Insulation: Multilayer foils vs Celotex
Discussion
Hi chaps,
It's that time of year, my attic conversion is old school and freezing.
A trade friend mentioned multilayer Superfoil SF60 with an R value of 4.63 as an alternative to Celotex etc
This has a lot of appeal in terms of fitting as I can just bang it up under the rafters instead of sawing and taping bits of Celotex which is a tedious job.
So, anyone used this stuff? Thoughts?
It's that time of year, my attic conversion is old school and freezing.
A trade friend mentioned multilayer Superfoil SF60 with an R value of 4.63 as an alternative to Celotex etc
This has a lot of appeal in terms of fitting as I can just bang it up under the rafters instead of sawing and taping bits of Celotex which is a tedious job.
So, anyone used this stuff? Thoughts?
Thermal Economics offer a few solutions - http://www.thermal-economics.co.uk/products/therma...
Its not cheap and we only tend to use it if head height is at a premium.
Its not cheap and we only tend to use it if head height is at a premium.
barryrs said:
Its not cheap and we only tend to use it if head height is at a premium.
We offer it as a solution, too, but I don't tend to specify it much.Even when head height is at a premium, you have to remember that for a multifoil to work effectively, it needs a battened void next to it so that the multiple layers are uncompressed. By the time you've allowed the thickness of this battened void, you might as well have just used a PIR/plasterboard thermal laminate, which gives you better insulation for an equally thin structural element.
With timber frame, it can be useful when you are planning to have an internal battened service void, anyway, but even then, as barryrs says, it's not a cheap solution.
MintSprint said:
We offer it as a solution, too, but I don't tend to specify it much.
Even when head height is at a premium, you have to remember that for a multifoil to work effectively, it needs a battened void next to it so that the multiple layers are uncompressed. By the time you've allowed the thickness of this battened void, you might as well have just used a PIR/plasterboard thermal laminate, which gives you better insulation for an equally thin structural element.
With timber frame, it can be useful when you are planning to have an internal battened service void, anyway, but even then, as barryrs says, it's not a cheap solution.
^WHSEven when head height is at a premium, you have to remember that for a multifoil to work effectively, it needs a battened void next to it so that the multiple layers are uncompressed. By the time you've allowed the thickness of this battened void, you might as well have just used a PIR/plasterboard thermal laminate, which gives you better insulation for an equally thin structural element.
With timber frame, it can be useful when you are planning to have an internal battened service void, anyway, but even then, as barryrs says, it's not a cheap solution.
Also, if you are upgrading the insulation, you may have to comply with current building regs (if you tell building control) and multifoil alone won't get you there.
DoubleSix said:
So is multilayer foil snake oil or not?
Not snake oil, but its a solution to a very specific problem: that of bumping up the U-value when you've only got a very limited thickness available to do it in.Remember that thermal resistance is a measure of how much a material resists heat transfer for a given thickness.
You need to multiply the resistance by the thickness (which effectively gives you the U-value), to get an idea of how much heat loss it's preventing. Multifoils have a very good resistivity, but very little thickness, so the total insulation effect isn't all that amazing. By comparison, a PIR foam like Celotex has a pretty good thermal resistivity and quite a bit of thickness, so multiply the two together and you're looking at something much more effective.
Ok, so given the Superfoil SF60 product im looking at is 100mm thick (not that thin) am I right in thinking this an easy install alternative to Celotex, Kingspan et al?....
http://www.just-insulation.com/002-brands/superfoi...
http://www.just-insulation.com/002-brands/superfoi...
I used it on a couple of lofts a fews back. There was a big debate going on about its claimed u values so LABC stopped us using it for a while. I quite liked it, it wasnt cheaper but saved loads of time and mess, it takes up far less storage ( try getting 20 8x4 sheets in a loft) and is much nicer to work with, celotex dust is not nice stuff. We did go back to using 2 layers of Celotex as most of the building inspectors prefered that method, but it does have its uses.
We used it on our loft conversion, but I also used insulated polystyrene, as I didn't completely trust it!
I think it would be great in principle when installed in perfect conditions, but that's probably down to airtightness rather than its thermal properties. I found it pretty easy to install in big areas, but detailing around the trusses and edges to avoid condensation or cold bridges was tricky.
So we battened out to create a second air space and then boarded out in this stuff; http://www.kingspaninsulation.co.uk/Products/Koolt...
I think it would be great in principle when installed in perfect conditions, but that's probably down to airtightness rather than its thermal properties. I found it pretty easy to install in big areas, but detailing around the trusses and edges to avoid condensation or cold bridges was tricky.
So we battened out to create a second air space and then boarded out in this stuff; http://www.kingspaninsulation.co.uk/Products/Koolt...
How do you fix it if it's 100mm thick? Staples won't work as they'll compress it to nothing. And how do you join it - tape won't work as it's presumably multiple layers of foil/bubble wrap.
Reflectivity and airtightness when installed right are positives, but the fact that some BC depts don't like it speaks volumes imho.
Reflectivity and airtightness when installed right are positives, but the fact that some BC depts don't like it speaks volumes imho.
andy43 said:
How do you fix it if it's 100mm thick? Staples won't work as they'll compress it to nothing. And how do you join it - tape won't work as it's presumably multiple layers of foil/bubble wrap.
Reflectivity and airtightness when installed right are positives, but the fact that some BC depts don't like it speaks volumes imho.
Well, that was type of discussion I was hoping to get into!Reflectivity and airtightness when installed right are positives, but the fact that some BC depts don't like it speaks volumes imho.
I called the manufacturer and they state it compresses to 20mm where it is stapled (around the edge). I don't think there's any issue with taping together as the outer sheets are heavy duty foil. There are around forty layers, no bubbles that I'm aware of...
The chap above mentions £10 a metre which again shows people have other products in mind - the stuff i have linked to above is not cheap!! Around £180 a roll. Maybe why BCs dont like it?
An expensive but easier to work with solution??
TA14 said:
Why not just run it across the lower edge of the rafters, stapling in the middle of each rafter? That would be quick, easy and effective for a storage area.
Yeah could. But a lot of strain on a few staples then. Battens would allow staples every 20cms as recommended.But tbh I started the topic as I'm interested in the efficacy of the product itself, installation not really an issue.
So far, only anecdotal or 'reckoning' has been put forward as a reason not to use it which isn't enough for me to dismiss what appears to be a good product. Especially when most seem to be refering to the thin stuff that makes big claims....
I am disappoint.
To be fair to the PH commumity I thought that this was quite a good post
Little Lofty said:
I used it on a couple of lofts a fews back. There was a big debate going on about its claimed u values so LABC stopped us using it for a while. I quite liked it, it wasnt cheaper but saved loads of time and mess, it takes up far less storage ( try getting 20 8x4 sheets in a loft) and is much nicer to work with, celotex dust is not nice stuff. We did go back to using 2 layers of Celotex as most of the building inspectors prefered that method, but it does have its uses.
TA14 said:
To be fair to the PH commumity I thought that this was quite a good post
Absoultely. I'm hanging on to it as an example of real world experience and someone who understood the OP.Little Lofty said:
I used it on a couple of lofts a fews back. There was a big debate going on about its claimed u values so LABC stopped us using it for a while. I quite liked it, it wasnt cheaper but saved loads of time and mess, it takes up far less storage ( try getting 20 8x4 sheets in a loft) and is much nicer to work with, celotex dust is not nice stuff. We did go back to using 2 layers of Celotex as most of the building inspectors prefered that method, but it does have its uses.
Cheers Lofty!
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