# Foil Insulation In Attic Ceiling



## Lex Foutish (4 Jul 2011)

I posted about this before. Has anyone here used foil insulation to insulate a converted attic ceiling? 

How did it work out? I've heard people who swear by it and also people who think it's not as good as the manufacturers claim it to be. It looks like it might be my only option, given the thickness of my rafters.


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## onq (4 Jul 2011)

Seeing as this is your second time asking, but I still haven't experience of this, I googled this link for you which I hope helps. 

[broken link removed]

I make no representations on behalf of the website or the report or the people testing it, but it seems well done and if what it says is true your fears may be well founded.
The trouble with most self builders is that they are not professionals and even professionals seldom have products tested competently an empirically.

Thus with no competent feedback loop, there is seldom any relevant information about past installations in circulation.
My preference is Rockwool, for its resistance to absorbing moisture and fire resistance as well as insulation.

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                                     matters         at                           hand.


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## Lex Foutish (5 Jul 2011)

Thanks, ONQ. A most helpful post, as always.

That's a very interesting article. I'm a bit disappointed, to be honest, as I thought it was the easy way out for me. But it's good to know in advance. My rafters are only 4 inch and I don't have a breathable membrane. Ideally I should remove the tiles, put in Metac (I prefer it to Rockwool as it has a much better U-value) and put in a breathable membrane before replacing the tiles. But all of that is a big job with scaffolding, etc. Insulated plasterboard isn't an option, at all, due to restricted head height. That's why I'm so disappointed with those foil test results......


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## onq (5 Jul 2011)

Lex,

Without wishing to prejudice your position, 4" or 100mm deep rafters  don't seem deep enough for a roof unless it is a very short span.

From:

http://www.environ.ie/en/Publicatio...ng/BuildingStandards/FileDownLoad,1683,en.pdf

Structural work on timber:
IS 193: 1986, Timber trussed rafters for roofs
SR 11: 1988, Structural timber for domestic construction
Superseded by 
IS 444: 1998, Use of structural timber in buildings
Superseded by 
I.S. EN 1995-1-1:2005                 
                Eurocode  5: Design of Timber Structures - Part 1-1: General - Common Rules and  Rules for Buildings (including Irish National Annex)               

http://www.coford.ie/media/coford/content/publications/projectreports/eurocodea520061031.pdf

I'm sorry I started this post now LOL!
While this is the relevant code its not very useful for laypeople. :rollseyes:

Suffice it to sat that you seldom see joists less than 150mm holding up a roof unless its an engineered truss.
In relation to your problem, if insulating _between_ the rafters isn't a possibility, can you consider external insulation, i.e. on a flat roof?


 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                                     matters         at                            hand.


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## Lex Foutish (6 Jul 2011)

Hi ONQ. For once, I'm going to totally ignore what you said in your post! Otherwise, I'd never get a night's sleep again! 

The roof was made from engineered trusses. The guy who converted it did some serious propping during the job. An engineer friend looked at it and said he did a good job.

I don't think that any kind of externel insulation is an option. I live in a semi-detached house and it has an A roof...........


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## onq (6 Jul 2011)

I read the document and was sorry I did - bEuro-speak which I'm sure *someone* understands.

It makes you appreciate the accessibility of the information in TGDs in our own building regs.

Trusses can have fairly minimal members and its good an engineer looked it over.

Not many solutions popping up about this one unfortunately. 


 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                                     matters          at                            hand.


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## sinolam (7 Jul 2011)

as a salesmanager in a manufacturer of foil insulation , I tell you the truth
every producer or supplier claim their foil could barrier 97% or 95% radiant, that is theoretical data means nothing!

the fact is it could be block appox. 30-35% energy. will be more effective if foil insulation work together with glass wool or rock wool, actually foil insulation was designed as a accessory facer to glass wool in the begining.

you will find more info. in youtube, there is a guy did some experiments to prove is that foil helpful, just seach foil insulation in youtube





Lex Foutish said:


> I posted about this before. Has anyone here used foil insulation to insulate a converted attic ceiling?
> 
> How did it work out? I've heard people who swear by it and also people who think it's not as good as the manufacturers claim it to be. It looks like it might be my only option, given the thickness of my rafters.


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