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Pumped cavity Insulation V's Drylining and cavity insulation

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  • 02-11-2009 6:23pm
    #1
    liamolaighin
    Registered Users Posts: 160 ✭✭


    It has been recommended to me that I increase my cavity to 6 inches and pump the cavity of my house rather than use normal insulation and dry lining on the inside. What do people think of this?

    How would both options compare in terms of U-value?

    Also I've been told that by doing this i'll save 3,000-4,000 in materials and almost achieve the same u-value and to use this saving against the cost of a heat pump. How would pumped cavity stand up against normal cavity + drylining of external walls price wise?
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    #2
    mark2003
    Registered Users Posts: 59 ✭✭mark2003


    liamolaighin wrote: »
    It has been recommended to me that I increase my cavity to 6 inches and pump the cavity of my house rather than use normal insulation and dry lining on the inside. What do people think of this?

    How would both options compare in terms of U-value?

    Also I've been told that by doing this i'll save 3,000-4,000 in materials and almost achieve the same u-value and to use this saving against the cost of a heat pump. How would pumped cavity stand up against normal cavity + drylining of external walls price wise?

    They are both going to achieve the same u-value,i went for the cavity wall insulation and dry lining on the inside because its tried and trusted and the 6" pumped insulation is relative new.Nobody will have a definite answer for which is best


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    #3
    No6
    Registered Users Posts: 2,489 ✭✭✭No6


    They are not the same, off the top of my head I believe cavities over 120mm require engineered walltie solutions (ie bigger steel sections therefore with increased repeat thermal bridging) Pumped bead insulation is not as good as a polyiso board insulation, I have done calcs using both and have found that a 110mm cavity is required to achieve complaince with the pumped insulation where as a 100mm cavity with 60mm standard board achieves the same. Drylining internally if done correctly, sealing all joints etc will improve airtightness and reduce thermal bridging and can work very well. One way some people have found to reduce the cost is to pump the standard 100mm cavity and dryline using perhaps a slightly thicker board. You should get dew point calcuations done for this though to ensure there is no interstital condensation causing mould behing the drylining. Your architect or a good BER asssessor could advise you further.
    As for price pumped is a lot cheaper but i think you will negate any savings when using the wider cavity and heavier ties and if you get it wrong will pay through the nose on the running costs of the heat pump.


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    #4
    liamolaighin
    Registered Users Posts: 160 ✭✭liamolaighin


    Does the dry lining of the walls on the inside not have the effect of negating the use of these same walls as a thermal store. The reason i ask is that I am totally unsure of what heating system to use also. Want to spend money on insulation and airtightness without going mad either. Are chimney balloons a really effective way of making chimneys airtight or a complete fad???


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