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attic insulation

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  • 05-02-2013 4:58pm
    #1
    pa990
    Registered Users Posts: 3,884 ✭✭✭


    I have 150 mm Rockwool in my attic between the joices.

    I have gotten some more Kahn 100mm loft insulation in b&q recently at half price.

    I was gonna lay this insulation over the existing insulation but in the opposite direction
    ie. current insulation runs east- west between joices.
    I was gonna run this new insulation north-south over the joices, creating a nice deep layer.
    am I at risk of dry rot in the joices?

    ( the attic isn't and never had been used for storage, and I plan on installing a frost protector )


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    #2
    jjf1974
    Registered Users Posts: 924 ✭✭✭jjf1974


    i would not think there is any risk of any rot in joists from doing this.thats the way a lot of attics are now insulated.I put 3 layers in mine as I had a lot left over from another job and I can feal the difference in the house.


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    #3
    pa990
    Registered Users Posts: 3,884 ✭✭✭pa990


    jjf1974 wrote: »
    i would not think there is any risk of any rot in joists from doing this.thats the way a lot of attics are now insulated.I put 3 layers in mine as I had a lot left over from another job and I can feal the difference in the house.

    cool.


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    #4
    snow mad
    Registered Users Posts: 127 ✭✭snow mad


    is there cross ventalation in your attic adding more insulation can sometimes cause condensation on older attics inner roof surface during cold months as sarcing felt does not allow the moisture to pass threw if you have a more modern wind barriers this will not be a problem.

    you are right in the way you intend to lay the insulation but you should make sure you end up with 300mm of insulation and make a bag of the same thickness on the back of the trap door. It is also very important to remember that you are starving your attic of heat so your water tank and pipes that are over half way up the insulation need to be insulated and dont insulate under the tank unless it is raised over 300mm over the ceilling joists


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    #5
    pa990
    Registered Users Posts: 3,884 ✭✭✭pa990


    it's a relatively new build, so ventilation should be good.
    I have no insulation under the water tank, but have a sheet of king span as a cover on it.
    planning on improving the overall insulation of the water tank as well


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    #6
    homer911
    Registered Users Posts: 5,113 ✭✭✭homer911


    pa990 wrote: »
    am I at risk of dry rot in the joices?
    QUOTE]

    You cant have dry rot, without having wet rot first.


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    #7
    CBYR1983
    Registered Users Posts: 336 ✭✭CBYR1983


    snow mad wrote: »
    is there cross ventalation in your attic adding more insulation can sometimes cause condensation on older attics inner roof surface during cold months as sarcing felt does not allow the moisture to pass threw if you have a more modern wind barriers this will not be a problem.

    you are right in the way you intend to lay the insulation but you should make sure you end up with 300mm of insulation and make a bag of the same thickness on the back of the trap door. It is also very important to remember that you are starving your attic of heat so your water tank and pipes that are over half way up the insulation need to be insulated and dont insulate under the tank unless it is raised over 300mm over the ceilling joists

    Can anyone verify this statement regarding insulating below raised tanks. I have a tank that I think is raised about 20 inches above the ceiling. It does not sit directly on the joists and it seems like a source of heat loss as it is also right beside the hatch door. I'll get exact measurements but is this regulation or just a practice. Thanks.


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