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Insulating old vaulted ceilings.

  • 24-10-2012 3:52pm
    #1
    TTTT
    Registered Users, Registered Users 2 Posts: 222 ✭✭


    I'm currently insulating my attic. Half of the house has vaulted ceilings with no insulation. I'm not going to pull down the ceilings to insulate so I'm wondering what's the best loose fill insulation that I can pour down.

    I know that I'm supposed to leave a 50mm air gap but the rafters are only 100mm and the eavs are already blocked off on one side with a flat roof. The attic is open plan and has a lot of air circulation through other draughts.

    will loose fill vermiculite work?


Comments

  • #2
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,146 Mod ✭✭✭✭BryanF


    what weight will this be on the 100mm joists?? And ceiling???

    100mm joist should have nothing but the lightest insulation placed above

    As regards ventilation, can you be sure there will be adequate ventilation? Maybe you should consider some tile / slate vents..


  • #3
    esox28
    Registered Users, Registered Users 2 Posts: 800 ✭✭✭esox28


    I have the same bother insulating a small area in a section of dormer window structure...what is the most effictive loose fill insulation or fiber insulation?


  • #4
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,146 Mod ✭✭✭✭BryanF


    We'd need to know a lot more. Firstly is there a chance the insulation could get wet or create a due point zone?


  • #5
    esox28
    Registered Users, Registered Users 2 Posts: 800 ✭✭✭esox28


    The area is between dormer cheeks and the eves, also areas around the dormer construction. Osboard and airtightness taped over the insulated areas plus solitex and counterbattons on other side of insulation.


  • #6
    TTTT
    Registered Users, Registered Users 2 Posts: 222 ✭✭TTTT


    BryanF wrote: »
    what weight will this be on the 100mm joists?? And ceiling???

    100mm joist should have nothing but the lightest insulation placed above

    As regards ventilation, can you be sure there will be adequate ventilation? Maybe you should consider some tile / slate vents..

    Well the water tanks, current ceiling and attic boards are currently hanging from them. I'm removing the boards and adding 300mm of mineral wool insulation so that will mean a reduction in weight. The loose fill vermiculite isn't heavy either and the vaulted area is only 1m approx. I'm just wondering if vermiculite is the right material for this? I know it will absorb moisture but will shed it again?

    The attic is open at one end where an second story extension has been built so I'm going to put an air vent on the new gable wall and there's also plenty of air whistling around through the slates/felt on a windy day!


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  • #7
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,146 Mod ✭✭✭✭BryanF


    Not keen on the vermiculite, apart for potential moisture issues what is it thermal resistance ? When compared to say blown mineral wool?


  • #8
    TTTT
    Registered Users, Registered Users 2 Posts: 222 ✭✭TTTT


    BryanF wrote: »
    Not keen on the vermiculite, apart for potential moisture issues what is it thermal resistance ? When compared to say blown mineral wool?

    well I'm not prepared to get a contractor in just to insulate those small areas.

    Thermal Conductivity Vermiculite at normal atmospheric temperature K = 0.062 - 0.065 w/mc
    Thermal Resistance R Value: 1.6 m2K/W

    So I guess it's not as good as mineral wool but it'll be better that the nothing that's there at the moment and I might put insulated slabs on the underside in the future.


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