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sealed unit size - Green Building Forum


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sealed unit size

Hi All,
I am about to make a four pane mono pitch roof light, can any one tell me what is the best cavity for the sealed units. I am thinking that 16mm with Argon with Pilkington K on the outside pane is the minimum I should be looking at, but would like any input from any one with experience of this. For safety should the inner pane be toughen or laminated?
thanks in advance


  • edited November 2014
    You can experiment with the parameters here, bearing in mind what is 'best' depends upon what your priorities are (pay attention to the weight/m2) as well:
  • Laminated or toughened probably worth it in case of free-fall pigeons.

    Unless they have changed it, I believe Pilk K is a hard-coat Low E coating. I tend to suggest a soft-coat such as Planitherm. The coating is normally on the outside of the inner pane, not on the outer pane.
  • May as well go 3g, I would go 4 toughened on the outside and inside with 4.6 laminated in between, make it up as one thing with dividers in the right places, it will be heavy though, crucially the top glass over sails by 50mm at the bottom to protect the unit. Glue on glazing bars later.

    So 4:16:4.6:16:4 with gas and coatings.if your four panes are large beware of Freznel fringes.
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