Several members have stated "put 200mm EPS on it", or words to that effect, on various threads.
6 days ago Fred56 reported that he "did not find anyone offering 200mm of insulation" ( on the single block ACC block thread).
Previously, another member has posted that a contractor simply refused to tender for 200mm EPS EWI; I can't find the post now.
My sole experience, so far, was researching the method and getting the materials for the plasterer doing my refurb to fix 25m2 of 60mmK5 EWB ( phenolic ) on a dense brick solid 9" wall of a single storey offshot kitchen.
This involved an adhesive mortar levelling coat, K5 boards mechanically fixed with nylon hammer-in fixings, cementitious base coat incorporating nylon mesh and a final JUB acrylic trowel-on finish. Although expensive the results have been so impressive that the plasterer has undertaken several more jobs using the method that I 'taught' him. I will certainly use EWI on a new build that I am currently researching.
However, the mechanical integrity of the bond of 200mm EPS to blockwork and the durability of the finish causes me concern. Is mechanical fixing, as well as adhesive, used at these depths?
The location is sheltered.

Almost routinely in much of central Europe, not even sure that they bother with foam just mechanical fixings?

http://www.wbs-ltd.co.uk/images/pdfs/certificates/Epsitec%2009-4625_PS1.pdf

Covers fixing up to 60mm Phenolic

I approached 3 or 4 EWI/render system suppliers (including some of the big names like Weber and Wetherby) a year or so back and none of them had any problem doing with 200mm phenolic as EWI. I need to go back and look at the details, but I think most of them specified 2 layers of material. I think some used mechanical fixings and some used "glue".

If you look at the AI PassivHaus/Underhill House, then they used something like 300mm of EPS just glued on. According to http://www.sto.co.uk/99760_EN-Company-sto_passivhaus.pdf they can support up to 400mm of EPS.

Technically it is possible. Cost is another factor of course.

Jim,
thank you for the precise info about a system you have used successfully. Broadly similar to the JUB system I used with 60mm phenolic to achieve a U value of 0.28. Drilling for the 90mm nylon fixings was a problem on a proportion of the fixings when the drill deflected into the lime mortar course instead of the 1930's hard red brick. The prospect of this 200mm deep on concrete blocks was a concern. The aerated concrete blocks you are using do appeal for this reason; ordinary drill bits should even be possible.
Do you think that Tony's concerns about cracking and movement apply more to the 100mm aerated blocks rather than the 215mm? Regards, Martin.

me too

Posted By: MarkBennettmost of them specified 2 layers of material

That is surprising, as it's far more work than a single 200 thickness.

Posted By: MarkBennettsome used mechanical fixings and some used "glue"

that is also surprising, that there's such variation is 'best practice' still, after many years' experience.

Posted By: MarkBennettPassivHaus/Underhill House ... used something like 300mm of EPS just glued on. According to http://www.sto.co.uk/99760_EN-Company-sto_passivhaus.pdf they can support up to 400mm of EPS.

That's incredible. I mean, I assumed it would be all-glued to start with, but was then had impressed upon me the importance of mech fixings because of the considerable (?) outboard weight of thick EPS + render, as well as holding in place while the glue sets. How can there be such disagreement?

Posted By: jamesingramuse 2 fixings per board/part board , I like this as it should reduce thermal bridging caused by the fixings ( compared to the 5/board systems)

Too right, but again, how can they so disagree? Another variant (the excellent Chris Hirst http://thinjoint.com/)is to put one mech fixing at each board corner, on the joint line, so it straddles 3 boards.

Illbruck CT375 contact adhesive is specifically designed for bonding polystyrene:

http://www.tremco-illbruck.co.uk/products/02947_index.html

I don't know if they have EWI fixings, but EJOT are often recommended for warm roof fixings:

http://www.ejot.co.uk

David

Re. Fixings for 200mm EWI , just ordered these up from Fischer ,
http://www.fischer.co.uk/PortalData/18/Resources/fixing_systems/salesinformation/_documents/10insulation/07.pdf
Unfortunatley the full range (on the german site) is only available to larger EWI supplier
http://apps.fischer.de/poc/default.aspx?page=layer&sprache=en&kat=$MART-HK-$MKAT-HK-$MPG-WDVS&ekat=$EKAT-HK-EN&path=$MART-HK-$MKAT-HK&path=$MART-HK-$MKAT-HK-$MPG-WDVS

http://www.thermalinstallations.com.au/imagesDB/wysiwyg/TDS_Expanded_Polystyrene.pdf

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 ) approx 5mm , though in shade didn't. Whether this would happen underneath when covered by render I'm unsure.

Posted By: TimSmallreplacement of expanding agent by air in the cells

What is the expanding agent in EPS, BTW?

Is that OK stuff?

GWP is 5ish (it photo-degrades by combining with O2 to form CO2 + H2O I believe). I'm not sure what % of the pentane outgases during manufacture, and what % evaporates later. I get the impression that some of the more advanced EPS manufacturing plants capture the pentane for re-use.