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Closing the gaps between ceiling joists for air tightness

  • 20-05-2021 12:22pm
    Registered Users Posts: 14 ben 11

    Hi everyone
    I'm looking for advice. I'm trying to improve airtightness on a 20 year old dormer bungalow and one of the things suggested to me is to close the gaps between the ceiling joists under the knee wall. This can be done by cutting for each gap a piece of plywood or maybe some 25mm floor insulation and then for the ultimate job taping the joints. I have access to the crawl space for the full perimeter of the upstairs although it would still be a pretty cumbersome task as it is a cut roof and every gap is bound to be slightly different. My big concern is, will this create a ventilation issue for the part of the ceiling joist that will be enclosed or are the joists considered ok as they will hopefully be on the warm air side. The last thing I want to do is for a short term gain is to create a massive headache down the line.
    It would be great to hear from someone who has experience or who has done this especially a number of years ago.