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Green Building Bible, Fourth Edition
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Products: Sprayed insulation

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    Has anybody got any experience of sprayed polyurathane insulation to the inner face of a stone barn conversion?
    A friend did his barn conversion a few years a go and he is still happy it was the correct solution. He has 50mm of foam sprayed to the inner face then he plastered directly on to it. The inner surface maitains the look of the inner walls of the barn as the foam expands to a constant 50mm so you keep all the bumps and lumps. It does look very good and provides an excellent moisture barrer and very low infiltration. Any thoughts?
    • CommentAuthorJulian
    • CommentTimeSep 7th 2009
     
    Onto stone? I wouldn't even contemplate it. There are plenty of other insulation options which would work as well or better. Why not hemcrete for example?
  3.  
    Agreed - a v bad idea, and almost impossible to remove when you need to get rid of it.
  4.  
    Did he use it on the timbers of the roof?
  5.  
    The OP's friend is clearly not a regular on the Green Building Forum.
    :)
  6.  
    In "The Whole House Book" it says that polyurethane releases hydrogen cyanide gas when burned and is now no longer permitted for cavity wall insulation!
    • CommentAuthorCWatters
    • CommentTimeSep 7th 2009
     
    Pure polyurathane perhaps. Celotex and Kingspan are modified polyurethane foams and still allowed and in wide spread use.
  8.  
    Guys, thanks for the feedback but nobody is actually saying why it a bad idea. What are the technical drawbacks?
    Everybody wants air tightness. This solution does it. It maintains the charecter of the barn. That must be good. It provides good insulation properties so come on guys give the technical reasons.
    • CommentAuthorJulian
    • CommentTimeSep 9th 2009
     
    Hi Tim
    The advantages you state i.e. good insulator; maintains the character of the barn; air tightness are true of other materials - such as hemcrete for example. Gervase makes the point above that the stuff is impossible to remove. And I would question how it is better at draught sealing than, say, hemcrete? Given that you're going to plaster it anyway I cannot see any good reason to use such a toxic material - particularly on stone. And it would also kill off any sort of breathability in the stonework.
    This material is marketed as the solution to all problems such as damp and poor insulation. I have seen what it does to the materials it is sprayed onto and its not good practice - even worse under roof tiles. There's discussion elsewhere on this forum about how rigid foam insulation loses it effectiveness fairly quickly as the blowing agent leaks out. But even so these materials are made in the controlled environment of a factory. With site applied foam that process is going to happen much more quickly and I wouldn't want to rely on that notional 50mm of foam - you can do much better.
  10.  
    Hi Julian,
    Hemcrete is not a good insulator. The U value of hemcrete is very poor compared with modern thermal insulation. Hemcrete uses thermal mass where as we already have ample thermal mass from our 2 foot thick gritstone walls. The architects current proposals are to dry line the internals of the barn walls and install mineral wool insulation between the batterns. We need to considerably improve on the thermal properties of this building so the obvious solution would be to use Kingspan or similar. This has twice the thermal performance for the same thickness as mineral wool. The client doesnt want to lose huge amounts of space off the building by adding a huge thickness of internal insulation. Hence the consideration to apply 100mm of sprayed foam or 100mm of kingspan.

    I am not sure why you would ever want to remove the insulation and plaster from the inner face of the wall as once the barn is converted it should stay like that. It certainly hasnt been an issue with my pals Barn that he converted several years ago.

    We need to get the barn heatloss down to 11kw. This is the largest single phase GSHP we can get and we dont have 3 phase available. The site is exposed and 250m above sea level in the peak park. It is a listed building and currently the conservation officer doesnt want us to use double glazing.

    Just for the record, spray foam is used in steel yacht construction as the way to insulate and vapour seal the internal surface of the hull before all the furniture is installed. I have never seen a yacht where the insulation has failed or noticbly lost its performance.
    •  
      CommentAuthorfostertom
    • CommentTimeSep 9th 2009
     
    Icynene is different from the other spray polyurethanes - water as blowing agent (so not such brilliant k-value but doesn't degrade with time), stays soft and rubbery (so retains its airtightness), very water permeable (breatheable). See http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3341&page=1#Item_24.

    However, on stone is a terrible idea, for the reasons stated by others. Any internal insulation e.g. Kingspan, except Hemcrete, is a poor idea but this is the worst.

    Posted By: timevans2000Hemcrete uses thermal mass where as we already have ample thermal mass from our 2 foot thick gritstone walls
    but with internal insulation (except Hemcrete) you'll be isolating yourself from the benefit of the walls' thermal mass.

    Internal Hemcrete is a compromise that seems to work - and part of that is due to its mediocre k-value plus medium massiveness; the ratio of the two gives excellent decrement behaviour, that is almost unique outside of massive/non-insulating materials. A Hemcrete-lined building with non-brilliant U-value can perform surprisingly well - consult Hemcrete.

    There is no satisfactory solution to your requirement for good insulation in thin thickness, internally. Think of something else.

    Posted By: timevans2000GSHP
    Uh!
    Posted By: timevans2000the conservation officer doesnt want us to use double glazing
    Oof!
  12.  
    We now have a reason why we cant use sprayed foam insulation. The conservation officer sees this as a permenant solution as he considers it an adhesive. Looks like we are are now going the kingspan route as there is nothing else that keeps the thickness down.
  13.  
    We always use breathable-natural insulation with a breathable wall.
    Kingspan drylining will make the wall cold and condensation will occur where the insulation meets the wall causing fungus and mould growth. You are not allowed to dryline with non breathable insulations in Germany anymore.
    The fact that the Kingspan isn't breathable stops the condensed moisture on the wall drying out.
    A natural insulation would be a better solution because it can deal with the moisture and help it dry out.

    Many people think that Kingspan is better than other insulation materials because you can get the same U-value using thinner insulation. This is not correct, the real Lambda of PUR is actually 30% less than what is claimed when all the Pentane gas has escaped. I posted this report http://www.iea-dhc.org/reports/summary/8DHC-08-01.pdf on another thread here that Icelandic tests on PUR insulated district heating pipe showed that the Lambda dropped from 0.025 (which is the aged Lambda claimed by many PUR manufacturers)to 0.32. So it is no better than good EPS, the stuff with the grapphite.
  14.  
    The net climatic effect of increasing the amount of insulation in buildings through the use of halocarbon-blown foam insulation involves three factors: the greenhouse gas emissions associated with the energy used to make the insulation; the climatic impact of leakage of the halocarbon blowing agent from the insulation during its manufacture, use, and at the time of disposal; and the reduction in heating and/or cooling energy use and associated greenhouse gas emissions.

    Recent studies and assessments leave the impression that the use of halocarbon-blown foam insulation has a strong net positive impact on climate, with the reduction in heating-related emissions being 20–100 times greater than the CO2-equivalent halocarbon emissions.

    For typical blowing agent leakage rates and for insulation levels found in high-performance houses, marginal payback times can be in excess of 100 years using halocarbon blowing agents, but are only 10–20 years using non-halocarbon blowing agents.
    • CommentAuthorskywalker
    • CommentTimeSep 10th 2009
     
    Pentane is not a halocarbon it is an alkane (hydrocarbon) of which family methane is the most significant in greenhouse terms, other hydrocarbons such as pentane are not currently thought to contribute much - they are a bit heavy. As I posted in the other thread the 'report' you posted uses figures extrapolated from modeling, until we know the assumptions we should be careful about the conclusions, particularly from a short summary designed to arouse interest such as this one.

    Your second paragraph confuses me as you appear to be having an argument with yourself! As this very much appears to suggest that the affect of the PUR insulation in reducing the energy used is up 100 greater than the contribution it's emmissions make to global warming which sounds rather good

    The net climate affect of all insulation is much the same as you describe PUR is not unique. So far as I can tell the 'real-world' lambda of almost All insulation is somewhat different to the theoretical figure.

    I wouldn't spray the stuff on the inside of a barn either by the way.

    Timevans, have you considered aerogel? expensive but form hugging, breathable & thin (thread with links to projects is around here somewhere).

    S.
  16.  
    Unfortunately I dont have the influence over the client on this project. I am just the m&e consultant trying to get the project to work.
    I quite like the idea of using sprayed foam as I have seen the installation on my friends barn and it works. You dont get a condensation problem becuae there is no air gap. The barn is pointed with normal sand and cement and isnt particulary breathable but I guess the gritstone is breathable. Either way it doesnt seem to be a problem.
  17.  
    Posted By: timevans2000I am just the m&e consultant trying to get the project to work.



    ... a true classic country and western song....

    J

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