13 April 2012 at 7:52 am #31668
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?
Nigel13 April 2012 at 11:10 am #38518
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?
Nigel13 April 2012 at 1:25 pm #38519
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…
Nigel13 April 2012 at 3:57 pm #38520AnonymousInactive
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.13 April 2012 at 4:34 pm #38521
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?
Nigel13 April 2012 at 5:09 pm #38522AnonymousInactive
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.16 April 2012 at 10:28 pm #38523
Any readers seen the ceiling of the Ikea Dublin carpark? Reported as having shrunken boards and delaminating foil???20 April 2012 at 5:15 pm #38524Mark SiddallParticipant
If you have seen the above you could post photos here.30 April 2012 at 8:38 pm #38525AnonymousGuest
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.12 May 2012 at 9:20 am #38526Mike WhitfieldMember
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.4 June 2012 at 11:49 am #38527AnonymousInactive
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?5 June 2012 at 6:51 pm #38528Mark SiddallParticipant
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….
Mark6 June 2012 at 8:12 am #38529AnonymousInactive
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.7 June 2012 at 9:05 am #38530AnonymousInactive
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?8 June 2012 at 10:56 am #38531
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?
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