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Attic conversion - how to better insulate

  • 01-12-2021 11:45am
    Registered Users Posts: 5 YouKnowYourself

    Hello, I recently bought a mid-terrace house with an attic conversion done, but it doesn’t seem well insulated, the entire roof down to the block work has been done with spray foam insulation, the eaves at the front and back also have some rockwool type insulation on the floor/downstairs ceiling which continues under the floorboard. Access to the eaves is through a thin wooden door. The room is skim coated and the plasterboard is the only barrier between the eaves and the bedroom, should this be insulated too? The storage space above the room is also just separated by plasterboard but the hatch into it is sealed and insulated. The room also has 2 double glazed skylights which seem perfect.

    The eaves and attic space are very cold and there’s a lot of air movement and as a result the room getting cold very quickly, once the heat turns off we’re losing 1degree celsius per hour until the room drops from about 20degress to 15degrees where it slows cooling.

    I’m wondering what’s the best thing to target first? Find the source of the air flow? (It’s not obvious anyway!) Upgrade the access hatches to be airtight and insulated or insulate the back of the stud walls and ceiling with ~100mm roll?

    Any suggestions would he appreciated!


  • Registered Users Posts: 2,584 ✭✭✭ MicktheMan

    Yes, the knee walls need to insulated.

    The crawl and attic space are supposed to be well ventilated but your problems seems to be air leakage into / out of the bedroom space. This is a very common issue with attic conversions & dormers.

    Adding insulation won't solve this. You need to find the air tight weaknesses (heat loss survey) and then tackle each one with air tight products such as membranes, tapes, mastics etc.