13 June 2012 at 7:22 pm #38532AnonymousInactive
Not once rendered , but then it would be hard to tell.
I left some EPS installed on the wall, unrendered on one job for a couple of months, the boards exposed to the sun shrunk (after aged prior to installation ) approx 5mm , though in shade didn't. Whether this would happen underneath when covered by render I'm unsure.14 June 2012 at 2:40 pm #38533AnonymousInactive
posted here re. phenolic
“BTW, the rendering company which I'm using was warning me off Phenolic due to the realively high failure rates which they'd been hearing about from their EWI supplier's rep.”7 August 2012 at 8:50 pm #38534Tom FosterParticipant
Any further comments on this?
The various proprietary suppliers of EWI systems do charge a lot for their non-standard-size (e.g. 500×1000) insulation boards, which I think are invariably 'aged'. It's tempting to buy 8x4s of standard insulation and cut it up, but I for one think there's good reasons to pay up for the proprietary suppliers' boards, certainly when it's going to be rendered. We don't want to see 'giant brick' effect after a couple of years or less, esp knowing the shrinkage gaps that will lie behind.
But what about EWI that's going to be clad e.g. with boarding. Not sure that's really called EWI? I have found myself treating it differently, as ordinary builders work, using those 8x4s of insulation board – seamless with same on the roof slopes. Of course no one ever sees the telltale 'giant brick' effect but I guess the shrinkage gaps are there. Or are they? We glue the boards with roofing contact adhesive to continuous OSB, and we foam all the joints however tight they are. or we do both of those in one go if using foaming polyurethane glue.
In this latter non-rendered case, should be be using aged insulation boards? If not, if we're doing enough to ensure no shrinkage gaps, then why must the boards be aged when rendered?6 November 2015 at 11:31 am #38535AnonymousInactive
I'd be grateful to learn if rigid insulation boards of various types are still considered at risk of shrinkage, and whether leaving them to age on site for a few weeks is sufficient. I'm currently deciding whether to use EWI or mineral fibre filled wall/larson trusses for a Passivhaus.
Cheers10 November 2015 at 9:29 am #38536AnonymousInactive
Thanks for that Nigel.
I'm fairly sure I once did the calculations and found that the energy saving was much greater than the embodied energy over the lifetime of a building. However, I never regarded this as particularly useful if I could make the same savings using an insulation with lower embodied energy. I tend to use the best insulation for the job, which could result in a wide range of materials in one project. Not everybody wants 2' walls!
I personally hope that PH doesn't change to take embodied energy into consideration. I think it would kill the standard if every item used in the building, and presumably all of the energy of the building process, had to be recorded. It brings back memories of last year's Code 6 build on Grand Designs. Mountains of paperwork.10 November 2015 at 10:45 am #38537Tom FosterParticipant
Yes AFAIK all the artificial insulations pay for themselves multi multi times over. Insulation is the best possible use of oil/hydrocarbons, if you must. What was that podcast?
… to take embodied energy into consideration. I think it would kill the standard if every item used in the building, and presumably all of the energy of the building process, had to be recorded
It surely should be an essential part of the building process in general – though we and the world are still practically a long way from taking that on board – otherwise we're knowingly omitting about half the point.
Paperwork – well that's something that's potential with BIM – on-the-fly embodied energy (in fact whole LCA) totalling as the design/documentation progresses – though again, the BIM cos haven't go round to incorporating that data/facility yet. Strangely, mech eng/product design software is much further aheads on just this, than building's, even though sustainability awareness is much higher in building than in engineering.
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