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Improving Dormer Attic Insulation

  • 08-05-2021 6:46pm
    #1
    Registered Users Posts: 349 ✭✭ fitzie79


    I have a 10 year old dormer bungalow that whilst it is relatively well insulated I am trying to improve. My main focus is the kneel space upstairs. There is 6” of insulation above the ceiling of the ground floor and on the side walls there is 4” insulation on the attic side and insulated dry lined plaster boards on the internal wall. The sloped ceiling has the same dry lined plaster board along with fixed insulation boards on the roof side.

    I am looking for some tips on how to improve the insulation level and/or recommendations in the cork area for any companies who would have good experience in this area. My own initial thoughts are as follows

    - Add 6 inches insulation above ground floor ceiling but not sure how to handle the electrical wires and hrv air ducts?
    - can the side walls be improved by adding fixed board insulation? Could this help some drafts that I can feel coming through sockets?
    - are there options to stop air passing through between joists between ground floor and ceiling and would this help heat loss. Could foam type insulation be a possible solution here?
    - improve insulation of the attic access hatches as these seem quite poorly insualted

    Attachments don't seem to be working right now so I'll have to try again later to add these


Comments

  • Moderators, Home & Garden Moderators Posts: 10,101 Mod ✭✭✭✭ BryanF


    10 years old? Is there an air-tightness membrane? If so how is it sealed from sloped roof to the external wall?

    I’d focus on air-tightness, you say you can feel drafts, so you know that’s an issue.


  • Registered Users Posts: 2,544 ✭✭✭ MicktheMan


    As BryanF says, focus on air tightness. And forget foam as part of your solution.
    Perhaps test the house for air tightness as part of an overall heat loss survey for the best options on how to address.


  • Registered Users Posts: 10,926 ✭✭✭✭ Calahonda52


    fitzie79 wrote: »
    - are there options to stop air passing through between joists between ground floor and ceiling and would this help heat loss.

    What do you mean by this?

    My guess is you mean between the ground floor ceiling and the attic floor, under the knee wall.
    They need to be sealed.
    i recommend ply cut to size and screwed to the base plate of the knee wall, sealing any gaps between the ceiling joists and the ply ,

    Two issues here:
    1 cold attic rooms
    2: draught is sockets?
    Whats the finish down stairs?
    My guess re 2 is that it is dot and dab pb with the wall vents not sleeved all the way to outer face of pb, take off a room vent and look.

    re the attic, my guess is that the air is getting into the insulation from the ventilated eaves, due to the absence of ventilation baffles.


  • Registered Users Posts: 349 ✭✭ fitzie79


    Thanks for the replies everyone. I maanged to get the attachements working so this may help explain and I'll also try to clarify questions as follows:

    - Is there an air-tightness membrane? If so how is it sealed from sloped roof to the external wall?
    There is an air tightness membrane - it's sealed from the sloped roof to the knee wall I think.

    I’d focus on air-tightness, you say you can feel drafts, so you know that’s an issue.
    Drafts are only by where the sockets are in the rooms - probably because the air tightness membrane is not sealed and because the wool insulation is not stopping drafts?

    Perhaps test the house for air tightness as part of an overall heat loss survey for the best options on how to address.
    Are there companies that provide this service alone with someone to remedy the issues that anyone would recommend by PM


    My guess is you mean between the ground floor ceiling and the attic floor, under the knee wall. Yes - that's what i meant
    They need to be sealed.
    i recommend ply cut to size and screwed to the base plate of the knee wall, sealing any gaps between the ceiling joists and the ply.
    Makes sense as this would stop the wind blowing across the ground floor ceiling

    Whats the finish down stairs?
    My guess re 2 is that it is dot and dab pb with the wall vents not sleeved all the way to outer face of pb, take off a room vent and look.
    I have a HRV unit so no wall vents. Walls downstairs are drylined

    re the attic, my guess is that the air is getting into the insulation from the ventilated eaves, due to the absence of ventilation baffles.What are ventilation baffles? From a quick google these "guide" the wind so that it doesn't pass over the knee wall insualtion?


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