Green Building Forum - External insulation - any pitfalls? Thu, 11 Jun 2026 21:42:50 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71120#Comment_71120 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71120#Comment_71120 Fri, 08 Jan 2010 11:52:09 +0000 headgear Just had a look at the products section of their website.
The technical details section section discussing resistance and u values fails to give sufficient details of the construction for the given figures to have any value for comparison with other potential solutions.
Of all the reports listed, ONLY the thermographic imaging report has it's own active link; why is this?

Of the thermographic images, without calibration points these are worthless. I have never seen such images used in a report without calibration points. Have a good look at the before and after images, paying particular attention to items like surrounding vegetation, house next door etc.

Make sure your bullshit detector is switched on at all times.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71126#Comment_71126 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71126#Comment_71126 Fri, 08 Jan 2010 12:33:24 +0000 fostertom Posted By: jamesingramthe job was 55m EWI with acrylic render 35m just arcylic render
the 35m required a key coat and a leveling coat which took a similiar amount of time as fixing the EWI
so I think it fair to say if we'd insulated that also costs would have been similiarinteresting - I'd had it in mind that, if rendering on blockwork or whatever, the extra cost of making it into rendered EWI would be small, because the render is such a major part of the total. Now you're saying that adding EWI behind the render in fact comes almost free!

Posted By: jamesingramEWI materials £ 28m2
Other material costs £ 10m2
labour £47m2
Does 'EWI materials' include the render, mesh etc, as part of the patent EWI system? So what does 'other materials' include?
Do you have a price for the EPS material alone? Cos if that's only a small part of the £28/m2, at 70mm thick, then it shd make little difference to the overall price, to double or quadruple the EPS thickness? Or do you think that EPS thicknesses greater than say 100mm start to involve more expensive/longer/specialist fixings, or more labour/time? EWI specialists have told me that the answer to the latter is 'not really' but I find that hard to believe.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71129#Comment_71129 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71129#Comment_71129 Fri, 08 Jan 2010 12:39:12 +0000 jamesingram Yes , EWI materials include the render, mesh etc, as part of the patent EWI system
oh soups ready back in 5 min]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71139#Comment_71139 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71139#Comment_71139 Fri, 08 Jan 2010 13:20:57 +0000 jamesingram
render only to block was on aerated so poor key required keying coat , so standard brick would only require levelling coat. swings and roundabouts , probably a bit more work in insulation fixing
other onecoat systems dont require leveling/priming coats etc.

other material include scaffolding , bit and bobs
I'll email supppliers spec. and pricing over to you

I'd have thought the moment you run out of space under the sofit , verges etc you're going to get large price increases , also its nice to leave a reasonable soffit etc to offer some longterm protection for the wall
so this would be a limiting factor on thickness/price]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71141#Comment_71141 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71141#Comment_71141 Fri, 08 Jan 2010 13:30:56 +0000 fostertom External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71142#Comment_71142 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71142#Comment_71142 Fri, 08 Jan 2010 13:37:20 +0000 jamesingram extra scaffold lift required new sofit/fascia/gutter work , finding matching 2nd hand tiles etc
would there be any planning issues ?]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71145#Comment_71145 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71145#Comment_71145 Fri, 08 Jan 2010 14:30:33 +0000 fostertom
Yes, would need Planning at present - and lots of resistance of course if in conservation area etc let alone for listed building. I think it has to come, even for LBs. it will certainly be done hideously in v many cases - no change there then!]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71165#Comment_71165 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71165#Comment_71165 Fri, 08 Jan 2010 17:02:29 +0000 bella
Many (?most) architects are just not there yet, surveyors have even further to go and structural engineers – well what can I say. There is a certain look that comes over them when the client says “Reducing heat loss is a very high priority for us”. It is a mixture of disdain and disbelief.

Then there are the planners. We are currently in negotiation with a National Parks Planning Authority who turned down an application to raise a roof by 250mm in order to add external insulation to a Victorian schoolroom (“open roof” with its original pine sarking boards on view internally and in fine condition). After two visits and lengthy explanations they might agree to 150mm if “thin fascia boards can be retained” but it is touch and go. They have allowed EWI on two sides of the building (stone) because the aesthetics had already been “spoilt” by a combination of cement render and “water-proofing” paint. They hate the two “solar” porches around external doors (so out of keeping, stone in the gothic style would look so much better!) but again may agree to reduced versions. The Authority has a pretty good policy document on “sustainability” with sections on solar gain and heat retention – great we thought that will really help us. However the planners feel entirely free to ignore the content. They know even less than us when it comes to reducing heat loss and reckon that internal insulation is the way to go – so much better from the aesthetic point of view.

If they do agree to the plans there will then be the problem of builders and building control because 1. architect + 2.surveyor have already decided the project is not for them – we have ignored their advice (1. dry line and 2. Beam and block floors and once you have underfloor heating the heat will only rise to about 6 feet so you won’t need to insulate the roof!!!). We are left with a reluctant technician modifying the drawings while the clock ticks on to the deadline. If we are lucky enough to get planning permission we will still have to --------------ahhhhhh. See what I mean?]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71167#Comment_71167 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71167#Comment_71167 Fri, 08 Jan 2010 17:20:37 +0000 headgear I did a heat and moisture control preliminary survey for a house in Snowdonia a year ago and have just finished writing it up for a module essay. I believed at first that the client was over paranoid about the planners attitudes - now I know he was right all along.

The trade off is this. If the overall policy is to retain the Parks as living communities all sorts of people need to be able to afford to live in the houses. Increasingly this means energy conservation is a greater priority, in conflict with aesthetic and built fabric conservation policy. If the latter are prioritised then the houses can only be used in summer; ie as holiday homes.

WE have to keep driving this home to the planners at all levels, officials and decision makers. In Wales it also goes to the issue of the native language - also a material consideration in planning applications.

Whichever Park you are in, I wish you the very best with this.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71169#Comment_71169 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71169#Comment_71169 Fri, 08 Jan 2010 18:15:31 +0000 fostertom External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71220#Comment_71220 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71220#Comment_71220 Sat, 09 Jan 2010 13:43:19 +0000 bella
If we get PP we will need a new architect who understands old buildings but also knows how to think through the insulation/design issues for retrofit, plus a really skillful roofer cum external insulator. The detail on how to install insulation over the pine sarking boards (insulating boards straight on or false rafters+boards on top??), which material to use (woodfibre or EPS or PUR??), whether or not to put a membrane (breathable?? ) between pine sarking boards and insulation (completely open to interior for 160 years remember), how to deal with walls (cement render off, pointing out, “paint off”, then lime pointing + render and insulation on top (woodfibre boards or EPS), lime render over or Hemcrete onto restored substrate??) .

External drainage and internal floor are other very important basics requiring skilled decisions. In fact it is the level of skill needed all round which is so daunting for a householder who gets “the message” but goes there only once. Following this forum is not good for one’s health – raises the bar awfully high and leaves no way back. If we are lucky enough to get through the above we will probably already have run out on money and probably won’t be able to afford those porches anyway!!]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71229#Comment_71229 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71229#Comment_71229 Sat, 09 Jan 2010 15:42:06 +0000 fostertom Posted By: bellaforum ... raises the bar awfully high and leaves no way backSo true! I look forward to discovering where you are - sure we can find you a good designer, for a start.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71369#Comment_71369 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71369#Comment_71369 Mon, 11 Jan 2010 13:27:17 +0000 bjd
V interested in your post. I live in the PeakDistrict in a conservation area - just about to initiate a plan to put EWI up on our 1920's Stone house - at least a part of it (done/ doing IWI in the visible areas). Would love to know about your progress. My own work to date confirms your experience with the Planning department being "politically" into climate change measures, but only a distant second to their take on the "conservation" of aesthetics (instead of conservation of trivial things like conservation of our economy/ society/ habitat etc.).

BTW, James, et al:
- my EWI project encompasses a central part of the building enclosing several small rooms, bathroom/ kitchen etc. - you can imagine what the outside looks like with soil stacks/ multuiple windows/ drains etc. Do I understand that the solution is always to move all the services outboard of the EWI. I can't see a way around this, but it may make the whole project unfeasible (especially re underground drainage) - £100/m2 would become unachievable.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71378#Comment_71378 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71378#Comment_71378 Mon, 11 Jan 2010 14:46:41 +0000 tony External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71383#Comment_71383 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71383#Comment_71383 Mon, 11 Jan 2010 15:28:23 +0000 jamesingram Possiblities to get the price down , by not using a "all in sytem" from specialist supplier/manifacturer
standard insulation/mesh/render brought from a local builders merchant
But these light-weight acrylic or lime finish through colour systems do seem to be more suitable products and hopefully longer lasting etc.
cheers Jim]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71386#Comment_71386 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71386#Comment_71386 Mon, 11 Jan 2010 15:56:20 +0000 tony External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71391#Comment_71391 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71391#Comment_71391 Mon, 11 Jan 2010 16:22:33 +0000 jamesingram
Thats at £28 per hour for plasterer and labourer , fair going rate in SE ( no mark up for MC )
the trouble with the EWI system its at least 7 visits to the wall .
here's a basic run through of whats involved

Remove downpipes , clear area , scaffolding etc
Clean and prime, drying time
Fit base rail
install insulation , similiar to dot and dab fitting plus drill through insulation fixings ,drying time
Mask up
fit beads , drips etc.
1st ,6mm coat
install mesh ,trowel into render
2nd 6mm coat ,to level sponge finish , remove masking, drying time
coloured primer, drying time (perhap another mask ,before and after)
Mask up
Apply acrylic 3mm top coat , float up
remove masking, drying time
replace/ adjust fitting, downpipes , clean up etc.

with sand cement render on galv. mesh on battons on insulation+ painting whats the m2 rate for labour ?]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71397#Comment_71397 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71397#Comment_71397 Mon, 11 Jan 2010 17:23:20 +0000 jamesingram I was obviously over optimistic with my £55m2 a few months ago !]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71402#Comment_71402 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71402#Comment_71402 Mon, 11 Jan 2010 17:44:42 +0000 headgear
Have you considered sandblasting to remove the paint? One bonus is it also can get behind broken cement pointing, making it loads easier = quicker= cheaper.

I've seen it done on an oak frame house ( the one on my website being lime washed), so stone should be no problem.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71405#Comment_71405 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71405#Comment_71405 Mon, 11 Jan 2010 18:02:53 +0000 fostertom External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71409#Comment_71409 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71409#Comment_71409 Mon, 11 Jan 2010 18:25:36 +0000 headgear
Obviously one has to find a sandblaster with some clue about building materials and how they respond to his various grades of sand and of blast power !]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71410#Comment_71410 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71410#Comment_71410 Mon, 11 Jan 2010 18:28:32 +0000 bella External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71412#Comment_71412 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71412#Comment_71412 Mon, 11 Jan 2010 18:57:30 +0000 fostertom Posted By: bellabest way is to chip off by hand. Could do some ourselves where it is loose alreadyIf it's smooth ashlar limestone, 'Dress off' wd be the description - they'll chisel off (with a broad toothed chisel) 2-3mm of stone in the process (as top layer will be patchily impregnated with stuff), prob point in some places with matching stonedust/lime, and drag-finish (with a serrated flat steel plate hand scraper) beautifully smooth. Skilled job. So you doing the few bits where it's loose wouldn't help.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71414#Comment_71414 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71414#Comment_71414 Mon, 11 Jan 2010 18:58:27 +0000 Peter Clark
I am correct in thinking that cladding instead of render might make this less expensive?

Is cladding more doable for someone like me with low level skills and none at all in plastering?

Peter]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71415#Comment_71415 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71415#Comment_71415 Mon, 11 Jan 2010 18:59:44 +0000 tony External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71425#Comment_71425 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71425#Comment_71425 Mon, 11 Jan 2010 19:31:46 +0000 bella External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71429#Comment_71429 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71429#Comment_71429 Mon, 11 Jan 2010 20:09:12 +0000 fostertom External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71430#Comment_71430 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71430#Comment_71430 Mon, 11 Jan 2010 20:11:58 +0000 jamesingram but I wouldn't let them near one of my jobs ! Like most things, easy to do unless you're looking for that top notch
finish, then it require some real skill
The acrylic renders systems certainly easier than plastering , much more forgiving , just a bit time consuming
some good info here on detailing for EWI systems including possible DIY wood cladding
http://www.azobuild.com/downloads/GPG-external%20wall%20insulation%20MK.pdf]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71462#Comment_71462 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71462#Comment_71462 Tue, 12 Jan 2010 10:05:37 +0000 headgear
If it's an acceptable exterior finish for the Park then it opens up huge potential solutions for weather proofing EWI. Still needs the wall behind the insulation to be dry, but at least it's something!]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71473#Comment_71473 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=71473#Comment_71473 Tue, 12 Jan 2010 11:24:57 +0000 bella
headgear, A massive, gable end (SSW) wall was originally (or at least for first half of the 20th century) slate hung. The house sits on a very exposed site and this wall takes the prevailing wind and rain. Our proposed plan included a long lean-to glazed porch along this wall (leading up to the back door) under a slate roof at 45 degree pitch starting about 0.5m below the eves of the gable as a sort of echo functionally and aesthetically of the slate hanging - they did not like it one bit - but could they really object to re-instituting the slate hanging especially as they were so very concerned about "implications for wild-life" (by which they mean bats) as a consequence of our proposals. We don't have bats but wouldn't mind if we did and slate hanging is bat heaven.]]>