# Extruded polystyrene and fire safety



## jameson (25 Oct 2011)

Hi all, new to the site and looking for some advice please. I am in the latter stages of an ICF self build. 
I have a gable wall with an internal chimney breast built into it.The chimney breast is block built which is tied into the 6" concrete core. The  construction of the chimney consists of 8" round earthenware flue liner, the void which is a minimum of 2" is filled with well compacted sand lime cement mix and the outer skin is 6" dense concrete block. The exterior of the gable is clad with 4" extruded polystyrene which has yet to receive its Acrylic render finish.
My concern is to whether or not the depth of the construction between the flue and the external extruded polystyrene is enough, fire safety wise. The flue is for a solid fuel range cooker.
Thank you in anticipation for any advice offered.


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## onq (25 Oct 2011)

This isn't a general comment, but one that's specific to the form of construction used.
Its very difficult to "write" a building construction detail 
What does the supplier/installer/manufacturer say?


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                            as a defence or support - in    and    of        itself  -         should       legal        action       be           taken.
Competent legal and building professionals should be asked to advise in                                            Real Life with rights to   inspect     and       issue         reports    on     the         matter   at  hand.


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## jameson (25 Oct 2011)

The suppliers of the system don't actually seem to have any details on chimney construction. I have installed the system, in fact I have built the entire house myself; did the formwork, built the chimney and poured the concrete. I have been searching for an answer to my concern for some time but can't find one. I would suppose a hopefully near passive house with chimneys is a bit of a contradiction so hence there seems to be little information on the subject.
If you imagine a chimney breast on the inside of a house would normally have a thickness between the flue and the surface of the wall of no more than about 6" I would have thought it would be enough but was looking for some reasurrance.


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## lowCO2design (26 Oct 2011)

jameson said:


> The suppliers of the system don't actually seem to have any details on chimney construction. I have installed the system, in fact I have built the entire house myself; did the formwork, built the chimney and poured the concrete. I have been searching for an answer to my concern for some time but can't find one. I would suppose a hopefully near passive house with chimneys is a bit of a contradiction so hence there seems to be little information on the subject.
> If you imagine a chimney breast on the inside of a house would normally have a thickness between the flue and the surface of the wall of no more than about 6" I would have thought it would be enough but was looking for some reasurrance.


if its the guys I dealt with in the past, there great at sales but not at the details  and also thin on building physic's. when you get in to it with the sales guys, you get stuff like 'its U-value is .2 but it'll preform much better' - much better than WTF? excuse my little rant, in general the products grand, a good foundation system!

as regards your chimney details - your architect and engineer are the people you should be talking to 

also check out page 7 of the B'regs TGD-J
http://www.environ.ie/en/Publicatio...ng/BuildingStandards/FileDownLoad,1650,en.pdf


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## onq (26 Oct 2011)

I haven't considered the detailing of this kind of construction before, but its clear the chimney flue is a key detail.

Looking at the details referred to by LCO2D this suggests you may need a shield plus a cavity!

Your architect should have sorted this out for you well before you went to site.


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                             as a defence or support - in     and    of        itself  -         should       legal        action        be           taken.
Competent legal and building professionals should be asked to advise in                                             Real Life with rights to    inspect     and       issue         reports    on     the         matter    at  hand.


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## jameson (26 Oct 2011)

Thanks for the input guys. Looking at diagram 2 (a),without shield, I should just about be ok with my 6" blockwork and sand,lime,cement backfill  fullfilling the 200mm solid non combustable material requirement between clay flueliner and external extruded polystyrene,or am I misreading somthing???


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## onq (26 Oct 2011)

ICF buildings are not well known or understood in and Irish climate and not "traditional" buildings.
You have reached the point where self-build stops and professional comment begins.
Take advice from a building professional in writing and pay him for it.
The entire detailing of your house should have been signed off.


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                              as a defence or support -  in     and    of        itself  -         should       legal         action        be           taken.
Competent legal and building professionals should be asked to advise in                                              Real Life with rights to     inspect     and       issue         reports    on     the         matter     at  hand.


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## jameson (26 Oct 2011)

ONQ, You may be a frequent poster and this may be my first post but I find your answer ever so slightly smug. I was under the illusion that this site was where one could look for friendly advise from someone who may have heard of or have been in a similar situation, but maybe I was mistaken and in fact the site is for profesionals to solicit for businness.
You don't know who I have contacted regarding my concern and you don't know what information I have been give by so called professionals, manufacturers or whoever, and you know nothing of my background. As I previously mentioned many manufacturers of ICF systems would consider  a chimney a bit of a contradiction with regard to air titeness, at least from my experience. To say ICF is not well known or understood in Ireland is a bit of a generalisation. I  Know and have spoken to many who have built and fully understand  the system both professionals and non professionals. I have also spoken to  both professionals and non professionals who  wouldn't have a clue regarding my question. There are still an great number of professionals, manufacturers and suppliers around that have little time for new technology and would possibly be a reason for for the lack of understanding you believe there to be regarding this system. I was looking for advice not a written guarantee and  from what I understand  "professional comment" has lead to mistakes being made as well as self build errors. Thanks for your input anyway.


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## onq (26 Oct 2011)

Taking professional advice and paying for it means you've covered yourself.
You will then have a formal relationship with the professional.
Thus you may be able to seek redress if the need arises.

I'm not soliciting work, I'm offering you good advice.
I said in Post #5 above I'm not familiar with ICF.
Thus I cannot answer your question in #4.


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                               as a defence or support -   in     and    of        itself  -         should       legal          action        be           taken.
Competent legal and building professionals should be asked to advise in                                               Real Life with rights to      inspect     and       issue         reports    on     the          matter     at  hand.


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## onq (26 Oct 2011)

I googled this link which may offer some information.

I'm not certain how this relates to compliance in Ireland.

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                                as a defence or support -    in     and    of        itself  -         should       legal           action        be           taken.
Competent legal and building professionals should be asked to advise in                                                Real Life with rights to       inspect     and       issue         reports    on     the           matter     at  hand.


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## onq (26 Oct 2011)

There is a disturbing consistency to the information in the following booklets on ICF systems

[broken link removed]

Par 2.1.11 Chimneys are not part of the Kore ICF system and are not covered by this certificate.

[broken link removed]

Par 2.1.11 Chimneys are not part of the Thermo House ICF system and are not covered by this certificate

However this company suggests its products are suitable for use with ICF

[broken link removed]

As stated above I am unfamiliar with the form of construction.
I do not recommend these companies or their details.
This is offered for information only.

You should seek advice from a competent professional in relation to the compliance or otherwise of details with the requirements of the Building Regulations.


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon                                                 as a defence or support -     in     and    of        itself  -         should       legal            action        be           taken.
Competent legal and building professionals should be asked to advise in                                                 Real Life with rights to        inspect     and       issue         reports    on     the            matter     at  hand.


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