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diminishing returns..

  • 22-07-2009 9:06am
    #1
    stylers
    Registered Users, Registered Users 2 Posts: 188 ✭✭


    Hi All,

    just wondering are wider cavities becoming the norm now for new one-off builds.. e.g. 140 mm and 100mm insulation, and are they actually being built this way ?. from my reading it seems to me like we are approaching a point where its getting impossible to get the overall U-values and efficiencies the new part L are looking for.. and thermal bridging and other problems are becoming the bigger factor. In a wall for example which has say 15% of its area occupied by the normal small windows nowadays, are the window details becoming more important than the insulation thickness ?. also, for actual construction are the longer wall ties and closer blocks more difficult to get ?


Comments

  • #2
    sydthebeat
    Subscribers Posts: 42,171 ✭✭✭✭sydthebeat


    stylers wrote: »
    Hi All,

    just wondering are wider cavities becoming the norm now for new one-off builds.. e.g. 140 mm and 100mm insulation, and are they actually being built this way ?. from my reading it seems to me like we are approaching a point where its getting impossible to get the overall U-values and efficiencies the new part L are looking for.. and thermal bridging and other problems are becoming the bigger factor. In a wall for example which has say 15% of its area occupied by the normal small windows nowadays, are the window details becoming more important than the insulation thickness ?. also, for actual construction are the longer wall ties and closer blocks more difficult to get ?

    your correct with a lot of what you are saying...

    as we get to very low u values, the impact thermal bridging has the performance greatly increases..... picture it like a dam, the insulation is the dam holding back the heat... the thermal bridges are pin pricks and gaps in the dam... the greater the pressure internally the faster the heat loss through the thermal bridges...

    wider cavities seem to be the way the industry has taken to adapt to the new tougher regulations. Folly, in my opinion, because the very same issues exist with a wider cavity as exists with a narrower one, actually these issues are exacerbated in wider cavities.... insulation is not held tight against the blockwork due to inadequate ties and workmanship... mortar snots, warped boards, broken t+g etc all are issues which result in the insulation boards not being perfectly connected to each other....


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