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Good Insulation - How long is a piece of string?

  • 16-05-2008 1:53pm
    Registered Users Posts: 12,553 ✭✭✭✭ AckwelFoley

    In my line of work, when a customer looks for a heat pump, my first question is what spec is your insulation.

    The words "well insulated" always makes me giggle inside.

    When a price is given initally we always assume a B1 rating on their house, to acheive this the person must meet certain insulation requirments.

    Ive visited houses where ppl claimed their house was well insulated.. only for me to fing 4" fiberglass in the attic :rolleyes:

    Ive visited a man this week.. He has his timber frame specs Hes using..

    150mm Polyiso Kingspan between the external stud walls plus 38.5mm insulated plasterboard on the external walls to provide extra insulation and prevent cold bridging.

    110 hyloc polyiso inbetween the rafters and then the 38.5mm plasterboard on the attic walls..

    120mm polyiso floor insulation downstairs and all internal walls insulated to prevent heat loss into rooms that are not being used.

    Obv this all needs to be fitted correctly and there are other areas of insulation required, but he is alos going to fit a HRV system to cut down on heat loss from ventilation.

    I was pretty impressed by his preparation for his heating system.

    To many fail to plan for their heat system, and by the time they get around to doing it.. its too late, they've gone too far and are unable to comfortable accomadate a HRV system or underfloor. :/

    Plan in advance, prior to breaking any soil on site!!



  • Registered Users Posts: 37,607 ✭✭✭✭ Mellor

    How well insulated is subjective indeed.

    What most consider as well insulated, I (and most professionals) would consider it as minimum.

    The above is one of the few that is very good. I'm assuming he has zoned heating, if not then some is a waste

  • Subscribers Posts: 37,739 ✭✭✭✭ sydthebeat

    His 'between rafter' insulation wouldnt meet regs :eek:

    are you sure of the dimensions quoted?

  • Registered Users Posts: 37,607 ✭✭✭✭ Mellor

    I read that as 210+CB, my bad
    135 or so total isn't a whole lot

  • Registered Users Posts: 12,553 ✭✭✭✭ AckwelFoley

    sydthebeat wrote: »
    His 'between rafter' insulation wouldnt meet regs :eek:

    are you sure of the dimensions quoted?

    100 mm kingspan + 39.5mm insulated board wont meet regs?

    What would? If you have a 4" truss roof rafter whats his options?

    130mm Polyiso kingspan is alot of insulation imo

  • Registered Users Posts: 37,607 ✭✭✭✭ Mellor

    In a wall it is, in the roof it isn't.
    2 main reasons,
    Firstly, most heat ecapes through the roof so a decent level of insulation is need, hence the roof having the lowest limit.

    Scondly, 100mm is th wall is much more than 100mm in the roof. This is down to the bridging of the insulation by roof members (either rafters or joists depending on location

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  • Registered Users Posts: 12,553 ✭✭✭✭ AckwelFoley

    is there a link to the regs anywhere?

  • Closed Accounts Posts: 5,433 ✭✭✭ sinnerboy

    hold up guys - 100 pu between and 40 below will give u value of 0.2

    that will suffice,16557,en.pdf

    see page 19

  • Closed Accounts Posts: 5,433 ✭✭✭ sinnerboy

    having said that , insulation provision has to be taken together with

    1. air tightness and ventilation strategey and
    2. m+e spec

    the following indicates , amongst other things , elemental u value for compliance , which exceed what TGD L mins advise,15662,en.pdf

  • Subscribers Posts: 37,739 ✭✭✭✭ sydthebeat

    i took this to be a 'flat ceiling' insulation... snyper... is it flat or sloped....

    besides this fact, it is barley minimum standards... you should aim for a lot more... it certainly wouldnt be considere 'well insulated'....

    my min spec for ceilings is either 300mm quilted or 200 PU / PIR...