Green Building Forum - External insulation - any pitfalls? Thu, 11 Jun 2026 20:34:16 +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=62606#Comment_62606 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62606#Comment_62606 Wed, 23 Sep 2009 13:40:48 +0100 Peter Clark
http://www.sei.ie/Grants/Home_Energy_Saving_Scheme/HES_FAQ/Homeowner%20FAQ/#avail

I don't think such help is available in UK, is it?

What is the opinion of the forum, is this likely to be made available in the near future in UK?

Peter]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62608#Comment_62608 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62608#Comment_62608 Wed, 23 Sep 2009 13:50:37 +0100 jamesingram External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62609#Comment_62609 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62609#Comment_62609 Wed, 23 Sep 2009 14:03:39 +0100 Peter Clark
I found some generally discouraging posts here:

http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=1899&page=2

But some slightly more encouraging (2011 maybe) in respect of CESP - Community Energy Savings program:

http://www.decc.gov.uk/en/content/cms/consultations/open/cesp/cesp.aspx

Peter]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62620#Comment_62620 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62620#Comment_62620 Wed, 23 Sep 2009 18:23:23 +0100 sinnerboy At the time of the start of the grants system early on this years there was only such system . Subsequently Weber moved quickly to amend their existing certification to include refurbs ( previously it stated new builds ) .

The SEI stance is reasonable - tax money must be spent properly and IAB ( BBA equivalent ) sets a quality threshold

So
Pitfall 1 - does the system you are looking have certification pertinent to the application ? New / Existing

Pitfall 2. Earlier this year , one of system providers - can't recall which one now - altered their certification to remove phenolics from the choices of insulation types . Holding on that thought notice that If you approach Kingspan about their EWI board and ask them ANYTHING about anything other than their own board product - ( fixings, lathings , renders ) - well don't expect much help

Pitfall 3 . Even with the cert document in front of you - be careful of the details . By that I mean the Technical Architectural Detailing

For example - this cert geared specifically towards refurbs

http://www.nsai.ie/modules/certificates/uploads/pdf/IAB090332.pdf

Turn to pages 6+ 7

The jamb detail would be improved enormously if the window was repositioned outwards so it aligned with the insulation layer . If analysed using Therm or similar ( which I have not done ) one may even find that the suggested deatil here may lead to surface or interstial condensataion

The cill and eaves details are GAURENTEED to lead to localised condensation - no need for Therm here
The existing cill must be first cut flush with the block and the window moved forward
And the eaves detail .... well just imagine how the uninsulated wallplate / top block course would be affected if the EWI is stopped below the roof soffit . The soffit must be removed for the EWI insulation to be made continuous with the roof insulation .]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62623#Comment_62623 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62623#Comment_62623 Wed, 23 Sep 2009 18:34:15 +0100 sinnerboy
http://www.nsai.ie/modules/certificates/uploads/pdf/IAB090336rev1.pdf]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62625#Comment_62625 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62625#Comment_62625 Wed, 23 Sep 2009 18:45:59 +0100 sinnerboy That was during boom . Mind you the SEI grant may work to keep the rate up - grants always get "swallowed" in this way * . Measure through windows to cater for reveals + cills detailing
even factoring in €/£ variation the costs mentioned earlier in the thread seem high .



*off topic rant - no more grant aid for renewables - this artificially inflates consumer costs for solar panels etc etc etc]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62634#Comment_62634 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62634#Comment_62634 Wed, 23 Sep 2009 20:25:21 +0100 fostertom External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62654#Comment_62654 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62654#Comment_62654 Wed, 23 Sep 2009 21:47:34 +0100 Mike (Up North) No matter how specialised or bespoke anyhting is, everything get comodotised - eventually. Not sure if that is a real word but it happens anyway.
Cheers
Mike up North]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62657#Comment_62657 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62657#Comment_62657 Wed, 23 Sep 2009 21:55:50 +0100 Nick Parsons External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62658#Comment_62658 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62658#Comment_62658 Wed, 23 Sep 2009 22:01:25 +0100 jamesingram I'll let you know if I drop a clanger in a week or 2 , if I can get my hand on the stuff that is]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62666#Comment_62666 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62666#Comment_62666 Wed, 23 Sep 2009 23:44:43 +0100 Saint External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62669#Comment_62669 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62669#Comment_62669 Wed, 23 Sep 2009 23:57:01 +0100 fostertom External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62683#Comment_62683 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62683#Comment_62683 Thu, 24 Sep 2009 09:29:48 +0100 Peter Clark Posted By: fostertomI was rung up by NBT who told that if I was getting prices above £75-90/m2 fixed

presumably that is m2 of wall surface?

If so ,should i include window/door area?

And for the whole caboodle - scaffolding etc?

Posted By: sinnerboy*off topic rant - no more grant aid for renewables - this artificially inflates consumer costs for solar panels etc etc etc


As an amateur and committed cynic, this makes sense to me, installers will just add the grant aid to the cost and take that money for themselves?

Peter]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62695#Comment_62695 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62695#Comment_62695 Thu, 24 Sep 2009 11:39:35 +0100 fostertom Posted By: Peter Clarkpresumably that is m2 of wall surface?

If so ,should i include window/door area?It's customary to ignore/include the window areas (assuming average-%age window area) as the missing EPS/render pays for the extra work forming reveals etc.

Posted By: Peter ClarkAnd for the whole caboodle - scaffolding etc?
Yes, that's yet to be checked.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62723#Comment_62723 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62723#Comment_62723 Thu, 24 Sep 2009 16:01:24 +0100 jamesingram Not really a clear picture though for pricing external insulation , but job is 90m2 Meshed thro-colour render 55m2 on 60mm EPS insulation , 35m2 on block ,Trying to get external walls to U=0.25 (AECB silver) yes it could be better but this doesn't involve resetting verges etc.
material for above about £28m2
working out at £62m2 all in , scaffolding etc. It'll be me and my usual plasterer doing the work + a labourer
Trying to do it as cheap a possilbe whilst still earning my normal rates
done this kind of stuff before as a subby/labour a while back , but that was just on day rates.

Saint, do you anyone that wants to pay you for sitting in the rain?
when I was a subby, some days we'd leave about 6.00 am drive a hour and half to a job to see what the weather was up to, have a cup of tea, then drive home again, get back about 11.00 one tank of diesel worse off and no money earn't that day. I always presumed that was the name of the game.]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62725#Comment_62725 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62725#Comment_62725 Thu, 24 Sep 2009 16:35:51 +0100 fostertom Posted By: jamesingramworking out at £62m2 all in , scaffolding etc. It'll be me and my usual plasterer doing the work + a labourThat means scaffolding's included in the £62/m2? - but what about the labour - is that included? Any idea how much £/m2 is added by using thicker EPS? (60 is thin, in my book).

Interesting that the usual thing of diminishing returns (reducing heat loss) from paying for incremental extra thicknesses of insulation, doesn't really apply to EWI. The render, half the total price, is the same whatever the insulation thickness; and labour is about half the remaining price for the insulation itself, and again is much the same whatever the insulation thickness. So the material cost of the insulation is only about a quarter of the total, and halving or doubling its thickness makes relatively little difference to the total cost. So go for max possible thickness!]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62731#Comment_62731 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62731#Comment_62731 Thu, 24 Sep 2009 17:06:04 +0100 jamesingram
All in , as in labour and materials , like I mentioned, i'm trying to do it at a good fair price
perhap £75+m2 would be more realistic

60mm EPS (from render supplier , have to buy the lot of them for warranty) around £5m2
60mm PHS around £13.50m2
a bit pricey in my mind

totally agree about the opposite law of diminishing returns in regard to EWI , other than when the additonal thickness requires additional costs of moving verges,external pipe work, sofit width restrictions etc]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62732#Comment_62732 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62732#Comment_62732 Thu, 24 Sep 2009 17:12:35 +0100 tony External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62748#Comment_62748 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62748#Comment_62748 Thu, 24 Sep 2009 19:15:34 +0100 arthur
Is it possible to ever get old victorian houses airtight enough to justify MHVR?]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62750#Comment_62750 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62750#Comment_62750 Thu, 24 Sep 2009 19:33:57 +0100 fostertom External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62758#Comment_62758 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62758#Comment_62758 Thu, 24 Sep 2009 20:20:15 +0100 jamesingram right
Whats the thoughts on using EPS or PHS( phenolic board) is it worth the extra 18% overall cost increase for PHS
U values 1/3 lower for PHS , but I've been lead to believe reducing U values of materials does not result in a linear
reduction in heat loss?
I'm concerned about points raised regarding gases leaking out of the PUR/PIR/PHS
boards over time making them similiar to EPS/XPS in regard to U value , also there's the additional enviromental impact of production of PUR/PHS boards compared to EPS to consider ?
My original plan was to use standard 60mm PUR board , but the render supplier wont give warranty unless I buy the full kit from them.
cheers Jim]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62768#Comment_62768 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62768#Comment_62768 Thu, 24 Sep 2009 22:56:32 +0100 fostertom
Both kinds of EPS are fairly eco-virtuous, all the foamed plastics considerably less so. EPS is satisfactorily water-vapour-permeable, the foamed ones not at all. EPS can't be used in waterlogging conditions e.g. for u/ground downstand insulation; unfortunately the closed-cell foamed plastics have to be used for that.

Then there's wood-fibre!]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62779#Comment_62779 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62779#Comment_62779 Fri, 25 Sep 2009 07:57:30 +0100 Saint External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62781#Comment_62781 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62781#Comment_62781 Fri, 25 Sep 2009 08:20:31 +0100 jamesingram condensation risk came up ok (ish) on builddesk

I worked it out at approx U= 0.24 with PUR (celotex) taking the cavity as only 50mm due to possibly not fully filled

haven't checked with EPS yet
as Builddesks no longer free

Ps. just had a look on a simple U calculator,

U= 0.3 render/60mm EPS/brick/50mm filled cavity/brick
or
U=0.25 render/60mm EPS/brick/75mm filled cavity/brick
(EPS lambda @ 0.037)]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62789#Comment_62789 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62789#Comment_62789 Fri, 25 Sep 2009 10:37:38 +0100 Saint Yes that would be the concern, the dew point is probably going to be between the cavity fill insulation and the EPS]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62794#Comment_62794 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62794#Comment_62794 Fri, 25 Sep 2009 10:59:13 +0100 caliwag
"I believe that old terraces etc should be (government funded) seriously draught stripped and have MHVR installed.".

Is it possible to ever get old victorian houses airtight enough to justify MHVR?

Agree entirely, and people that have MHVR seem entirely happy with the kit, particularly the increase in air quality, but sadly it doesn't seem to fall within the governments radar. A lack of coherent lobbying from the industry perhaps!]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62797#Comment_62797 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62797#Comment_62797 Fri, 25 Sep 2009 11:16:24 +0100 jamesingram I've made effort to seal the cavity as much as possible to help reduce risk]]> External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62800#Comment_62800 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62800#Comment_62800 Fri, 25 Sep 2009 12:52:00 +0100 djh External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62965#Comment_62965 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=62965#Comment_62965 Mon, 28 Sep 2009 21:37:32 +0100 jamesingram External insulation - any pitfalls? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=70827#Comment_70827 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3025&Focus=70827#Comment_70827 Tue, 05 Jan 2010 13:44:41 +0000 jamesingram did the job on day rate in the end. SE UK
70mm EPS , acrylic mesh render 2 coat system ,90m2 all in came to £85/m2

EWI materials £ 28m2
Other material costs £ 10m2
labour £47m2

the 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 similiar

Spent quite a bit of time getting use to the system , render take up times etc
so I think labour cost will reduce on the next job
As it was all done at cost any potential labour savings would probably have to go toward
contingencies , profit and offsite costs
so I think the £85m2 + figure seems quite fair for a non-specialist jobbing builder with low overheads
increased thickness as mentioned would not effect the material costs greatly until you get to
having to adjust other part of the building to allow for it .
cheers Jim]]>