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Thickest double glazing unit?

  • 26-08-2022 2:20pm
    Registered Users Posts: 472 ✭✭

    Looking to replace a piece of double glazed glass and am trying to figure out the thickest double glazing plane I can get made up

    i.e. the great distance between the 2 pieces of glass. Also any suggestions on who might supply would be great


  • Registered Users Posts: 5,657 ✭✭✭10-10-20

    Glass at 4mm and between 6mm to 20mm of a gap, with 12mm being the average/norm, I believe.

    Ask a local glass company for supply-only.

  • Registered Users Posts: 751 ✭✭✭C. Eastwood

    The optimum cavity for reducing heat loss in windows is 20 mm cavity between the panes of glass. Any cavity less than this will increase the heat loss slightly, as it will increase the U value.

  • Registered Users Posts: 30,972 ✭✭✭✭Lumen

    For some time I've wondered why we don't have thicker glazing (i.e. more total interstitial gap). Is it harder to design the frames or what? I'd have thought at least with alu frames anything is possible.

    When I made my own timber triple glazed windows I went for 6/16/6/18/6 for a large fixed pane and 6/14/6/14/6 for a set of French doors that I wanted to be thinner (to make it easier to get the closing right).

    Not relevant for double, but for triple glazing you ideally want different sized gaps and glass thicknesses to reduce sound propagation.

    Glazing is really cheap compared to total window cost.

  • Registered Users Posts: 5,667 ✭✭✭The Continental Op

    iirc because 12mm was found to have the best thermal efficiency for its size big improvement over 6mm but 20mm seems to have been more of a sales thing so salesman could say our product is better than 12mm which it is but only marginally.

    Then the wider the gap the more complex the problems become with what gas you fill the gap with. Can't remember why but you need more expensive gas and not air for wider gaps and the more expensive gas tends to escape.

    Wake me up when it's all over.

  • Registered Users Posts: 30,972 ✭✭✭✭Lumen

    Ah yes.

    So with wider gap you get issues with circulating convected air (presumably this is less of an issue with narrower gap due to fluid friction, i.e. the opposing flows are coupled together).

    Argon is more dense and so circulates more slowly, so is popular with wider gaps, but tends to leak out eventually. I got mine argon filled and I don't remember it being prohibitively expensive).

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  • Registered Users Posts: 30,972 ✭✭✭✭Lumen

    @BigGeorge to your original question, you don't say where you are, but ...Wicklow?

    For a small glazing order delivery can make up a large part of the price, so get quotes incl. delivery before deciding. I'm in north Wicklow and got quotes from Diamond and FirstGlass. Not sure there is anything closer to you.

  • Registered Users Posts: 472 ✭✭BigGeorge

    thanks folks, am in Wicklow, will see who can do what, appreciate the advice

  • Registered Users Posts: 38,471 ✭✭✭✭Mellor

    You can get up to 80mm thick units. Or 150mm in non-insulated units (acoustic double glazed). Glass is not the limiting factor.

    The largest you can get depends on your existing frames. As you mentioned it's replacement.

  • Registered Users Posts: 5,667 ✭✭✭The Continental Op

    Anyone that supplies double glazing glass will be able to do 20mm one of the standard sizes.

    Wake me up when it's all over.