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Housing - Renovation: Fire risk of External wall insulation systems (EWI) ?

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    • CommentAuthorjamesingram
    • CommentTimeNov 16th 2012 edited
     
    Mention this briefly here http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=3341&page=2#Item_22
    and also on other threads.

    A fella over on AECB forum has posted various info/links regarding fires on building with EWI on ,
    Most posts are what i'd describe as a bit lively :) but still , there's an underlying point which i think would merit from some discussion.

    The general concensus here on GBF seems to be EWI is the great 'cure all' for improving the performance of
    the building and reducing heatloss without damaging the structure with damp, condensation etc. keeping it all nice an warm.
    I've installed various systems and versions of it over the last 20 years
    Clearly it's going to take off here in the UK ,
    Suppliers are increasing marketing to the trade, and I believe building up for a big push with the 'Green deal'

    I'm starting to wonder if we're sleep walking into a situation where we're only see the posistives of EWI
    and as a result, perhap creating some serious problems for the future. Especially in flats etc.
    In the links fire seems to spread rapidly in EWI fascades and is quickly out of control.
    Should we not be looking more to Europe to learn from thier experiance of EWI as they've been at it for longer than us.

    Video of fascade fire in France
    http://www.dailymotion.com/video/xquk2n_exclu-l-incendie-de-roubaix-filme-par-un-voisin_news
    German Tv program on fire testing of EWI ( I cant understand a word, but I think I get the drift)
    http://www.ndr.de/fernsehen/sendungen/markt/media/markt6567.html
    more here.
    http://www.aecb.net/forum/index.php/topic,3765.0.html
    http://www.aecb.net/forum/index.php/topic,3615.0.html
  2.  
    Shocking stuff James.

    It seems that the thickness of the insulation is a contributing factor, as is the presence of any cavity.

    Is this yet another argument against the never ending reduction of u-values, especially given the law of diminishing returns?

    Many years ago BRE established the optimum u-value for a wall as 0.35W/m2K Others have concluded the same. References available.

    Jo Little has conducted research which suggests a u -value below around 0.5 can lead to serious problems within the make up of an internally insulated wall.

    Is it time that we settled for the MASSIVE reduction in heat loss gained from a typical wall u-value of say 2.0W/m2K to say 0.35W/m2K

    Rotten tomatoes at the ready.....
    • CommentAuthorTimber
    • CommentTimeNov 16th 2012
     
    I personally would think twice about wrapping my house in EPS, to be honest!

    I know the risks are small, and fires are fairly rare. Especially those that start outside the building (lets face it, if a fire inside the building is bursting out the windows (and starting to set the EPS alight) you got bigger problems!)

    I have seen the stuff on the AECB website and as mentioned, some of it is a bit 'fruity' but it does make you think.
    • CommentAuthorRobinB
    • CommentTimeNov 16th 2012
     
    I always thought polysterene fro EWI was specially fire retardant. This from a EWI website...


    3. Flame retardant and dimensionally stable

    4. The Reaction to Fire Classification is Euroclass E

    5. When specifying in an External Wall Insulation system BRE document BRE135 should be followed for positioning and specification of fire barriers ....

    I wonder if the materials in the videos were treated.
    • CommentAuthorGavin_A
    • CommentTimeNov 16th 2012
     
    has anyone got any idea what material was in use in those examples?

    a ventilated void running all the way up the height of the building between the insulation and the cladding would seem to be enabling the fire to rapidly spread up the entire height of the building.

    seriously worrying stuff
  6.  
    If 9mm plasterboard and skim gives a half-hour fire resistance, maybe 6mm (?) light render doesn't. Food for thought. Also how well are penetrations seales? I know how well they *should* be, but saw a job recently with some edges left 'raw' around air-bricks.
    • CommentAuthorJonti
    • CommentTimeNov 17th 2012
     
    Posted By: Gavin_Ahas anyone got any idea what material was in use in those examples?

    a ventilated void running all the way up the height of the building between the insulation and the cladding would seem to be enabling the fire to rapidly spread up the entire height of the building.

    seriously worrying stuff


    When I have the time I will watch the whole of the German clip but it is very slow loading on my PC. Why have a ventilated gap with EWI. If it has any vents (intentional or not) wouldn't that render it useless?

    Jonti
    •  
      CommentAuthorfostertom
    • CommentTimeNov 17th 2012
     
    Fire regs are for 2 purposes
    1) to resist fire for long enough for people to escape - then let it burn
    2) to prevent spread across property boundaries.
    They're not to prevent the building from burning as such.

    1) is served by regs-stipulated period of resistance of 'structural elements', but no resistance reqd for other elements.
    2) is by controlling the combustibility of the surface/cladding where close to a property boundary, but little stipulated for the elements behind the surface/cladding (unless they're 'structural elements').
    Plus other more minor things about spread thro cavities, internal linings etc.

    So the combustibility or otherwise of plastic insulations as EWI is basically not controlled because it can be allowed to burn without loss of life or risk to neighbours.

    Having said that, there are rated fire resistant grades of EWI render, and of the plastic insulation, in the suppliers' catalogues, as reqd.

    So this is just a panic story.
    • CommentAuthorEd Davies
    • CommentTimeNov 17th 2012
     
    Thatch is a pretty combustible external insulation. It is something you have to be a bit careful with but I don't think anybody would consider it to be a serious problem.
    • CommentAuthorCerisy
    • CommentTimeNov 17th 2012
     
    As Tom says - a panic story.

    Pretty much most of what we chat about on here is one / two storey single occupancy housing. No issue.

    The problem arises with flats and that has been know about for decades. When I worked for CLASP in the 80's we had issues with ceiling cavities spreading serious fires and we were then putting cavity closures into horizontal and vertical cavity details. Just don't let the accumulated experience be lost - but enough about government cut backs! :confused:
    • CommentAuthorsinnerboy
    • CommentTimeNov 17th 2012 edited
     
    All the same it is wise to bear the issue in mind. When using EPS based EWI systems switch to Rockwool for a 200mm zone around boiler flue and other heat producing appliance penetrations. Irish regs and IAB ( BBA equivalents ) all require it. Sad to say that does not mean it is always site practice.
    • CommentAuthorGavin_A
    • CommentTimeNov 17th 2012
     
    Posted By: Jonti

    When I have the time I will watch the whole of the German clip but it is very slow loading on my PC. Why have a ventilated gap with EWI. If it has any vents (intentional or not) wouldn't that render it useless?

    Jonti

    the venilated cavity is between the render and the insulation, hopefully with a breather membrane forming a relatively air tight barrier before the insulated layer.

    Without it you're relying entirely on the render for water proofing, which isn't a good idea and you can just end up with sodden insulation and damp pentrating the internal walls, then the entire thing having to be ripped off to start again.

    As I know happened with one EWI pilot.
  13.  
    Hi Gavin,

    Are you sure about the location of the cavity? All of the render systems I have seen the render is applied directly to the insulation.

    I assumed (maybe wrongly) that the system was some kind of cladded panel
    • CommentAuthorGavin_A
    • CommentTimeNov 17th 2012
     
    I'm not saying it's the case on all systems, but clearly must have been in that fire, as that's the only way the fire could spread up the building that fast.

    and yes, in that sort of system that's where the cavity is.
    • CommentAuthorjamesingram
    • CommentTimeNov 17th 2012 edited
     
    Flame retardent ( nasty polutive stuff on it's own) is genrally added to EPS used for EWI ,
    Having experimented in the past on small bits with a blow torch , it does light then shrinks to nothing rapidly.
    whilst letting off noxious fumes

    I'm unsure of exact details due to the language difference in most of the links posted.
    Be interesting to hear your view Jonti.
    It's claimed the insulation in the French example is mineral wool

    As far as I can make out the cavity is either behind the cladding ( in the case of metal panels) or is create by the shrinking insulation (eps) as it melts away from the flames. the fire than wicks up the insulation layer spreading the fire rapidly around the fascade of the building.

    Tom , you describe the fire regs . but my concern would be with:
    2) to prevent spread across property boundaries.
    and
    "So the combustibility or otherwise of plastic insulations as EWI is basically not controlled because it can be allowed to burn without loss of life or risk to neighbours."

    It's the speed at which it appears to spread across the external boundaries between flats that is of concern of the local fire service in the various reports ( using bing translate)
    If the spread across boundaries then create fire in other apartments ,say via plastic windows , again something that ignite rapidly, this may then fall foul of:
    1) to resist fire for long enough for people to escape - then let it burn.

    I'm not sure if it's just scare mongering, the view of local fire services that have investigated these examples would be useful info.
    • CommentAuthorjamesingram
    • CommentTimeNov 17th 2012 edited
     
    here's a section from this report http://www.bgdna.com/energy-green-tech/improper-construction-contributed-to-the-spread-of-the-fire.html
    "Cecilia Uneram (fire engineer at Fire Protection Association. )recommend that non-combustible material should be used as insulation instead of foam.
    In accordance with legal requirements is acceptable if the foam is encased in non-combustible material, but for good fire protection, we recommend the Fire Protection Association a non-combustible insulation. Otherwise, you get a contribution to the fire from the foam as soon as the surface layer is burned through, says Cecilia Uneram.
    Fire Protection Association believes that there are major skills shortages in construction and property managers.
    With the increased energy demands, we now see a rapid increase in the use of just foam insulation. The material insulates well, is relatively inexpensive and easy to use. The development of such use has gone so fast that research and knowledge about fire hazards in this type of construction has not had the time, says Cecilia Uneram"
    •  
      CommentAuthorSteamyTea
    • CommentTimeNov 17th 2012
     
    Was it GRP cladding?
  18.  
    Steel, I think, looks like it .
    • CommentAuthorjamesingram
    • CommentTimeNov 17th 2012 edited
     
    Posted By: Mike GeorgeShocking stuff James.
    Is this yet another argument against the never ending reduction of u-values, especially given the law of diminishing returns?
    Rotten tomatoes at the ready.....

    probably best to go over that on another thread :wink:
  20.  
    Posted By: jamesingram
    Posted By: Mike GeorgeShocking stuff James.
    Is this yet another argument against the never ending reduction of u-values, especially given the law of diminishing returns?
    Rotten tomatoes at the ready.....

    probably best to go over that on another threadhttp:///forum114/extensions/Vanillacons/smilies/standard/wink.gif" alt=":wink:" title=":wink:" >


    Yes, a late night half drunken comment on my part
    • CommentAuthorCav8andrew
    • CommentTimeNov 17th 2012
     
    Mike, was that before or after you placed the winning bid on the Humvee and job lot of patio heaters !
    • CommentAuthorMike George
    • CommentTimeNov 17th 2012 edited
     
    Got two Humvees already and I don't need patio heaters with the hot tub in the garden :boogie:
  23.  
    Posted By: Gavin_AI'm not saying it's the case on all systems, but clearly must have been in that fire, as that's the only way the fire could spread up the building that fast.

    and yes, in that sort of system that's where the cavity is.


    I got that impression from the clip as well, but assumed that the facade was some kind of panel cladding, rather than a render.

    Aside from the thread discussion here. I'd be most interested in looking at render systems which incorporate a cavity outboard of the insulation. Do you have a name of one please?
    •  
      CommentAuthorfostertom
    • CommentTimeNov 17th 2012
     
    Good ole Renderlath?
  25.  
    Did that have a cavity?
    • CommentAuthorMike George
    • CommentTimeNov 17th 2012 edited
     
    Just checked out the Bekaert website. Renderlath does indeed use a cavity but only with timber frame it seems. I'm assuming new build then and not retrofit. Rendering over PUR, phenolic etc directly applied http://www.bpindex.co.uk/supplier/2338/ (follow link to 'download documents')

    What I was after was the name of a cavity system used in retrofit say on solid walls, as that is the context the argument of fire spread seems to be used against
    • CommentAuthorborpin
    • CommentTimeNov 17th 2012
     
    I'm not sure of the BR in Scotland wrt EWI but for my build, where I have the insulation external to the steel frame, the BCO insisted that I build in cavity closers that cross the whole cavity which they regarded as the gap between the *frame* and the blockwork. I had to build in 6mm Supalux at a maximum of 8M gaps and at first floor level to act as a fire barrier. I am also having to line the plywood boxes around the windows with 6mm masterboard. Thus there are limits on how far the fire can penetrate through the insulation (in theory).
    • CommentAuthorJonti
    • CommentTimeNov 18th 2012
     
    Just had the time to look at the German TV article.

    Concern had been raised after multiple incidents by different people include several fire brigades.

    The German regulations state that EWI material must be fire resistant for at least 20 minutes and on top of this that in blocks of flats window and door joists should be protected by a fire break or a complete fire break should be used at every second floor. The latter seems to be the norm in Germany.

    Basically they tested an EWI system produced by the second most popular company in Germany. They took 160mm and added a popular render. They found that after only 8 minutes the test fire went out of control and that the burning EWI created pools of burning melt polystyrene. The conclusion was that the material did not meet the BR and was flammable to the point of making the fire breaks insufficient to prevent the fire spreading.

    An example was also given where a skip caught fire and 5 of the surrounding building with EWI also caught fire apparently due to the heat of the skip fire.

    There were also several other pieces on the site where different experts stated their lack of confidence that the EWI work being pushed by state regulations really brought anything like the benefit claimed. Also, one expert raised his concern about damp issues where EWI was fitted to existing housing stock plus the EWI's susceptibility to getting wet itself.

    All in all they seem to all agree that EWI was good in theory but did not deliver the promised results in practice.

    Jonti
    • CommentAuthorsinnerboy
    • CommentTimeNov 18th 2012
     
    Thanks Jonti for the synopsis. Was Rockwool referred to as an alternative insulation ?
    • CommentAuthorJonti
    • CommentTimeNov 18th 2012
     
    Posted By: sinnerboyThanks Jonti for the synopsis. Was Rockwool referred to as an alternative insulation ?


    Not that I recall but will watch it once more later on to be sure,

    Jonti

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