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  • 18-03-2009 11:46pm
    #1
    Registered Users Posts: 314 ✭✭


    Hi guys,

    Doing a rating on this house attached,
    Can you see the tiled facade above the two front windows? It is basically a timber frame, with plastrboard internally, with the concrete tiles covering outside. Ive never done this before, and just want confirmation on what i should do here. Because the house is existing DEAP is giving me default u-values for the walls. I can work out the area of these tiled sections no problem, my question is should i try to calculate a more realistic u-value for these sections, i.e a timber frame wall, and adjust the value by finding out the thermal resistance of the concrete tiles or is that over the top for an existing house??
    Appreciate any advice.
    3366663936_9f3b09284d.jpg


Comments

  • Subscribers Posts: 41,586 ✭✭✭✭sydthebeat


    only work out a specific u value IF you can confirm what the construction make-up is.... and what the thickness of each material is, and what resistance each material has, including all thermal bridges....

    can you do this without doing an invasive survey.???


  • Registered Users Posts: 2,489 ✭✭✭No6


    Use defaults only unless you actually have substantive proof of the specific build up.


  • Registered Users Posts: 314 ✭✭burly


    Thanks for the reply guys,

    The answer is i cant be 100% confident of the thickness of the timber frame behind the tiles.
    (From my own experience i have seen this kind of construction done before, and i know that it is usually a frame made of 3"x2" studs, with battens running across the studs and the tiles nailed onto the battens.)
    But i cannot completely guarantee that this is the case here. I also cannot guarantee that insulation was placed within this timber frame behind the tiles.
    My gut feeling is that this section of the facade will have a higher u-value than the DEAP default, which is why im concerned about taking the defaults, which might give the dwelling a higher rating than it actually is.

    Am i being too scientific about all this?????!!!!!!!!!


  • Registered Users Posts: 2,489 ✭✭✭No6


    Without written or visual proof you cannot do a U value calculation and put the result in instead of the default. Use the default and move on your experience is not proof, theres nothing you can do, unless you have a hammer!!!:D


  • Registered Users Posts: 314 ✭✭burly


    No6 wrote: »
    Without written or visual proof you cannot do a U value calculation and put the result in instead of the default. Use the default and move on your experience is not proof, theres nothing you can do, unless you have a hammer!!!:D

    Thanks for that, think il leave the hammer in the toolbox, and use the defaults. They really should expand the DEAP software to take into account things like this. It would make the whole process a lot easier!!

    Thanks guys


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  • Subscribers Posts: 41,586 ✭✭✭✭sydthebeat


    burly wrote: »
    Thanks for that, think il leave the hammer in the toolbox, and use the defaults. They really should expand the DEAP software to take into account things like this. It would make the whole process a lot easier!!

    Thanks guys

    just work out the area of the TF wall and enter it as a TF wall in DEAP.... the age band will automatically generate a u value. In general TF u values are better than masonry as you go back in age...


  • Registered Users Posts: 314 ✭✭burly


    sydthebeat wrote: »
    just work out the area of the TF wall and enter it as a TF wall in DEAP.... the age band will automatically generate a u value. In general TF u values are better than masonry as you go back in age...

    Yeh but the problem with that is, when i select TF as the wall type, will DEAP not assume there is insulation there?? And i cant guarantee that there is!!!


  • Subscribers Posts: 41,586 ✭✭✭✭sydthebeat


    burly wrote: »
    Yeh but the problem with that is, when i select TF as the wall type, will DEAP not assume there is insulation there?? And i cant guarantee that there is!!!

    no it wont, it will assume a u value...

    similarly if you input that the wall is a cavity wall, the default will simply give it a u value based on construction at that time....


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