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Wooly insulation

  • 10-07-2008 10:34pm
    #1
    c class 226
    Registered Users Posts: 35 ✭


    Hi
    Just wondering has any one any thoughts on Metac ( think thats how its spelt) - a fibre glass type insulation though it appears denser than fibre glass. How does it compare with rigid boards (Kingspan etc.)? Does it suffer the same problems of sinking and absorbing moisture as fibre glass? I am putting in a flat roof extension with probably 200 mm rafters and I have been told by an insulation installer that that depth of metac will give the same performance as a rigid board and will not sink noticeably.
    Thanks
    C class 226


Comments

  • #2
    RKQ
    Registered Users, Registered Users 2 Posts: 2,292 ✭✭✭RKQ


    The easiest way to compare insulation is to compare u-values.
    Check manufactures data / BBA cert etc.


  • #3
    ardara1
    Closed Accounts Posts: 495 ✭✭ardara1


    c class 226 wrote: »
    Hi
    Just wondering has any one any thoughts on Metac ( think thats how its spelt) - a fibre glass type insulation though it appears denser than fibre glass. How does it compare with rigid boards (Kingspan etc.)? Does it suffer the same problems of sinking and absorbing moisture as fibre glass? I am putting in a flat roof extension with probably 200 mm rafters and I have been told by an insulation installer that that depth of metac will give the same performance as a rigid board and will not sink noticeably.
    Thanks
    C class 226

    A flat roof must be a WARM roof - over joist insulation in UK - Metac is only denser fibre - do the U-value calc for U-value - if the insulation is between only - YOU MUST ventilate 50mm over insulation - air in at eaves - out att other end - each rafter.


  • #4
    dungay
    Closed Accounts Posts: 9 ✭dungay


    hi,

    was just wondering if you went ahead with the metac insulation, we are thinking of getting it in our attic, but anyone i'v mentioned it to has never heard of it, also you had some comments on aluclad windows, we hope to put in aluclad windows this year...any comments on them.

    thanks for your help,

    dungay


  • #5
    endplate
    Registered Users, Registered Users 2 Posts: 991 ✭✭✭endplate


    I never heard of Metac till a few months ago. I have it in the slopes of my dormer roof. As stated before it's a denser fiberglass. With the high density foam if there are any gaps between the rafter and insulation you are losing insulation


  • #6
    Slig
    Registered Users, Registered Users 2 Posts: 1,550 ✭✭✭Slig


    Seems to just be denser glass fibre insulation. Cold deck flat roofs are nearly an archaic construction now. Too many problems with them and a short life span. It is probably better to use a product like mineral fibre between the joists in this instance, you wont get a great u-value but it will promote more ventilation than a rigid PU board.

    If you are going with the trad method of construction make sure to use marine grade plywood as the decking and use a ventilation layer below your bitumen felt. Also a good idea to over spec the joists (to take a snow load, something a pitched roof doesnt need to take) and use a vapour check or air proof membrane below the joists, not just foil backed plasterboard. Condensation and damp will be your major problem with a flat roof.

    If anybody is interrested here is a Link to the product


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