Kingspan for loft flooring?

Discussion in 'Building' started by Agile, 13 Oct 2015.

  1. SmileyDan

    SmileyDan

    Joined:
    14 Oct 2013
    Messages:
    88
    Thanks Received:
    2
    Country:
    United Kingdom
    Perhaps someone else can point out where I am wrong, but according to http://www.quinn-therm.com/wallinsulation/timbersteel-walls.cfm that will give you U=0.3ish which isn't even meeting building regs, which is itself worse-allowable practice. Might depend on your blockwork.

    Should be aiming for more like 200mm imo unless space is an issue.
     
  2. Sponsored Links
  3. u587162

    u587162

    Joined:
    17 Jan 2015
    Messages:
    615
    Thanks Received:
    5
    Location:
    Hertfordshire
    Country:
    United Kingdom
    Last edited: 16 Oct 2015
  4. SmileyDan

    SmileyDan

    Joined:
    14 Oct 2013
    Messages:
    88
    Thanks Received:
    2
    Country:
    United Kingdom
    The use of Quinn-lite probably explains it - they have lower conductivity than standard block.
     
  5. u587162

    u587162

    Joined:
    17 Jan 2015
    Messages:
    615
    Thanks Received:
    5
    Location:
    Hertfordshire
    Country:
    United Kingdom
    Lower conductivity = good right?
    Typo in my previous post. Have corrected it to say building regs guy is ok with it.
     
  6. SmileyDan

    SmileyDan

    Joined:
    14 Oct 2013
    Messages:
    88
    Thanks Received:
    2
    Country:
    United Kingdom
    Yes, unless you want a cold house :D
     
  7. u587162

    u587162

    Joined:
    17 Jan 2015
    Messages:
    615
    Thanks Received:
    5
    Location:
    Hertfordshire
    Country:
    United Kingdom
    :)

    I actually misunderstood. But in general you're saying that 50mm Quinn rigid board foam is not better than 100mm rockwool. My builder (friend) believes it is better and covered the higher cost, mainly because we were taking our time on brick selection and he needed to crack on so didn't put rockwool.

    For lofts room and single storey he has / will use 100mm of the same rigid board as part of a warm deck.
     
  8. Sponsored Links
  9. SmileyDan

    SmileyDan

    Joined:
    14 Oct 2013
    Messages:
    88
    Thanks Received:
    2
    Country:
    United Kingdom
    It is not twice as better in "laboratory" conductivity terms. The lambda of Rockwool is 0.037 W/mK, the lambda of quinn-therm is 0.022.

    The lambda of generic mineral wool can be up to 0.044, so that would mean Quinn-therm would be exactly twice as better if you happened to choose one of those products.

    But as I said it depends what you mean by "better" - conductivity is not the only question. Insulation is very sensitive to quality of installation, so a product that is easier to install might be able to achieve the desired result, whereas another product may not.

    If you have room I would maximise insulation everywhere. It's a lot more expensive to add later.
     
  10. Agile

    Agile

    Joined:
    26 Jun 2004
    Messages:
    64,039
    Thanks Received:
    4,595
    Location:
    London
    Country:
    United Kingdom
    Can someone update me on the current cavity wall requirements.

    I thought that it was still a cavity of 50 mm filled with 50 mm of insulation?

    The earlier reference was for a cavity of 100 mm but only half filled with 50 mm of insulation!

    Tony
     
  11. ey143

    ey143

    Joined:
    18 Oct 2013
    Messages:
    1,030
    Thanks Received:
    6
    Location:
    London
    Country:
    United Kingdom
    Yes you cannot completely fill the cavity. Need to leave room for air due to moisture etc. had this confirmed by my building regs inspector.
     
  12. SmileyDan

    SmileyDan

    Joined:
    14 Oct 2013
    Messages:
    88
    Thanks Received:
    2
    Country:
    United Kingdom
    No, assuming you are not on an exposed site you can do full fill, with batts anyway. In fact there's some good evidence that it works better, because otherwise you get convection in the cavity (especially with an insulant as shallow as 50mm).

    Remember lots of BR inspectors sometime need convincing or a friendly pointer to the regulations.

    http://www.planningportal.gov.uk/bu...ments9/acd#MasonryCavityWallInsulationDetails

    I would prefer 100mm full fill batts to 50mm PIR/PUR (assuming a non-exposed site again).

    Actually I'd prefer about 300mm batts but...
     
  13. Agile

    Agile

    Joined:
    26 Jun 2004
    Messages:
    64,039
    Thanks Received:
    4,595
    Location:
    London
    Country:
    United Kingdom
    Isn't the difference for an exposed site because of the fear of moisture penetrating the outer skin and getting through to the inner skin?

    Tony
     
  14. SmileyDan

    SmileyDan

    Joined:
    14 Oct 2013
    Messages:
    88
    Thanks Received:
    2
    Country:
    United Kingdom
    Yes, wicking through the insulation (also rendering the insulation useless, as well as the damp effects).
     
  15. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page