I have old double hung windows with 6 panes per section. Can I remove dividers and replace them with a single piece of glass, then install a cosmetic dividers?

Glass was 1/8". Opening approx 24" * 24". Window is painted. Can't seem to add a picture.

closed as too broad by isherwood, ThreePhaseEel, Daniel Griscom, The Evil Greebo, Machavity Jul 9 '18 at 23:15

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  • 2
    Yes. Yes you can. Did you have a more specific question? – isherwood Jul 5 '18 at 19:49
  • If you're going to replace them with a single pane with cosmetic dividers, why not get double or triple pane glass with embedded dividers? – The Evil Greebo Jul 5 '18 at 19:51

No, you cannot remove the wood “dividers” (mullions) and install a single pane, because 1) mullions will leave a gap at sash, 2) “stop” will have gap at sash that will leak, 3) thickness of glass may need to be changed, 4) energy code requires thermal pane windows, 5) glass may need to be tempered.

1) Those mullions are part of the sash. That is to say, the sash has a built-in reveal (at the perimeter of the sash) that creates one side of the stop. When the interior mullions are removed, you can’t just cut them off without leaving a gap. Trying to infill that gap to blend with the existing reveal will be impossible.

2) The “stop” (probably on the exterior side of the window) will leave a gap where the mullions are removed. You’ll need new stops around the entire perimeter of the sash.

3) Your glass is probably 1/8” thick float glass. That’s fine for small panes, but a larger glass opening will require thicker glass...probably 3/16” ...maybe 1/4”, depending where you live (wind loading requirements,etc.)

4) I don’t know where single pane glass is allowed. The energy code will require you to upgrade to double pane. This additional thickness will require a new sash.

5) If your window is within 18” of the floor or within 12” of a door, you’ll need tempered glass. This additional thickness will not fit in the existing glass thickness space.

If your sash has lead weights, they will need to be adjusted for the heavier glass load.

IMHO I think it would be cheaper and better to replace the entire sash.

  • 2
    So many no's. A person could quite easily cut out the original stops (even integrated ones) and apply new stops to both faces. This eliminates the glass thickness concerns, too. Code? Nah. Does not apply (though energy efficiency is worth considering). And the need for tempered glass isn't prohibitive. I have to wonder if you ever do any projects around your home or just spend massive amounts of time thinking up elaborate reasons why you shouldn't. :P – isherwood Jul 5 '18 at 21:11
  • @isherwood Ouch...if I don’t agree with you, you attack my character? You need to apologize. – Lee Sam Jul 5 '18 at 21:30
  • @isherwood So you’re going to cut the inside stop off, including the “weather notch” and then install two “applied” stops and expect it not to leak? No amount of caulk, glazing tape, etc. can keep the rain out. That’s why the weather notch was invented. Also, are you going to ignore the other issues, (i.e.: wind loading on larger piece of glass, energy requirement, etc.) – Lee Sam Jul 6 '18 at 19:07
  • The point is that we can't know exactly what the right solution is without more information. I assume that there is a way to accomplish something until I know otherwise. It's a waste of our time to speculate at great length with the almost nothing we know. – isherwood Jul 6 '18 at 19:36
  • And obviously there are ways to prevent leaks in wooden joints or virtually everything would leak, including the interface with the glass. The sky is not falling. – isherwood Jul 6 '18 at 19:38

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