300mm External Insulation on New House

dgray_ie

Registered User
Messages
30
Hi,

I am considering building new house with single leaf 215mm blocks on the flat and 300mm external insulation aeroboard platinum to give a U value of 0.10W/m2K however the quote I received from Greenspan is extremely high, approx €115 supply & fit + VAT. Sounds crazy to me for Polystyrene and render....

Has anyone here built a new house using this construction method other than Tomas O'Leary in Wicklow? Would you recommend it - have you had any problems with weather or algae growth?

I presume if this is the price then there are very few out there. If there are I would love to know of your experience

Perhaps there are some northern contractors who are more competitive, any suggestions or contacts would be much appreciated.

Thanks,
Dgray
 
Last edited:
there are several systems of this type on the market

if you go to facades.ie, they do the sto system, and ask for a list of approved suppliers (i.e. plasterers)
you can then get quotes from each of them...
also do a search for viking-house, they also do it.
i have found that most of the cost of this system is labour, as the additional cost to upgrade from say 200mm to 300mm insulation. for example, is very small...
it is a great system if done correctly imo.
in that respect this system should be getting cheaper as labout costs go down, so i'm surprised that it is still this high per sq.m.
dont forget to take into account the cost of painting, and the additional cost of building a cavity wall, etc. into consideration when comparing.
also, bear in mind that an insulated cavity wall will almost certainly not give you the u-value in practice that it was designed to, whereas this system should, as well as avoiding cold bridges etc...
 
Hi 3Bedsemi,

I contacted a technical rep in Belfast office today and she said they dont go above 100mm and expressed concern at my suggestion to use more due to the weight (she had never heard of anyone going beyond 100mm). She said there could be a danger of wall sections falling off with the weight if not fixed properly or water penetrating behind the polystrene. She sseemed to more familair with applying coatings onto ICF for houses.

Are there any other companies other than Greenspan who do the 300mm. It would be nice to know how many houses out there have had 300mm external insulation applied and what their experience has been.

Dgray
 
...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.......... :(


hi there,
if the render is sagging in parts this is being caused by bad initial workmanship,rather than a render fault or a system failure.
as for the algae problem,this can all depend on the type of render used and the location of the house,but i have seen it happen.simple solution would be to just paint the house with an algae resistant paint,although this defeats the purpose of the thru coloured renders.
hope this helps
 
...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.......... :(

If you externaly insulate a masonry wall the theory is that you only heat the block leaf from cold once i.e. when you move in. From then on there will always be a reasonable level of residual heat. Plus externally insulated masonry walls is one of the most common build methods for passive houses in germany so it works. There is no debating this.

There are problems with render failure on ICF that I've heard of. The most prominent one was on a development in Ennis. The BRE did an investigation on the failure and concluded that the problem was caused by the render applicators i.e they screwed up. The system was deemed reliable when applied correctly.

Mould growth is not specific to ICF or EWI renders either, it's just something the vested interests on the other side like to use to down play these systems. My inlaws have a new traditional build (1 year old) and they are having problems with mould growth on the house already. It has as much to do with renders as it has to proximity to trees\hedges or excessive shading that prevents the wind from drying the surface of the buildings.
 
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.
 
Hi SAS,

Who supplies Baumit in Ireland.

Heres a link to their product from their website.

[broken link removed]


Dgray
 
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.


good to hear that there are fixings available they must be huge tho.
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
 
Off topic, but a dilute copper sulfate solution should cure the algal problem. The red "mould" that's common in the west is also an alga and can be cleared this way
 
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?

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

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

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.

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.

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.

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

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.
 
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.
apologies on the calculations,it was secondhand info which i picked up incorrectly from a friend,who is using breeze blocks and also i believe drylining the walls.its still saving you nearly a third in space.
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.the testing involved to achieve these certs is done in the only way possible under
simmulation.by your logic all technology should be tried and tested over 30 yrs before it is released onto the market,as you are aware this would be absured.
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.
 
the bead detail to which you refer is creating a such a small cold bridge that i dont feel i warrants mention..

unfortunately when you are planning on building a low energy or passive house, these thermal bridges can make a very significant impact

who is using breeze blocks and also i believe drylining the walls.

i hope your friend has their homework done on this type of construction, because internally drylining externally insulated walls is a dangerous form of construction. I hope your friend has done a 'dynamic condensation risk analysis' using an approved software package.

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.

i would agree that certifiction is a very important factor when choosing materials, but do not be fooled into thinking they are a guarantee of performance, far from it to be honest. Most certifcation tests are done under lab conditions. The only insulation material that i know of that has been assessed 'by performance' is cellulous. I think sas is correct to be wary of using newer materials that have not yet shown the effects of ageing. these materials are tested homogenously in labs, but are not tested inhomogenously in practise. For example, it has become almost inductry standard now to incorportate a 'slipping sheet' over foil backed insulation under poured concrete because it hs been shown infield tests that the alkaline concrete reacts with the aluminium foil. The lab tests did not show this....
 
the bead detail to which you refer is creating a such a small cold bridge that i dont feel i warrants mention.

Syd has already covered this. But to add... A friend of mine is building a certified passive house. He showed the details of the weber system to the PHI and they were less than impressed with that rail detail. All they would have had to do was use a pvc based rail and the issue is resolved. Why not do this in the first place. I don't believe that you should be spending money on external insulation systems and not aiming high. Actively adding a cold bridging material is a bad start.

as for cost in comparison between eps v phenolic,its far from massive,its approx 2e per sqmtre of a difference,not really significant.

You work in the industry so are aware what the cost to you is. I priced the weber system for equivalent u-values and their own rep told me I'd be looking at 20 - 30 Euro per square metre extra for the phenolic. So my 370 square metres costs me 7400 extra assuming equivalent u-values. Thats significant to me. It is likely based on the fact that the phenolic boards are available in limited thicknesses and hence you may need to double up on the boards. This doubles the labour for the fitting of the insulation naturally enough and leads to the higher price.

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.

Again, what exactly does this legal standing provide? If a system that is IAB certified starts to show problems 15 years down the line, the IAB cert will likely be revoked. That's it. I don't get compensated. They don't accept any responsibility. What constitutes this legal standing, I genuinely don't understand so I'd be grateful if you could explain its significance. Is it a case that if the IAB has certified a system, a certifying engineer must then be prepared to sign off on house built with that system? Even if they don't want to?

If the IAB actually knew what they were doing then why are the window details in the cert for the weber system the 2 thermally weaker details of the 3 actually used?

On the phenolic, the Germans are at EWI for a hell of alot longer than us. They have as good a reason to use thinner insulants (such as phenolic) as we do. They pretty much don't however from what I've seen. So I'll follow their lead on this.

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.

I didn't state that I would be happy to give systems successful in different climates the all clear. It's a far better starting point however to ensure that aging is not an issue than lab testing. Syd has covered alot of this quite nicely so I'll leave it there.
 
I have noticed a lot of people where I live are just bringing in the whole house from Germany, it is economic and done to a very high standard. It completely eliminates the risk of poor workmanship etc.
try www.riko-haus,

Plenty of the hanse houses around dublin, they arrive in big trucks and are erected in a couple of weeks.
 
Had to dig this one back up...

The IAB has dropped Phenolic insulation from the Weber external insulation system.

The cert has been updated (badly) to remove references to it.

See [broken link removed]

You'll notice the first paragraph in section 2.1 makes reference to 3 insulation options and then proceeds to name 2.

Bottom line, when externally insulating go with EPS (white or grey) or if you are rolling in it you could consider the mineral fibre variants.
 
Back
Top