Welcome to the AECB Forums Materials and products EWI insulation shrinkage

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  • #31668
    Nigel Murray
    Participant

    At yesterdays local group meeting – SW Cornwall – there was some discussion about EWI systems.
    There were some recommendations for the best options for insulation however there was also some experience of Phenolic or PIR/PUR boards shrinking over time.
    Has anyone else had experience of this?
    Anyone got any published reports or manufacturers statistics showing how to deal with this? or rates of shrinkage? etc.

    The Denby Dale passivehaus used the expanding foam method to 'seal' the irregular gaps. Does anyone think this method would bind the boards together and resist any shrinkage?

    Nigel

    #38518
    Nigel Murray
    Participant

    Unfortunatelly I cant get the Search function to work.. saw the post thanks Kate… but while looking elsewhere i found this thread

    I am doing the same research. We recently visited Adam Dadeby's PH refurb in Totnes, where he is using phenolic insulation to keep the thickness down. A stack of boards seemed to show degradation from the sun, and I have heard warnings about phenolic delaminating. I am looking at EPS with graphite, which seems to give a good price to performance ratio. It has the additional feature of being vapour permeable, unlike the extruded products.

    Any further info Rob ? or Adam?

    regards
    Nigel

    #38519
    Nigel Murray
    Participant

    And to top off this non-discussion the chosen rep for the job I'm involbved in just called to say that they had had trouble with phenolic and they wanted to steer me away from using it – recommending graphite EPS instead… and for less cost
    Now just have to persuade the owner…

    Nigel

    #38520
    Anonymous
    Inactive

    I am going to stick my oar in here. EPS is the most stable of the sheet insulation mentioned but I worry about the Neopor due to lack of data with regards to renders adhering to. Depending on density the advantage over Styropor varies but the worry for me is, as graphite is used as a lubricant, to expect render to stay stuck to it over time is the question I feel needs answering.

    #38521
    Nigel Murray
    Participant

    Thanks for the input.

    … but I worry about the Neopor due to lack of data with regards to renders adhering to. … the worry for me is, as graphite is used as a lubricant, to expect render to stay stuck to it over time is the question I feel needs answering.

    Good point, but is the surface not textured in any way?
    I would assume the surface is hardly smooth with all the gaps between the beads. Dont you think this will provide enough keying?

    Nigel

    #38522
    Anonymous
    Inactive

    Any good installer of thin coat renders will/should rasp the wall first to create a good “key” before applying the base coat and imbedding the mesh.

    #38523
    Nigel Murray
    Participant

    Any readers seen the ceiling of the Ikea Dublin carpark? Reported as having shrunken boards and delaminating foil???

    #38524
    Mark Siddall
    Participant

    If you have seen the above you could post photos here.

    #38525
    Anonymous
    Guest

    Nigel,
    Been meaning to reply for a while but haven't been able to track down the article I promised. There is growing concern within the industry about phenolic shrinkage – a phenomenon acknowledged in this article here http://www.ehow.com/info_8315624_risks-phenolic-foam-insulation.html. I have seen pictures of a recent installation in Plymouth where the shrinkage in an EWI situation was pronounced and visible as horizontal lines. When the boards were cut out, large gaps were apparent and the boards had bowed when compared to a new board. Phenolic is also vulnerable to moisture within the existing structure trying to migrate out of the original construction. EPS doesnt have these risks but still requires great skill in ensuring there are no angular gaps at junctions. It also has twice the embodied energy of stone wool or wood fibre alternatives and none of the acoustic and fireproof qualities.

    #38526

    There is a very good article in the American magazine 'Fine Homebuilding', issue no. 225, March 2012, page 55. A builder in Massachussets who did a 'deep-energy retrofit' on his house and office/ barn conversion sixteen years ago decided to update the barn conversion. He stripped it down again and analysed the performance of the various components. He had wrapped the barn in a single layer of EPS taped and mastic-ed at the joints. The boards shrunk, the tape /mastic cracked, and the joints opened. He could see this starting in the first winter with frost melting on the joint lines. He had used a single layer of XPS sealed with Tyvek tape on parts of his main house, so he removed the weatherboards and investigated that, and found that the joints and tape were in perfect condition after 16 yrs.

    #38527
    Anonymous
    Inactive

    My understanding was that foam insulation does most it's shrinking just after manifacture , so board used for
    EWI should be aged ( allowed to shrink ) prior to installation . Might it be the case that this was not done correctly in some instance?

    #38528
    Mark Siddall
    Participant

    A few years ago at an AECB Conference Berthold Kaufmann from the Passivhaus Institute noted that EPS can shrink by about 10-20mm per meter within the first 30-60 days. Like John he suggests a maturation period before installing on site. Unfortunately manufacturers do not make this allowance when supplying theior materials to industry….

    Mark

    #38529
    Anonymous
    Inactive

    Mark, not all suppliers do that. We have all of our products go in a curing oven for 48 hours after coming out of the moulds, for precisely the reason being discussed.

    #38530
    Anonymous
    Inactive

    Yes, a supplier I use for graphite EPS advises 'ageing for shrinkage' of boards for EWI use also and usually does this at the production plant. I was wondering if perhaps on the larger jobs , where product was manifactured specificially for a project, this may be missed ? or is it the case that phenolic needs a longer time to allow for intial shrinkage?

    #38531
    Nigel Murray
    Participant

    Yes, a supplier I use for graphite EPS advises 'ageing for shrinkage' of boards for EWI use also and usually does this at the production plant. I was wondering if perhaps on the larger jobs , where product was manifactured specificially for a project, this may be missed ? or is it the case that phenolic needs a longer time to allow for intial shrinkage?

    Thanks J, and when I phoned Kay-Metzeler, they said 'most customers ask for it to be 'aged' 2-3 weeks in block form i.e. before cutting to sheet thickness. Have you seen any further shrinkage on jobs using this product?
    Nigel

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