Fri, 04 Sep 2026 13:40:46 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53632#Comment_53632 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53632#Comment_53632 Fri, 08 May 2009 00:05:50 +0100 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53634#Comment_53634 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53634#Comment_53634 Fri, 08 May 2009 00:53:49 +0100 Saint
The savings would be mid £20s i.e £25- 26/m2 down to maybe £16/m2 so its significant

CommentAuthorwellburn CommentTime2 hours ago quote
don't get blown away by aerogel, - it's less than twice as good as kingspaN / pir / pur
ie - 10mm aerogel is only about the same as 18mm kingspan - which while being an improvement, - is no where near enough !!! - not for building regs, - not for anyone. - and it is WAY expensive. It really is about labour, - not cost of materials UNLESS you choose aorogel, - so just bite the bullet, - do the maths, - and buy big fat foam boards.

Wellburn is of course mathematically correct. You save 8mm of space by using Aerogel against Kingspan but then then again equally you save 11mm of space by using Kingspan against super cheap old mineral wool and at what cost?
Of course and again I agree we're not talking just 10mm Aerogel on a solid wall to meet Building Regs, more like 30mm or for Kingspan 54mm or mineral wool 88mm. Then do you need battens? Ultimately how much do you value internal space? In London and inner cities pretty much, in the shires maybe not so]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53635#Comment_53635 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53635#Comment_53635 Fri, 08 May 2009 01:10:47 +0100 Saint 50mm EPS externally is little better than what we achieve by full filling 1970s built cavities and that costs £400-£500. Admittedly not such a perfect solution but one that would seem to cost just 10% of the external option. Likewise internal insulation would probably be 50% of that cost.

Isn't it time we got to grips on this forum with what the definition of thermal insulation is?
Just because the brand name contains a prefix referencing an organic product, a prefix referencing a "state of the art technology", is made from recycled waste, is derived from animals or is credited with a performance not measurable by any internationally recognised norm should not detract from the fact that a thermal insulation should provide a reasonable, achievable and measurable resistance at a given thickness.
Some so called thermal insulations mentioned herein have thermal performances no better than wood.
Perhaps we should insist on a thermal resistance no lower than 1.25m2W/k for a 50mm thickness before we can call the product thermal insulation in the true sense. Any thoughts/comments?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53642#Comment_53642 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53642#Comment_53642 Fri, 08 May 2009 10:50:08 +0100 tony
I was doing 50 mm 30 years ago and am embarrassed about that but all the effort of doing external insulation and using so little insulation seems mad!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53651#Comment_53651 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53651#Comment_53651 Fri, 08 May 2009 12:01:46 +0100 Paul in Montreal
If you have a solid double brick wall, its R value is about R2. If you add 50mm EPS, the R value increases to about R12. You have now reduced your heat loss by a factor of 6. So, say you were losing $1200 of heat through your walls per year, now you are losing only $200. If you increase the insulation from 50mm to 200mm, your R value is now R42 and so your heatloss is reduced by a factor of 21, so now you'd be losing $57 of heat through your walls per year. The 50mm of insulation saved you $1000 per year, the extra 150mm of insulation only saves $142.

Now, it's true that labour costs dominate external insulation. Don't forget, though, that the improvements in air tightness will be the same with the 50mm of insulation as with the 200mm. I don't know how much extra material cost the 200mm of insulation would have over the 50mm, but the payback of that extra 150mm is much much longer than the first 50mm. And the lower your heating bills were in the first place, the worse the ROI on the incremental insulation is.

Paul in Montreal.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53664#Comment_53664 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53664#Comment_53664 Fri, 08 May 2009 13:41:12 +0100 Saint Exactly and there's the rub. U value of a solid brick wall is accepted as 2.1W/m2K.
Adding 50mm EPS takes it to 0.54 W/m2K, allowing for a bit of render then maybe 0.52W/m2K.

Not quite the 6 times savings as quoted by Paul in Montreal but still substantial.
Nowhere near building Regs of course which I know is where you're heading. To achieve that you'd need 85-90mm EPS

** Leepike, our postings crossed over. How do you get 0.37W/m2K with 50mm EPS???]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53665#Comment_53665 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53665#Comment_53665 Fri, 08 May 2009 13:45:53 +0100 leepike https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53666#Comment_53666 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53666#Comment_53666 Fri, 08 May 2009 13:49:41 +0100 leepike https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53670#Comment_53670 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53670#Comment_53670 Fri, 08 May 2009 14:20:12 +0100 Saint https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53671#Comment_53671 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53671#Comment_53671 Fri, 08 May 2009 14:24:03 +0100 mike7
9in solid brick .36, 12mm plaster .08, surfaces int and ext .18, total .62 or u-value 1.62
As above .62 plus 50mmEPS 1.35 and 12mm render .02, total 1.99 or u-value .50
As above but plus 100mm EPS 2.70 and 12mm render, total 3.34 or u-value .30

Hope this helps]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53674#Comment_53674 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53674#Comment_53674 Fri, 08 May 2009 15:32:24 +0100 leepike https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53676#Comment_53676 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53676#Comment_53676 Fri, 08 May 2009 15:41:13 +0100 Saint
If you use the BRE U value calculator you'll get:

Solid brickwork thermal conductivity 0.77W/mK so at say 225mm thick an R value of 0.292 m2k/W
An internal resistance (Rsi) 0.130 m2k/W
An external resistance (Rse) 0.04 m2k/W

Adding all the R values gives you 0.462m2k/W This converts then to a U value of 2.16 W/m2K
The BRE, EST and Ofgem all use this figure rounded down to 2.1W/mK as the baseline value for a 9" solid brick wall

So unless Lee's EPS has a thermal conductivity approaching 0.02W/mK (like phenolic) its impossible for 50mm EPS to achieve a 0.35W/m2K U value]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53679#Comment_53679 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53679#Comment_53679 Fri, 08 May 2009 15:46:20 +0100 Nick Parsons https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53680#Comment_53680 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53680#Comment_53680 Fri, 08 May 2009 15:51:48 +0100 Saint
Exactly. The same wall with 50mm phenolic would give you 0.35W/m2K (taking phenolic at 0.021 W/mK)]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53682#Comment_53682 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53682#Comment_53682 Fri, 08 May 2009 17:13:05 +0100 mike7 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53688#Comment_53688 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53688#Comment_53688 Fri, 08 May 2009 19:17:47 +0100 NTP Posted By: SaintNTP,

The savings would be mid £20s i.e £25- 26/m2 down to maybe £16/m2 so its significant

CommentAuthorwellburn CommentTime2 hours ago quote
don't get blown away by aerogel, - it's less than twice as good as kingspaN / pir / pur
ie - 10mm aerogel is only about the same as 18mm kingspan - which while being an improvement, - is no where near enough !!! - not for building regs, - not for anyone. - and it is WAY expensive. It really is about labour, - not cost of materials UNLESS you choose aorogel, - so just bite the bullet, - do the maths, - and buy big fat foam boards.

Wellburn is of course mathematically correct. You save 8mm of space by using Aerogel against Kingspan but then then again equally you save 11mm of space by using Kingspan against super cheap old mineral wool and at what cost?
Of course and again I agree we're not talking just 10mm Aerogel on a solid wall to meet Building Regs, more like 30mm or for Kingspan 54mm or mineral wool 88mm. Then do you need battens? Ultimately how much do you value internal space? In London and inner cities pretty much, in the shires maybe not so

Thanks Saint,

I have misunderstood you. As mentioned quite rightly, space is important for me and that being due to not fiddling with the window frames. 20 mm aerogel will fit my window frames (30mm off the wall) nicely and to be honest the price wouldn't be a problem since I have only got a few external walls and most of them have big sash windows.


What do you think is the better/easier option: fermacell or plasterboard ?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53689#Comment_53689 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53689#Comment_53689 Fri, 08 May 2009 19:19:54 +0100 NTP
I have got a leasehold and the flat downstairs is still owned by the council so I'd rather do the internal insulation. Thank for the post anyway.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53692#Comment_53692 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53692#Comment_53692 Fri, 08 May 2009 19:42:12 +0100 Moderator https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53697#Comment_53697 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53697#Comment_53697 Fri, 08 May 2009 20:56:37 +0100 jamesingram Its nice to see some people giving sensible quotes for external insulation ,its similar to what I'd charge
I'm a trademen myself and done some eps,xps/external render work in the past
as you where advertising yourself , I was interested to see what you called ' not expensive'
As I mentioned I think external insulation needs keener pricing to get a better uptake , otherwise
it will just be to expensive for the average Jo to consider.
I'm a bit confused about the 50mm EPS on solid walls though , I thought current UK regs where looking for U =0.3
on walls , which 100mm EPS approximately achieves.
I understand why its easier to sell 50mm at a fair price , its not the extra insulation cost , which is surely only several £ per m2 , but the issue of dealing with detailing such as verges, soffit, pipework ,50mm will usely
slot in without to much greath, anymore and you've got some large additonal costs
Really though I think we should be looking toward U=0.25 as a minium and better where possible
I believe in Germany they got a massive program to upgrade the housing stock and 200mm EPS is quite common
surely we should be following there lead
what insulation/render system do you use , if you dont mind me asking.

cheers Jim]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53708#Comment_53708 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53708#Comment_53708 Fri, 08 May 2009 22:11:30 +0100 Nick Parsons https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53750#Comment_53750 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=53750#Comment_53750 Sat, 09 May 2009 11:34:03 +0100 Saint
Apparently the Fermacell laminate is outselling the plasterboard and by some. I'd have thought the other way but what do I know?
Reasons are given as durability and the fact that cabinets can be fixed to it. Here's a link for the Fermacell
http://www.xella.co.uk/downloads/gbr/broschures/HandyGuide_s1104.pdf]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=54568#Comment_54568 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=54568#Comment_54568 Tue, 19 May 2009 20:04:07 +0100 NTP
I have read some material about cavity wall insulation and was wondering if it would apply to my Victorian flat. I only own the top floor flat so if I were to use cavity wall insulation could it be restricted only for the one of the 2 flats in the house? In other words is there a cut off level between the 2 flats in relation of this space between the bricks? I would have thought that if I were to go for it I might need to get my neighbour to join me.

Any ideas guys?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=54573#Comment_54573 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=54573#Comment_54573 Tue, 19 May 2009 20:36:40 +0100 jamesingram
If so really you need to get your neighbour involved , the wont be any cut off point like you suggest, tell them they'll get there money back in 2 years (ish)
in fuel bill savings ,]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=54578#Comment_54578 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=54578#Comment_54578 Tue, 19 May 2009 21:36:55 +0100 NTP
Involving the neigbour means not doing it because they are renting the place from the council.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=54580#Comment_54580 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=793&Focus=54580#Comment_54580 Tue, 19 May 2009 21:46:36 +0100 jamesingram
Councils need to get off there arses and start improving the housing stock for those
most affected by fuel poverty by organising this as the freeholder/landlords

http://www.government-grants.co.uk/cavity-wall-insulation-grants.shtml
http://www.freeinsulation.co.uk/?gclid=CMuyi-efyZoCFRUhnAod3Fz22g]]>