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Another Drylining question

  • 18-01-2013 9:56am
    #1
    mayoman1973
    Registered Users, Registered Users 2 Posts: 1,392 ✭✭✭


    We are about to start an extension + garage conversion and had a question as regards drylining. We will have 100mm inner, 150mm cavity and 100mm outer. I was looking to know how much kingspan can I or should I put on the inside of the external wall. I have never been one for you should/shouldn't do such and such without some explanation better than, "well that's the way it's usually done".
    I have read here that the thickness of insulation you can put on the inside is directly linked to the thickness you put in the cavity with the reason being if you put 100mm on the inside and 50mm in the cavity ( for example ) then the inner leafs temperature will drop to such a point as to allow for condensation. This would happen because you over insulated the wall. 100mm in the cavity and 50mm on the inside would avoid this problem.
    What I wanted to know was if you go with 50mm in the cavity and then fix 100mm directly to the inside wall with no studding then is it still possible for condensation to form. My understanding of condensation is if you have no air gap between your insulation sheets and the inner wall then there is no water vapor to condense on the brick surface behind the sheets


Comments

  • #2
    archtech
    Registered Users, Registered Users 2 Posts: 1,046 ✭✭✭archtech


    Read the Breaking the Mould Series of Articles they will provide guidance as to why putting insulation on the inside face of a concrete block is not the best idea. I would suggest you would be best to engage a professional to advise you on the best solution for your situation.


  • #3
    tred
    Registered Users, Registered Users 2 Posts: 1,473 ✭✭✭tred


    mayoman1973 wrote: »
    We are about to start an extension + garage conversion and had a question as regards drylining. We will have 100mm inner, 150mm cavity and 100mm outer. I was looking to know how much kingspan can I or should I put on the inside of the external wall. I have never been one for you should/shouldn't do such and such without some explanation better than, "well that's the way it's usually done".
    I have read here that the thickness of insulation you can put on the inside is directly linked to the thickness you put in the cavity with the reason being if you put 100mm on the inside and 50mm in the cavity ( for example ) then the inner leafs temperature will drop to such a point as to allow for condensation. This would happen because you over insulated the wall. 100mm in the cavity and 50mm on the inside would avoid this problem.
    What I wanted to know was if you go with 50mm in the cavity and then fix 100mm directly to the inside wall with no studding then is it still possible for condensation to form. My understanding of condensation is if you have no air gap between your insulation sheets and the inner wall then there is no water vapor to condense on the brick surface behind the sheets

    Whats your ventilation strategy in the new build??. A lot of the mold and dry ling problems I have being reading of late seem to relate more to houses build in estates in the 50's,60s', 70's equating less in build quality and technology's to modern day cow sheds. I suspect they'd be riddle with mould with or without drylining, If you have a well designed air tightness and ventilation strategy with "clean" air coming in, meaning you filters are clean and your getting the required constant air changes, then i have yet to see a case of an issue of mould behind dry-lining. Maybe someone has that case to show.


  • #4
    mayoman1973
    Registered Users, Registered Users 2 Posts: 1,392 ✭✭✭mayoman1973


    All existing walls are cavity walls witl the old polystyrene insulation against the inner leaf. I want to improve the insulating properties of this wall by adding as thick a sheet of kingspan as possible on the inside of the wall.
    The extension will have a 150mm cavity with 100mm against the inner leaf but again I want to add as thick a sheet as possible of Kingspan to the inside of this wall also. What I am trying to find out is should I be concerned with having too much insulation on the inner leaf and as such with no heat getting to the inner block work will it cause condensation. "archtech" had a good link there that seems to explain the issue in a way


  • #5
    tred
    Registered Users, Registered Users 2 Posts: 1,473 ✭✭✭tred


    mayoman1973 wrote: »
    All existing walls are cavity walls witl the old polystyrene insulation against the inner leaf. I want to improve the insulating properties of this wall by adding as thick a sheet of kingspan as possible on the inside of the wall.
    The extension will have a 150mm cavity with 100mm against the inner leaf but again I want to add as thick a sheet as possible of Kingspan to the inside of this wall also. What I am trying to find out is should I be concerned with having too much insulation on the inner leaf and as such with no heat getting to the inner block work will it cause condensation. "archtech" had a good link there that seems to explain the issue in a way

    this is why i mentioned ventilation strategy, and you should discuss this with your engineer, by ventilating properly, you are removing the condensate from the air.


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