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    • theGrinch
    • By theGrinch 7th Aug 18, 7:42 AM
    • 2,923Posts
    • 697Thanks
    Building Regs and Insulation
    • #1
    • 7th Aug 18, 7:42 AM
    Building Regs and Insulation 7th Aug 18 at 7:42 AM
    In terms of rigid insulation boards which is the general building regs requirement for

    a) roofs and floors of extension
    b) roofs and floors of a loft conversion

    I gather they are done on a rating, but just want to get an idea of costs based on 100mm or 125mm or 150mm boards at the moment.
    "enough is a feast"...old Buddist proverb
Page 1
    • Doozergirl
    • By Doozergirl 7th Aug 18, 8:42 AM
    • 26,325 Posts
    • 70,906 Thanks
    • #2
    • 7th Aug 18, 8:42 AM
    • #2
    • 7th Aug 18, 8:42 AM

    Not sure why you'd insulate the floor of a loft conversion?

    It's not unheard of, but unusual to build extension walls using solid insulation. Ditto, an extension roof, unless of course it is vaulted.

    There's different ways of hitting u-Values, often dependent on the size of rafters. You might use a mix of boards in a loft conversion to achieve similar results, so attempting to pricing it up without a spec may not be useful.
    Last edited by Doozergirl; 07-08-2018 at 8:49 AM.
    Everything that is supposed to be in heaven is already here on earth.
    • MX5huggy
    • By MX5huggy 7th Aug 18, 8:58 AM
    • 4,151 Posts
    • 2,732 Thanks
    • #3
    • 7th Aug 18, 8:58 AM
    • #3
    • 7th Aug 18, 8:58 AM
    Its complicated.

    The extension floor depends on what type of floor your having, suspended or solid. And its P/A ratio that is the length of the perimeter over the area.

    The loft, the spacing a depth of rafters, are you able to completely fill the rafter space and use insulation over the top and put the roof back on? Or only under.

    Then which boards are you considering each board type and product and in some cases thickness has a different performance.
    • ComicGeek
    • By ComicGeek 7th Aug 18, 12:36 PM
    • 353 Posts
    • 287 Thanks
    • #4
    • 7th Aug 18, 12:36 PM
    • #4
    • 7th Aug 18, 12:36 PM
    And it may vary if you have a lot of glass in the extension and need to offset any additional heat loss from this with increased insulation...
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