was -3ºc outside when we came back from a meal, and the rad goes off at 11pm on a Saturday night and I woke up at 5am and it was still 18ºc in there.
It used to get to 35ºc in summer in there when 30ºc outside, now when 30ºc outside it only gets to 22ºc in there, even with the big windows which are south facing. It does an incredible job.
I bought 3 rolls of eBay for about £200 which gave me 45 square metres, always people who have over bought on a job.
This was my conservatory once stapled on and battened out...
This should give you an idea on the size of the room...
As I said, the idea was to add hopefully 50mm of Celotex from above, 100mm if the quilt didn't perform as well as we hoped. That was 2 years ago and we use that as our main room now, all year round with absolutely no need for any Celotex. Makes me wonder why the building regs ask for so much insulation?
I fell asleep in there the other night, it was -3ºc outside when we came back from a meal, and the rad goes off at 11pm on a Saturday night and I woke up at 5am and it was still 18ºc in there.
It used to get to 35ºc in summer in there when 30ºc outside, now when 30ºc outside it only gets to 22ºc in there, even with the big windows which are south facing. It does an incredible job.
roofer said:
http://www.thermablok.co.uk/products/thermabloksp-...
And
http://www.thermablok.co.uk/wp/wp-content/uploads/...
On a loft conversion where purlins are being removed and rafters increased in depth, how would you recommend insulating? Is this sort of stuff worth using or is celotex still the way to go?And
http://www.thermablok.co.uk/wp/wp-content/uploads/...
gizlaroc said:
In an area like that where space is a premium I would consider Superquilt.
Staple over your studwork/rafter, then batten over the top and attach plasterboard.
One layer of that will give you the same results as 100mm Celotex.
Can you tell me where you found that info ?Staple over your studwork/rafter, then batten over the top and attach plasterboard.
One layer of that will give you the same results as 100mm Celotex.
I've had a quick google as I'm sceptical of these products and I cannot find it's actual U value, I can only find values combined with other products.
The best I can find is:
"SuperQuilt is Equivalent to 200mm of Glass Wool in a two layer Roof Application"
So two layers = 200mm glass wool = (roughly) 100mm celotex.
V8RX7 said:
Can you tell me where you found that info ?
I've had a quick google as I'm sceptical of these products and I cannot find it's actual U value, I can only find values combined with other products.
The best I can find is:
"SuperQuilt is Equivalent to 200mm of Glass Wool in a two layer Roof Application"
So two layers = 200mm glass wool = (roughly) 100mm celotex.
That was what they were saying when I did it a couple of years back. I've had a quick google as I'm sceptical of these products and I cannot find it's actual U value, I can only find values combined with other products.
The best I can find is:
"SuperQuilt is Equivalent to 200mm of Glass Wool in a two layer Roof Application"
So two layers = 200mm glass wool = (roughly) 100mm celotex.
I was thinking about this more this morning. I think what they said was, I could use the Superquilt in the loft along with the Celotex instead of 75mm under the rafters, or use two layers instead of using the 100mm between the rafters if we used a 40mm insulated board, something like that. We didn't do the loft in the end so can't remember.
Edited by gizlaroc on Thursday 19th January 10:20
roofer said:
http://www.thermablok.co.uk/products/thermabloksp-...
And
http://www.thermablok.co.uk/wp/wp-content/uploads/...
Do they put gold in that ?And
http://www.thermablok.co.uk/wp/wp-content/uploads/...
gizlaroc said:
In an area like that where space is a premium I would consider Superquilt.
Staple over your studwork/rafter, then batten over the top and attach plasterboard.
One layer of that will give you the same results as 100mm Celotex.
Staple over your studwork/rafter, then batten over the top and attach plasterboard.
One layer of that will give you the same results as 100mm Celotex.
although it is better than celotex
R-value
50mm Celotex 2.25m²K/W
40mm Superquilt 2.70m²K/W
100mm
Celotex 4.50m²K/W
Edited by dmsims on Thursday 19th January 03:07
dmsims said:
R-value
50mm Celotex 2.25m²K/W
40mm Superquilt 2.70m²K/W
100mm Celotex 4.50m²K/W
50mm Celotex 2.25m²K/W
40mm Superquilt 2.70m²K/W
100mm Celotex 4.50m²K/W
roofer said:
http://www.thermablok.co.uk/products/thermabloksp-...
And
http://www.thermablok.co.uk/wp/wp-content/uploads/...
R-value 0.714 at 10mm thickAnd
http://www.thermablok.co.uk/wp/wp-content/uploads/...
dmsims said:
roofer said:
Do they put gold in that ?roofer said:
dmsims said:
roofer said:
Do they put gold in that ?Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff