Insulating outhouse roof

Discussion in 'Builders' Talk' started by M9Hawk, Nov 14, 2023.

  1. M9Hawk

    M9Hawk New Member


    Im wanting to insulate the roof of my outhouse/wash house. It currently has nothing but what seems to be like a hessian sheet covering??? Im wanting advice on what would be the most cost effective. I have a depth of 100mm from roof to rafter, i was thinking of a 50mm insulating board between rafters then fix over the too with something like 6mm ply??

    Attached Files:

  2. M9Hawk

    M9Hawk New Member

    Would i need to go over the top with ply or can i leave it just the PIR board? Not fussed on what it looks like
  3. Jord86

    Jord86 Screwfix Select

    You’ve got no vents between the joists so you may as well full fill the voids with 100mm kingspan, staple a visqueen vapour barrier over the whole lot or use foil tape over the joins, then choose to cover it or leave it.
  4. M9Hawk

    M9Hawk New Member

    Oh i was told to leave an air gap to the roof to prevent moisture?
  5. Jord86

    Jord86 Screwfix Select

    If there’s no gap or void whatsoever then no air can circulate, therefore nothing can rot. If you’ve got vents there, then leave a 50mm gap.

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