How To - Installed an insulated glass unit on existing window. Please help

[MrSal]

Good morning everyone,

Needing a little bit of help regarding this.

We have in our house a big old bay window built out of what looks like 2x4s in a grid fashion and with old glass. The window has always been fine and we never though of replacing it especially because we never saw the need for it in terms of improvement and ROI. We have storm windows on the outside so it's always been ok regarding cold - prbably not as good as triple pane windows but good enough that wouldn't justify the investment for changing it. The window is a 3x4 windows measuring about 90-+ inches wide and 55 or so high. Each square is 21 inches wide by 17 wide.

However one of our storm windows broke and it's been condensing a lot to the point water pools at the bottom of that grid.

When looking for prices regarding a new storm window it was pretty much the same price of a custom built IGU unit, so I went for an IGU thinking of just putting in place in the cavity.

Now this is where I have some doubts and here are some pictures to help visualize it:












The detail pictures of the grid you can probably see the outer storm window. It seems that the current glass pane is missing silicone on the edges as well.

My idea was doing the following:

But a 3/4' wood to work as a spacer and frame it around the perimeter of the current glass. Put some silicone between such wood spacer and current glass pane.

Then, place the new IGU against the wood spacer also with some sort of sealant on the edges.

To finalize everything, again, frame a 3/4 or some other sort of frame to act as a stoper/block. I would be using glass setting blocks at the bottom as well.

In essence this would make it a triple pane window? and in the grids that still have the storm window it would be a rudimentary quadruple pane window. Or is it better to just break the fixed window pane and put the IGU in place alone?

Would this method be okay? Any other methods that would be more proper? Do i need glazing tape at all or is some type of window clear silicone ok?

Im a big fan of do it once and do it right and I am a perfectionist so don't be afraid to tell me what the correct way is. I'm not afraid of DIY.

Thank you

EDIT: I added some annotations on picture #2

[MrSal]

C'mon... someone has got to have a bit of an idea :)

[big_owl]

I've read your post 3 or 4 times and I still can't really figure out what you're trying to do.  Maybe others are having the same problem?  Are you trying to home make insulated glass windows?   If yes then I think the result will not be so nice wihlthout insulating gas sealed between them.  Usually haze and fog develop.  The "do it once do it right" method would probably turn out the best if you just bought a new double or triple pane window.

I just stroked a $90k check to replace all the shitty builder grade windows in my house.  It was tough but the result is night and day. 

[MrSal]

No I'm not. I bought the unit panels already. I bought 12x insulated glass units - picture 4 and 5. These were manufactured from an actual window company.
Now, my window has nothing wrong with it and I was thinking of just installing these behind the single plane glass already in place by just building a spacer around the old plane glass and then putting the new unit behind it.

I was wondering if this could be done and in essence having a triple window, or if I need to remove the single pane entirely and just have the new double pane window

[bacchi]

I'm dubious of this idea. Have you ever seen a leaky double-pane window? Moisture gets in between the panes and condenses.

[MrSal]

?? I didn't build the double pane. The double pane is completely manufactured at the shop/factory where double pane windows are made. This is a IGU (insulated glass unit) just as when you break your double pane window you can buy just the panel.

So in your opinion, it's best to remove the original single pane glass and just put the new double pane by itself is that correct?

[big_owl]

No I'm not. I bought the unit panels already. I bought 12x insulated glass units - picture 4 and 5. These were manufactured from an actual window company.
Now, my window has nothing wrong with it and I was thinking of just installing these behind the single plane glass already in place by just building a spacer around the old plane glass and then putting the new unit behind it.

I was wondering if this could be done and in essence having a triple window, or if I need to remove the single pane entirely and just have the new double pane window

Ah so you're trying to install an insulated double pane behind a single pain.  The problem is going to be the new non-sealed airspace between the single pane and the double pane.  You are effectively trying to install 12 windows in this manner. Some will invariably condense and/or fog.  Seeing as you have wood frames then they will eventually start to rot.  Whether you can put up with hazy windows is up to you but condensation is a non-starter.  Just haze is enough to drive me nuts.

Tear out out the single pane and replace with the double pane units.  Future you will thank yourself. 

[Abe]

Agree with taking out the existing windows. The insulation benefit is minimal and you’ll get condensation for certain.

[MrSal]

Even if I use sealants on single pane and stoppers with sealant?

My idea was to build a frame around the single pane with sealant and silicone and put the igu against it with sealant again... Would this still cause condensation? I guess the air needs to be dehydrated when enclosing between panes right?

Thanks

[Lulee]

I'm guessing but based on the comments so far, it seems no one can think of a way, even with your talents, to remove and keep moisture out from between the IGU and current window structure in any long term way.

I tried something similar to your plan in a previous apartment where each winter I used the shrink sheets of plastic which did, if I was careful, give me a very good air seal from the inside of the house.  I had issues the first year with either the moisture I trapped against the windows or moisture leaking in from the windows causing fogging, mold, and icing/puddling issues.  So I saved up desiccant packs from pill bottles and placed those inside plastic bottle tops by the windows before I sealed them up one winter (from experience, I knew not to let the packs sit on anything that could rust or rot so the moisture they sucked up wouldn't cause harm).  My experience was middling at best but it was a worth trying.

You could try something similar but I suspect that in a year or two, you'll also find moisture penetration wins out over your sealing efforts and any desiccant/other remediation you try.

[big_owl]

Even if I use sealants on single pane and stoppers with sealant?

My idea was to build a frame around the single pane with sealant and silicone and put the igu against it with sealant again... Would this still cause condensation? I guess the air needs to be dehydrated when enclosing between panes right?

Thanks

The problem is that try as you might, you're never going to be able to get the thing airtight.  Your wood frame has moisture in it, wood isn't airtight, it expands and contracts with the seasons breaking whatever caulk seal you've made, and humidity from the summer will condense in the winter, etc.

I don't see where removing the single pane glass and just replacing with your IGUs should be that expensive vs. what you are proposing. Plus it'll probably look better. Only having to look out through two panes of glass vs three.

[MrSal]

Even if I use sealants on single pane and stoppers with sealant?

My idea was to build a frame around the single pane with sealant and silicone and put the igu against it with sealant again... Would this still cause condensation? I guess the air needs to be dehydrated when enclosing between panes right?

Thanks

The problem is that try as you might, you're never going to be able to get the thing airtight.  Your wood frame has moisture in it, wood isn't airtight, it expands and contracts with the seasons breaking whatever caulk seal you've made, and humidity from the summer will condense in the winter, etc.

I don't see where removing the single pane glass and just replacing with your IGUs should be that expensive vs. what you are proposing. Plus it'll probably look better. Only having to look out through two panes of glass vs three.

Nop it wasn't a thing of being more expensive... Either way I would have to buy the molding in order to build the frame out. It was just a matter of less labor and thinking that it would be more efficient.. But since it has a lot of cons, I'll go the way of removing the older panes. It shouldn't be that difficult to be honest. Well see how it goes

Thanks for everyone's input and happy holidays

[Jon Bon]

I just stroked a $90k check to replace all the shitty builder grade windows in my house.  It was tough but the result is night and day.

What the? Were the windows made of gold or was that just a typo? Even 9k is very high for windows.

And op, if I understand your queation my guess is the efficiency gain by putting in triple paine glass would not be worth it. Remove the old glass and put in your fancy double paine glass pannel.

[Blue82]

I just stroked a $90k check to replace all the shitty builder grade windows in my house.  It was tough but the result is night and day.

What the? Were the windows made of gold or was that just a typo? Even 9k is very high for windows.

And op, if I understand your queation my guess is the efficiency gain by putting in triple paine glass would not be worth it. Remove the old glass and put in your fancy double paine glass pannel.

While I agree, $90K is on the higher end, it's not unheard of in FL to get that high if you're buying specific kinds of windows or have a large number of them.  Hurricane glass, turtle glass, hurricane sliding glass doors... all these things get pretty pricey even if doing the install yourself.

[big_owl]

I just stroked a $90k check to replace all the shitty builder grade windows in my house.  It was tough but the result is night and day.

What the? Were the windows made of gold or was that just a typo? Even 9k is very high for windows.

And op, if I understand your queation my guess is the efficiency gain by putting in triple paine glass would not be worth it. Remove the old glass and put in your fancy double paine glass pannel.

No it's not a typo.  Just middle of the road Pella windows, nothing too fancy.  It was for something like 55 windows, installed.  If you can get that many windows for 9k then you must be using plexiglass or saran wrap for the pane.

[MrSal]

Was able to do this today... It was easy. And it looks good as well.

No more condensation now. Will post pics

[MrSal]

updating with pictures:










All needed now is to caulk the wood stopper/frame I made so it looks more finished and wait for the caulk that I used on the panel to cure and trim the oozed excess, then paint the trim!

I used finishing screws to I can easily remove the frame if needed for some reason in the future.

Super quick! And also great savings... the 12 panels cost in total around $500 shipped to my door for an 8x5 foot window. I can't even imagine how much a window company would charge for a new double pane window.

Condensation issues completely gone. I still had space in front to keep the old storm windows, so I put them in as well - even though 1 window is still missing one since it was broken. So I have 11 panels that are in essence "triple" and 1 panel being double.