Home |
Search |
Today's Posts |
|
UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
Hi, Im in the process of insulating the roof of my garage. I am planning on using 50mm Celotex between the rafters. Due to cost, I was planning on using 25mm polysterene from B&Q over. Would I still need the vapour barrier plasterboard ? Or if I ditch the polysterene could I just tape up the joints where the Celotex meets the rafters and use standard plasterboard ? Thanks, Matt |
#2
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
|
#3
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
|
#5
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
On Wed, 29 Nov 2006 13:43:20 +0000 The Natural Philosopher wrote :
Whereas the extra cost of the foil backed plasterboard is probably about 10p for the same area.. If you can find it in stock .... Wickes don't sell it, not mine anyway -- Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk |
#6
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
wrote in message oups.com... Hi, Im in the process of insulating the roof of my garage. I am planning on using 50mm Celotex between the rafters. Due to cost, I was planning on using 25mm polysterene from B&Q over. Would I still need the vapour barrier plasterboard ? Or if I ditch the polysterene could I just tape up the joints where the Celotex meets the rafters and use standard plasterboard ? why plasterboard a garage roof/ceiling? Plasterboard won't perform well in an unheated building. Where foil backed PB is specified in construction it's to prevent warm moist air from an inhabited space condensing out in a cold space. You seem to be expecting the vapour barrier to prevent moisture vapour entering your garage. Not necessary due to ventilation of the garage space and would be a bad thing for your roof structure. Jim A |
#7
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
The Natural Philosopher wrote:
Ian Stirling wrote: wrote: Hi, Im in the process of insulating the roof of my garage. I am planning on using 50mm Celotex between the rafters. Due to cost, I was planning on using 25mm polysterene from B&Q over. Would I still need the vapour barrier plasterboard ? Or if I ditch the polysterene could I just tape up the joints where the Celotex meets the rafters and use standard plasterboard ? Take sheet of non-vapour barrier plasterboard. Dilute PVA to milk-like consistency. Arrange some way to prop up the sheet so that it's off the floor, vertical, or sloping slghtly backwards, with the long side parallel to the floor. Spray a meter with the PVA solution from a small pump-up sprayer. Lay two lines of kitchen foil, slightly overlapping. Spray another meter, repeat. This gets you a foil coated bit of plasterboard for well under 30p, and in under 5 min or so. Whereas the extra cost of the foil backed plasterboard is probably about 10p for the same area.. Oh well. I got quoted an extra fiver per sheet. Kitchen foil is only 10p/sheet or so. |
#8
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
|
#9
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
Hugo Nebula abuse@localhost wrote:
On 29 Nov 2006 04:07:48 -0800, a particular chimpanzee named randomly hit the keyboard and produced: Im in the process of insulating the roof of my garage. I am planning on using 50mm Celotex between the rafters. Due to cost, I was planning on using 25mm polysterene from B&Q over. snip You'll get better value from your insulation if you use the Celotex over the rafters and the polystyrene between. There is heat lost through the rafters and the more insulation you can cover them with the better. To put some numbers on this - wood has a conductivity of about three times that of rockwool or polystyrene, and six times that of kingspan. |
#10
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
In article ,
Tony Bryer writes: On Wed, 29 Nov 2006 13:43:20 +0000 The Natural Philosopher wrote : Whereas the extra cost of the foil backed plasterboard is probably about 10p for the same area.. If you can find it in stock .... Wickes don't sell it, not mine anyway Mine does, and since it's only a few hundred yards away, that's where I buy it. I think they might have foil-backed only in 9mm though. -- Andrew Gabriel |
#11
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
I am planning on using 50mm Celotex between the rafters. Due to cost,
I was planning on using 25mm polysterene from B&Q over. Technically, the top layer of insulation has to be better or the same than the bottom layer of insulation. That means that if you have 50mm Celotex between the rafters, you can have either have up to 50mm below the rafters, or 50mm or more above the rafters. The top layer being polystyrene makes it even worse. This is to avoid condensation forming between the insulation layers. If you are going to suck it and see, then DEFINITELY use vapour check plasterboard, as that will significantly reduce the problem. Taping the celotex with foil tape would, I presume, have a similar function to vapour check p/b. Christian. |
#12
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
Ian Stirling wrote:
The Natural Philosopher wrote: Ian Stirling wrote: wrote: Hi, Im in the process of insulating the roof of my garage. I am planning on using 50mm Celotex between the rafters. Due to cost, I was planning on using 25mm polysterene from B&Q over. Would I still need the vapour barrier plasterboard ? Or if I ditch the polysterene could I just tape up the joints where the Celotex meets the rafters and use standard plasterboard ? Take sheet of non-vapour barrier plasterboard. Dilute PVA to milk-like consistency. Arrange some way to prop up the sheet so that it's off the floor, vertical, or sloping slghtly backwards, with the long side parallel to the floor. Spray a meter with the PVA solution from a small pump-up sprayer. Lay two lines of kitchen foil, slightly overlapping. Spray another meter, repeat. This gets you a foil coated bit of plasterboard for well under 30p, and in under 5 min or so. Whereas the extra cost of the foil backed plasterboard is probably about 10p for the same area.. Oh well. I got quoted an extra fiver per sheet. Kitchen foil is only 10p/sheet or so. enough for mow much? and then add in glue, your time...? I didn't think plasterboard was much more than a fiver a sheet last time I looked anyway.. |
#13
Posted to uk.d-i-y
|
|||
|
|||
Celotex between rafters, polstyrene over. Vapour barrier ?
The Natural Philosopher wrote:
Ian Stirling wrote: The Natural Philosopher wrote: Ian Stirling wrote: wrote: Hi, Im in the process of insulating the roof of my garage. I am planning on using 50mm Celotex between the rafters. Due to cost, I was planning on using 25mm polysterene from B&Q over. Would I still need the vapour barrier plasterboard ? Or if I ditch the polysterene could I just tape up the joints where the Celotex meets the rafters and use standard plasterboard ? Take sheet of non-vapour barrier plasterboard. Dilute PVA to milk-like consistency. snip This gets you a foil coated bit of plasterboard for well under 30p, and in under 5 min or so. Whereas the extra cost of the foil backed plasterboard is probably about 10p for the same area.. Oh well. I got quoted an extra fiver per sheet. Kitchen foil is only 10p/sheet or so. enough for mow much? and then add in glue, your time...? I didn't think plasterboard was much more than a fiver a sheet last time I looked anyway.. I got quoted 10 quid a sheet for vapour barrier, 5 for not. Tesco do foil for 68p for 3m^2. It used about a litre of PVA for 24 sheets. It takes about 3 minutes per sheet to do (once I stopped being silly and getting a perfect mirror finish on each sheet of plasterboard, with no wrinkles and perfect butting joins, which was admittedly very pretty, but diddn't add a whole lot). |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Vapour barrier question | Home Repair | |||
Between rafters insulation - cheaper then Celotex? | UK diy | |||
Vapour barrier in loft conversion... | UK diy | |||
installing vapour barrier | Home Repair | |||
Effectiveness of Celotex/Kingspan insulation on rafters? | UK diy |