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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorecopaddy
    • CommentTimeMar 16th 2007 edited

    I am looking to insulation a floor area that will have underfloor heating on top of it. I have read in a number of articles that synthetic insulation such as polyurethane, phenolic, polystyrene, etc offgas.

    Is there actually any documented research on this area?

    If so, I would like to know what type of substances they offgas and what the possible health implications are.

    I would consider natural alternatives in the first place but based on the thermal conductivity, the natural insulations seem far less effective that the synthetic variety.

    Hi Paddy, I have heard similar stories but have not seen any documented research. There are also concerns regarding shrinkage and some here have provided anecdotal evidence of this. It may be reasonable to assume a link between shrinkage and off gassing though if the gas used in manufacture is escaping, it would be repaled by air, which is itself a very good insulator. Again, nothing published about shrinkage that I am aware of.

    For my own anecdote - I have been monitoring some PUR in my loft for about two years with no discernable shrinkage.

    I would also be interested to read any research into this, anyone?
    Sick building syndrome is the thing to watch out for Paddy. If you have any sensitized people in the family. Most people are unaffected until the burden of synthetic products overwhelms the ventilation available to the room.

    Most studies of SBS have concluded that ventilation can cure it. My advice is just be aware of the total non natural components in any given room. if the insulation is the only large surface area then maybe OK but if you have vinyl wallpaper, lots of chipboard cabinets and loads of fireproofed furniture and curtains then the burden will be greater and the need for extra ventilation than normal levels will increase. Also electrical equipment such as TV's and computers will add to the burden.

    People are thought to become sensitized when constantly exposed to poorly ventilated spaces full of synthetic products.
    • CommentAuthorGuest
    • CommentTimeMar 20th 2007
    Have you tried cork?
    john, York
    • CommentAuthorGuest
    • CommentTimeApr 2nd 2007
    Off gassing does occur to a certain degree but is accounted for under the new CE standards of measurement for insulation materials 13165 etc. Most PIr/Polyiso materials achieve lambda values much better than those quoted in their literature - they add a 'penalty' to the measured factory performance to 'age' the insulation and account for any off gassing in the future.
    That's very interesting guest, do you have inside information?
    • CommentAuthorPaul_B
    • CommentTimeApr 2nd 2007
    I read somewhere that it is possible for even "natural" products to off-gas. For example sheeps wool.

    In the UK most sheep had to be dipped in organophosphate's up until 1992 but how long would this last in the blood stream of the sheep and would it pass to lambs?
    I don't think these products do offgas to any notable extent. The glues used to bind them are MDI, which seems to be much less volatile than formaldehyde, and the gas used as a blowing agent is mostly pentane, which is very similar to butane used for cooking. I think the reputation for offgassing goes back to the 1980s when there was a lot of cavity wall insulation carried out using formaldehyde and this did offgas and caused respiratory problems for homeowners. It resulted in Part D of the building regs: today the problem seems to be sorted. When did you last hear someone refer to Part D?

    As a rule, the best test for offgassing is your nose - if you can smell it, it's offgassing, if you can't, it's inert.
    • CommentTimeApr 2nd 2007
    Posted By: Mark BrinkleyAs a rule, the best test for offgassing is your nose - if you can smell it, it's offgassing, if you can't, it's inert.
    Mark are you the Brinkley that played Tom Hanks' Golden Retriever in You've Got Mail? One thing I'd really love is a keen sense of smell, and a tail, but sadly for us humans I doubt we can so reliably detect offgassing - some things are odourless anyway.
    • CommentAuthorPaul_B
    • CommentTimeApr 2nd 2007
    Have to agree both Carbon Monoxide and Carbon Dioxide are odourless but not nice
    It's a fair cop. Not everything smells. But everything that smells is offgassing.:fierce:
    • CommentAuthorPaul_B
    • CommentTimeApr 2nd 2007
    Darn got us there :cry:
    • CommentAuthorGuest
    • CommentTimeMay 7th 2007
    I have radiant heat in my bathrooms. I am assuming you are talking about radiant flooring. I insulated the floors with cotton insulation (bonded logic). I have a sensitivity to fiberglass. What do you want to use to insulate? Don't put cork flooring over radiant heat. It will be like floor is wearing a sweater.

    Johns Manville has a product that is fiberglass insulation that is formaldyhe free. Usually radiant heat has aluminium faced insulation (R-6). I hope this helps. Anna Hackman , www.green-talk.com
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