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External Insulation for a dormer

  • 12-05-2010 7:58am
    #1
    gabbo is coming
    Registered Users, Registered Users 2 Posts: 998 ✭✭✭


    Hello,

    I have two dormer bedrooms in one structure that is built out from the sloped roof. The dormer has a flat felt roof.

    Given that it was built in the 70s, I would imagine it has little or no insulation. I have changed the large windows to be PVC double glazed, refelted the roof. However, I would like to insulate the walls and roof.

    As the rooms are not large, is it possible to go for external insulation? I.e. boards that would screw on to the current external wooden boards, and (maybe this is laughable) but place a new roof with insultation on top of the existing one and refelt?

    As you can tell I'm looking for minimum of disruption inside the house...


Comments

  • #2
    MarkZ
    Registered Users, Registered Users 2 Posts: 20 ✭MarkZ


    I also have a double dormer. We got a roofing company to do exactly what you suggested in the second part of your query - they put down a 4 inch slab of instulation and refelted the roof. They had to work on the tiled roof where the dormers meet the roof because the dormer roofs were now 4 inches taller.

    We were also getting PVC cladding for the dormers at the same time so it all looks great. Dormer is now warmer in winter and cooler in summer.

    If you find a way of insulating the walls of the dormer, post it here please. The only way I can think of is injecting beads into the walls from the inside. Not sure what depth I would get, and there would be some redecoration to do afterwards. Also not sure if the beads companies would take it on.

    gabbo is coming wrote: »
    Hello,

    I have two dormer bedrooms in one structure that is built out from the sloped roof. The dormer has a flat felt roof.

    Given that it was built in the 70s, I would imagine it has little or no insulation. I have changed the large windows to be PVC double glazed, refelted the roof. However, I would like to insulate the walls and roof.

    As the rooms are not large, is it possible to go for external insulation? I.e. boards that would screw on to the current external wooden boards, and (maybe this is laughable) but place a new roof with insultation on top of the existing one and refelt?

    As you can tell I'm looking for minimum of disruption inside the house...


  • #3
    PeteHeat
    Registered Users, Registered Users 2 Posts: 648 ✭✭✭PeteHeat


    Hi,

    The best chance to insulate the cheeks of the dormer is when fitting the PVC cladding.

    It is always advisable to remove old timber cladding because if any rot has set in it can continue spreading hidden behind the new cladding.

    On some of the older dormers insulating the flat roof from outside can be difficult because many of the flat roofs were kept tight to the ridge leaving little or no room to add further height.

    Beware of offers to felt over the ridge as it is a difficult detail to get right and can ruin the appearance of the house and if depending on primer it will not last.

    .


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