Warm Roof

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Does anyone know how to convert a cold vented at the eves roof with tiles and sarking, to a warm roof? Is sealing up the air vents, installing insulation and putting a layer or two of vapour barrier enough? A vapour barrier under plasterboard should prevent any warm moist air getting to the sarking.
thx
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The first thing is that you don't want to seal the vents at the eaves. You will still need the airflow past the rafters to avoid rot. Assuming 100mm rafters, I'd use 50mm Celtoex between them, with another 50mm of Celotex fixed to the rafters, and with joints sealed. Then plasterboard. I'd also include ridge vents at the apex of the roof.
Cheers Clive
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But that's not a warm roof. Warm roofs have all the insulation above the rafters, and ventilation and vapour barriers are unnecessary. That means stripping and relaying the tiles and battens.
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On this subject, has anybody used "Framefoil" which is sold by Sheffield Insulations. It is a series of thin silver foils and felt (11 layers I believe) which is fixed (stapled?) to the underside of rafters, before then fixing the plasterboard. This eliminates the cutting of the Celotex/Kingspan to fit between the rafters, and then huge amount of waste; ever noticed the amount of Celotex in the skip outside a loft conversion? It's still a cold roof, but I'm surprised it's not used more often.
IanC

You
100mm
also
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On Thu, 15 Jan 2004 19:13:49 -0000, a particular chimpanzee named
and produced:

It sounds very similar to Tri-Iso Super 9. (http://www.enigma-insulations.co.uk/triiso.asp ) It has been accepted in my area on loft conversions, despite not having a BBA certificate (nor any european equivalent). It has a (questionable) test certificate from TRADA as having the equivalent U-value to 200mm Rockwool.
--
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This Framefoil also does not have a BBA certificate, I believe it's Finnish or Norwegian, but as you say, its been accepted as achieving the 0.3 loft conversion standard, and (I suppose sheeplike) I've also been accepting it.
RT
randomly hit the keyboard

then
waste;
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I was going to say smoke & mirrors, quite appropriate really as all the foil based insulations seem to work by reducing radiated losses and need a significant airgap (without air movement) to achieve their 'results'. So fine if you can create an even, sealed airgap _and_ the foil retains it's mirror like finish over the years.
--
fred

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randomly hit the keyboard

then
waste;
I looked at the web site. Is there any independent tests on this stuff? Is it cheaper than Kingspan? The left hand picture is the normal roof arrangement. It looks easy to fit by pining to the rafters, batons and then plasterboard. It doesn't mention if the eves vents should still be there. If this stuff works then this is the way to go for loft conversions.
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When first I came across it in a loft conversion, I couldn't find out much about it, so via Sheffield Insulations spoke to their supplier (the details are at work) and they informed me of the either Finnish or Norwegian tests it had undergone. I should have followed this up, but didn't have time - will have to get one of our trainees on the case. If I get an answer I'll post it here.
The guys who are using it seem to think everybody will be using it soon, because of the ease of fixing, no cutting and no waste, but I don't know about comparitive costs with Kingspan or Celotex.
RT
randomly hit the keyboard

Sheffield
conversion?
Is
then
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details
It has been around for at least 5 years, in differing forms.
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Is there any of these similar products with a BBA Certificate?
regards

much
tests
time -

I'll
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On Sat, 17 Jan 2004 11:04:04 -0000, a particular chimpanzee named
and produced:

No. Actis (who make Tri-Iso) admit that the product won't meet the standard BS hot-box test for insulation, but claim that the test is a load of cack and doesn't show the benefits of their product.
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IMM wrote

The eaves vents are still required for the under-rafter application as this is a cold roof. (The Building Regs don't take vapour barriers into account, so the timbers are likely to collect condensation in their eyes). The over-rafter application is a warm roof and does not require vents, although there will still be a risk of condensation on the tiles and battens!!
What always worries me a lot about the foam insulants is their behaviour in fire - they must give off tons of toxic smoke, or am I wrong? I imagine this foil/foam combination only 25mm thick has got to be better in this respect. I am certainly very interested in finding out more about it.
Peter
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Is
then
there.
this is a

the
So if you cut away the sarking from inside with a Stanley knife, exposing the timbers to the outside air, staple this Actis stuff on, battens, plasterboard with vapour barrier behind (I assume the Actis stuff is also a vapour barrier) and block up the vents, then that should do it.

still
in
this
respect. I

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IMM wrote

Technically yes, as long as there is adequate air passage through the tiling, but try telling that to a BCO who doesn't have any guidance on unfelted tiling to refer to in his bible. But what's the point of doing this? You could just leave the felt and the vents as they are.
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exposing
also a

tiling,
tiling
just
I thought the thread was about making a warm roof and blocking up loft vents.
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IMM wrote

Look, either you're being incredibly stupid or you're winding me up. In the faint hope you're basically a decent bloke who wants to understand I will keep my cool and explain one last time. I thought we had cleared this up over a year ago.
If you had read all the messages on the thread you would have understood the thread was about providing insulation underneath and in between the rafters. This does NOT create a warm roof. The word "roof" means just the timber structure, not the loft, roofspace or roof void whatever you want to call it. So a "warm roof" is where the timber structure is completely inside the insulation. Anything else is a cold roof, even if the loft is as hot as a sauna. Please try to get this in your head once and for all - a warm roof has ALL the insulation outside the timber structure.
The Building Regs do not require ventilation to warm roofs as there are no cold timber surfaces on which condensation is likely to form. But ventilation IS required to cold roofs in order to evaporate any condensation forming on cold surfaces. If the rafters have insulation fitted between them then part of their surface is cold, so the Regs require that an air gap of at least 50mm must be left above the insulation, with vents at the eaves and possibly the ridge.
Fitting insulation under the rafters creates a warm LOFT, but not a warm roof. The roof (remember - this means the structure) is still cold, as it is on the outside of the insulation. So it needs to be ventilated. If you already have eaves vents then these will do the job nicely, so why block them up?
If you still can't get your head round this you're a dickhead. Please show me you're not, otherwise I will treat you as such from now on.
Peter
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the
keep
a year

OK, a well insulated roof on the rafters and the vents blocks off. I personally see no point in insulating rafters when a gale is coming in at the eves bring in air at less than 0C. To me that sounds very dumb indeed. A warm loft is what many people want, whether it is termed warm roof or loft, the end result is still the same.. ...no vents at the eves and a well insulated loft (at the rafters).

show me

The OP wanted to do it from the inside from what I gleaned, so that would preclude a "warm" roof which means ripping the roof off. read what he wrote and you will see that he didn't want vents and the loft well insulated. You have an inability not to get the big picture, immediately delving into technicalities.
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IMM wrote

???
No, the OP wanted to know how to convert his cold roof to a warm roof. I quote: "Does anyone know how to convert a cold vented at the eves roof with tiles and sarking, to a warm roof?" That seems clear enough to me.

???
Ah well, I did try.
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email me at richard at olifant d-ot co do-t uk
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