...why so much heating on the outside leaf of a new build ? On an existing build, where options are limited, I can understand, but on a new build, you're advocating heating that huge 215 wall first, and then your rooms.................just heat the rooms, and isolate the walls.
There is a large house not too far from me, with render-on-polystyrene, and the render has 'slumped' in several places - it looks like it has sagged. And another house, with render on ICF, has a permanent algae problem. Owner tells me the keep washing the bottom of the wall and cills with bleach, to get the green growth off..........
...why so much heating on the outside leaf of a new build ? On an existing build, where options are limited, I can understand, but on a new build, you're advocating heating that huge 215 wall first, and then your rooms.................just heat the rooms, and isolate the walls.
There is a large house not too far from me, with render-on-polystyrene, and the render has 'slumped' in several places - it looks like it has sagged. And another house, with render on ICF, has a permanent algae problem. Owner tells me the keep washing the bottom of the wall and cills with bleach, to get the green growth off..........
ive never come across anybody trying to put that much insulation on,the person who you spoke to is right there is a very real possibilty that with that kind of weight the insulation would just drop off the wall.i dont believe that there are any fixings big enough to secure this type of board.adheisive on it own would not be suffcient.
have you considered using a phenolic board,an 80mm board will get you a u-value around a 0.18.i will make a few enquires and see if they do 100mm.
300mm of insulation is not terribly common because it's primarily used for passive houses. The more typical 100mm layer Facades spoke of is most likely because they spend most of their time on commerical projects where they don't exactly reach for the stars in thermal performance terms.
There most certainly are mechanical fixtures available for that depth of insulation. Brillux, Baumit and STO all have them. All german systems of course. The more commonly available local systems e.g. weber, may not have them. Weber also only have a metal base rail I'm told, no pvc variant (this may have changed recently but it was certainly the case a few months ago). So basically you start your external insulation by adding a cold bridge, brilliant!
None of the German EWI systems I've seen the technical details have variants using Phenolic or PUR, only EPS (white and grey) and mineral wools. This alone is sufficient reason for me to avoid them. Phenolic insulation has not been around long enough for us to know how it performs over 30 years for example. The IAB\BBA does accelerated age testing but this is a simulation, it is not the same thing. This is my personal opinion of course.
im unsure as to your info regarding the metal base rail,do you mean a metal tracking,such as a type of partition or do you mean a plinth bead detail?
as for reaching for the stars,if you can achieve a u-value of of 0.18 from an 80mm phenolic board i can only imagine what you would achieve if you doubled this,and even then you would still be nearly half the thickness of the polystyrene
with regards to using the eps over phenolic,im curious as to your point regarding the fact that phenolic has not been around for 30yrs and this is your reason for not trusting it,are you calling into question the validity of iab/bba certs which are legally binding.
are you also relying on 30yr old technologhy,by that logic all advances in both insulation and building products which have certs should be discarded due to their lack of longevity
Who supplies Baumit in Ireland.
I'm talking about the metal rail seen supporting the insulation and render on page 3 figure 1 on the Weber IAB cert,
http://www.nsai.ie/modules/certificates/uploads/pdf/IAB%20353%20D6.2%20XM%20171207.pdf
I think your initial figures are incorrect. Based on a thermal conductivity of 0.022 for phenolic, 80mm phenolic on regular 4 inch solids gives 0.26. You need approx 115mm to get to 0.18. Phenolic gets you to 0.1 at 210mm and grey eps needs 300mm. Given the massive price difference between them I'll take the EPS system anyday. Plus it doesn't sit well with me that none of the german systems I've seen use phenolic.
I wasn't aware the IAB or BBA certs were legally binding. In what sense is this the case? They aren't an insurance company, they won't be compensating you if you use an IAB approved system and you suffer a loss due to a problem with it. There are IAB and BBA certs for systems (especifically timberframe systems) that are considered very poor in countries with long established histories of timber buildings. So yes, basically I am doubting the ability of the IAB or BBA or any organisation to simulate aging. The IAB do alot of there certification based on finger in the air testing. One company I spoke to are currently putting a system through the IAB. The IAB wants them to increase the thickness of the render on their EWI system. They provided no tests, documentation or anything else to support this. They just felt it would be better. Before we go putting blind faith in the IAB I would like to point out that most of us thought the financial regulator was watching over things very closely until recent events unfolded.
I suppose the last comment is somewhat deserved. However, I'm not talking about a 50 euro dvd player. I'm talking about a 50000 Euro external wall insulation system. The more I have to fork out, the more cautious I'm going to be.
With any relatively new system I believe caution is necessary. If a system has enjoyed success over a longer period in another country then I would be interested in seeing it in use here. However, as I've said previously, the only insulating materials in EWI systems I've come across used outside of Ireland and Britain are EPS and Mineral Wool. No pur or phenolic.
the bead detail to which you refer is creating a such a small cold bridge that i dont feel i warrants mention..
who is using breeze blocks and also i believe drylining the walls.
certs are there for a reason,in all walks of life.the testing involved to achieve these certs is done in the only way possible under simmulation.
the bead detail to which you refer is creating a such a small cold bridge that i dont feel i warrants mention.
as for cost in comparison between eps v phenolic,its far from massive,its approx 2e per sqmtre of a difference,not really significant.
what i meant by legally binding is that they have a standing in law and are used to set an industry standard and create a confidence within an industry.certs are there for a reason,in all walks of life.
i agree with your point in some respects regarding tried and tested systems but again you are relying on the longevity of a system which has worked in other countries which have a different climate to ours,be it harsher or milder.
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