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Insulating a concrete roof

  • 19-05-2023 4:23pm
    Registered Users Posts: 17

    Hi all, I own a 1950s bungalow and on the side is a 2m x 4m garage with a concrete roof. On top of the roof is a layer of felt.

    I would like to externally insulate the roof and what I'm think is, leave the existing felt to act as vapour barrier, then 150mm insulation on top with a channel for gutter, then fiber glass on top.

    Does this option sound ok our would anyone have another way to tackle it?

    All opinions welcomed.



  • Registered Users Posts: 123 ✭✭FJMC

    In principle yes that is OK - but you should speak to the manufacturer of the fibreglass roofing system (or roofing membrane) and get more detailed advice / guidance from them for the detail and specification - RE any preparation, priming, fixing the insulation, boarding (if any) on top of insulation, fixing/applying the membrane, perimeter details, etc.