5 December 2009 at 11:26 am #35817
Any more on Icynene? The project on which I was weighing up Warmcell vs Icynene didn't happen.14 April 2010 at 8:05 pm #35818AnonymousInactive
I see there's a Jeff Hood who works for Icynene:
Vice-President, Sales – International (Europe, South & Central Americas): Jeff Hood
I guess you're not aware that generally in this country and on this board in particular we prefer people to declare any commercial interests they have. I see you didn't mention your website or email in your profile either.
I think you'll also find you get more traction here by adopting a less competitive approach than is sometimes usual in north America. You might like to start by explaining about Fourier's second law of thermodynamics and how it differs from the regular second law of thermodynamics accepted by most people. And especially about how it explains your statements about 3% more energy.
Having said that, people are keen to hear the facts about icynene and the other soy-based foams.16 April 2010 at 6:28 am #35819
The issue of heat transfer needs to be married in with lifecycle costs. You then find that there is a plateaux that is reached at about 300-500mm. As an economic range this also allows for the mitigation of energy demand and co2 emissions.16 April 2010 at 10:28 pm #35820
I'm aware of only two between-studs insulations that are capable of providing an in-depth air barrier which, while not being as absolute as a newly-installed plastic membrane /tapes/mastics, should last indefinitely and be immune to drills, saws and other accidents, and won't suffer from environmental degradation/embrittlement, nor from the constant 'working' of pressure reversals gradually pull-pulling at the tape joints.
The air-test guys and the building fault diagnosis boys do tell the same tale – of tape joints beginning to part even after one year. It seems incredible to me that anyone still puts their faith in fragile membranes and sticky tapes, however impressively tough and grab-some they seem to be. It's inconceivable that they will last the life of even a 25yr building, let alone one built for posterity.
We have to abandon those membranes and tapes and find robust tolerant durable alternatives. OSB glued and screwed; quality mastic injected into a cleaned 3mm in-depth gap with backing strip; blown-in Warmcel; sprayed/foamed-in-place Icynene. Any others?17 April 2010 at 9:36 am #35821
So how does spray foam achieve it's airtightness when you have two studs abutting one another? There will be a air leakage gap between the two studs. Similarly sole plates, first floor junctions and eaves details etc all pose similar challanges. Due to coordinateing dims windows may be less of a problem. There are European examples of homes that have had 5 and 15 year air tests and no decay in performance has been determined. These homes have an air leakge of < 0.6 ach @ 50pa (some built examples of < 0.3 ach @50pa). So how do these spay foam products really compare? It strikes me that for robust performance the air barrier can not be in the same plane as the studs – which it the method that you seem to suggest.
P.S. There are only two taping systems that I have heard of that are considered to be sufficienctly robust one is Pro-Clima (from Green Building Store) and the other is SIGA (from NBT). Both products have been recomeneded to me by two different building physicists – so there appears to be some convergent thinking on this.17 April 2010 at 4:53 pm #35822
Great PS about 'if you must' tapes Mark – thanks.
Your other questioning about spray foam – I assume you'd ask the same about blown Warmcell? Or not? NB I'd put no faith in other spray foams – only Icynene.
I would not rely on Icynene or Warmcell alone. As recently discussed on http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=5657&page=1#Item_27,
and referring back to previous http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=4167&page=2,
this is my current spec:
tiles/slates on battens over metallised breather felt, shiny side down, draped over 35×50 downslope battens on 100 EPS or wood fibre on 9 OSB3 glued and screwed (as air barrier cum slight vapour check) to 145 high rafters with blown Warmcel or sprayed Icynene between (as supplementary, long-term robust, un-puncturable air barrier), plasterboard and skim beneath.
Note no VCL – this is a breathing construction, with the 'inboard' vapour check (the OSB) about 5 x the vap resistance of the outboard breather. It seems from Euler-diagram condensation-check program that having the 'inboard' resistor not strictly 'inboard' but that far out thro the insulation is satisfactory. However, no-one should take my word for that – make your own check and satisfy yourself.
two studs abutting one another
If you mean two studs side by side, I wouldn't – if necessary structurally I'd specify a fatter timber.
If you mean abutting as at a corner, so there's free space in the angle between them, then that space wd be filled with the insulant, closing the through-gap between the studs.
Similarly sole plates, first floor junctions and eaves details etc
I dunno – I seem to avoid any such problems Sole plate on conc/masonry wd of course be bedded on mastic.
for robust performance the air barrier can not be in the same plane as the studs – which it the method that you seem to suggest
I think I'm suggesting a tea-cosy –
not only of EWI-type (incl roof) insulation ouitboard of the studs/rafters
but also of the air barrier, in the form of OSB glued and screwed to outer face of studs/rafters
which could still be breached whether during construction or long in-use life,
so as an extra-robust (but not so absolutely tight) supplementary air barrier in the form of blown Warmcel or Icynene between the studs/rafters.17 April 2010 at 9:19 pm #35823
Warmcell is certainly not an air barrier. (Yes, yes it can tidy up some sloppy UK building but it is not an air barrier.)
Mark17 April 2010 at 11:22 pm #35824
Has anyone told Excel that? They seem to claim airtightness e.g.
From http://www.excelfibre.com/press/2006/warmcel-at-ecobuild.html : Warmcel ensures that the entire wall cavity is completely filled with insulation, eliminating gaps, cracks or other cold bridges, thereby delivering an airtight solution.
And from http://www.ecowise.ie/warmcel.html : Warmcel is Airtight
When cellulose is installed to a density of 48 Kg/M3 or more, it acquires a unique air-sealing ability.
I've never got any hard data out of Excel about this, except some test Wimpey did, which seemed to prove little either way – what's the source of your info or knowledge, Mark?18 April 2010 at 9:36 am #35825
If memory serves the Canadian building scientists define an air barrier as having an air leakage of < 0.07 m3 @75pa and an air barrier system if it has an air leakage of < 0.7m3 @75pa. Their test data shows that fibreous materials can not satisty these criteria i.e. you need a proper air barrier system.
Whilst it may be that the Warmcell did help to plug a few gaps that sloppy UK workmanship presented is it really reliable and long term? It may have helped to cork a few gaps (just like secondary sealing with a low expansion foam) but that'll be about it.18 April 2010 at 10:19 am #35826
I'll try again to see what Excel really say. Warmcell must be different to ad-hoc plugging – it's systematic and continuous, for whatever it's ideally worth. It depends totally on no slumping, so that's a major objective that has to be detailed in. Given that, anything else I'm overlooking, about why it wouldn't it be reliable long term (as far as its best-case air performance goes)?21 April 2010 at 10:44 pm #35827
Foam seems to expand with amazing rapidity – see http://www.youtube.com/watch?v=-o6M4a-Fhqg&NR=1
On another video I noticed the installer spraying a very light coat over the wall studs, presumably to link the foam between studs for airtightness and to reduce heat loss through studs? But also noticed the final cut with the long saw blade to cut back to face of timber studs – a conflict?27 April 2010 at 8:27 am #35828
I think we would also seriously consider doing this – but with some areas of felt cut out and a vapour open sheathing membrane fitted to drain to eaves. I think this could be possible as I wouldnt want to introduce (waste) 50mm of 'ventilated' airspace between the rafters before the foam is sprayed. as this discussion progresses I will develop a proposed detail for this28 April 2010 at 8:51 am #35829
Claus – I think we want to aim for a U Value circa 0.12 – 0.15 if we can – so we would need to build a layer and structure to support the insulation(s) back into the loft space.
I imagine the loft will only be used for MVHR duct runs and storage, rather than as habitable space – but the loft space would be within the airtight and thermal envelope, although without heat emitters (radiators) in the loft it will be cooler than the main house.
Jeff – do we need to protect the foam for fire spread reasons? Can it be directly rendered/plastered?
To avoid the risk of unavoidable gaps/shrinkage/damage etc and perhaps some general diffusion leading to water vapour movement from warm space to cold side of construction (leading to potential interstitial condensation on underside of existing bituminous felt) – I do feel that we shouldl find a cheap way to make the bit. felt more vapour open without risking roof leak water ingress into the construction AND without reroofing – to this end, some ideas:
a) if we perforated the roof felt in some way – would the icythene, when sprayed, prevent direct ingress of water from a broken tile getting past the felt/foam interface – or would the foam potentially get damp and give rise to more risk to the rafters than interstitial condensation?
b) if we cut out larger areas of bit. felt and replaced it with vapour open roofing membrane, then spryaed would this be a solution – remembering of course to lap the new membrane in the right way to deal with any water ingress.28 April 2010 at 8:54 am #35830
Claus – what did the Isospray rep say about the risk of interstitial condensation risk leading to early decay of the rafters?!7 May 2010 at 9:07 pm #35831AnonymousInactive
Sorry I don't have any more on the ParISOTherm system other than what is on the Peinteco website http://www.peinteco.com/lemoniteurDec09.pdf
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