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Cavity wall insulation question.

Discussion in 'Building' started by Brian Lacey, 2 Feb 2018.

  1. Brian Lacey

    Brian Lacey

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    Location:
    Rutland
    Country:
    United Kingdom
    We moved into our 1970's built bungalow about 18 months ago.
    As a result of a kitchen /diner extension build I was wondering ....

    The structure of the bungalow is ..
    Outer brick skin
    40mm air gap
    Building paper
    12mm Ply
    4” stud walls with polystyrene infills
    Foil membrane
    Plaster board and plaster.

    Would it make sense to have the 40mm air gap filled with an injected insulation material i.e. loose fill/foam ? I know that this is a narrow gap but I believe that there are modern infills that can now be used in such spaces.
    What about damp bridging the gap ? There are endless horror stories about this so how can it be prevented
    OR
    should I just leave things as they are ?

    Part of the reason for asking is that our heat source for C/H is an air to water heat pump and every thing I read about this is that insulation is the key.
    If it is a good idea to insulate the cavity (first time we will have ever done anything like this) then what do I need to look for when googling local installers and any tips/advice ?

    Many thanks
    Brian.
     
  2. garyo

    garyo

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    I didn't think they were suitable for properties of that age. How many kw is it? Impressed if it's coping... I might consider one myself.
     
  3. Brian Lacey

    Brian Lacey

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    It was already installed when we bought the place. Unit is about 6 yrs old (Altherma LT), feeds 11 rads and 2 towel rails, Works perfectly OK. No idea what KH it is.
    Cheers
    Brian.
     
  4. Notch7

    Notch7

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    I would say definitely not, you would effectively be changing the wall construction which could lead to condensation risk. A pain in an all masonry cavity wall, but disastrous in a combined brick and timber frame construction.

    I would suggest 50mm celetex on the coldest external walls, 50 x 25mm battens laid flat over then plasterboard. Or insulated plasterboard. I know its a pain, meaning radiators, skirting etc being moved but the safest solution. Thats assuming your walls need improving more than other areas like loft, draughts etc.
     
  5. Brian Lacey

    Brian Lacey

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    Many thanks for the advice. All noted.
    Cheers
    Brian.
     
  6. ^woody^

    ^woody^

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    A timber frame needs a ventilated air cavity.
     
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  7. Brian Lacey

    Brian Lacey

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    Thank You, will not do it !
    Cheers
    Brian.
     
  8. ajstoneservices

    ajstoneservices

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    There is a data tag on the outdoor unit that shows it's KWs.
     
  9. Brian Lacey

    Brian Lacey

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    No tag that I could see but original paperwork from 2009 installation says 11.2KW. I assume it's the same.
     
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