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External insulation, cavity block walls

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  • 08-01-2013 12:24pm
    #1
    isup
    Registered Users Posts: 649 ✭✭✭


    i 've been strongly thinking of getting external insulation in my 70's semi-d.
    the walls are cavity block. ive been trying to understand the ins and outs of it all.
    my main worrys are heat loss on the gable wall where it meets the attic and the roof, also the house has some flat roof on the rear and on the front,

    id like to know if this can be attchieved or should i opt for the cheaper internal option , thanks if anyone has any imput

    http://photos.myhome.ie/media/6/2/3/1243326/22c86982-1_m.jpg
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    #2
    archtech
    Registered Users Posts: 1,046 ✭✭✭archtech


    External wall insulation(EWI) is by far the best solution currently available to you, in that you will reduce condensation risks and thermal bridging and also it won't reduce the floor area of your dwelling.

    What I would recommend is that you engage a professional examine the dwelling and prepare details and solutions for any critical junctions, as leaving it up to the EWI may not resolve all the issues for you.


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    #3
    isup
    Registered Users Posts: 649 ✭✭✭isup


    archtech wrote: »
    External wall insulation(EWI) is by far the best solution currently available to you, in that you will reduce condensation risks and thermal bridging and also it won't reduce the floor area of your dwelling.

    What I would recommend is that you engage a professional examine the dwelling and prepare details and solutions for any critical junctions, as leaving it up to the EWI may not resolve all the issues for you.

    I will do that. Its just a little bit down the line with otherwork to be done to get it ready. I was just looking for an opinion on the issue. Cheers


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    #4
    Seraphim1
    Closed Accounts Posts: 17 ✭Seraphim1


    I would suggest that the cavity blocks need to be sealed along Downstairs ceiling line and at upstairs ceiling line to prevent heat from escaping out into cavity, blocked by EWI and forced into top of gable and out of roof. This would not be an issue with solid walls. Walls without gables would probably be ok as wall plate will act as a barrier ?


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    #5
    isup
    Registered Users Posts: 649 ✭✭✭isup


    thanks ive seen that stuff they spray into the cavity blocks, im still just thinking the gable wall is a hopless cause to externally insulate


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    #6
    Seraphim1
    Closed Accounts Posts: 17 ✭Seraphim1


    EWI fitted to your external walls, gable or not, will provide a good insulation. My thoughts are that unless you somehow seal the top of a hollow block (cavity block) wall the heat will escape In to the cavity and out the top. If you can seal it off you will not lose heat. I don't think a full cavity fill is the answer (it is not possible to fill a cavity block wall) but rather a seal along the wall at ceiling levels. One possible method is to drill a series of holes externally along the ceiling line and fill with expanding foam but I don't know anyone that does this as normally part of a EWI job. gable walls especially are susceptible to this heat loss as other walls may have a wall plate, u beam etc to seal off cavity and mitigate losses.


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    #7
    isup
    Registered Users Posts: 649 ✭✭✭isup


    i will try and go for this if its affordable to me, cavity blocks really are a joke to insulate, im trying my best not to internally insulate because of condensation/mould and loss of space
    Seraphim1 wrote: »
    EWI fitted to your external walls, gable or not, will provide a good insulation. My thoughts are that unless you somehow seal the top of a hollow block (cavity block) wall the heat will escape In to the cavity and out the top. If you can seal it off you will not lose heat. I don't think a full cavity fill is the answer (it is not possible to fill a cavity block wall) but rather a seal along the wall at ceiling levels. One possible method is to drill a series of holes externally along the ceiling line and fill with expanding foam but I don't know anyone that does this as normally part of a EWI job. gable walls especially are susceptible to this heat loss as other walls may have a wall plate, u beam etc to seal off cavity and mitigate losses.


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